Tag Archives: habitat management

Radar love: Weather data detects hotspots for migratory birds

Have you ever taken a long road trip covering hundreds or even thousands of miles, during which you were pretty much flying by the seat of your pants navigationally? Let me guess: You were broke, moving, between jobs, between semesters, on a journey of discovery, or all of the above. And if your trip took place in the not-so-distant pre-smartphone era, you were also constantly trying to figure out your next move based on maps, vacancy signs, and billboards promising all-you-can eat anything, though usually not salad.


Migratory birds like yellow warbler need to make many stops to rest and refuel during their annual journeys to wintering grounds as far away as South America. Credit: FWS

Migratory birds that breed in North America embark on a similar journey every fall to reach wintering grounds as far away as South America. Similar in that they are also flying by the seats of their pants, but different in that they are actually flying, are not wearing pants, and face much graver dangers than overindulging at the waffle bar.

Tall buildings, food scarcity, high winds, cats — rife with threats, migration is a stressful time in the life of birds. They suffer higher mortality in this period than in any other phase in their annual life cycles, and that can put a strain on entire populations. It’s critical that birds have safe places to rest and refuel along this perilous journey, and the more we can do to help manage and protect important stopover sites for them, the more likely they will be to reach their destinations.

The first step to protecting the most important stopover sites is to figure out where they are located. I know what you’re thinking: Bird migration road trip


Radars detect birds initiating migratory flights from stopover sites, and provide an estimate of the relative density of birds leaving a given location

Dr. Jeff Buler at the University of Delaware had a better idea. “In the Northeast, nothing provides more comprehensive coverage of the land surface than radar,” he points out. “It detects birds over more than a third of the land area in the Northeast.” 

With support from the U.S. Fish and Wildlife Service and other partners, Buler and his colleagues analyzed seven years of weather surveillance radar data to predict potentially important stopover sites for migratory landbirds in the region. They also conducted surveys for two fall seasons at 48 sites in the Delmarva peninsula and mainland Virginia to corroborate the radar detections with that they observed on the ground.

“We wanted to know: What are birds doing during stopovers, and why are they choosing certain sites over others?” says Buler. Here is what they found out:

Bright lights, bird city

When was the last time you gazed up at the Milky Way galaxy shimmering in the night sky from your front steps? For 70 percent of the population of the United States, it’s been awhile. Light pollution has increased dramatically in the past century, and the Northeast is one of the brightest areas on the entire planet. It’s affecting more than star gazers.

“Birds flying at about 500 meters above the ground can always detect the sky glow of some large city on the horizon,” says Buler. For migratory birds, artificial light is never out of sight, and it appears to be attractive. The study showed that migrant bird density increased with proximity to the brightest areas. Also known as cities.


A composite satellite image of the Northeast and Midwest shows the extent of artificial night light in the region. Credit: NASA

Two other key factors that determine where birds are likely to stop are the distance to the Atlantic coast, and the amount of hardwood forest cover on the landscape. “Migrant density is higher in places where there is more food, but migrants also become concentrated in coastal areas because winds push them out over the ocean, and they need need to retreat back to land,” explains Buler.

Across the landscape, results showed that birds responded positively to the coast, bright lights, hardwood forest, and any combination of those variables, indicating that migrant stopover was extra concentrated in woods of urban and suburban parks near the Atlantic coast.

“We need to recognize the importance of urban parks for migratory birds,” says Buler. For the thousands of individual birds representing hundreds of species that are passing through in the fall, these areas are like oases in the concrete jungle. Enhancing the habitat quality of urban forests for migrants by planting native vegetation that will host more insects and fruit during migration may be the best way to maximize the conservation value of these parks.

He also points out an important demographic detail: The relative intensity of use of urban areas is higher in the fall than in the spring. “Fall is when you see naive birds that are migrating for the first time, and studies show that juveniles have strong orientation to bright lights,” says Buler. “Probably in fall, parks are hosting a lot of young birds.” Which represent future generations of their species.

Between meals

If in the midst of a long road trip, you crashed on the floor of a friend’s studio apartment overlooking a busy intersection, you might be inclined to hit the road first thing the next morning. Especially if it’s that friend with the enormous dog who could use a bath and always seems to want to lick your face. If during that same trip, however, you crashed in the guest room of your grandparents’ quiet country home, and they were eager to cook for you, you’d probably stay until they kicked you out.

The ground surveys that Buler and his colleagues conducted at stopover sites in Virginia, Delaware, and Maryland not only helped them corroborate what they were seeing on the radar, they helped them figure out how long birds stayed at certain stopover sites, and why. As with people, it has a lot to do with the quality and quantity of resources available to help them rest and refuel.

“We could see the whole spectrum of uses across the framework of site types,” said Buler, explaining that the framework ranges from so-called “fire escape” sites that only offer a safe place to land in an emergency, to sites with lots of food and space where birds can comfortably rest and refuel.

“The fire-escape sites – which are typically along the coast and in urban areas — get heavy day-to-day use, but there is a lot of turnover,” he says. “Whereas birds tend to stay longer at sites away from the coast with lots of food.”


Shrubs that fruit in the fall, like American cranberry bush, are an important food source for birds during their seasonal migration. Credit: USDA

But the surveys showed that birds tend to stay the longest at sites in the middle of the resource spectrum. While that may seem counterintuitive to those of us who can’t get enough of grandma’s cooking, it’s consistent with what ornithologists call optimal migration theory. “If food is really good or really poor at a given site, you will only stay for a short time: Either there is nothing to eat, or you get a giant satisfying meal right away,” explains Buler. “At places where there is only a moderate amount of food available, it takes longer to refuel, so birds tend to stay longer.”

The surveys also provided detailed intelligence on what exactly migratory species are eating during their stopovers, and the researchers used that information to model habitat relationships for 14 of the most common species.

“For example, both black-throated blue warblers and American redstarts seem to be more closely associated with Lepidoptera larvae – caterpillars of moths and butterflies — than just insects in general,” says Buler.

Sky’s the limit for use on the ground

The combination of the regional radar data and the survey data equips people involved in conservation at any scale to identify important stopover sites and make management decisions that reflect the needs of specific species, such as ground foragers that feed on insects in the leaf litter.

The radar data capture nearly half of the National Wildlife Refuges in the Northeast, emphasizing their importance as stopover habitat, particularly in properties near the Atlantic Coast.

While the maps are useful for informing management strategies on protected lands — Buler says the data can help identify new priorities as well. “We can see many places with heavy use by migratory birds that are not yet protected.”

When Gwen Brewer of the Maryland Department of Natural Resources looked at the study results, she said, “The Pocomoke River corridor on the Eastern shore just lit up like crazy as a migratory hotspot.”

Pocomoke State Forest - Pocomoke River

The Pocomoke River corridor shows up as a hotspot for migratory birds on the radar. Credit: Maryland DNR

The DNR provided funding to help ground truth the radar data in coastal Maryland and the Delmarva Peninsula through the Resource Assessment Service Power Plant Research Program. Brewer, who is the Science Program Manager for the Wildlife and Heritage Service, said the study can direct her agency to other priority areas where they can use fine-scale data to narrow in on the forest patches that offer the greatest value to migratory birds.

“By showing us what stands out as important in Maryland, the study also helps us understand what our role should be in the big conservation picture,” she said. “It helps us think about the responsibility we have as part of the larger landscape, and that can inform our in-state process for acquisition, easements, and grant proposals.”

The full report, maps, and data depicting predicted bird density during fall migration are now available in the Northeast Stopover Sites for Migratory Landbirds gallery on DataBasin, and you can find a short video that the University of Delaware produced about the artificial light finding here.

Calling All Birdwatchers: For the Birds, and for Us

Imagine knowing the abundance, distribution, habitat preferences, breeding ecology, migration pattern, and wintering habitat for 100+ bird species in the State of Connecticut. This is no simple task, but it is one that the University of Connecticut and the Connecticut Department of Energy and Environmental Protection, along with many other partner organizations, citizen scientists, and bird lovers alike are willing to take on. The Connecticut Bird Atlas, starting in Spring 2018, will be the second such atlas conducted in the state, with the first Atlas of Breeding Birds in Connecticut published in 1994.

The scarlet tanager, a neotropical migratory species, was identified as a “Forest Health Indicator Species” by the Connecticut Forestlands Council Forest Ecosystem Health Committee for deciduous woodlands.

Unlike the first Connecticut Breeding Bird Atlas which aimed only to identify breeding distributions of Connecticut’s birds, the new study will survey distribution and abundance patterns throughout year, during both the breeding and non-breeding seasons. “The assessment will give us more detailed ecological information in terms of breeding dates, timing of migration, when wintering species arrive to overwintering areas, and how long they stay in overwintering areas,” says Randy Dettmers, senior migratory bird biologist for the U.S. Fish & Wildlife Service division of Migratory Birds, and contributor to the Connecticut State of the Birds.

Almost three decades since the first Atlas, the habitat for birds in Connecticut has changed significantly. Development and expanding infrastructure have fragmented habitats, a benefit to birds who are habitat generalists but a detrimental change for species that require large areas of undisturbed forest; reforestation of previously developed land has benefited birds that use both mixed hardwood and coniferous forest, but presents challenges for birds that rely on early successional habitats (young forests); loss or conversion of agricultural lands has negatively impacted birds that prefer the old agricultural fields or grasslands but benefit birds who prefer forested habitat; and more variable climate conditions have resulted in birds with a historically “southern” range to now reside in Connecticut year-round. The new Atlas will capture the changes in abundance, distribution, and species composition as a result of these habitat changes, and the data will have implications for creating sound conservation plans, including the Connecticut State Wildlife Action Plan, that will benefit birds and other wildlife.

Zone land cover change in Connecticut from 1985-2010.

Birds are an indicator species for the health of our environment, meaning the presence, abundance, or absence of birds is indicative of a change in the biological health of an ecosystem.

Birds make an excellent proxy for diagnosing the health of an ecosystem which includes birds, other wildlife, and people. They serve as an indicator for how we are adapting or not adapting to the changing landscape and changing climate, making the new Atlas an essential decision-making tool for land managers, municipal planners, developers, state and federal agencies, and conservationists alike.

The cerulean warbler was identified as a “Forest Health Indicator Species” by the Connecticut Forestlands Council Forest Ecosystem Health Committee for deciduous woodlands. Among the rarest Neotropical migrant songbirds, their populations continue to decline due to loss of breeding, migrating, and overwintering habitat.

As often stated, birds do not recognize boundaries, and can be thought of as having dual citizenship. Therefore, the new Atlas will not only provide important implications for the state of Connecticut, but will be used to develop and implement comprehensive, region-wide conservation management strategies. “The updated information from the new Atlas will help us understand how different bird species are shifting their distributions and abundance in southern New England,” says Randy Dettmers. “When comparing the data to information from surrounding states, we will gain a better understanding of how birds are responding to larger environmental changes, including changes in land use, levels of contaminants in the environment, and changes in temperature and precipitation patterns.”

The golden-winged warbler was identified as a “Forest Health Indicator Species” by the Connecticut Forestlands Council Forest Ecosystem Health Committee for shrubland and young forest habitats. Populations are declining due to loss of breeding and wintering habitat.

Without citizen science, scientists would not be able to collect the necessary data to accomplish the task at hand.

The CT Bird Atlas project will be accomplished through the collaborative work of professionals and citizen scientists. Interested in taking advantage of this opportunity to learn about birds and their habitats, gain science skills, and connect with nature while giving back? Check out the CT Bird Atlas website here to see how you can get involved!


Habitat partnership bats a thousand in Pennsylvania

Today we’re sharing the hard work of Tom and Wendy Belinda, who have dedicated themselves to conserving habitat for endangered Indiana Bats on their land in Blair County, Pennsylvania. White-nose syndrome, human disturbance, and habitat loss have caused our nation’s bat populations to plummet. Close proximity to places where bats roost and hibernate makes the Belindas’ property prime real estate for bat conservation in Pennsylvania.

Indiana Bats

Credit: Ann Froscheaur/USFWS

Working with federal agencies like the USDA’s Natural Resource Conservation Service and the U.S. Fish and Wildlife Service, along with the Pennsylvania Game Commission and local partners, has allowed the Belindas to manage their property for the benefit of Indiana Bats and other vulnerable species. However, enhancing the health of their forests not only improves wildlife habitat, it also boosts the value and productivity of their land. A true win-win.

Check out our bat story map to learn more about the nationwide effort to conserve bats.

For more information about white-nose syndrome, visit www.whitenosesyndrome.org.