Tuesday, May 20, 2008

What Is A Point Count?

What is a point count? We're Audubon South Carolina, so it doesn't have anything to do with sports...it's all about birds!

Answer: It is a survey method for estimating breeding bird density. An observer stands in a fixed location for 10 minutes and counts all the birds heard and seen within 25 meters, 50 meters, and 100 meters. Obviously the observers have to be pretty good at identifying bird species by sound, hence the rigorous training that Brad & Denise (our seasonal naturalists) have undergone during the past two months.

Let's say we wanted to know the density of breeding Hooded Warblers at Beidler Forest. If we conduct a point count, we can determine the density of breeding Hooded Warblers per acre for that particular location. Multiply that number by 16,000 acres and we would have an estimate for Beidler Forest. However, unless all of Beidler Forest is represented by the habitat at the particular point where we counted, we would have a bogus estimate. That is why we have laid out 100 point count locations that are representative of the habitat composition of Beidler Forest: 80 in forested wetlands, 8 in pine plantations, 8 in non-forested wetlands, and 4 in mixed upland forest. Once we have conducted all the point counts, we can average the density of breeding Hooded Warblers per acre for all 100 points and that number will be representative for all of Beidler Forest.

Don't we already know this information from the bird surveys that are conducted each year at Beidler Forest?

Answer: Past bird surveys at Beidler Forest have focused on the old-growth portion of the sanctuary. They provide excellent estimations of breeding bird density within the old-growth forest, but provide no data for the 14,000 acres of Beidler Forest that are not old-growth.

What do we gain from conducting point counts?

Answer: The biggest benefit will be determining the breeding bird density for all of Beidler Forest. After conducting point counts this year, we will have baseline data that we can compare to future point counts at Beidler Forest and point counts other sites. The point counts will help us monitor changes in populations of breeding birds at Beidler Forest.

Another interesting benefit is that it will help us with land management and acquisition. We can go back to the 100 point count locations in June/July and do vegetation surveys, which will help us determine which particular habitat characteristics Kentucky Warblers, Swainson's Warblers, Prothonotary Warblers, or other species are focusing on at Beidler Forest. As property comes on the market, we will have a much clearer picture as to which bird species would benefit from such an acquisition.

With the Boston Celtics in the playoffs, we thought we heard a flashback, "Larry BIRD stops... shoots...it's good!...and a foul, the point counts!"

Images by Mark Musselman

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