Annual Bird Counts Give Scientists Climate Clues
Armed with flashlights, recordings of bird calls, a small notebook and a stash of candy bars, scientist Rich Kostecke embarked on an annual 24-hour Christmastime count of birds along the Texas Gulf Coast. Yellow rail. Barn owl. Bittern. Crested Cara-Cara. Kostecke rattled off the names and scribbled them in his notebook.
His data, along with that from more than 50 other volunteers spread out into six groups across the 7,000-acre Mad Island preserve, will be analyzed regionally and then added to a database with the results of more than 2,200 other bird counts going on from mid-December to Jan. 5 across the Western Hemisphere.
The count began in 1900 as a National Audubon Society protest of holiday hunts that left piles of bird and animal carcasses littered across the country. It now helps scientists understand how birds react to short-term weather events and may provide clues as to how they will adapt as temperatures rise and climate changes.
"Learning the changes of habit in drought could help us know what will happen as it gets warmer and drier," said Kostecke, a bird expert and associate director of conservation, research and planning at the Nature Conservancy in Texas.
Scientists saw birds change their habits during last year's historic drought that parched most of Texas. Some birds that normally winter on the coast - such as endangered whooping cranes - arrived and immediately turned back when they couldn't find enough food. Other birds didn't even bother flying to the coast. Snowy owls, who sometimes migrate from the Arctic to Montana, suddenly showed up as far south as Texas.
There has been some rain this year, but Texas still hasn't fully recovered from the drought and many areas remain unusually dry. Wetlands, a crucial bird habitat, have been damaged. Trees and brush are dead or brown. There are fewer flooded rice fields, prime foraging grounds for birds. And sandhill cranes, for the second winter in a row, are staying in Nebraska.
An initial report on the 24-hour count that began midnight Monday and ended midnight Tuesday included 233 different species - a drop of 11 from last year when 244 were counted on Mad Island. While the area likely still has one of the United States' most diverse bird populations, the species that were missing raise questions.
Where are the wild turkeys? Why were no black rails found? What about fox sparrows and the 13 other species that are commonly counted on the preserve? Where have they gone?
"There are several possibilities," Kostecke surmised. "Conditions may be better in the east, like Louisiana. Some may still be north, because it's been mild, and they tend to follow the freeze line."
With weather in the north still relatively warm, some birds might choose to stay put and conserve energy for the nesting season, Kostecke added.
Similar changes in bird behavior could be seen this year in the Midwest and parts of the South, areas that have been gripped by a massive drought that covered two-thirds of the nation at its height. The drought's severity is unusual, but scientists warn that such weather could become more common with global warming. Birds - as well as other animals - will have to adapt, and the data collected in the Christmas count gives crucial insight on how they might do that.
The dataset is notable for its size and the decades that it covers. Along with showing how birds adapt to climate change, it reveals the impact of environmental changes, such as habitat loss, which has contributed to a 40 percent decline in bird numbers during the past 40 years, said Gary Langham, vice president and chief scientist for the National Audubon Society.
"We've converted the landscape dramatically, and then you add climate change to the mix ... and the results are more alarming," Langham said.
Scientists have used the data to predict bird populations and behavior in 2020, 2050 and 2080. They also could use it to advance conservation work or calls for emergency action, he said.
Birds, though, are only one part of an ecosystem. As they move from place to place, they encounter new predators and species that may be competing for the same food. Vegetation also is changing as the Earth warms and some areas become more drought-prone. What happens as all these changes take place?
"It's the million dollar question. When you have that kind of ecological disruption, no one knows what happens," Langham said. "There are going to be winners and losers. There will be some that become more common, and some that will go extinct."
The survivors are the big unknown.