The types of birds coming through your neighborhood are probably changing, and so is the timing of their migrations. Birdwatchers noticing these differences are on the front line in figuring out how climate change and more severe weather events are putting stress on bird populations.
"Birders have to be much more alert to when birds are coming through than they used to be, since birds may be coming through much earlier or later than they used to," says John Rowden, director of community conservation at the National Audubon Society.
Birdwatchers are increasingly noticing unfamiliar birds normally found elsewhere, he says, and are seeing fewer of the birds they'd taken for granted.
"People are shocked when I say it. But just because we've seen these birds (year after year) doesn't mean they'll always be there. They are declining in numbers because we're throwing so many things at them, so we need to do what we can to help them," says Rowden.
At least 314 species of American birds are expected to lose 50 percent or more of their range by the end of the century, and have been listed by the Audubon Society as climate-threatened or endangered, Rowden says.
A United Nations science report issued Monday says 1 million species of plants and animals are at risk of going extinct. Scientists issuing the report in Paris blamed development that has led to loss of habitat, climate change, overfishing, pollution and invasive species.
Conservationists say there are a few easy steps people can take to help struggling bird populations, like planting native species, even in window boxes or patio containers, to encourage the native insects upon which birds depend, particularly for feeding their young.
The Audubon Society's Plants for Birds program encourages people to plant native plants; there's a website where you can type in your zip code to find out which plants will help birds in your area, and where to find those native plants and seeds locally.
During spring and fall migration seasons, people are encouraged to help migrating birds by minimizing outdoor lighting and covering reflective surfaces like large windows. Make indoor plants less visible to passing birds.
Birdwatchers can also help efforts to save the birds by tracking what they see on ebird.org, a national online data base run by The Cornell Lab of Ornithology.
"We also have a community science program called Climate Watch, which tries to collect data on how bird ranges are changing. It asks people to go out and do point counts of certain species, and runs from May 15 to June 15. That's something very helpful that birders can participate in," says Rowden.
"Birders love to see the same birds year after year, and keep track of when they are they going to come back each year during migration. Now, the timing may change and the windows may shift. You've got to be on the ball to spot them," he says.
"It's helpful if communities can pitch in to help," he adds.
Geoff LeBaron, director of the Christmas Bird Count at the National Audubon Society, says he has seen the effects of climate change firsthand.
"I've been a birder since I was a little kid," he says. "It's clear that climate change is affecting and will continue to affect birds on a global scale, and it's a question of whether or not they can adapt to what the climate is throwing at them."
Record droughts, floods, hurricanes and more are having a dramatic impact, he says.
"Hurricanes tend to happen during migration season and they happen initially over water, so they have a big effect on sea birds and can send them thousands of miles off track. Birdwatchers spot them when they get displaced over land."
Most at risk from climate catastrophes are sea birds and grasslands birds, experts say. Birds known as aerial insectivores, like swifts and nighthawks, are also at risk because the insects they depend on are getting harder to find.
One bird, the rufous hummingbird, is expected to lose all of its range in the United States within this century. And the yellow warbler, which is found across the country and is considered one of the more common birds, has declined by 25 percent since the 1960s, Rowden says.