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Christmas Bird Counts

Citizen Science Environmental Monitoring

“We do not see nature with our eyes, but with our understandings and our hearts.”

- William Hazlitt

Every year thousands of people — over 57,000 last winter — participate in more than 2,000 Christmas Bird Counts (CBC). It is not only the largest example of citizen science, but also, because of its longevity and breadth, the most significant. The data that is collected on these counts is instrumental in tracking the dynamics of bird populations. That data reveals that while some species have increased in both numbers and territory, others have become much less common and belong on watch lists.

Downy Woodpecker

Carolina Wren	Frank Chapman started the first Christmas count in 1900 in reaction to a form of competition called “side hunting.” At that time people chose sides and then went out and shot the most birds they could find. The team that shot the most birds, as proven by who had the largest pile of dead birds, was the winner. Along with many others, Chapman realized that bird populations could not handle such wanton over-hunting, especially when combined with the feather trade for embellishing hats and with collecting eggs for personal collections. He proposed counting birds as an alternative activity. For over 30 years he oversaw and managed an ever-increasing number of Christmas Bird Counts.
An official count circle is 15 miles in diameter, or approximately 177 square miles, an area equal to about one third of Loudoun County. From December 14 through January 5, counters head into fields and forests, travel down rivers by canoe, cross bays by boat, comb city parks, and investigate feeders in suburban subdivisions. They tally every wild bird they find. By the time they are finished, participants have counted about one percent of every bird in North America.
Song Sparrow	As a result of the data that is collected nationwide, we have learned that Hooded Mergansers, one of our most beautiful ducks, have been increasing in number throughout most of the U.S., except in Mississippi and Alabama. We know that Northern Mockingbirds have extended their reach north and west. We know West Nile Fever did have an impact on bird populations, but that most of the bird species that were negatively impacted have begun to rebound. We know from the counts that some birds, such as Rusty Blackbirds which nest in the boreal forests but winter in the lower 48 states, have been decreasing by more than five percent a year for over 20 years and belong on watch lists.

Weather can have an impact on the annual count data. If the weather is bad enough, it is more difficult to find birds, plus fewer birders head into the field to count birds. However, the influence of bad weather isn’t only limited to the count season. Last year, the impact of the record-setting hurricane season on the Gulf Coast was dramatic as were the drought conditions in a number of western states. The hurricanes not only destroyed invaluable wildlife habitat that will take years to recover, but also moved birds hundreds of miles north that were trying to migrate south. This resulted in many birds, which should have been long gone or aren’t even normally in those locations, being reported in northern areas. Amazingly, in spite of much personal loss, all of the Gulf Coast bird counts still took place in the winter of 2005-2006. The data they collected will serve to show what and how much recovery occurs in those areas in the years to come in terms of the local avifauna. The wildlife habitat that was lost along the Gulf Coast is an invaluable source of food and shelter for migrating birds and is bound to have an impact on bird populations in the future.	Red-bellied Woodpecker
In 2002-2003 the impact of the West Nile Virus was noted in a number of bird species, especially American Crows. In our area we saw a tremendous drop in the number of American Crows, Carolina Chickadees, and Eastern Bluebirds. While this decrease continued into 2004, it appears to have been reversed in 2005. At least some species have rebounded, such as Eastern Bluebirds, though American Crows have not yet fully recovered. However, another factor in declining populations was an unusually cold and damp spring in 2003 in the Mid-Atlantic region, which resulted in a number of unsuccessful nesting attempts. Interestingly enough, the number of Fish Crows reached an all time high on the 2005 Central Loudoun CBC. Although too soon to tell, it is possible that Fish Crows are filling the niche that American Crows previously filled.
Another fascinating factor in what species are seen during Christmas Bird Counts is the health, or lack thereof, of the bird’s food supply, even thousands of miles away. Last year, a record number of Snowy Owls were observed on counts in areas where they are rarely seen. The most likely reason for this was very high birth rates for this species in the tundra due to an over-supply of lemmings and other small mammals during nesting season. This was probably followed by a crash in those same mammal species or by very deep snows in the birds’ normal wintering areas. Snowy Owls were then forced south to find sufficient food. Due to similar factors the year before, large numbers of Northern Hawk Owls, Boreal Owls, and Great Gray Owls were pushed south from their normal wintering home in the northern boreal forests.	Tufted Titmouse, inspecting a seed

Without the tens of thousands of CBC participants in thousands of locations over more than a hundred years, our knowledge of early-winter bird distribution and health would be far less comprehensive. These thousands of participants include everyone from beginners to experienced ornithologists, and the counts are invaluable and fun for both groups. For those who are counters, listers, and especially new listers, the counts are a fantastic tool as they give any birder an opportunity to increase the number of birds seen in one fell swoop. And for beginners, especially children, the opportunity to get close looks at birds as varied as Northern Cardinals and White-throated Sparrows is unprecedented. And when you toss in some of our beautiful waterfowl, such as Green-winged Teals or Hooded Mergansers, the day becomes sheer pleasure. There is no doubt that one of its greatest values is that Christmas Bird Counts are for everyone.