Operation Migration On Estimating Whooper Numbers



Operation Migration’s “In The Field” web page explains, “Debate continues in the Whooping crane world about the methods US Fish and Wildlife Service is now using to count Whooping cranes at the Aransas National Wildlife Refuge.”

Lots of bugling going on about changing methods of counting whooping cranes.

“For almost 30 years, retired Whooping Crane Coordinator, Tom Stehn made a direct count of each bird while flying transacts over the refuge. The accuracy of that method was questioned because birds may move between the aircraft passes and been counted more than once.”

“The new system employed since Stehn’s retirement is called ‘distance sampling’. It consists of making multiple parallel survey flights over a large area and applying a formula to the number of cranes spotted to come up with a population estimate.”…

“The concern is that distance sampling is generally used to estimate the size of large populations and there are fewer than 300 Whooping cranes at Aransas. Many feel that a direct count could provide a more accurate number.”

To read the complete article, click on: http://operationmigration.org/InTheField/2013/02/01/controversy-heats-up/