Advocate Editorial Board opinion: crucial to know number of birds in refuge

Mar 8, 2013 | Victoria Advocate by Advocate Editorial Board | Related Press

The count is in. This year, the U.S. Fish and Wildlife Service estimates there are about 279 whooping cranes in and around the Aransas National Wildlife Refuge. This year’s estimate was gathered using a new method of counting.

In the past, the flock was counted by Tom Stehn, the former whooping crane coordinator, who started conducting surveys in the early 1980s. Because the flock was smaller, Stehn could fly over the refuge and count each individual bird. As time passed and the flock grew, he grew more experienced. But Stehn retired in 2011, and the wildlife service decided it was time to change the counting method.

Now, instead of trying to count every bird, the service uses a method known as hierarchical distance sampling, which can be adapted and reproduced, no matter who is doing the counting. This year’s count estimates there are about 257 birds living on the refuge with a 95 percent confidence interval, meaning the actual number could be between 178 and 362 whoopers, with another 22 birds estimated living off the refuge.


Read the entire article »