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Flying the Friendly Backyard Skies
by Jake Farley
Once Number 4 on the highest population list of birds across the continent, the American crow dropped to number 10 last year. Great Backyard Bird Count and Christmas Bird Count data show that in New York, Chicago and Illinois, American crow populations declined after an outbreak of West Nile Virus. In some New York City locales, their numbers dropped 90 percent.
American crows are particularly susceptible to West Nile Virus, which they get from mosquitoes. In the lab 100 percent of those infected, die. “Scattered locations along the New England coast began showing declines in 2000, the year that migrant birds began to carry the virus along the Eastern seaboard," says Miyoko Chu, GBBC spokesperson.
Why should anyone wonder or care about such a common species? Chu reminds us of the 3 to 5 BILLION passenger pigeons, once the most common bird in North America, that went extinct forever in less than 100 years. “Just because a bird is common it doesn't mean we should be complacent in our effects for them and their habitats," she says.
Cornell Lab of Ornithology conducts two nationwide programs for people who enjoy watching birds. The programs are not only fun, but result in databases that help scientists understand trends of bird movement, population flows, and bird behavior. Ultimately, they may help stop the demise of birds whose numbers are decreasing by providing critical data to government agencies that can protect them.
Will one such bird be the American crow?
The Great Backyard Bird Count is a four-day snapshot from February 18 through 21.
Project FeederWatch is a compendium of avian knowledge acquired through checklists sent in by about 100,000 people a year from November through early April. The program just received its one-millionth checklist since 1987.
With just a few clicks of a mouse, data is instantly sent, received, sorted, and applied. Participants can look at their contributions just moments later, and see how it affects scientific observations.
David Bonter, ornithologist and project leader for Project FeederWatch, offers a few interesting trends discovered through that program:
1. There is an impressive movement of Great Gray Owls from out of boreal forests into the backyards of southern Minnesota, Michigan, Quebec, and Ontario. About every ten years their food supply of rodents decreases, and that is when the owls move south. The owls in Minnesota were banded twice this winter, but have been observed coming into backyards since late November, says Bonter.
“Great Gray Owls are tame because they don't see people where they live." Banders discovered that all the birds were adults with no juveniles, inferring poor reproduction last year. Great Gray Owls are 33 inches tall with a 60-inch wing span.
2. Hummingbirds that breed west of the Rockies usually winter in Central and South America - up until now with reports of them heading to feeders in southeastern U.S. Calliope, the smallest US hummer at 2¾ inches, fed in Delaware and Ohio; Rufous in Delaware and South Carolina; and black chins probably in Mississippi.
3. The red-bellied woodpecker, a species common to the mid-Atlantic, has been seen in Vermont and Quebec. “It's consistent with the northward march of this species, plus a few others like the Carolina wren and tufted titmouse," says Bonter, who can only speculate why.
It may be that milder winters allow a higher survival rate in the northern edge of their range. When young resident birds disperse in the fall, they fly in all different directions, some heading north. In harsh winters - all it takes is a few subzero days - these birds will typically not survive and breed. But with an abundance of high quality food such as peanuts at bird feeders, they can keep their energy up to survive those days.
Feeding the birds may help those northward bound. From 40 to 70 million Americans feed birds these days. Some resident birds cache food under tree bark and in crevices. “They have a remarkable ability to remember where they stash food and they can remember where they put the highest quality food and get that first,"¯ says Bonter.
American robins move in large nomadic packs in winter, looking for fruit. “A flock of 40 to 60 robins in mid-February can strip all the fruit off a crabapple tree and leave in a day," Bonter says. “That leaves a lasting impression and we hear about it all winter." There seems to be no pattern to their movement, but sightings of flocks can be followed on the animated map on the lab's website below.
So why else besides observing the fascinating behavior of birds and contributing data that may help conserve their numbers should you participate? “You have a better idea of what's happening in your backyard or forest or down the street, more than a few grumpy old ornithologists in the lab," says Bonter. “By participating, you learn more about the birds in your own backyard and learn about behaviors and nature and connecting with nature again."¯
Chu says the GBBC is important because, “We can look back in time and see patterns. American robins in winter are so widespread and common, so the data is wonderful because you can get 100s and 1000s of people from a wide area to construct where they are."¯
Carolina wren experienced a dramatic drop last year compared with 2003 - from 252 to 99 individuals.
So how to protect? By getting them listed on endangered and threatened species lists, and by protecting habitat -- but it all starts here with the data. “To get an overall picture, we need to rely on these studies," says Chu, who says it's fun to participate in the GBBC.
“It's simple, from enjoying seeing the birds and taking a minute to count them and sending it. It's one step to take you from watching birds as a hobby to participating in research. Once you hit that button to send that data, anyone can instantly see the map and tallies from towns in a permanent, historical database."
So get yourself a bag of feed, a good bird book, a pair of binoculars and have fun!
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published February 10, 2005
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