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Research Faculty

Interested in research at the Cornell Lab of Ornithology? Here are our Cornell faculty websites:



In the quest to understand nature, Cornell Lab scientists use cutting-edge technology to reveal secrets hidden in DNA, document rare wildlife, and discover how animals survive and communicate in a changing world.

A renowned center for bird study for nearly a century, the Cornell Lab of Ornithology is an exciting place where scientists and students investigate a diversity of topics and organisms (not just birds!). We enjoy a rich network of intellectual interaction among our community here, on the Cornell campus, and at collaborating institutions worldwide.

The Cornell Lab is a non-profit organization, with 99% of our support provided by members of the Lab, grants, and contracts. We are also a proud unit of Cornell University, which provides a wealth of academic resources and collaborations.

The Cornell Lab combines the best of a nonprofit environmental organization with scientific research of the highest standards, focused on our mission to interpret and conserve the earth’s biological diversity.

Project Highlights

Technology and Information Science

We develop new tools to record, gather, display, and analyze vast amounts of data, revealing new insights about wildlife.

Creating Automated Devices for Recording Animal Sounds

We develop the technology to remotely record the sounds of animals on land or in the ocean. Our underwater “pop-up” devices record sounds from the ocean floor, then pop up to the surface when the data are ready to be retrieved. Researchers have used pop-ups in more than 20 countries worldwide to monitor the sounds of marine wildlife as well as human-caused noise pollution.

In collaboration with the Woods Hole Oceanographic Institution, we developed an auto-detection buoy system to detect vocalizing right whales in near real-time. This enables us to notify ships of the presence of whales within a 5 nautical mile listening range of the buoy, alerting them to slow down and avoid deadly collisions with these endangered whales.

To record the sounds of animals on land, we developed devices that can be programmed and left in remote locations to record the sounds of rare and elusive wildlife for months at a time. We have used these devices to monitor endangered forest elephants, to detect the presence of endangered Black-capped Vireos and Golden-cheeked Warblers, and to document the calls of migratory songbirds as they migrate overhead at night.

Developing Digital Tools to Analyze Animal Sounds

We create software applications for biologists and the interested public to visually display, measure, and analyze sounds. With support from the National Science Foundation, we created Raven and Raven Lite, powerful user-friendly research and teaching tools for understanding sounds.

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Acoustic Technologies for Monitoring Bird Migration

Most songbird migration happens at night, when it’s hard to detect. With durable, autonomous recording devices pre-programmed to run for months at a time in remote sites, we gather information about the timing, location, and species composition of nocturnal bird migration. These audio recordings describe massive movements of migrating birds and they represent data that are unavailable by any other methodology. The recordings are crucial for conservation plans for migratory species. Andrew Farnsworth and colleagues developed a “Rosetta Stone” for the calls of 48 warbler species. Using remote microphone and analysis software, the team can identify birds flying overhead in darkness, yielding new information about migration over military bases, planned wind farms, and other locations. We have processed tens of thousands of acoustic recordings of more than 200 species of birds. Cornell Lab scientists have also developed sophisticated software enabling them to monitor Whip-poor-wills and other elusive species.

Tracking Night Migrants Across the Gulf of Mexico

Each spring and fall, hundreds of millions of birds embark on a 600-mile, nonstop flight across the Gulf of Mexico—even tiny thrushes, warblers, and hummingbirds. Ornithologists have been interested in these trans-Gulf migrations for decades, but it has proved very difficult to track such small birds over such huge distances. We are collaborating with researchers at the University of Southern Mississippi, University of Illinois, and Illinois Natural History Survey to deploy a “virtual fence” of automated radio-telemetry antennas and receivers across the northern coast of the Yucatán Peninsula, Mexico. Field workers on the U.S. Gulf Coast (Alabama) attach tiny radio-tags to birds as they migrate through; the receivers along the Yucatan coast relocate them as they arrive, noting where and when each individual makes landfall. In 2009, the Conservation Science program deployed seven autonomous recording units to the Yucatán coast to assist in this cutting-edge monitoring study.

The Macaulay Library's Online Archive of Biodiversity Media

We are building the world’s most comprehensive online archive of audio and video recordings of animal biodiversity. This online database can be used to explore the largest collection of avian vocal diversity in the world, to search for recordings of a given species, or to find scientific information about animal behavior and species occurrences in space and time. Explore the online archive, or contact us to find out how you can contribute your own recordings.

Avian Knowledge Network

Avian Knowledge NetworkWith more than 100 million bird observations online, the Avian Knowledge Network has amassed the world’s single largest collection of data on species occurrence. Made possible by collaborations with international experts and institutions, the Avian Knowledge Network organizes data and makes them widely accessible. The goals include educating the public about the dynamics of bird populations, providing interactive decision-making tools for land managers and advancing new exploratory analysis techniques to study bird populations. Learn more on the Avian Knowledge Network website.

Advances in Species Distribution Modeling

Why do birds occur where they do? And why do the distributions of some species change through time? This information is crucial for conservation of bird populations, but current methods of analyzing spatiotemporal dynamics are unreliable. We developed a modeling framework that allows researchers to incorporate time- and region-specific elements into a predictive analysis. The resulting models are called spatiotemporal exploratory models, or STEMs, which can be used to study how populations respond over time to broad-scale changes in their environments—for example, changes in land-use patterns, pollution patterns, or climate change. Using STEMs, we will be able to systematically map and monitor changes in migration flyways, providing necessary information to develop conservation strategies for migratory species. We expect STEMs to have a broad and important impact in ecology and conservation.

Human Impacts

We aid conservation efforts by advancing the understanding of how ecosystems are affected by human-caused change, including habitat loss and fragmentation, pollution, and energy development.

Birds and Habitat Fragmentation

Fragmented landscapes, in which natural habitat exists as isolated patches, are a common side-effect of human activities. We study the effects of fragmentation with the help of citizen-science participants. Our Birds in Forested Landscapes project involved volunteer birders at 3,800 sites across North America. The project yielded valuable insights about habitat fragmentation and factors such as occupancy by birds and local extinction rates. Results were published in scientific journals including the Journal of Animal Ecology, the Proceedings of the National Academy of Sciences, and Ecology and Society. The results have also been compiled into guidelines for land managers interested in conservation of tanagers, forest thrushes, and Golden-winged Warblers.

Habitat Fragmentation and the Florida Scrub-Jay

The Florida Scrub-Jay (Aphelocoma coerulescens) is a federally threatened species restricted to remnant patches of oak scrub in Florida. Habitat fragmentation, development, and fire suppression have contributed to steep population declines of this species. We have used genetic techniques to learn about movement patterns, both past and present, between habitat patches across the scrub-jay's entire range. These analyses help wildlife managers preserve what remains of the genetic variation in this dwindling species, by translocating birds and preserving and restoring their habitat. We are also using genetic techniques to study why these jays are susceptible to periodic epidemics of viral disease.

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Effects of PCBs on Bird Song

Polychlorinated biphenyls (PCBs) are worldwide chemical pollutants to which bird populations may be especially sensitive. Even at low concentrations, PCBs cause neurological damage and mimic estrogen activity, thereby altering sexual development and reproduction. Hormonal balance plays a key role in bird song, so it might be possible to monitor PCB exposure by studying songbirds. To test this hypothesis, researcher Sara DeLeon recorded songs and collected blood and feather samples from Black-capped Chickadees and Song Sparrows along a gradient of PCB contamination along the Hudson River in New York. Her preliminary results suggest that nonlethal levels of PCBs in the environment do affect bird song, a finding with implications for wild birds in polluted landscapes.

Assessing Pollution Risk and Forest Health

We are working with scientists from The Nature Conservancy in the Catskill Mountains of New York to quantify pollution risk and forest health. Trained volunteers gather data at 60 forest sites in the Catskills as part of a long-term monitoring project. We're also teaming with the Wildlife Conservation Society and other institutions to formally assess the risk posed by mercury deposition to New York biota. A report of this work can be found in the 2008 biennial report of the New York State Biodiversity Research Institute, p. 21 [Download PDF].

Effects of Acid Rain and Mercury on Birds

Led by scientist Stefan Hames, we are studying the biochemical pathways by which acid rain and mercury deposition reduce the availability of calcium, an important nutrient for nesting birds and their eggs. Data collected by participants in the Birds in Forested Landscapes citizen-science project indicated that Wood Thrushes are less likely to breed at sites heavily impacted by acid rain; the absence of high-calcium prey may be the cause. Further pollution research focuses on mercury contamination in birds, a condition that is surprisingly pervasive in upland habitats, particularly in combination with acid rain. With support from the Leon Levy Foundation, our researchers are developing a model of mercury contamination in New York forests and identifying regions and birds at high risk, including Wood Thrushes and Red-eyed Vireos.

Birds and Climate Change

Climate has an enormous influence on where birds survive and reproduce. In the short term, weather can influence the timing of migration, territory establishment, breeding, and egg laying. Over the long term, species have adapted to seasonal weather trends. As global climate patterns change, many harbingers of spring are occurring earlier each year. We combine data from citizen-science projects with long-term data on weather to examine climate's role in the changes we are seeing in the ranges of some bird species, as well as the timing and outcomes of breeding.

Reproduction, Climate Change, and Songs of North American Warblers

Mike Webster, director of the Macaulay Library, graduate student Sara Kaiser, and collaborators at the Smithsonian Migratory Bird Center are investigating how birds’ behaviors may change in response to climate change. The team studies Black-throated Blue Warblers to understand how changes in weather and food abundance affect reproductive hormones and behavior, and the prospects for the species’ long-term health. The study also uses recordings from the Macaulay Library to examine how song differences between populations may be leading to the splitting of this species in two.

Assessing the Impact of Wind Energy Development on Bird Populations

Wind power is a much-needed source of alternative energy, yet even as the industry grows rapidly, little is known about the risk to bird populations during construction and operation of wind facilities, and about where to site facilities to minimize harm to birds. We are working to develop and apply novel technology, such as acoustic monitoring of nocturnally migrating birds, to assess the risk to bird populations from proliferating wind-power development. With funding from the Leon Levy Foundation, our engineers are developing new applications that will assist decision-makers in siting wind turbines. We are working with a coalition of scientists from industry, government, and wildlife organizations to implement research priorities to minimize risk to wildlife. We are also helping Mexican ornithologists monitor birds at wind energy facilities at the Isthmus of Tehuantepec, a continental migratory flyway and Mexico’s largest and fastest-growing center of wind-power development.

Monitoring the Impact of the Wild-Caught Bird Trade

Many songbird species in Latin America are legally captured and sold as caged birds, including Indigo Buntings, Baltimore Orioles, and Painted Buntings. In collaboration with the U.S. Fish and Wildlife Service, the National Commission for the Knowledge and Use of Biodiversity (CONABIO), and Mexico’s General Wildlife Office, we have established a working committee to aid improved management, monitoring, and decision-making related to the cage-bird trade. These efforts will build capacity for monitoring the harvest of wild birds and provide scientific data on the impact to wild birds to inform decision-making.

Investigating Noise Pollution in the Ocean

In the underwater world, whales and many other animals rely on sound to communicate with one another. Yet the ocean is so noisy from shipping vessels, underwater energy exploration and development, sonar exploration, and other human activities that we are drowning out the sounds of whales. Right whales call to one another from 20 miles away or more, but scientists estimate that the area over which whales can hear one another has dropped by 90 percent because of noise pollution. The Bioacoustics Research Program is studying the responses of marine mammals to noise in the Stellwagen Bank National Marine Sanctuary in Massachusetts. In collaboration with international partners, we are also studying the role of noise pollution in the chain of events that lead to atypical mass strandings of beaked whales in the Bahamas.

Conservation Monitoring

Monitoring wildlife is challenging. Rare and elusive animals are hard to find, and widespread species are easy to find but difficult to keep track of across large geographic areas. We develop new tools, technologies, and citizen-science opportunities to surmount these challenges, providing critical information on the health and status of wildlife for conservation decisions and actions.

Protecting the World’s Last North Atlantic Right Whales

We use our high-tech systems to hear, monitor, and protect endangered North Atlantic right whales. Fewer than 500 of these magnificent animals remain in the world, and they are difficult to see and track as they migrate along the Atlantic seaboard. Our sound-detection systems provide valuable information about the whales’ numbers, locations, and activities along the East Coast. We use this information to understand how whales are affected by disturbance and noise pollution from energy exploration, shipping, and other human activities, and to advise industry and government on how to minimize harm to marine wildlife. In collaboration with other research agencies and the energy industry, we have established a right whale listening network in Massachusetts Bay. This network notifies shipping vessels to slow down when right whales are detected nearby, preventing deadly collisions between whales and ships.

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Advising the Energy Industry on How to Keep Whales Safe

We use sound to monitor whales and other marine mammals in areas proposed for oil and gas drilling. By detailing the numbers and activity of whales in these areas, we can inform energy companies about how to avoid interfering with the whales’ needs to find food and communicate with one another.

Listening to the Voices of Endangered Forest Elephants

In the dense forests of Central Africa, endangered forest elephants are difficult to study and protect because they are so difficult to see. We use sound-recording technology to listen for their vocalizations, giving us valuable information about their numbers, movements, and how they communicate with one another. We use this information to improve our understanding of elephants and to ensure their voices are heard in conservation decisions related to logging, hunting, and seismic exploration.

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Conservation of Focal Species

We conduct critical research to fill information gaps about threatened species and their habitats.

Ecology and Conservation of Endangered Yellow-headed Parrots

The Yellow-headed Parrot is an endangered species with isolated, fragmented populations. The species suffers from habitat loss in some areas and is still illegally trapped for the pet trade. Eduardo Iñigo-Elias from the Cornell Lab has conducted surveys to document the natural history and population status of the species in the Tres Marias Island Archipelago, Mexico. He is advising the Mexican federal government's National Institute of Ecology (INE-SEMARNAT) to protect the species.

Orange-breasted Falcon Research and Conservation

One of the least known falcons on the planet, Orange-breasted Falcons nest on steep cliffs where observing them is a challenge. With support from the Wolf Creek Charitable Foundation, we are improving and expanding the database of Orange-breasted Falcon records, including museum specimens, published articles, and records from birders. In collaboration with the Wildlife Conservation Society Petén Program and the Consejo Nacional de Areas Protegidas, we also conducted an expedition to Tikal National Park in Guatemala to record the sounds of these rare falcons.

Breeding Ecology and Conservation of the Common Nighthawk

The Common Nighthawk is a Neotropical migrant that breeds across North America. Although nighthawks are still locally common in some areas, they appear to be declining across their range, especially in urban and suburban areas. Unfortunately, nighthawk populations are difficult to census using traditional methods, so it has been difficult to assess changes in abundance over time. Cornell graduate student Rebecca Lohnes and Brett Sandercock at Kansas State University have developed a method enabling citizen-science participants across North America to monitor breeding populations of nighthawks. In addition, Rebecca has studied the breeding ecology of common nighthawks at the Konza Prairie Biological Field Station, Kansas, examining the influence of nest location, adult and chick behavior, and nest microclimate on nest success. She hopes that information about nest site characteristics of a relatively robust population of birds in native prairie will help to inform urban restoration efforts.

Clark’s Nutcracker and the Endangered Whitebark Pine Ecosystem

Whitebark pine ecosystems are rapidly disappearing in the western United States, and anecdotal evidence has shown that declining whitebark pine communities contributing to declines in local Clark’s Nutcracker populations. Clark’s Nutcrackers eat and store the trees’ seeds, and the seedlings sprout almost exclusively from seeds that the nutcrackers have stored. This interdependency between whitebark pine trees and Clark’s Nutcrackers has caused considerable concern about the future of both species, and leads to questions about the requirements for restoring deforested sites. Graduate student Taza Schaming is studying Clark’s Nutcrackers and conducting habitat surveys in Bridger-Teton National Forest, Wyoming, filling an urgent need to understand the survival, reproductive success, habitat use, and behavior of this unique, poorly known bird. Her work will help determine appropriate sampling methods for surveying Clark’s Nutcrackers in different habitat types, and she will model spatial and temporal changes of the birds’ occupancy and abundance as a function of whitebark pine and overall conifer density, cone crop, and the surrounding landscape. These data will be used to help generate a conservation strategy for the nutcracker-whitebark pine system.

Conservation Research: Black-capped Petrels

Black-capped Petrels are listed as critically endangered by the IUCN, due to drastic habitat loss on their breeding grounds and predation by invasive mammals including cats, rats, and mongoose. The global population is estimated to be as low as 2,000 birds. Of three remaining known breeding sites (two in Haiti, and one in the Dominican Republic), the site at La Visite, Haiti, is the largest, and harbors up to 90% of breeding Black-capped Petrels. Unfortunately, this forest is shrinking rapidly because local people have few or no economic alternatives to cutting trees for daily cooking fuel and expanding slash-and-burn agriculture to replace degraded lands. The tragic earthquake in January 2010 will inevitably increase pressure on the forest due to the exodus of people from the capital, Port-au-Prince. With support from the U.S. Fish and Wildlife Service and the John D. and Catherine T. MacArthur Foundation, graduate student Jim Goetz worked with collaborators to conduct surveys at the three main sites, trained local biologists, and will continue to collect data on the petrels’ abundance and breeding biology. Most importantly, the group will continue to engage with local and international partners to identify critical conservation areas and explore alternative livelihoods for local people to preserve as much remaining forest as possible.

Ecology and Conservation of the Endangered Cuban Parakeet

The Cuban Parakeet is a vulnerable species in Cuba, with highly fragmented and isolated populations. Cuban Parakeets are still trapped for the pet-bird trade, and habitat loss is important in some areas of Cuba where the species still breeds. Eduardo Iñigo-Elias is an advisor to Ph.D. candidate Maikel Cañizares, who is studying the distribution, behavior, and ecology of Cuban Parakeets. As part of the study, Maikel will learn bird-monitoring techniques and conduct research on how to augment breeding populations by providing artificial nest boxes.

Ivory-billed Woodpecker Research Project

In 1935, Arthur Allen and colleagues at the Cornell Lab, including Peter Paul Kellogg and graduate student James Tanner, embarked on the only formal study of the Ivory-billed Woodpecker. Less than 10 years later this magnificent bird was all but gone. In 2004 in the swamps of southeastern Arkansas, Gene Sparling observed a bird reminiscent of the famed "Lord God Bird." Soon after, search teams made five additional sightings and David Luneau captured a short video of a bird believed to be an ivory-bill. A five-year intensive, collaborative search of the bottomland hardwoods of the southeastern United States ensued—a second chance to find and protect a species that had become a vivid symbol of the most comprehensive conservation failure of 20th-century America. The Cornell Lab and partners searched more than 523,000 acres in 8 states, using acoustic monitoring technology to increase the chances of detecting Ivory-billed Woodpeckers. No definitive evidence was found and it is unlikely that ivory-bills still exist in the areas that were extensively searched.

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Golden-winged Warbler Conservation Initiative

We are working with partners to reverse the precipitous decline of Golden-winged Warblers, which have been extirpated from many areas because of habitat loss and hybridization with Blue-winged Warblers. As part of the Golden-winged Warbler Conservation Initiative, we have created a conservation strategy enabling state, federal, and private land managers in North and South America to manage habitat for Golden-winged Warblers and other species that depend on early successional habitats such as young forests. This strategy draws on monitoring, experimental management, and research to protect Golden-winged Warblers on their breeding grounds, wintering grounds, and during migration. It includes information from the Golden-winged Warbler Atlas Project, which engaged citizen-science participants in mapping the breeding range of Golden-winged Warblers. Primary funding is provided by the National Fish and Wildlife Foundation.

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Hybridization as a Conservation Threat

blue-winged warbler researchThe Golden-winged Warbler (Vermivora chrysoptera) is declining precipitously, due in part to the expansion of the closely related Blue-winged Warbler (V. pinus) into its range. The incursion of blue-wings has led to widespread interbreeding between the two species, followed by the rapid disappearance of golden-wings. We are using genetic approaches to map the pattern of hybridization throughout the past and present range of Golden-winged Warblers. One objective of this survey is to identify the most genetically “pure” remaining golden-wing populations, which have special priority for conservation.

Cerulean Warbler Atlas Project

Cerulean Warbler Atlas Project mapped breeding populations of Cerulean Warblers from 1997 to 2000 and identified critical sites and habitats in each state and province. This information formed the basis for a rangewide conservation plan developed through U.S. Fish and Wildlife Service. We continue to work with the Cerulean Warbler Technical Group, including the international El Grupo Ceruleo, which received a U.S. Forest Service International Cooperation Wings Across America award.

Conservation of Critically Endangered Purple-winged Ground-Doves

The Purple-winged Ground-Dove is a critically endangered bird of bamboo forests in Brazil, Paraguay, and Argentina. In collaboration with Argentinean ornithologist Juan Ignacio Areat and the conservation organization Armonia in Bolivia, we support surveys to find and document Purple-winged Ground Doves in the Atlantic Forest of Argentina and Paraguay during the flowering of Takuarusu bamboo. Research and monitoring of Purple-winged Ground Doves are needed to advance conservation efforts.

Tracking Vulture Declines

The catastrophic crash of White-rumped, Slender-billed, Long-billed, and Red-headed vultures in South Asia represents a particularly tragic case of wildlife being unintentionally harmed by human activity. In the past 20 years vulture populations in South Asia have fallen by more than 95 percent—likely the steepest population decline of any raptor group in modern history. It's largely due to an unexpected side-effect of an anti-inflammatory administered to cattle. We are striving to develop an understanding of population demographics (population size, rates of births/deaths, etc.) for several of these species in other parts of their Asian range as a crucial piece of information in saving them. To do this we are using noninvasive genetic mark-recapture techniques to obtain critical data on the biology and demographics of these birds that are otherwise very difficult to track and study in the wild.

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The Unique Birds of Hispaniola

The Caribbean island of Hispaniola (encompassing the Dominican Republic and Haiti) supports an unusually high number of endemic birds, including Broad- and Narrow-billed todies (Todus subulatus and T. angustirostris), Black-crowned and Gray-crowned palm-tanagers (Phaenicophilus palmarum and P. poliocephalus), Green-tailed Ground-Tanager (Microligea palustris), and Hispaniola Highland-Tanager (Xenoligia montana). Some populations of these species are critically endangered, particularly those in the poorly preserved forests remaining in Haiti. We study the genetic variation among these populations in order to identify those that are highly evolutionarily distinct. By prioritizing the preservation of these unique populations, we have a greater chance of preserving the adaptive diversity of these species and ensuring their long-term persistence.

Disease Ecology

We investigate the factors that drive the spread and impact of disease, using studies of behavior, genetics, avian immune responses, and citizen-science data to track continentwide changes in bird populations.

House Finch Eye Disease

In the winter of 1993–1994, people in the Washington, D.C., area began seeing House Finches at their bird feeders with a strange new disease. The area around the finches’ eyes was red and swollen, and in some cases the birds had become blind. The cause of the disease was identified as a common bacterial pathogen of domestic poultry. The bacteria had unexpectedly mutated and jumped to House Finches. Within three years, roughly 60% of House Finches in eastern North America were dead. The disease has persisted since then, and House Finch numbers have yet to recover completely. Bird Population Studies researchers developed a citizen-science monitoring program called the House Finch Disease Survey to document the spread of the disease and used additional citizen-science data to describe its impacts. Further work investigated why the pathogen has been so successful and the disease so persistent. The goal is to gain a better understanding of the ecology of other diseases in other organisms, including humans. This work involves close collaboration with researchers at five universities.

Genetics and House Finch Eye Disease

In the winter of 1994, people around Washington, D.C., began noticing House Finches with severe eye lesions caused by a bacterium called Mycoplasma gallisepticum. Within three years, this infection spread throughout House Finch populations east of the Rocky Mountains and killed many of them. We contribute to long-term studies of this epidemic by performing DNA-based diagnostics on samples taken from wild birds, and by studying the genetic diversity of House Finches in relation to their susceptibility to this disease. Among our findings is the discovery that the introduced population of House Finches in eastern North America is substantially less genetically diverse than the native population in western North America. We are also deciphering the evolutionary relationships between numerous strains of Mycoplasma, helping us learn where this infectious strain may have come from when it jumped into the House Finch population.

West Nile Virus

When West Nile virus arrived in North America in 1999, scientists began to document the sharp declines it caused in American Crow populations. Deaths of smaller, less common birds have been more difficult to detect; details of which species are affected, and how severely, are still not well known. We are analyzing data from citizen-science databases, including the Christmas Bird Count, North American Breeding Bird Survey, and Project FeederWatch. Our goals include understanding which bird species have been affected by West Nile virus, whether ecological factors such as bird species diversity have altered the virus's effects across the continent, and whether populations of affected birds are recovering.

Avian Malaria

Past students working in the Fuller Evolutionary Biology Lab have investigated the ecology of avian malaria. These studies have surveyed the host distributions of particular avian malaria species and tested the ability of particular mosquito species to transmit avian malaria among hosts.

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Mosquito Feeding Ecology

Many diseases and parasites are transmitted (or vectored) by insects and other arthropods, creating a complex transmission cycle involving the pathogens, the vector species, and the host species. To better understand this cycle we study the feeding patterns of one of the most notorious of all insect vectors, the mosquito. Using wild mosquitoes captured locally in Sapsucker Woods at the Cornell Lab of Ornithology, we use DNA bar-coding to analyze mosquito blood meals. After identifying each mosquito to species, we extract the blood meal from its abdomen to identify the species of bird or mammal the mosquito fed from.

Inbreeding and Disease in Crows

American Crows in Ithaca, New York, suffer from a suite of infectious diseases, including West Nile virus, avian pox, and numerous other bacterial, fungal, and viral infections. We have found evidence that there is a genetic basis for infection risk: Inbred crows have a higher probability of dying with disease symptoms than crows with unrelated parents. Inbreeding is rare and disadvantageous in nearly all animals, so it's a mystery why inbreeding is commonplace in these crows. We are now exploring the potential benefits of breeding with kin that might balance some of these disease costs.

Behavior and Ecology

We investigate the fascinating behaviors of animals and the complexity of the living world.

Banded Wren (Thryothorus pleurostictus)—Costa Rica

This species inhabits the tropical dry deciduous forest of the Pacific slope of Central America. Males sing 20 to 25 different song types and engage in intense vocal exchanges with rivals. We examine whether males with larger repertoires are more likely to sire extra-pair offspring, and whether males with smaller repertoires are more likely to be cuckolded. We developed and used a combination of single nucleotide polymorphisms and microsatellites to examine extra-pair paternity in this species with unusually low genetic diversity.

House Wren (Troglodytes aedon)—New York and Argentina

We are examining whether extra-pair paternity rates in the northern and southern subspecies of House Wren are higher when breeding is synchronized. In the northern subspecies, we are determining whether eggs fertilized by extra-pair mates are more likely to be laid earlier in the clutch. We are also investigating whether hatching order may explain survivorship and reproduction differences between nestlings sired by the social father and those sired by extra-pair males, using comparisons of nestling growth rates. We are also assessing how a male’s singing ability relates to his reproductive success, using paternity data to better understand mate choice.

Black-throated Blue Warbler(Dendroica caerulescens)—New Hampshire

Climate change is predicted to increase environmental variation. In species that engage in extra-pair copulations, adverse weather could cause males to spend less time and effort looking for mates, and reduce the incidence of extra-pair paternity. But the effects of weather on reproductive behavior remain poorly understood. We are examining the influence of weather on rates of extra-pair paternity in Black-throated Blue Warblers along an elevational gradient with a range of climatic conditions.

Acacia Ant (Crematogaster mimosae)—Kenya

We developed microsatellite DNA markers to study an ant species that lives in colonies with multiple queens. Our new methods allowed us to assess the parentage of female workers when neither parent was known. The work suggests that offspring from multiple queens may give an acacia ant colony a competitive advantage against foreign, neighboring colonies.

Cooperative Breeding: Acorn Woodpeckers

The remarkable Acorn Woodpecker of western North America lives in family groups of up to 15 individuals of both sexes and all ages. These permanent groups defend a territory together, store food together, and cooperate to raise young. For more than 30 years, Walter Koenig has studied individually marked Acorn Woodpeckers in central coastal California. Life in these groups is complicated, but it leads to an interplay of cooperation and competition that makes Acorn Woodpeckers unique in the avian world. Several related males compete to mate with several breeding females, all of whom lay their eggs in a single nest cavity. Offspring from these joint nests help raise the group's young for up to several years. Acorn Woodpeckers are also highly dependent on acorns, which they store, often by the thousands, in storage trees or granaries. This dependence provides much of the motivation for our Population Synchrony: Acorn Production by California Oaks study.

Population Synchrony: Acorn Production by California Oaks

Oaks are well known “masting” species—acorn production varies greatly from year to year, but is highly synchronized among trees. As a result, in good acorn years there is a bounty of acorns over a wide area, while in a poor year few if any are produced. Acorns are a critical food for many kinds of wildlife, including Acorn Woodpeckers. Walter Koenig leads a team in surveying acorn production across California and conducts a detailed study of oaks in central coastal California. His aim is to understand variability in acorn production, including why productivity differs, how far synchrony in acorn production extends, and what effects the variability has for California’s wildlife.

Documenting Courtship Behavior of New Guinea’s Birds of Paradise

For more than a decade, video curator Edwin Scholes has used digital video to document and study the courtship behaviors of New Guinea’s birds-of-paradise (family Paradisaeidae). In collaboration with wildlife photojournalist Tim Laman, this project has grown to become the most comprehensive collection of bird-of-paradise video footage in the world.

Florida Scrub-Jay (Aphelocoma coerulescens)—Florida

When molecular tools first showed that most birds mate with others besides their social mate, it came as a great surprise. Twenty years later, the discovery of a truly monogamous species is the surprise that begs explanation. The Florida Scrub-Jay is one such rare example. We are exploring whether this species deviates from monogamy in some parts of its range, which might help us to understand why genetic monogamy occurs in the first place.

Sexual Signals in Australian Fairywrens

In a collaborative study, Mike Webster, director of the Macaulay Library, studies the evolution of sexual signals in Australian fairywrens. The study aims to reveal how social and ecological environments interact to determine the plumage signals that males display during breeding, and how hormonal mechanisms maintain these plumage ornaments as honest signals of male health and condition. Graduate student Jenélle Dowling is further examining the role of male and female song in mating behavior, especially the information that song conveys to other birds and how females use song to select mates. Graduate student Dan Baldassarre is studying the evolutionary forces that lead to divergence in sexual signals across populations and the role that this might play in generating new species.

Superb Starling (Lamprotornis superbus)—Kenya

Superb Starlings live in cooperative family groups of as many as 30 individuals; their social structure is one of the most complicated in the avian world. They are “plural cooperative breeders,” meaning that several breeding pairs share a large pool of helpers. Some individuals form mating pairs for as long as five years and are strictly monogamous, but promiscuity can be high within family groups. We are investigating what drives some individuals to cheat and others to stay faithful, and what environmental factors influence whether an individual chooses to breed or to help raise another's offspring.

American Crow (Corvus brachyrhynchos)—New York

Parentage analysis of the socially monogamous American Crow have revealed that some offspring are sired incestuously, usually by the adult “helper” sons of breeding females. These incestuous matings are costly: genetically derived inbreeding coefficients suggest that disease probability is higher, and survival probability lower, for the most inbred birds in this population.

Citizen-Science Research on Bird Diversity, Distribution, and Abundance

Understanding changes in the distribution and abundance of populations is difficult because birds are so mobile and most species are widely distributed. In addition, fluctuations in food supplies or other changes in resources can cause local fluctuations that may not reflect broader patterns. Are populations really changing, or have the birds simply moved elsewhere? What effect do invasive, nonnative birds have on native bird communities? Do birds move in predictable patterns? These questions can only be answered by gathering observations across large spatial scales over long periods of time. Citizen-science programs such as Project FeederWatch are invaluable for collecting consistent information at spatial and temporal scales necessary to answer these questions. Using a hypothesis-testing approach to explore questions of importance to bird conservation, citizen-science researchers use long-term data, cross-validation with other surveys, and modern statistical approaches to detect patterns, investigate mechanisms, and understand changes.

Behavioral Ecology of Western Bluebirds

Citizen Science director Janis Dickinson leads a long-term study of Western Bluebirds focusing on cooperative breeding, sexual selection, and behavioral decision-making. For example, she has asked how territory quality, social environment, and individual characteristics influence life decisions—including how the survival and reproduction of young birds is affected by mistletoe wealth and living with parents. Graduate student Caitlin Stern is conducting experiments to examine the cryptic costs and benefits of living near a diversity of relatives during the breeding season. Another study focuses on mating behaviors. Like many songbird species, Western Bluebirds are socially monogamous and essentially mate for life, but nearly half the time females lay eggs that are sired by males other than the social father. Postdoctoral associate Elise Donnelly Ferree has used microsatellite DNA fingerprinting to explore the benefits of extra-pair mating for males and females, the age and plumage characteristics of individuals that are successful in extra-pair mating, and whether offspring sired by the social father or an outside male differ in survival, reproductive success, and future mating behavior. The research on Western Bluebirds is supported by grants from the National Science Foundation.

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Deciphering the Songs of Birds

Male birds use their melodious songs to attract females and defend their territories against rivals. How can their songs serve such different functions? We use microphone arrays to capture the dynamic interactions among singing Banded Wrens in Costa Rica to find out how males communicate with one another. We have investigated the dawn chorus, the meaning behind duets between males and females, and the ability of males to show their intentions to fight by matching the songs of their neighbors.

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Evolutionary Biology

We use field studies and the powerful tools of molecular biology to explore the history and diversity of life.

Understanding the Origins of Biodiversity

pipettingWe are exploring the process of speciation and how it is influenced by ecological factors and biological traits. Some species have patchy distributions, with areas of suitable habitat separated by uninhabitable areas. Are populations of these species more prone to diversify because of their physical isolation? Are sedentary populations more likely to diverge than those that are more mobile? When are differences in mating tactics and behaviors great enough to result in speciation? To investigate these questions, we gather information about the degree of genetic differentiation among populations, along with ecological and life-history data. Ongoing projects focus on the recent colonization of South America by breeding Barn Swallows, the effect of habitat on genetic divergence in cichlid fish and snails in Lake Tanganyika, Africa, and the influence of mate choice strategies on population differentiation in Australian fairywrens.

Understanding the Maintenance of Biodiversity

baltimore oriole paintingIn addition to investigating the origins of diversity, we explore how closely related species maintain their uniqueness. When two species interbreed, they may produce offspring that look, sound, and act intermediate between the parent species. So why, despite this occasional hybridization, do most species remain distinct? We are investigating the genetic reasons for this in pairs of species that often hybridize, such as Baltimore and Bullock’s orioles, and Indigo and Lazuli buntings.

Ancient-DNA Projects

By examining "ancient DNA," or DNA from old specimens, we can ask fascinating questions about extinct species or populations. But working with ancient DNA is technically demanding because degradation sets in soon after an animal's death. The Fuller Evolutionary Biology Program includes a dedicated ancient-DNA lab that we use when working with old or degraded specimens. We have successfully retrieved and analyzed old genetic material ranging from bird museum skins collected in the 1800s, to 5,000-year-old plant material recovered from receding glaciers in the Andes. Ancient DNA techniques also enable us to study materials from places that are difficult to access, and to examine the genetics of extremely rare, protected, or extinct species.

Evolution of Variation in Life Histories of Birds

We investigate reasons why the pace of life among birds varies so consistently with latitude. These patterns include slower metabolism and embryonic development, smaller clutches, and longer incubation periods in tropical birds than in their cousins at high latitudes. Most researchers have examined biotic explanations, such as differing food availability or predation rates. We focus on non-biological factors like differences in temperature and day length between the tropics and the temperate zone. Poultry scientists have pioneered understanding how temperature and photoperiod affect the physiology and development of birds. Following their lead, we take a tiered approach to investigate how incubation in wild birds is influenced by temperature and photoperiod. In turn, we study how local incubation patterns affect embryo development. We analyze data from citizen-science programs, such as NestWatch, and the NSF-funded Golondrinas de las Americas network, consisting of study sites focused on Tachycineta swallows across the Western Hemisphere.

How Many Genes Does It Take to Make a Good Evolutionary Tree?

Many questions remain about how best to uncover evolutionary relationships among species. This is partly because a phylogenetic tree resolved from a single gene sequence will differ somewhat from trees of other genes sampled from the same species. We are exploring this problem by analyzing many genes from small groups of birds such as North American chickadees. These studies help us better understand the relationships of these birds and how best to deploy our laboratory and analytical resources.

The Diversification of Skinks

Skinks of the genus Ctenotus are the most diverse vertebrate radiation in Australia, although exactly how many species of them there are remains an open question. With our Australian collaborators, we are building a Ctenotus phylogeny to define species and learn how this impressive diversification came about. Why are there so many species of Ctenotus skinks? How can so many closely related species coexist in the same habitats? And What could have isolated these populations enough to allow such diversification, given Australia's lack of major geographic barriers such as mountains or bodies of water?

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The Wood-Warbler Tree of Life

Our work on the evolutionary tree of the wood-warblers has yielded information on when and how this group of songbirds diversified. We have used this information to explore why some warbler species occur together in breeding communities, whereas others compete so strongly that they don't co-occur. We have shown that some wood-warbler lineages appeared rapidly early on in the group’s evolution, but diversification declined thereafter. This supports the idea that wood-warbler communities arose via “adaptive radiation” in which speciation slows as ecological niches fill. We have also taken an evolutionary approach to studying the life history, migration, and ecology of warbler species. We've found that warbler species living in taller trees or more open forest canopies tend to have higher frequency flight calls. View our Wood-Warbler Tree of Life for an introduction to our warbler work.

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Species Coexistence

Can closely related species coexist? According to a longstanding debate in evolutionary ecology, closely related species will compete until one excludes the other. But there's also the possibility that closely related species could overlap more than would be expected by chance because their evolutionary history constrains them to live in similar environments. Irby Lovette and Wesley Hochachka examined breeding distributions of North American wood-warblers along with data from a wood-warbler phylogeny (family tree). These data revealed that, in general, the degree of relatedness between two species had little effect on whether they coexisted at a site. Only very distantly related species pairs showed a greater likelihood of co-occurring than expected.

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