Current Projects
Mapping stopover habitat hotspots for bird conservation
Stopover sites, where birds land to rest and refuel during migration, are essential for the conservation of migratory species. Landbird migration occurs over relatively broad spatial scales and migrants often use a wide variety of habitat types during stopover – traits that increase their chances of encountering anthropogenic hazards. However, conservation plans often lack explicit consideration of the stopover period or threats to stopover habitats. Consequently, I am identifying and describing key stopover habitats and threats to those areas for inclusion in Maryland’s 2025 State Wildlife Action Plan, a comprehensive document that will guide conservation of wildlife and their habitats across the state for the next ten years.
For my postdoctoral research at UMCES, I am using weather surveillance radar and bird abundance data along with spatial covariates to map stopover hotspots across the state. Working closely with biologists from the Maryland Department of Natural Resources (DNR), I will identify threats to these key habitats from sources such as energy development and infrastructure that can pose collision risks to migrating birds. This project will provide valuable on-the-ground information about the habitat needs of birds migrating through Maryland at relevant scales for decision makers. Natural resource managers and policy makers can use these data to decide where to target management efforts for species of greatest conservation need in this highly developed yet biodiverse region of the Atlantic Flyway.
Stopover sites, where birds land to rest and refuel during migration, are essential for the conservation of migratory species. Landbird migration occurs over relatively broad spatial scales and migrants often use a wide variety of habitat types during stopover – traits that increase their chances of encountering anthropogenic hazards. However, conservation plans often lack explicit consideration of the stopover period or threats to stopover habitats. Consequently, I am identifying and describing key stopover habitats and threats to those areas for inclusion in Maryland’s 2025 State Wildlife Action Plan, a comprehensive document that will guide conservation of wildlife and their habitats across the state for the next ten years.
For my postdoctoral research at UMCES, I am using weather surveillance radar and bird abundance data along with spatial covariates to map stopover hotspots across the state. Working closely with biologists from the Maryland Department of Natural Resources (DNR), I will identify threats to these key habitats from sources such as energy development and infrastructure that can pose collision risks to migrating birds. This project will provide valuable on-the-ground information about the habitat needs of birds migrating through Maryland at relevant scales for decision makers. Natural resource managers and policy makers can use these data to decide where to target management efforts for species of greatest conservation need in this highly developed yet biodiverse region of the Atlantic Flyway.
This Motus receiver station in Pennsylvania records any animal carrying a "nanotag" radiotransmitter that flies within its detection radius - regardless of where in the world it was tagged! The Motus network allows us to track the movements of small birds across large distances without having to recapture them.
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Bird migration phenology
In temperate regions, spring is a time of increasing plant growth and food availability for migrating organisms. In many areas, this vegetation growth ("green-up") follows a relatively predictable pattern in space and time: green-up occurs earlier in the year at low latitudes and elevations, arriving later to more northerly and high elevation sites. This pattern in spring onset is known as the "green wave," and populations of some migratory herbivores time their migrations so that they travel with the leading edge of spring's green wave (a strategy known as "surfing"). Others herbivores migrate faster than the green wave and even "jump over" it, arriving to stopover sites or the breeding grounds before spring arrives. We were curious to learn what type of strategy insectivorous songbirds use while migrating through North America in spring. Using the Motus Wildlife Tracking System, a network of automated radio telemetry stations scattered across the western hemisphere (and beyond!), we attached tiny "nanotag" transmitters to individual songbirds and tracked them as they migrated northward from the southern U.S. towards their breeding grounds. Rather than surfing or jumping, songbirds in our study migrated faster than the green wave, catching up to its leading edge as they traveled northward. |
Hot off the presses!
Nemes, C. E., Marra, P. P., Zenzal Jr., T. J., Collins, S. A., Dossman, B. C., Gerson, A. R., Gómez, C., González, A. M., Gutierrez Ramirez, M., Hamer, S. A., Marty, J., Vasseur, P. L., & Cohen, E. B. (2023). Springing forward: Migrating songbirds catch up with the start of spring in North America. Journal of Animal Ecology 00:1-13. Free to read here, or email me for a PDF copy!
Nemes, C. E., Marra, P. P., Zenzal Jr., T. J., Collins, S. A., Dossman, B. C., Gerson, A. R., Gómez, C., González, A. M., Gutierrez Ramirez, M., Hamer, S. A., Marty, J., Vasseur, P. L., & Cohen, E. B. (2023). Springing forward: Migrating songbirds catch up with the start of spring in North America. Journal of Animal Ecology 00:1-13. Free to read here, or email me for a PDF copy!
Nonlethal effects of threats during migration
Humans have dramatically altered the landscapes and airspaces through which birds migrate, and migration is thought to be the most dangerous part of the annual cycle for most species. While we know that many anthropogenic threats - including building windows, free-roaming cats, wind turbines, and toxins - kill migrating birds directly, these threats can also have less obvious effects that don't cause immediate mortality, but have delayed consequences for reproduction and future survival in later phases of the annual cycle. In addition, birds often encounter multiple anthropogenic threats en route that produce additive or synergistic effects on fitness. For the American Ornithological Society's Wesley Lanyon Award competition, I led our lab group's review of these nonlethal effects on migrating birds. We found documentation of nonlethal and interactive effects from anthropogenic threat sources, but also identified many gaps in the scientific literature. We argue that failing to account for nonlethal effects may mean that we greatly underestimate the harmful consequences of human activity on migrating birds.
Nemes, C.E., Cabrera-Cruz, S.A., Anderson, M.J., DeGroote, L.W., DeSimone, J.G., Massa, M.L., & Cohen, E.B. 2023. More than mortality: Consequences of human activity on migrating birds extend beyond direct mortality. Ornithological Applications. Free to read here or contact me if you'd like a PDF copy!
Humans have dramatically altered the landscapes and airspaces through which birds migrate, and migration is thought to be the most dangerous part of the annual cycle for most species. While we know that many anthropogenic threats - including building windows, free-roaming cats, wind turbines, and toxins - kill migrating birds directly, these threats can also have less obvious effects that don't cause immediate mortality, but have delayed consequences for reproduction and future survival in later phases of the annual cycle. In addition, birds often encounter multiple anthropogenic threats en route that produce additive or synergistic effects on fitness. For the American Ornithological Society's Wesley Lanyon Award competition, I led our lab group's review of these nonlethal effects on migrating birds. We found documentation of nonlethal and interactive effects from anthropogenic threat sources, but also identified many gaps in the scientific literature. We argue that failing to account for nonlethal effects may mean that we greatly underestimate the harmful consequences of human activity on migrating birds.
Nemes, C.E., Cabrera-Cruz, S.A., Anderson, M.J., DeGroote, L.W., DeSimone, J.G., Massa, M.L., & Cohen, E.B. 2023. More than mortality: Consequences of human activity on migrating birds extend beyond direct mortality. Ornithological Applications. Free to read here or contact me if you'd like a PDF copy!
Bird responses to predators on migratory stopover
Most migrating songbirds don't fly nonstop to reach their destinations. Instead, they make relatively short (generally nocturnal) flights and then land at a stopover site to rest and refuel. At each new stopover location, birds must quickly find food, fend off competition, avoid predators, and take shelter from the elements - not to mention squeezing in time for sleep, rest, and recovery. Birds that are trying to complete the migratory journey as fast as possible (a time-minimizing strategy) may be more likely to take risks, such as spending less time watching for predators or foraging in more exposed habitat. Humans have introduced novel predators - free-roaming domestic cats - across the migration landscape. Despite this, the behavioral responses of migrating songbirds to cats and other predators have been little studied. I designed a field experiment to test how Gray Catbirds on stopover respond when faced with the threat of a native predator (hawk) or invasive predator (domestic cat). In addition to recording immediate behavioral changes, I attached nanotags to catbirds to assess how predator exposure affects their activity and departure from the stopover site. The wonderful staff at Powdermill Avian Research Center in Pennsylvania were kind enough to let me set up my aviary experiment there. Stay tuned for more results and forthcoming publications! (Powdermill's coverage of this research, re-created with marshmallow peeps) |
Free-roaming cats in Puerto Rico
Free-roaming domestic cats are a major threat to birds and other wildlife worldwide. Introduced predators such as cats are especially harmful on islands, which often have high numbers of endemic species and no native mammalian predators. In addition, many of the birds that breed in the U.S. and Canada migrate south to spend a large portion of the year in the Caribbean, and successfully conserving them requires understanding the threats they face in both non-breeding and breeding areas.
I designed a camera trapping project to estimate cat densities across a gradient of urbanization in San Juan, Puerto Rico, the island's most populous municipality. With collaborators in Puerto Rico, we collected tens of thousands of photos of cats at our camera trapping grids, as well as fecal samples to identify what birds and other prey cats may be eating. Using spatial capture-recapture models, we estimated extremely high numbers of cats across the municipality, even in exurban areas. DNA metabarcoding for the diet analysis is currently underway. Stay tuned for more results and forthcoming publications!
Free-roaming domestic cats are a major threat to birds and other wildlife worldwide. Introduced predators such as cats are especially harmful on islands, which often have high numbers of endemic species and no native mammalian predators. In addition, many of the birds that breed in the U.S. and Canada migrate south to spend a large portion of the year in the Caribbean, and successfully conserving them requires understanding the threats they face in both non-breeding and breeding areas.
I designed a camera trapping project to estimate cat densities across a gradient of urbanization in San Juan, Puerto Rico, the island's most populous municipality. With collaborators in Puerto Rico, we collected tens of thousands of photos of cats at our camera trapping grids, as well as fecal samples to identify what birds and other prey cats may be eating. Using spatial capture-recapture models, we estimated extremely high numbers of cats across the municipality, even in exurban areas. DNA metabarcoding for the diet analysis is currently underway. Stay tuned for more results and forthcoming publications!
Previous Projects
Cerulean Warbler microhabitat use
For my M.S. thesis at Ball State University with Dr. Kamal Islam, I studied habitat use of Cerulean Warblers in southern Indiana (yes, Indiana does have trees). This research was part of the Hardwood Ecosystem Experiment, a 100-year study of how flora and fauna respond to different forest management techniques, such as timber harvesting and prescribed burns. The Cerulean Warbler is a migratory songbird whose populations have declined precipitously in recent decades, and land managers in the US and Canada are interested in learning how to manage forests to provide good breeding habitat for the species. We searched for Cerulean Warbler nests in treatment and control units (easier said than done!), mapped out male territories, and measured nest site and territory characteristics along with control plots to see what small-scale ("microhabitat") features Cerulean Warblers prefer.
Nemes, C. E., & Islam, K. (2017). Breeding season microhabitat use by Cerulean Warbler (Setophaga cerulea) in an experimentally-managed forest. Forest Ecology and Management, 387, 52–63. https://doi.org/10.1016/j.foreco.2016.11.008 (PDF)
Bonus natural history observation: We found a weird Cerulean Warbler nest! What's going on with it?
Nemes, C., Islam, K., & Pirtle, D. (2015). First Documentation of a “Double-Decker” Cerulean Warbler ( Setophaga cerulea ) Nest. The Wilson Journal of Ornithology, 127, 534–538. https://doi.org/10.1676/14-157.1
For my M.S. thesis at Ball State University with Dr. Kamal Islam, I studied habitat use of Cerulean Warblers in southern Indiana (yes, Indiana does have trees). This research was part of the Hardwood Ecosystem Experiment, a 100-year study of how flora and fauna respond to different forest management techniques, such as timber harvesting and prescribed burns. The Cerulean Warbler is a migratory songbird whose populations have declined precipitously in recent decades, and land managers in the US and Canada are interested in learning how to manage forests to provide good breeding habitat for the species. We searched for Cerulean Warbler nests in treatment and control units (easier said than done!), mapped out male territories, and measured nest site and territory characteristics along with control plots to see what small-scale ("microhabitat") features Cerulean Warblers prefer.
Nemes, C. E., & Islam, K. (2017). Breeding season microhabitat use by Cerulean Warbler (Setophaga cerulea) in an experimentally-managed forest. Forest Ecology and Management, 387, 52–63. https://doi.org/10.1016/j.foreco.2016.11.008 (PDF)
Bonus natural history observation: We found a weird Cerulean Warbler nest! What's going on with it?
Nemes, C., Islam, K., & Pirtle, D. (2015). First Documentation of a “Double-Decker” Cerulean Warbler ( Setophaga cerulea ) Nest. The Wilson Journal of Ornithology, 127, 534–538. https://doi.org/10.1676/14-157.1
Gallery
© Claire Nemes, 2023