Avian ecologist and Georgetown University Ph.D. student Emily Williams examines a robin's feet and claws, Wednesday, April 28, 2021, in Cheverly, Md. This spring and summer, her research project tracking the annual migration of American robins has gotten a boost from the enthusiasm of homeowners in the greater Washington area, who’ve let her and a research assistant set up makeshift research stations in their backyards before dawn — and sometimes contributed their own notes and observations. (AP Photo/Carolyn Kaster)

A wren rests on a hand as it is held by the feet, Wednesday, April 28, 2021, in Cheverly, Md. Cornell University records show a boom in amateur bird-watching. The number of people submitting eBird checklists — recording their bird sightings — was up 37% in 2020 compared with the previous year. (AP Photo/Carolyn Kaster)

A red-shouldered hawk flies up from a lawn, Monday, May 17, 2021, in Columbia, Md. The pandemic that put much of normal life on pause — stopping travel and shutting people in their homes — also afforded more time for many families to study the wildlife in their own backyards. (AP Photo/Carolyn Kaster)

Princeton University graduate student Severine Hex holds a female blue jay in her open hand to release it Saturday, April 24, 2021, in Silver Spring, Md. Hex gently removed the blue jay from a mist net used to capture birds for banding or other research projects. (AP Photo/Carolyn Kaster)

Avian ecologist and Georgetown University Ph.D. student Emily Williams holds a robin, Wednesday, April 28, 2021, in Cheverly, Md. Williams often begins her fieldwork at 4:30 a.m., but she can only be in one backyard at a time. And so her research, like that of many biologists, benefits from the cooperation and excitement of a growing number of citizen scientists — some of whom record their daily observations on Cornell University’s popular bird-watching smartphone app, eBird. (AP Photo/Carolyn Kaster)

A robin nestling reaches out with an open beak to be fed, Thursday, May 6, 2021, in Silver Springs, Md. (AP Photo/Carolyn Kaster)

A red-shouldered hawk perches in a tree with a worm in its mouth, Monday, May 17, 2021, in Columbia, Md. (AP Photo/Carolyn Kaster)

A female cardinal bites the finger of Princeton University grad student Trey Hendrix as he holds her moments before release Saturday, April 24, 2021, in Silver Spring, Md. Hendrix had gently removed the cardinal from a mist net used to capture birds for banding or other research projects. (AP Photo/Carolyn Kaster)

Home owner and bird watcher Sheila Salo watches from her deck as a female cardinal is held by a researcher and removed gently from a mist net, Wednesday, April 28, 2021, in Cheverly, Md. Cornell University’s records show a boom in amateur bird-watching. The number of people submitting eBird checklists — recording their bird sightings — was up 37% in 2020 compared with the previous year. (AP Photo/Carolyn Kaster)

A catbird flies form the open hands of avian ecologist and Georgetown University Ph.D. student Emily Williams, Thursday, May 6, 2021, in Silver Springs, Md. “Maybe you’d have to travel to Alaska or Canada to see a grizzly bear, or go to Africa to see a zebra — but birds are literally right outside your door, anywhere you are in the world,” she says. (AP Photo/Carolyn Kaster)

Bird watchers Matt and Sheila Salo look out over their backyard with binoculars, Wednesday, April 28, 2021, in Cheverly, Md. The pandemic that put much of normal life on pause — stopping travel and shutting people in their homes — also afforded more time for many families to study the wildlife in their own backyards. (AP Photo/Carolyn Kaster)

Four blue robin eggs are seen in the morning light, Thursday, May 6, 2021, in Silver Springs, Md. (AP Photo/Carolyn Kaster)

Avian ecologist and Georgetown University Ph.D. student Emily Williams holds a robin to examine its wings, Wednesday, April 28, 2021, in Cheverly, Md. “Realizing that this tiny animal that can fit in the palm of your hand can travel thousands and thousands of miles one way in spring, and then does it again later in the year, was just amazing to me,” she said. “I have always been dazzled by migration.” (AP Photo/Carolyn Kaster)

Avian ecologist and Georgetown University Ph.D. student Emily Williams releases an American robin after gathering data, Wednesday, April 28, 2021, in Cheverly, Md. “Realizing that this tiny animal that can fit in the palm of your hand can travel thousands and thousands of miles one way in spring, and then does it again later in the year, was just amazing to me,” she said. “I have always been dazzled by migration.” (AP Photo/Carolyn Kaster)