Jessica Colby had just seen the first yellow-rumped warbler of the spring.
Next, a pelican arrived at the lake at the Majestic View Nature Center in Arvada.
“Turkey vultures are a sign of spring,” said Colby, the nature center’s assistant director and a Denver Audubon master birder. “They started arriving the last few weeks. All of the fly eaters are showing up. They can’t be here in the winter because we don’t have flies. Phoebes, meadowlarks, flycatchers.”
It’s an exciting time of the year for Colorado birdwatchers.
Over the next two to three weeks, millions of birds will fly through the state’s night skies as they migrate north for the summer. All will pause to rest and eat during the day. Some may stay until fall to mate and raise offspring. Others will continue their journeys north, to as far away as Alaska.
And all of them will be in danger.
As Colorado enters its peak bird migration season, forecast to run Sunday through May 18, songbird populations are in decline. The list of declining species includes the lark bunting, Colorado’s state bird, which has seen its population drop by 38% in the last 11 years, according to eBird, an online database that tracks bird populations in the United States.
But scientists and bird watchers say humans can do things to help their migratory visitors.
“It’s a pretty dramatic shift, unfortunately, for that species,” said Kyle Horton, an assistant professor of fish, wildlife and conservation biology at Colorado State University
The 2025 State of the Birds report, produced by the U.S. North American Bird Conservation Initiative Committee in March, found a third of all American bird species — 229 — are at what researchers call a “tipping point,” meaning they are showing long-term declines and, in some cases, have “perilously low populations.”
The report for the first time this year also expressed concern for ducks, which have trended downward in recent years after historically being a bright spot.
Furthermore, the journal Science on Thursday published a new study that showed 75% of North American bird species are in decline, and populations dropped most steeply in places where those species were the most abundant.
The reports come five years after a landmark study published in Science that showed a loss of 3 billion birds in North America in 50 years. That report sounded the alarm and led scientists and conservationists to begin public awareness campaigns on how to help birds.
That’s the origin of the National Audubon Society’s semi-annual Lights Out Program, which encourages people to turn off outdoor lights at night when birds are on the move.
“For many, many thousands of years these birds have migrated under the cover of darkness, looking at stars to navigate,” said Horton, who is also the principal investigator at CSU’s AeroEco Lab, which studies bird migration. “In the last 100 years, it’s gotten much brighter.
Migratory birds are attracted to the glow of cities and might fly off course or waste energy circling them. In the most extreme cases, they collide with buildings, he said.
But even turning off outdoor floodlights in the suburbs helps. If a person is leery of having their property completely dark, they should use lightbulbs with a more orange glow, Horton said.
“It’s hard to think that would matter, but it’s a collective action that, if we buy into it, we can make a difference,” he said. “It helps migratory birds, but it also helps a lot of wildlife that’s disrupted as well.”
Birds migrate at night for various reasons.
Nighttime travel means cooler temperatures and calmer winds for the birds, which migrate because of food resources.
“They’re going to have to stop and refuel. Eat a bunch of food and insects to continue on their migration,” Horton said. “So, to be able to fly all night and forage all day, it speeds up their migrations. During migration, they don’t have to sleep much.”
The birds, however, face threats in flight and on the ground.
Habitat loss is a leading cause of bird population decline.
Prairies converted to agricultural land and suburban development not only take away the grasses that attract the insects that birds eat, but they also create pollution from insecticides or other chemicals people use to alter the landscape. Wildfires also destroy habitat, Horton said.
“There are a bunch of things on the landscape that we do to hurt birds,” he said.
Cats are also killers. They catch millions of birds every year.
“These poor birds,” said Colby, from the Majestic View Nature Center. “They just migrated overnight. They’re exhausted and they’re hungry. They’re just interested in finding food and resting. They’re vulnerable to house cats.”
Finally, buildings — especially tall ones with big windows — are dangerous for birds that are confused by the reflections.
Birds are “smack in the middle” of the ecosystem, and it’s important to help protect them, Colby said.
Predators such as owls, hawks and eagles help manage mice, rats and voles. On the other end of the spectrum, bird eggs feed snakes and some birds themselves are food for other animals.
“They fill all of the ecological niches,” Colby said. “They are so tightly connected to our pollinator population, and that pollinator population is connected to the plant population, and we need those keystone pieces. You can’t look at any ecosystem without looking at birds.” So, what do experts recommend people do to help birds take flight?
How you can help migrating birds
- Turn off outdoor lights at night
- Build pollinator gardens and plant native grasses
- Put decals on windows so birds can see them
- And, for the love of birds, keep your cats inside
“Anyone can make a small difference and all those small differences can help to scale up with help our bird species,” Horton said.