December 23, 2005

Cold Weather Birding

[Ed: this is another of my articles which was first published in the January 2004 issue of the Vox Populi Nebraska eZine.]

The first time I participated it was a typical Oregon winter day: soggy and cold, and as the grey day faded into night, the steady drip turned into sleet. When the section leader stopped at another park, I started to moan to myself, "What, another stop? Doesn't he realize it is getting dark? And it's so cold. No respectable bird would be out in this stuff, so why are we stopping again?" Later, I realized why we stopped. He was hoping to add yet one more species and to increase the count we had been maintaining throughout the day. We had been gathering data about the number and types of birds found in a Portland neighborhood. At that stop, we got our first Brewer's blackbirds and a smattering of other sparrows, crows and gulls, so even though I was miserable, it was worth the trouble.

Townsend's Warbler

Townsend's Warbler
Santa Cruz, California
January 2003 © Peter LaTourrette

Every year birders in North America celebrate the Christmas holidays (December 14th to January 5th) by counting the number of birds they can find (both number of species and number of individuals in each species) in the Christmas Bird Count (CBC). Started in 1900 as a response to the extensive Christmas holiday hunts, the idea was to compete for number of birds sighted rather rather than the number shot. The original Christmas Bird Count has 27 eagar participants in 25 different locations throughout the US and into Canada who found 18,500 individuals of 90 different species. Since then the number of counts and the number of volunteers has increased greatly. By 2000, 52,000 volunteers took part in more than 1800 counts throughout North America.

Reed College Canyon

Reed College Canyon

For the CBC, Portland is divided into 5 districts and each district is divided into areas which cover a 7 mile circle. Each area is assigned a small team of observers who attempt to survey and census every bird that is seen or heard during a single day. Fortunately, my traditional area has some great birding spots to cover within the city, including Crystal Springs, the Reed College canyon and a whole slew of other parks and graveyards. The day starts out early and cold (around 7am) and ends when the twilight puts further birding to rest. And we are grateful when we get some hours without a steady rain. Of course, those doing their CBC birding in North Dakota or in Maine probably think we have it pretty darn good.

With the number of observers increasing nationally as well as the number of counts, the data collected becomes considerably more valuable because the trend lines for different species can be tracked year over year for the same locations. As the Audubon Society says, this is truly citizen science in action. Data from the CBC taken in early winter is added to data from the springtime Breeding Bird Surveys and provides an excellent picture on the health and well-being of a species in North America.

The Christmas Bird Count is designed to capture information about the local wintering birds, yet sometimes, if you are really lucky, a rare bird drops in for the count.

Brambling

Brambling
Photo: Mícheál Casey

One year in Portland a Brambling (normally found in Europe or Asia) showed up near Oaks Bottoms Park in Southeast Portland. Of course, birders were estatic and because it hung around for a week or more, birders came from all over the country to see this rarity. Only 7 Bramblings were seen during that year's CBC with all other individuals sighted in British Columbia or Alaska.

Scientists use data gathered by citizen scientists to learn more about birds and to conduct studies on particular species or specific birding behaviors. One study produced by scientists from Audubon and the Cornell Lab of Ornithology used the Christmas Bird Count data to learn about the irruptive behavior of pine siskins. Irruptive behavior is when birds will travel to a different, more southerly winter location than normal, often because the standard food supply has collapsed. It turns out that pine siskins irrupt every other year, but when they irrupt, sometimes they travel east and sometimes they will head west, alternating between the two sides of the continent. We don't understand why that is, but now we know what to look for.

Scientists have also used the data to chart some population trend lines for birds such as the American kestrel. Kestrels, like other hawks and other predatory birds experienced a significant population decrease when DDT was used extensively. After DDT was banned, the kestrel population had been recovering until 1997 when there was a new drop-off in the numbers spotted. The theory for the latest drop-off is that they have been affected by the pesticides that target their prey (large insects and rodents) and the loss of habitat as farmlands and open pastures are turned into developments.

When you are counting birds, it is always a thrill to see one of the more unusual species for a locale. Since the banning of DDT, Portland has had nesting Peregrine falcons and bald eagles within the city limits, which is really nice by my book. So it is not too surprising that one of my best birds for a CBC was a juvenile bald eagle flying overhead.

This year, the scientists are looking for data on the types and numbers of birds common to the boreal forest and where they were found during the CBC. They will match up data from this year's count with the work going on with the Boreal Songbird Initiative to understand how the boreal birds are faring.

Anyone can participate in a Christmas Bird Count. If you don't have much practice with identifying birds, you can contribute by watching for any movement and pointing it out to the leader of the group (extra eyes are a big help) or by being responsible for recording the birds seen. (This can be a challenge for some species like crows in Oregon which always seem to number more than one can accurately count.) You can also participate by watching birds that come to your feeders on the day the CBC is going on in your neighborhood.

To find out more about the Christmas Bird Count visit the Audubon CBC webpage. While there you can also discover what types of birds have been spotted in your neighborhood and review the historical records that are available for the counts all the way back to the first CBC in 1900.

Posted by Mary at December 23, 2005 01:41 PM | Science | Technorati links |
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