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The official blog of ornithology journals The Auk and The Condor
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Scientists Remind Their Peers: Female Birds Sing, Too

Thu, 03/15/2018 - 10:08

Northern Cardinals are among the familiar North American bird species in which females sing in addition to males.

When North American ornithologists hear a bird singing, they’re likely to assume it’s a male. But in many species, the females sing too—and a new commentary in The Auk: Ornithological Advances argues that a better understanding of these unappreciated female songs could lead to advances in many aspects of bird biology.

Authors Karan Odom of Cornell University and Lauryn Benedict of the University of Northern Colorado both discovered the world of female birdsong through their own research. “I started studying California towhees 17 years ago, and I was fascinated by the duet vocalization given by females and males,” says Benedict. “That led me to start looking for female song in other North American bird species, and I was surprised to learn that it was much more common than I expected. The reports of female song are buried in odd corners of the literature, but when you put them all together, you start to see some interesting patterns.”

Though singing females were likely the norm among the ancestors of today’s songbirds, female song today is understudied and is underrepresented in collections of bird sound recordings. This, say Odom and Benedict, may be result of bias toward the world’s temperate regions—though more widespread in temperate species than many ornithologists appreciate, female song is most common among tropical birds. They argue that better documentation of which species female song is present in and more detailed descriptions of female song structure and output could improve our understanding of birds’ comparative physiology, neurobiology, behavioral ecology, evolution, and even conservation. Birds of conservation concern are often located and identified by song during surveys, and assumptions that all singing birds are male could mislead wildlife managers about the state of populations.

Odom and Benedict urge their fellow ornithologists to spread the word that female birds sing, to share resources, and to disseminate their findings. You don’t need to be a professional ornithologist in order to help expand our knowledge of female song, either—Odom has created a website where any birdwatcher can upload their observations. “If you hear a bird singing, do not assume it’s a male,” she says. “If you observe a female bird singing, document it by uploading field notes, audio, or video to the collections on our website, Make sure to indicate how you recognized the bird was female.”

“Odom and Benedict have written an excellent appeal to document and record more female bird song,” adds Leiden University’s Katharina Riebel, a former collaborator of Odom’s. “They rightly point out that the extent of female bird song has been starkly underestimated, as almost by default we assume that a singing bird must be the male of the species. As a consequence, we might have missed out many aspects and the dynamics of male and female vocal signaling in songbirds—clearly, there is still lots to discover! I am confident that ornithologists in the field can make substantial contributions toward these questions by sharing their observations and recordings, as I very much hope this article will encourage them to do.”

A call to document female bird songs: Applications for diverse fields is available at

About the journal: The Auk: Ornithological Advances is a peer-reviewed, international journal of ornithology that began in 1884 as the official publication of the American Ornithologists’ Union, which merged with the Cooper Ornithological Society in 2016 to become the American Ornithological Society. In 2009, The Auk was honored as one of the 100 most influential journals of biology and medicine over the past 100 years.

AUTHOR BLOG: Recognizing the Importance of Female Birdsong

Thu, 03/15/2018 - 10:08

Karan Odom & Lauryn Benedict

Linked paper: A call to document female bird songs: Applications for diverse fields by K.J. Odom and L. Benedict, The Auk: Ornithological Advances 135:2, April 2018.

House Wrens are among the familiar birds in which females sing. Photo credit: J. Hudgins/USFWS

Can you name ten North American or European bird species in which females sing? Can you name twenty? Fifty? That may seem like a lot, but in fact it’s only a small percentage of temperate-zone bird species with female song. There are at least 144 North American passerine species with female song, and many more non-passerines with elaborate vocalizations that could be classified as song (defining “song” is a topic we won’t even go into here!). Across all avian species, approximately 64% have female song, but these estimates are rough. The true numbers could be much higher. Why are the estimates so rough? Because documentation and reports of female song are lacking. We highlight this problem in our paper “A call to document female bird songs: Applications for diverse fields.” We ask all of you to help us address the deficit.

We know that the data are out there; we regularly have conversations with ornithologists and citizen scientists who tell us that they have observed singing females in myriad species. Our response: Publish it! Archive it! We’ve chatted with many senior researchers who have years of data including observations and recordings of female song in their study populations, but who haven’t published these data because female song is rare or is not their main research focus. We’ve also heard from students working as field assistants whose cohorts regularly observe singing females, but those observations are seldom documented. On field projects with many technicians, word-of-mouth data can be extensive and highly informative, but staff turnover means that known population traits never get put down on paper (or audio).

Citizen scientists frequently tell us about singing females, and many of them have taken the next step to document their observations through The Female Bird Song Project. Contributors have recorded female song in species as diverse as the Mexican Sheartail (Doricha eliza), Black-goggled Tanager (Trichothraupis melanops), Saffron Finch (Sicalis flaveola), and Cerulean Warbler (Setophaga cerulea), all of which seem to be the first documentation of female song in their species!

Each of these contributions plays a role in understanding the distribution of species with female song – data that researchers can use to address a wide range of biological questions. A complete picture of when and how female birds sing will offer insights into the biological mechanisms, evolution, and applications of avian vocal signals. Neurobiologists can ask how bird brains perceive and produce these variable signals, and whether that differs by sex. Evolutionary ecologists can ask why songs differ among species with different ecology and life-history traits. Conservation biologists can use songs to census and monitor the presence of males and females across populations.

What can you do? Don’t assume that a singing bird is a male. Look, listen, and document without bias. Teach your students to do the same. In 73% of all bird species we lack enough published information to even determine whether females sing. We are confident, however, that in some of those species females do sing because we have talked to colleagues about them. Common knowledge suggests that female song is rare, but our experiences make us question that: if all ornithologists talked to each other about female song the way that they talk to us, then that assumption would change. Your random observations of a female warbler singing can probably be backed up by the observations of many others. Females of temperate-breeding species may not sing as often as males, but when we pool all our knowledge and observations it’s likely that we’ll find more parity than we expect.

AUTHOR BLOG: Latitudinal Gradients in Bird Survival

Tue, 03/13/2018 - 16:25

Gonçalo Ferraz

Linked paper: Age effects on survival of Amazon forest birds and the latitudinal gradient in bird survival by A.P. Muñoz, M. Kéry, P.V. Martins, and G. Ferraz, The Auk: Ornithological Advances 135:2, April 2018.

A Guianan Warbling Antbird, Hypocnemis cantator, banded and ready for release. Photo credit: E. Johnson

Bold, recurring patterns are fascinating, and more so if they are unexplained. For biologists living in the tropics, perhaps the most striking examples are the various latitudinal gradients in community and life history metrics. Science excites our curiosity in the search for universal rules, but large-scale latitudinal patterns hint that some things may be fundamentally different in different parts of the world. Could there be really such a thing as “tropical biology”?

One of the best-documented of these latitudinal gradients is the tendency for avian clutch size to increase with increasing latitude. Since there is no evidence that high-latitude populations grow faster than equatorial ones, it’s been widely assumed that some other life history trait must also change with latitude to compensate for the variation in clutch size. Thus, throughout the second half of the 20th century, the idea that adult tropical birds live longer than their temperate counterparts became widely accepted among ornithologists.

A Rufous-throated Antbird, Gymnopithys rufigula. Photo credit: E. Johnson

The acceptance of a latitudinal gradient in survival, however, was more based on common sense than hard data—so much so that when Karr et al. (1990, The American Naturalist 136: 277-291) challenged the idea in a paper subtitled “Will the dogma survive?” there were not many voices sounding in defense of the “dogma.” Indeed, two decades later, Corey Tarwater and colleagues suggested that, if there is no latitudinal trend in the survival of adult birds, there could be a trend in the survival of juveniles (2011, Ecology 92: 1271-1281). Their work drew on detailed analysis of age-dependent survival in one Central American passerine species and proposed that tropical juveniles survive more than temperate juveniles. If adult survival shows no relationship with latitude this implies relatively little difference between adult and juvenile survival in the tropics.

For a paper just published in The Auk, Alejandra P. Muñoz, myself, and our colleagues used bird banding data to tackle the problem of the latitudinal gradient in bird survival on two fronts. First, we quantified the effect of age on survival for forty species of Amazon forest passerines, showing that adults at our tropical site had substantially higher survival probabilities than juveniles. Second, we compared our adult survival estimates with estimates from 175 species from Peru to Alaska and found that survival does decrease with increasing latitude. This latitudinal effect persists even after accounting for effects of migration mode, phylogeny, and time of data collection, and we conclude that the latitudinal gradient in survival is a fact after all, at least as seen among New World forest passerines.

Our work benefited a great deal from two recent advances. First, there is an ongoing transformation in how tropical ornithologists assess bird age. The Wolfe-Ryder-Pyle molt-cycle system, which we employed, is extremely useful for aging birds in populations that have poorly delimited breeding periods, which is typical of tropical regions. This was central for quantifying the effect of age on survival. Second, we tapped into the phenomenal database of Vital Rates of North American Birds made available by the Institute of Bird Populations (IBP), enabling us to include data from as far north as Alaska. The IBP estimates, combined with a wealth of tropical passerine survival estimates published since 1990, made it possible to take up Karr et al.’s (1990) challenge anew.

From the analytical perspective, we used a multi-species Cormack-Jolly-Seber (CJS) approach, a standard method for estimating apparent survival from capture-recapture data on open populations, to model our Amazon data. We treated each of the forty species in our dataset as a random draw from a wider distribution of species, and the inference about age effects was made at the level of this wider distribution, strengthening the generality of the conclusions. The CJS accounts for the possibility of capture failure, and a “mixture” component of the model, developed by co-author Marc Kéry, makes it possible to incorporate birds of unknown age in the analysis. Our work thus addresses a variety of sources of uncertainty before reaching its final conclusions.

The observation of a latitudinal trend in survival probability helps explain the maintenance of a latitudinal trend in clutch size, but it need not be the only explanation. It’s also possible, for example, that the number of clutches laid each year also varies with latitude in association with the length of the breeding season. With or without latitudinal change in number of clutches, one cannot tell whether the variation in survival we documented is a sufficient explanation for the current variation in clutch size. What’s more, even if one explains the maintenance of current variation, there is still the question of how that variation evolved. There is certainly still much to explore in the latitudinal variation of bird life history traits.

Long Incubation Times May Defend Birds Against Parasites

Wed, 02/21/2018 - 12:12

Some tropical birds have longer egg incubation times than their temperate cousins, even though their habitat is teeming with egg-eating predators. The reason why has long been a mystery, but a new study from The Auk: Ornithological Advances applies new methods to confirm the evidence for an old hypothesis—that a longer development period leads to a stronger, more efficient immune system.

The University of Missouri-St. Louis’s Robert Ricklefs first studied this relationship in the early 1990s, using data from microscopic examination of avian blood samples for the presence of parasites, primarily those that cause malaria. He found that the longer a species’ incubation period, the lower its prevalence of parasites. However, Ricklefs remained concerned that especially low parasite loads could have been missed during microscope examination, affecting parasite prevalence estimates.

Advances in DNA sequencing offered a new solution. For their new study, Ricklefs and his colleagues collected blood samples from birds in the eastern U.S. and several Neotropical countries and checked for the presence of parasite DNA, tabulating how many individuals from various families of birds were sampled at each site and how many were infected with Haemoproteus or Plasmodium parasites. About 22% of individual birds in both temperate and tropical regions had parasite DNA in their blood. While incubation time varies little among temperate species, it does vary among tropical species, and in tropical birds parasite prevalence was significantly lower in species with longer incubation times.

These results confirm those of the old blood smear analysis. While there is still no direct evidence for the hypothesis that a longer incubation time promotes a stronger immune system, this correlation provides a strong hint that this could indeed be the solution to the mystery of why the embryos of some tropical birds take so long to develop. “My interest in blood parasites was stimulated by a former graduate student, Victor Apanius, primarily in the context of community ecology. However, I had been working on the diversification of avian life histories, particularly embryo and chick growth rates, and I couldn’t help but notice a connection between the two,” says Ricklefs. “I wasn’t surprised that the new results confirm the old ones so well, really, because the two techniques estimate the same attribute. However, more detailed studies of the avian immune response and how variation in host defense is related to development certainly are warranted.”

“This paper is a nice follow up the 1992 study that showed an inverse relationship between parasite prevalence and egg incubation period. Since that time, PCR methods have been developed that detect more infections than microscopy, and the work is important because it verifies the previous results with revised methods,” according to San Francisco State University’s Ravinder Sehgal, an expert on avian blood parasites who was not involved in the study. “Moreover, it renews interest in a phenomenon that has gone largely unexplored. It will be now be important to test the work in an experimental system, to study the parasitology and explore the tradeoffs between embryo growth rate and immune function.”

Duration of embryo development and the prevalence of haematozoan blood parasites in birds is available at

About the journal: The Auk: Ornithological Advances is a peer-reviewed, international journal of ornithology that began in 1884 as the official publication of the American Ornithologists’ Union, which merged with the Cooper Ornithological Society in 2016 to become the American Ornithological Society. In 2009, The Auk was honored as one of the 100 most influential journals of biology and medicine over the past 100 years.

Are Flamingos Returning to Florida?

Wed, 02/21/2018 - 12:10

American Flamingos should be considered native to Florida, argue the authors of a new review. Photo credit: J. Patterson

Flamingos are a Florida cultural icon, and sightings of American Flamingos in the state have been on the rise in recent decades. However, whether they’re truly native to the U.S. or only arrive via escape from captivity has long been subject to debate, making developing a plan for managing Florida’s flamingo population challenging. A new study from The Condor: Ornithological Applications reviews the evidence and provides a fresh argument that the birds should be considered part of the Sunshine State’s native fauna.

Zoo Miami’s Steven Whitfield, along with colleagues from Audubon Florida’s Everglades Science Center, the National Park Service, Big Cypress National Preserve, and the Rookery Bay Estuarine Research Reserve, reexamined the historical evidence of flamingos in Florida and evaluated the likely origins of birds seen in recent years. Overall, they conclude, the evidence from both narrative accounts and museum records suggests that American Flamingos once occurred naturally in large flocks in Florida and probably even nested there before being eliminated by hunting around 1900. From 1950 to the present, however, birdwatchers have reported almost 500 new observations of flamingos in Florida, with both flock size and the frequency of observations increasing over time. While it’s plausible that some of these individuals could be escapees from captive flocks, there is also strong evidence for dispersal from wild populations in Mexico and the Caribbean.

The population history Whitfield and his coauthors describe is consistent with that of some native species already protected by state and federal endangered species laws, and they hope that their study will lead to a better plan for managing wild flamingos in Florida. “Living in Florida, you see flamingos everywhere—in advertising, in place names, even on the logo for the state lottery—but as an actual organism, as a species, there was essentially no information available on the biology of flamingos,” says Whitfield. “Some biologists considered them native birds that were extirpated during the plume trade of the late 1800s, and urged for population recovery measures, while others considered the rare flamingos seen around Florida to be escapes from captive colonies. We often say that in south Florida we have just two types of species, introduced and endangered, but a species can’t be both at the same time.”

“This article finally sheds welcome light on status of these iconic birds in Florida. The authors meticulously researched historic records and compiled more recent sightings to reconstruct the history and population trends of flamingos in Florida,” adds the American Museum of Natural History’s Felicity Arengo, a flamingo conservation expert who was not involved in the study. “Flamingo numbers have increased notably since the 1950s due to protections to species and habitats in Florida and throughout the Caribbean. The authors are cautious and recognize the limitations of the data in their study, but they provide ample evidence that Florida was the northernmost extent of the American Flamingo prior to the early 1900s and that populations have been recovering.”

Status and trends of American Flamingos (Phoenicopterus ruber) in Florida, USA is available at

About the journal: The Condor: Ornithological Applications is a peer-reviewed, international journal of ornithology. It began in 1899 as the journal of the Cooper Ornithological Club, a group of ornithologists in California that became the Cooper Ornithological Society, which merged with the American Ornithologists’ Union in 2016 to become the American Ornithological Society. In 2016, The Condor had the number one impact factor among 24 ornithology journals.

Fracking Tied to Reduced Songbird Nesting Success

Wed, 02/14/2018 - 09:29

A researcher handles a Louisiana Waterthrush chick. Photo credit: M. Frantz

The central Appalachian region is experiencing the country’s most rapid growth in shale gas development, or “fracking,” but we’ve known almost nothing about how this is affecting the region’s songbird populations—until now. A new study from The Condor: Ornithological Applications demonstrates that the nesting success of the Louisiana Waterthrush—a habitat specialist that nests along forested streams, where the potential for habitat degradation is high—is declining at sites impacted by shale gas development in northwestern West Virginia.

West Virginia University’s Mack Frantz and his colleagues mapped waterthrush territories and monitored nests along 14 streams from 2009 to 2011 and again from 2013 to 2015. They also mapped and measured disturbances to streams and to the forest canopy, using aerial photographs and satellite imagery as well as extensive ground-truthing, and classifying them according to whether they were related to shale gas development. Their results show that as shale gas development has expanded in the area, nest survival and productivity and riparian habitat quality have declined. At the same time, the size of individual waterthrush territories has increased, suggesting birds need to range farther to find sufficient resources. This study is one of the first to demonstrate that shale gas development can affect songbird reproductive success and productivity, both directly through the presence of fracking infrastructure and indirectly through effects on habitat quality.

“I hope our findings lead to robust protections of our forested headwater stream ecosystems, which are currently overlooked for regulation despite their critical role in providing nutrients and organic matter downstream, not to mention as an important source for drinking water,” says Frantz. “Waterthrushes are a modern-day ‘canary in the coal mine,’ and there are many more opportunities to study how anthropogenic disturbance affects and entangles food webs at the aquatic–terrestrial interface.”

“After twelve years of research conducted with this species, I have seen the numerous impacts hydraulic fracturing has had on waterthrush survival and the toll that the industry has had on our nation’s wild places and wildlife,” adds Louisiana State University-Alexandria’s Leesia Marshall, a waterthrush expert who was not involved in the Condor study. “This paper should serve as a call for all scientists to redouble efforts across all related disciplines to document the present impacts of shale gas extraction and to develop strategies for mitigation and avoidance of potential impacts in the future.”

Demographic response of Louisiana Waterthrush, a stream obligate songbird of conservation concern, to shale gas development is available at

About the journal: The Condor: Ornithological Applications is a peer-reviewed, international journal of ornithology. It began in 1899 as the journal of the Cooper Ornithological Club, a group of ornithologists in California that became the Cooper Ornithological Society, which merged with the American Ornithologists’ Union in 2016 to become the American Ornithological Society. In 2016, The Condor had the number one impact factor among 24 ornithology journals.

AUTHOR BLOG: Finding the Perfect Spot: Nest-Site Choice and Predator Avoidance in Asian Houbara

Wed, 01/24/2018 - 15:27

João L. Guilherme

Linked paper: Consistent nest-site selection across habitats increases fitness in Asian Houbara by J.L. Guilherme, R.J. Burnside, N.J. Collar, and P.M. Dolman, The Auk: Ornithological Advances 135:2, April 2018.

A female Asian Houbara runs away from the nest area.

For birds that nest on the ground, discretion is everything. As they are especially at risk from predators, choosing where to nest may carry life or death consequences for themselves, their eggs, and their progeny.

We study the ecology of the Asian Houbara (Chlamydotis macqueenii) in the semi-deserts of southern Uzbekistan, as part of a long-term effort to gain insight into the dynamics of this wild population. The landscape has extensive low-density shrub coverage and tends to all look the same on first glance, but a closer look reveals subtly distinct habitats with shrub communities that differ in not just species composition, but also in the size and number of shrubs. The Asian Houbara is a highly cryptic ground-nesting bird inextricably associated with these habitats, breeding throughout. For 23 long days, females have the sole responsibility of laying, incubating, and protecting the eggs, and themselves, from the freezing cold and the strong sun, and from the desert predators such as foxes and monitor lizards.

This behavior of nesting in structurally different habitats made us question if females were choosing similar vegetation structure for nest sites and whether these choices had an impact on their nest success.

A rare glimpse at a female Asian Houbara on her nest.

By following houbara tracks, we succeeded at finding 210 nests. Then we took it upon ourselves to identify and measure the height of the shrubs around all nests and at 194 random locations. Obviously, this was done after the nest was finished and the female and chicks had left the area. In the end, we identified 30 species and measured a total 35,853 shrubs! After running some statistical analysis we found that females were indeed choosing the same nest site features consistently across three structurally different habitats. Their selection was so fine-tuned that the optimal shrub height of about 30 centimeters had the greatest probability of being selected in all habitats. Furthermore, the scrape was consistently in the middle of shrubs that offered some degree of concealment, but enough visibility for the female to anticipate approaching predators.

So, females were choosing similar nest site across habitats, but we wondered if these features were helping them avoid nest predation.

To investigate this, we monitored the nests, placing temperature loggers inside the nest scrape and setting video cameras to collect information through the entire incubation so that we could classify if a nest was successful or if it had failed and, in that case, why (see video here). We found that nests in higher vegetation had a lower probability of being predated, with the likelihood being that the higher vegetation offered more concealment from predators. However, females would not nest in even higher vegetation, as this would eliminate their ability to see around and anticipate approaching predators. In fact, from more than 200 monitored nests, there was not a single time when a female was predated, which normally occurs in other ground nesting birds—females seem to value the old adage “run and hide, live to fight another day.” Nest camera footage showed us that females were eternally vigilant, with their heads extended so they could see just above the vegetation and surreptitiously leave the nest before a predator arrived. In this way, we found the connection between the choice of nest site and the chance of losing the nest to predation.

In a landscape where everything looks the same, there were in reality different habitats where nesting Asian Houbara had to find the “perfect spot” that maximized the chances of hatching while reducing the danger of being depredated. For a species of conservation concern, it is very important to maintain good productivity and minimize changes in vegetation structure away from the optimal choices, as these may lead to abandonment of previously suitable nesting areas, lower nest survival, or increased predation risk for the incubating female.

Warming Temperatures May Cause Birds to Shrink

Wed, 01/24/2018 - 12:18

The size of adult House Sparrows is predicted by maximum temperatures during development. Photo credit: P. Deviche

Biologists have known for a long time that animals living in colder climates tend to have larger bodies, supposedly as an adaptation to reduce heat loss. However, understanding how temperature affects animals has gained new importance thanks to climate change. A new study from The Auk: Ornithological Advances uses European House Sparrows, which have spread into a variety of climates in Australia and New Zealand since their introduction in the mid-19th century, to show that this trend in birds might actually be due to the effects of high temperatures during development—raising new alarms about how populations might be affected by global warming.

Macquarie University’s Samuel Andrew and his colleagues captured and measured approximately 40 adult House Sparrows at each of 30 locations across Australia and New Zealand. They found that maximum temperatures during the summer, when the birds breed, were a better predictor of adult body size at each location than winter minimum temperatures. This adds support to the idea that excessive heat during development may affect birds’ growth throughout their lives, raising concerns that increasing summer temperatures due to climate change could drive down the average adult body size, with potential effects on the birds’ fitness.

“If variation in body size is linked directly or indirectly to adapting to different climates, then body size could be useful for monitoring the extent to which bird populations are capable of adapting rapidly to changing climates,” says Andrew. “Our work on this common species helps us to understand the adaptive responses of birds to a changing climate and their constraints, and this fundamental knowledge will help future workers and managers focus their work on other species and potentially identify those species most at risk from climate change.”

“This paper is an important addition to a growing body of work that is changing our understanding of the relationships between climate and body size. The big question generated by these results is the extent to which the observed relationship is the outcome of adaptive evolutionary differences among sites as opposed to direct developmental responses to different temperatures. Interestingly, some of these same authors just published experimental evidence for a direct effect of temperature on growth in another bird species,” adds Whitman College’s Tim Parker, an expert who was not involved with the research. “This is not a new idea, but it has been largely ignored by those who have assumed that most morphological variation in birds is due to evolved adaptive variation. We need more work on the direct effects of temperature variation on development in endotherms.”

Clinal variation in avian body size is better explained by summer maximum temperatures during development than by cold winter temperatures is available at

About the journal: The Auk: Ornithological Advances is a peer-reviewed, international journal of ornithology that began in 1884 as the official publication of the American Ornithologists’ Union, which merged with the Cooper Ornithological Society in 2016 to become the American Ornithological Society. In 2009, The Auk was honored as one of the 100 most influential journals of biology and medicine over the past 100 years.

Endangered Woodpeckers Persist, but Still Struggle, on Private Land

Wed, 01/24/2018 - 12:15

Red-cockaded Woodpeckers nesting on private land continue to face challenges. Photo credit: B. Beck

The U.S. Fish and Wildlife Service started the Safe Harbor program in North Carolina in 1995 to reduce conflict between landowners and conservation officials and to encourage private landowners to take steps to benefit endangered Red-cockaded Woodpeckers on their land. The program has successfully reduced conflict over conservation and reduced the abandonment of nest clusters, but a new study from The Condor: Ornithological Applications shows that while the program may have raised landowners’ awareness of and tolerance for their feathered neighbors, it has largely failed to improve breeding success of birds on private lands.

Virginia Polytechnic Institute and State University’s Jennifer Smith and her colleagues compared Red-cockaded Woodpeckers’ breeding success on Safe Harbor properties before and after enrollment with that on control properties, monitoring a total of 55 breeding clusters in the North Carolina Sandhills between 1980 and 2014. Nest cluster abandonment increased on control properties while remaining constant and negligible on Safe Harbor properties, but other measures of breeding success such as clutch size, nest failure rates, and fledging success were unaffected by Safe Harbor habitat management efforts. These results suggest that the Safe Harbor program often failed to maintain or increase high-quality foraging habitat for the birds.

Regular fires are essential for maintaining high-quality Red-cockaded Woodpecker habitat, and prescribed burns are not feasible on a large proportion of Safe Harbor properties in the Sandhills due to their proximity to residential areas. In addition, the researchers believe that inadequate funding may have limited the Safe Harbor program’s impact. However, they believe the program and the monitoring efforts that have accompanied it still have value. “The longevity of the research project combined with the initiation of Safe Harbor has had marked benefits because it has allowed us to build relationships with private landowners,” says Kerry Brust, co-author of the paper. “Exchanges with private landowners have presented an ideal opportunity to draw attention to the listed species and the management needed for the persistence of Red-cockaded Woodpeckers.”

“This study identifies the great value that Safe Harbor has brought to Red-cockaded Woodpecker conservation but also highlights important and daunting limitations of the program,” according to U.S. Forest Service biologist John Kilgo, who works on Red-cockaded Woodpecker conservation and was not involved in the study. “As these are primarily related to funding constraints and less stringent habitat management requirements under the program, new and creative approaches will be required if the effectiveness of Safe Harbor is to be improved.”

How effective is the Safe Harbor program for the conservation of Red-cockaded Woodpeckers? is available at

About the journal: The Condor: Ornithological Applications is a peer-reviewed, international journal of ornithology. It began in 1899 as the journal of the Cooper Ornithological Club, a group of ornithologists in California that became the Cooper Ornithological Society, which merged with the American Ornithologists’ Union in 2016 to become the American Ornithological Society. In 2016, The Condor had the number one impact factor among 24 ornithology journals.

AUTHOR BLOG: Tracking the Japanese Bush-Warbler Invasion of Hawaii

Wed, 01/17/2018 - 15:15

Jeff Foster

Linked paper: Population genetics of an island invasion by Japanese Bush-Warblers in Hawaii, USA by J.T. Foster, F.M. Walker, B.D. Rannals, and D.E. Sanchez, The Auk: Ornithological Advances 135:2, April 2018.

A Japanese Bush-Warbler in Hawaii. Photo credit: J. Denny

Over the past several centuries, Hawaii’s native bird populations have been decimated due to an array of factors, including introduced diseases (avian malaria and pox), introduced rats, habitat change, and hunting. As a result, most live near the tops of the mountains and have small populations. Few birds and remote locations make studying many of these native populations incredibly challenging.

In contrast, Hawaii is also home to many introduced birds that can be seen everywhere, from Brazilian Cardinals and Common Mynas on the beaches to Japanese White-eyes and various game birds at the mountaintops. Various organizations in Hawaii introduced these birds from elsewhere in the world to have birdsong fill the air again and occasionally to serve as pest control for crops. Over 170 species have been brought to Hawaii and released into the wild. Of these releases, at least 54 species now have breeding populations, and most seem destined to stay for the long haul. Many species, such as the Japanese White-eye, Northern Cardinal, Zebra Dove, and Common Myna, have robust populations and can be found in a variety of habitats.

One introduced species, the Japanese Bush-Warbler, is perhaps the coolest of them all. However, despite its prominent place as the iconic harbinger of spring in Japan, few people in Hawaii think much of this species—perhaps because it is often heard but rarely seen, or perhaps because when one does finally spy a bush-warbler, it is a drab olive-brown with few prominent markings. Whatever the reason for overlooking it, bush-warblers have successfully colonized most brushy habitats on all of the main Hawaiian Islands. They were released on the island of Oahu in the 1920s, and after decades of population growth on Oahu, they naturally spread to the remaining main Hawaiian Islands by 1997.

Birds on islands have provided some of the best historical examples of the evolutionary process—think Charles Darwin in the Galapagos and Alfred Russel Wallace in the Malay Archipelago. Capturing cases of evolution “in action” is difficult. However, introductions of non-native birds into the Hawaiian Islands provide numerous opportunities for research, particularly in assessing potential evolutionary changes over a relatively short time frame. In this study, we were afforded a unique opportunity to look at the evolution of the Japanese Bush-Warbler within the past several decades by combining population genetic analyses of this species with a detailed invasion timeline on each island. As a result, we were able to see how rapidly genetic changes can occur during an invasion. We found both expected patterns, such as a decline in genetic diversity on the most recently invaded island, and an unexpected pattern, potential assortative mating on each island. These findings suggesting substantial room for future work in a system and setting that is pretty hard to match.

Genetic Drift Caught in Action in Invasive Birds

Wed, 01/17/2018 - 14:41

Japanese Bush-Warblers have experienced genetic drift as they’ve invaded the Hawaiian islands. Photo credit: S. Price

Studies of island bird populations have taught us a lot about evolution, but it’s hard to catch birds in the act of naturally colonizing new islands. Instead, a new study from The Auk: Ornithological Advances examines what’s happened by looking at the genetics of a species that arrived in Hawaii in the twentieth century through decidedly unnatural means—us.

Japanese Bush-Warblers were introduced to Oahu in 1929 and have since become established on all the main islands of Hawaii, providing a unique opportunity to follow post-invasion evolution on a known, recent timescale. Northern Arizona University’s Jeffrey Foster and his colleagues took blood and muscle samples from 147 bush-warblers living on five islands between 2003 and 2005. Their results indicate genetic drift is occurring—Oahu’s birds have higher genetic diversity than those on other islands, whose populations were founded by smaller groups of individuals, just as population genetic theory predicts. Kauai bush-warblers, however, appear to be on a distinct genetic trajectory from those on other islands. Kauai is three times as far from Oahu as the closest other islands, and appears to have received a unique subset of the overall genetic diversity found elsewhere, but it remains to be seen whether the trend on Kauai will continue in the future or if continued dispersal of birds among islands will blur these differences. “This study nicely showed genetic divergence for a very short period using the artificially introduced Japanese Bush-Warblers,” according to Shoji Hamao of Japan’s National Museum of Nature and Science, an expert on the species.

“I got the idea for bush-warblers as a study system due to the challenges associated with my previous work on native Hawaiian birds,” says Foster. “Most of the native bird species I had worked on were exceedingly rare—several of them were endangered species, in fact—so focusing a new project on species in decline or with low numbers was a risky proposition. However, many of the introduced birds are quite common and one species, the Japanese Bush-Warbler, caught my attention with its loud song.

“Bush-Warblers first arrived on the Big Island when I was living there in the 1990s. The idea that one could study this invasion in progress totally blew my mind. The genetic findings largely followed expectations, such as seeing the most genetic diversity on the island where the birds were introduced and less elsewhere. Birds on Kauai, the island just west of Oahu, appear to be more distinct than those birds on islands east of Oahu, suggesting that over time birds on the respective islands may continue to diverge genetically.” But, Foster adds, many questions remain to be answered. “How much are the birds still flying between islands and potentially mixing any genetic signals of differentiation? Why did it take 50 years for the bush-warblers to colonize other islands after Oahu? How have their vocalizations changed after colonization due to new environments or random chance? We still don’t know.”

Population genetics of an island invasion by Japanese Bush-Warblers in Hawaii, USA is available at

About the journal: The Auk: Ornithological Advances is a peer-reviewed, international journal of ornithology that began in 1884 as the official publication of the American Ornithologists’ Union, which merged with the Cooper Ornithological Society in 2016 to become the American Ornithological Society. In 2009, The Auk was honored as one of the 100 most influential journals of biology and medicine over the past 100 years.

Timing of Spring Birdsong Provides Climate Insights

Wed, 01/17/2018 - 14:25

Hermit Warblers are among the species monitored for a new study of the timing of spring birdsong. Photo credit: M. McGrann

Climate change has scientists worried that birds’ annual migration and reproduction will be thrown out of sync with the seasons. Because birds’ songs are correlated with their breeding behavior and are easily identifiable to species, monitoring birdsong can be a good way to keep tabs on this possibility, and a new study from The Condor: Ornithological Applications takes advantage of this approach to provide new baseline data for the birds of northern California.

The California Department of Fish and Wildlife Brett Furnas and William Jessup University’s Michael McGrann analyzed data from two bird survey programs from California’s Klamath Mountains and Southern Cascades, both of which used automated recorders to monitor bird sounds between 2009 and 2011. In addition to providing the first comprehensive assessment of songbird occupancy over a 40,000 square kilometer region of northern California, they were able to identify the precise dates of peak vocal activity for eight songbird species, and their work shows that this will be a feasible method to track advances in the timing of vocal activity over the coming decades. Species characterized by strong single peaks in vocal activity already tended to reach those peaks later than other species, perhaps because birds with tightly constrained timing are less able to adapt to changing climatic conditions.

“Climate change is disrupting songbird populations, distributions, and breeding behaviors in our mountain ecosystems. Mountains are particularly sensitive because temperature and precipitation interact in complex ways on mountains,” says McGrann. “If Neotropical migrants are unable to adjust their breeding behaviors, then there may be a mismatch in the timing of raising their young to the peak availability in food resources, namely insects. Our technique should allow us to track shifts in elevation, changes in the state of the population, and changes in breeding behaviors in response to climate change over the next ten to twenty years.”

“Furnas and McGrann provide a textbook example of how to detect differences in the timing of nesting among bird species using information on the peak date of singing derived from surveys and automated recorders,” according to UC Berkeley’s Steve Beissinger, an expert on avian phenology who was not involved in the study. “Their results support recent findings of a five to twelve day shift forward in the timing of peak singing by California birds in the nearby Sierra Nevada and coastal ranges in response to climate change.”

Using occupancy modeling to monitor dates of peak vocal activity for passerines in California is available at

About the journal: The Condor: Ornithological Applications is a peer-reviewed, international journal of ornithology. It began in 1899 as the journal of the Cooper Ornithological Club, a group of ornithologists in California that became the Cooper Ornithological Society, which merged with the American Ornithologists’ Union in 2016 to become the American Ornithological Society. In 2016, The Condor had the number one impact factor among 24 ornithology journals.

Engineered Sandbars Don’t Measure Up for Nesting Plovers

Wed, 01/10/2018 - 13:15

Piping Plovers were more successful nesting on natural sandbars than engineered ones. Photo credit: D. Borden

Dams alter rivers in ways that reduce the creation of natural sandbars, which is bad news for threatened Piping Plovers that depend on them for nesting habitat. Between 2004 and 2009, more than 200 hectares of engineered sandbars were built along the Missouri River to address the problem—but how does this engineered habitat compare to the real thing? A new study from The Condor: Ornithological Applications takes advantage of a natural experiment created by the region’s 2011 floods, demonstrating that the engineered habitat doesn’t provide the benefits of sandbars created by nature.

Kelsi Hunt of the Virginia Polytechnic Institute and State University and her colleagues collected data downstream of Gavins Point Dam from 2005 to 2014, monitoring more than 1,000 nests and banding almost 3,000 individual birds both before and after massive floods in 2011 created vast new areas of natural sandbar habitat. Nest success, chick survival, and total reproductive output all increased after the flood and remained high as flood-created sandbars began to age, even without the intensive predator management that had been done on the engineered sandbars. In contrast, Piping Plover populations nesting on engineered sandbars grew in the first year after the habitat’s construction, but there wasn’t enough space to go around—high population densities quickly led to high risk from predators and decreased reproductive rates.

“I realized just how interesting of a natural experiment the flood provided us with when my advisor and I boated the entirety of the Gavins Point Reach prior to the 2012 field season,” says Hunt. “The amount of sandbar habitat that the 2011 flood created was incredible to see. Where before there was just river, huge sandbars replaced it. Some of the sandbars it created were larger than city blocks and took hours to survey.” She hopes that managers can learn from this study to create better engineered habitat for sandbar-nesting birds, building more nesting space at one time and constructing new habitat close to existing sandbars so that young birds will have an easy time finding and colonizing it.

“This paper presents a clear contrast in demographic rates of Piping Plovers in naturally created and human-restored habitats that can be used to compare and refine conservation strategies,” adds Anne Hecht, Piping Plover recovery coordinator for the U.S. Fish and Wildlife Service. “Although it focuses on Missouri River sandbars, it has important implications for conservation of Piping Plover habitat rangewide, as well as for other species experiencing disruption of habitat formation processes.”

Demographic response of Piping Plovers suggests that engineered habitat restoration is no match for natural riverine processes is available at

About the journal: The Condor: Ornithological Applications is a peer-reviewed, international journal of ornithology. It began in 1899 as the journal of the Cooper Ornithological Club, a group of ornithologists in California that became the Cooper Ornithological Society, which merged with the American Ornithologists’ Union in 2016 to become the American Ornithological Society. In 2016, The Condor had the number one impact factor among 24 ornithology journals.

AUTHOR BLOG: Call Variation Suggests Roles for Natural History & Ecology in Marsh Bird Vocal Evolution

Wed, 12/27/2017 - 13:43

Sarah Luttrell

Linked paper: Geographic variation in call structure, likelihood, and call-song associations across subspecies boundaries, migratory patterns, and habitat types in the Marsh Wren (Cistothorus palustris) by S.A.M. Luttrell and B. Lohr, The Auk: Ornithological Advances 135:1, January 2018.

Marsh Wrens’ calls vary across their geographic range. Photo credit: S. Luttrell

Many bird species have unique geographic signatures in their vocalizations similar to human “accents.” Most of what we know about geographic variation in bird sounds comes from studies of bird song. Song has been a rich subject for studying geographic variation because it is typically learned, allowing song to change more quickly across space and time than a purely genetic trait. Song, however, is only one type of signal in a bird’s vocal repertoire. We wanted to build a broader picture of how vocal behavior evolves and changes among populations by looking at a large repertoire of sounds at once. Most birds have multiple call types in addition to their songs. Each call or song type is an individual trait used under unique circumstances, and that means that each one may be under different selective pressures. As a result, looking at multiple vocalizations may reveal multiple patterns of geographic variation, or, if their geographic patterns are similar, it may suggest a general process of vocal evolution. There are many ways in which vocalizations might change over time or distance. For example, changes could be random—as long as the signal still sends the correct message, some aspects of its acoustic structure could drift among populations. Additionally, vocal signals may be under selection to reduce distortion caused by the habitat in which they are produced and heard. Think about how sounds are distorted differently in an open, bare hallway versus a musician’s sound booth and how the local acoustics might alter a listener’s ability to understand you. Furthermore, if some aspect of the sound is learned, then copy errors or innovations during learning can result in passing down cultural changes over time. These are just a few ways in which sounds might be altered, and no two vocalizations are necessarily influenced in the same way by the same set of selective pressures.

In order to compare vocal repertoires among populations, we looked at several subspecies of the Marsh Wren. Marsh Wrens provide a natural experiment in vocal variation due to ecological and natural history differences among the subspecies. The five eastern North America subspecies we focused on are found in two distinct habitats (freshwater marshes and saltmarshes), and they exhibit three migratory patterns (resident, partially migratory, and fully migratory). Our first challenge was to describe and classify the call repertoire for Marsh Wrens. We identified seven discrete call types. Three of the seven calls varied in acoustic properties that were consistent with differences in either migratory pattern or habitat type. Surprisingly, we also found that four calls were more common in some subspecies than others and that the differences were greatest between habitat types. This variation in call production may indicate differences in behavior or timing of breeding among the subspecies with different ecologies. Our results suggest that while not all vocal signals are changing at the same rate or in the same way, differences in habitat type and migratory behavior may be related to the biggest differences in vocal behavior. Interestingly, the calls that showed the greatest differences were calls used in mate attraction and territory defense, while calls related to alarm or distress were similar across subspecies, natural history, and habitat type. This result suggests that sexual selection could be driving or reinforcing changes between populations with different ecologies.

In the future, we are excited to explore another unusual phenomenon that we report in this paper: the use of calls as embedded elements in song. Like most songbirds, Marsh Wren males sing during the breeding season to attract mates and defend territories. Unlike those of most songbirds, we found that, depending on the subspecies, 73-93% of male Marsh Wren songs contained embedded calls. Do embedded calls confer some additional message to the song? Does this behavior vary across the breeding season? Are there specific structural rules regarding the embedded call pattern within song? Stay tuned as we untangle the structural complexity and geographic variation in songs with embedded call elements in Marsh Wrens across the rest of their range. Does your study species use calls in a song-related context? If so, contact us at—we would be excited hear about it!

Wrens’ Calls Reveal Subtle Differences Between Subspecies

Wed, 12/27/2017 - 13:43

Biologist Sarah Luttrell records the calls of a Marsh Wren. Photo credit: S. Luttrell

Birds’ songs and the ways they vary between places have been well studied–but what can the simpler vocalizations known as calls tell us about bird biology? A new study from The Auk: Ornithological Advances provides the first detailed description of how Marsh Wren calls vary across eastern North America and hints at the evolutionary processes playing out between wren subspecies.

The University of Maryland Baltimore County’s Sarah Luttrell and Bernard Lohr recorded the calls of five Marsh Wren subspecies at nineteen different sites, encompassing the Gulf Coast, Atlantic Coast, and Great Lakes regions and including migratory, nonmigratory, freshwater marsh, and saltwater marsh populations. Categorizing the recordings into seven different call types, they analyzed how calls differed between subspecies. While some calls were associated with territory patrol, nest building, and courtship, others were used mainly during aggressive encounters with predators or other wrens. Both the acoustic characteristics of some calls and how frequently they were used differed from place to place.

“It was certainly a lot of work to compile data on multiple vocalizations and compare the results, but in the end, it makes for a more nuanced understanding of how various evolutionary processes shape animal behavior as a whole,” says Luttrell. “Twitter” calls differed between migratory and nonmigratory subspecies, for example, while “buzz” and “trill” calls differed between birds that lived in freshwater and saltwater marshes; while differences in habitat can’t directly explain this, all of these call types could be shaped by sexual selection that reinforces the boundaries between subspecies. Atlantic Coast populations produced the “chuck” alarm call more often than others, which suggests they may experience more threats from predators or nest at higher densities that lead to more antagonistic encounters between birds.

Could these differences eventually prompt Marsh Wren populations to diverge into fully separate species? “That’s impossible to say for sure—it all depends on the course that evolution takes!” says Luttrell. “We were excited that the patterns of call variation we observed seemed to coincide with differences ecology and life history, which suggests the possibility that these subspecies are evolving in different directions. In the future, we’re hoping to do some behavioral tests that might help us understand how much the acoustic differences matter to the birds’ behavior in the wild. If we do find that individuals respond less strongly to the vocalizations of another subspecies than to their own, then that would be additional evidence that at least some subspecies are on a trajectory of divergence.”

“This study highlights the diversity of calls that can be found in a single avian repertoire, and nicely illustrates how different elements of those repertoires can evolve independently,” according to the University of Northern Colorado’s Lauryn Benedict, an expert on communication in wrens and other songbirds. “The demonstrated patterns of call use in relation to behavioral context, caller sex, habitat, and migratory behavior raise many future avenues of inquiry. Avian calls are a generally understudied vocalization, and this paper demonstrates how and why we all should pay them more attention.”

Geographic variation in call structure, likelihood, and call-song associations across subspecies boundaries, migratory patterns, and habitat types in the Marsh Wren (Cistothorus palustris) is available at

About the journal: The Auk: Ornithological Advances is a peer-reviewed, international journal of ornithology that began in 1884 as the official publication of the American Ornithologists’ Union, which merged with the Cooper Ornithological Society in 2016 to become the American Ornithological Society. In 2009, The Auk was honored as one of the 100 most influential journals of biology and medicine over the past 100 years.

AUTHOR BLOG: Understanding How Management Affects a Flagship Reed Bed Bird Species

Wed, 12/20/2017 - 10:51

Thomas Oliver Mérő

Linked paper: Reed management influences philopatry to reed habitats in the Great Reed-Warbler (Acrocephalus arundinaceus) by T.O. Mérő, A. Žuljević, K. Varga, and S. Lengyel, The Condor: Ornithological Applications 120:1, February 2018.

A color-banded singing Great Reed Warbler male, April 2015.

Wetlands are inhabited by disproportionately large number of plants and animals and yet are among the most endangered habitats worldwide due to human-caused habitat loss and fragmentation. Ecologists and conservation biologists work hard on saving wetlands by using various techniques such as vegetation management (e.g. breaking up homogeneous reed beds), water regulation (e.g. maintaining a flood/drought cycle), or reintroduction of extinct species (e.g. cranes in the U.K.). Several recent studies have shown that the management of wetlands such as reed beds by controlling the water level and removing the vegetation by mowing, burning, or grazing can increase species richness and diversity; however, we know less about whether such management provides better conditions for survival and reproduction of single species whose presence is important to other species.

The Great Reed Warbler (Acrocephalus arundinaceus) is an Old World, long-distance migrant bird that breeds in reed habitats of the Western Palearctic and winters in sub-Saharan Africa. In central Europe, the Great Reed Warbler is a widespread breeder inhabiting almost all types of reed habitats (ponds, marshes, canals etc.). Great Reed Warblers arrive in mid-April from their wintering grounds and stay until the end of breeding season in late July.

We have studied the breeding ecology of Great Reed Warblers in northern Serbia for eight years. The region hosts a nice array of wetland habitat types, ranging from oxbows of the Danube to small and large canals, and from sand and clay mining ponds to marshes in natural depressions. For our work, we distinguished six types of reed habitats based on our own observations and information from local water management companies. The six types, which differ in their shape, size, vegetation cover, and water regime, are mining ponds, marshes, large canals, and three classes of small canals.

These wetlands are managed by reed mowing and burning, which led us to wonder how reed management influences the birds and other wetland animals. Specifically, we were interested in whether and how management influences the survival and reproduction of Great Reed Warblers, a flagship species of lowland wetlands in central Europe. Reed management by burning and mowing offered a good opportunity to study the responses of Great Reed Warblers in each of the reed habitat types. For example, we recognized early on that larger-winged, presumably higher-quality, males tend to occupy reed habitats with little management and deep, stable water, which are typically found along large canals.

We color-banded all individuals (both adults and hatch-year birds) from the beginning of our study and regularly checked all reed beds every year during the nesting season to explore potential differences in survival and reproduction of birds in the six reed habitats. We were also curious to find out how reed management and water availability influence survival and reproduction. We first analyzed data on survival and encounter probability that were collected over seven breeding seasons (2009-2015).

We found that the encounter probability of birds banded as hatch-year birds was higher in reed habitats with shallower water, while that of those banded as adults was higher in reed habitats with deeper water. These opposite relationships between hatch-year birds and adults may indicate that experienced adults occupy qualitatively better habitats, similarly to large-winged males (mentioned above). When data were analyzed separately for the sexes, we found that the encounter probability of males depended on variation in reed management and in water depth. In contrast, for females, encounter probability depended only on water depth, i.e. encounter probability increased with water depth. Furthermore, most of the adults and hatch-year birds returned to the reed habitat that they had been occupying initially, indicating that Great Reed Warblers display unexpectedly high fidelity to the reed habitat type they hatched in or bred in before.

How do these results translate to management recommendations? We all want the best possible management for the birds we admire and study. Evidence found in our study showed that reed management by mowing and/or burning influences return rates of juveniles and adult males and females in different ways. These results suggest that in practice, spatially variable reed management should be applied and water with varying depths should be maintained to maximize the return rates of Great Reed Warblers. This is often easier said than done. However, the multitude of reed habitats in our study and the good working relationships we developed with water management authorities and other stakeholders will allow more detailed, experimental studies of the influence of management and the allocation of optimal combinations of management for the benefit of wetland birds.

AUTHOR BLOG: A New Species of Antbird

Thu, 12/14/2017 - 13:13

Andre Moncrieff

Linked paper: A new species of antbird (Passeriformes: Thamnophilidae) from the Cordillera Azul, San Martín, Peru by A.E. Moncrieff, O. Johnson, D.F. Lane, J.R. Beck, F. Angulo, and J. Fagan, The Auk: Ornithological Advances 135:1, January 2018.

A male Cordillera Azul Antbird. Photo credit: A. Spencer

It was July 10, 2016, when Dan Lane, Fernando Angulo, Jesse Fagan, and I rolled into the coffee-growing town of Flor de Café in north-central Peru. This town lies in the Cordillera Azul—a picturesque series of outlying Andean ridges hardly explored by ornithologists. In fact, the first ornithological inventory in the region was only in 1996, when a team of researchers from the Louisiana State University Museum of Natural Science (LSUMNS) bushwhacked into the extremely remote eastern Cordillera Azul. It was on this expedition that Dan, then a beginning graduate student at LSU, discovered the distinctive Scarlet-banded Barbet (Capito wallacei) on “Peak 1538.” Now, twenty years later, we were back to see this iconic species, which graces the cover of the Birds of Peru field guide.

Flor de Café, in the somewhat more accessible western Cordillera Azul, has become the hub for barbet-chasers since LSUMNS associates Todd Mark and Walter Vargas confirmed its presence here in 2011. Thus, we were not surprised to run into another birdwatcher, Josh Beck, as we moved our gear into the single guest house in town. Within moments of meeting, Josh began telling us of a strange, ground-walking antbird he had encountered the previous day and documented with a sound recording. We quickly realized that his bird was a species new to science.

Fast forward a year and a half. This month, December 2017, The Auk is publishing the formal description of the Cordillera Azul Antbird (Myrmoderus eowilsoni). Based on our initial visit and a follow-up expedition led by LSU graduate student Oscar Johnson, we’ve learned a few things about this new species: its closest relative is the Ferruginous-backed Antbird (of which the nearest populations are about 1,500 km to the east in lowland forests of Brazil), it eats insects, the males and females sing different songs, it lives in pristine understory of humid forest, and its future near Flor de Café is very grim.

Chainsaws were an overwhelming component of the soundscape around town. We even asked some locals to delay cutting activities so that we could get better voice recordings of the antbird. Sun-coffee farming, which necessitates clear-cutting, is the main source of income for the residents of Flor de Café. By contrast, birding ecotourism benefits only a few residents, leading to some unfortunate and ongoing tensions within the town. There is clearly a great need for environmental education and conservation work in the region.

What I haven’t yet mentioned is that Flor de Café is located very near the Cordillera Azul National Park, which was created in 2001 and contains over 13,500 km2 of pristine habitat. We are very optimistic that future exploration within the park will produce new localities for the antbird and barbet, both presently facing severe habitat loss around Flor de Café.

From an ornithological perspective, the Cordillera Azul remains mysterious and tantalizing. Perhaps it holds a new hummingbird or tody-tyrant? Regardless of any future discoveries to be made in the Cordillera Azul, I hope that the new antbird brings attention to the incredibly biodiverse and distinctive avifauna of the region. I also hope that this discovery serves as a potent reminder of how far we still have to go in cataloging the diversity of life on this planet!

Urban Cooper’s Hawks Outcompete Their Rural Neighbors

Wed, 12/13/2017 - 10:16

An urban-dwelling Cooper’s Hawk. Photo credit: B. Millsap

Depending on whether a species flourishes in a city environment, urban wildlife populations can be “sources” or “sinks,” either reproducing so quickly that individuals leave to colonize the surrounding area or needing constant immigration from outside to stay viable. A new study from The Condor: Ornithological Applications examines the population dynamics of Cooper’s Hawks in urban Albuquerque, New Mexico, and finds that city-born birds aren’t just thriving—they’re actually forcing their rural neighbors out of their nest sites.

New Mexico State University’s Brian Millsap collected data on Cooper’s Hawks living in a 72 square kilometer area of northeast Albuquerque from 2011 to 2015, monitoring each year’s nests and tracking newly fledged females with radio transmitters. He found that 30 times more hawks emigrated out of the urban area than immigrated into it, suggesting it was a source population for the surrounding region. However, the details didn’t fit neatly with the traditional source–sink model. While the surrounding exurban hawk populations were breeding and surviving well enough to sustain themselves without immigration, females moving out of the urban area were able to beat them to their nesting sites—unlike their exurban neighbors, they didn’t migrate south for the winter.

White-winged Doves, which first became established in the area in the 1980s, provide an abundant food source for city-dwelling hawks. “Individuals living in urban Albuquerque actually have a fitness advantage over their neighbors living in natural habitats. This advantage comes from the higher prey populations in urban areas, which allow urban female Cooper’s Hawks to spend the winter near their eventual breeding sites, as opposed to rural females that migrate south in winter,” explains Millsap. “The urban female hawks begin searching out and claiming nesting territories before the rural hawks return in spring and thus obtain nesting sites without direct competition from migrants. Because of this advantage, the urban Albuquerque Cooper’s Hawk population not only supports itself but also serves as a substantial source of immigrant females for surrounding native habitats.”

Changes in migratory behavior that lead to segregation between different groups can have profound effects on populations, altering how they interact both with each other and with other species in a community. According to the Peregrine Fund’s Chris McClure, an expert on raptor ecology, “This study is a great example of how solid field work and sophisticated modeling can yield new insights in basic and applied ecology.”

Demography and metapopulation dynamics of an urban Cooper’s Hawk subpopulation is available at

About the journal: The Condor: Ornithological Applications is a peer-reviewed, international journal of ornithology. It began in 1899 as the journal of the Cooper Ornithological Club, a group of ornithologists in California that became the Cooper Ornithological Society, which merged with the American Ornithologists’ Union in 2016 to become the American Ornithological Society. In 2016, The Condor had the number one impact factor among 24 ornithology journals.

Timing of Migration Is Changing for Songbirds on the Pacific Coast

Thu, 12/07/2017 - 09:20

Volunteers collect data on captured songbirds. Photo credit: San Francisco Bay Bird Observatory

Changes in the timing of birds’ migration can have serious negative effects if, for example, they throw the birds out of sync with the food resources they depend on. A new study from The Condor: Ornithological Applications uses a long-term dataset from the Pacific coast and shows that the timing of bird migration in the region has shifted by more than two days in both spring and fall over the past two decades.

Gina Barton and Brett Sandercock of Kansas State University used 22 years of data from the San Francisco Bay Bird Observatory in northern California, where researchers captured and marked migrants as they passed through each year. Examining how migration timing was related to three indices of climate variation, including El Niño, they focused on five species—the Pacific-slope Flycatcher, Orange-crowned Warbler, and Wilson’s Warbler, which are short-distance migrants, and the Swainson’s Thrush and Yellow Warbler, which are long-distance migrants. They found that, over time, birds had been migrating earlier in spring and later in fall. About one third of this change in timing was explained by variation in climate indices, suggesting that some western songbirds can respond flexibly to changing environmental conditions. However, the two long-distance migrants had smaller changes in timing that were not as closely linked to climate indices.

The study of the timing of cyclic natural phenomena such as migration is known as phenology. “Long-term studies are valuable for understanding changes in the seasonal phenology of migratory birds and other organisms,” says Sandercock. “Our results join growing evidence that long-distance migrants may be less able to cope with rapid environmental change. However, the potential impacts of changing phenology on songbird population dynamics are difficult to predict, in part because our understanding of the migratory behavior of western songbirds remains incomplete.”

Sandercock adds that long-term projects like this one wouldn’t be possible without the commitment of many funders, technicians, and volunteers. “Our project was made possible by the dedicated efforts of many volunteers who assisted the staff of the San Francisco Bay Bird Observatory with systematic mist netting at the Coyote Creek Riparian Station. The long-term continuity could not have been maintained without stable financial support from funding by the Santa Clara Valley Water District, and the Pacific Gas and Electric Company.”

Long-term changes in the seasonal timing of songbird migration on the Pacific Flyway is available at

About the journal: The Condor: Ornithological Applications is a peer-reviewed, international journal of ornithology. It began in 1899 as the journal of the Cooper Ornithological Club, a group of ornithologists in California that became the Cooper Ornithological Society, which merged with the American Ornithologists’ Union in 2016 to become the American Ornithological Society. In 2016, The Condor had the number one impact factor among 24 ornithology journals.

Gina is now a Director for Cheesemans’ Ecology Safaris, an ecotourism company in Los Gatos, California. Brett is now a Senior Research Scientist with the Norwegian Institute of Nature Research in Trondheim, Norway.

Invasive Frogs Give Invasive Birds a Boost in Hawaii

Wed, 11/29/2017 - 16:02

Invasive coqui frogs are affecting nonnative bird populations in Hawaii. Photo credit: R. Choi

Puerto Rican coqui frogs were accidentally introduced to Hawaii in the 1980s, and today there are as many as 91,000 frogs per hectare in some locations. What does that mean for native wildlife? Concerns that ravenous coquis could reduce the food available for the islands’ native insect-eating birds, many of which are already declining, spurred researchers to examine the relationship between frog and bird populations—but their results, published in The Condor: Ornithological Applications, weren’t what they expected.

Working at fifteen sites on the island of Hawaii in 2014, Utah State University’s Robyn Smith, Karen Beard, and David Koons determined whether coquis were present at each site by listening for their calls at night and then estimated coqui density in invaded plots through a visual search.  Bird surveys at all sites recorded 20 species, of which only 5 were native. To the researchers’ surprise, native birds showed no response to coqui density or presence, but three of the nonnative species were more abundant in plots with coqui. The overall abundance of nonnative birds ranged from an average of 57 birds in coqui-free plots up to 97 where coqui density was highest.

Coquis forage mostly in leaf litter, while Hawaii’s native insect-eating birds forage mostly in canopy and understory, so perhaps they aren’t in direct competition for insects. Nonnative birds may be getting a boost directly by eating adult or juvenile coquis, or indirectly through coqui’s effects on the ecosystem—coquis may alter nutrient cycling and even increase fly populations thanks to the extra biomass their excrement and carcasses create. “I was very surprised with the results for birds. It had been hypothesized before our study that coquis would compete with birds, particularly natives, because we know that coquis reduce insects where they invade,” says Beard. “In retrospect, I guess it’s not too surprising that predation is a more important interaction than competition—that is a common finding in invaded systems—but it was definitely not what we went in to test. The response that we see for Common Mynas and Red-billed Leiothrix is pretty convincing. We’re pretty sure that some of this increase is due to these species eating live or dead coquis, and we’re suggesting that some non-native birds are likely consuming coquis and this novel resource appears to be increasing their populations.”

“The findings presented in the study by Smith, Beard, and Koons, where abundances of some species of non-native birds in Hawaii are correlated with invasive coqui frogs, are very intriguing,” according to the USDA’s Aaron Shiels, an expert on invasive species in island ecosystems. “Furthermore, their interesting findings beg for future experimental manipulations that would uncover the causal factors that explain the patterns that they have observed.”

Invasive coqui frogs are associated with greater abundances of nonnative birds in Hawaii, USA is available at

About the journal: The Condor: Ornithological Applications is a peer-reviewed, international journal of ornithology. It began in 1899 as the journal of the Cooper Ornithological Club, a group of ornithologists in California that became the Cooper Ornithological Society, which merged with the American Ornithologists’ Union in 2016 to become the American Ornithological Society. In 2016, The Condor had the number one impact factor among 24 ornithology journals.

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