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A week ago, I wrote a post on various bird counting activities that involve birders during the winter months. Today I would like to give an example of how the data can be used.
The National Audubon Society makes the results of past Christmas Bird Counts available on its webpage in various forms. Graphs are given both for the raw numbers reported and for the numbers reported per participant-hours. The latter helps control for differing levels of effort.
In some cases the count results can show an improvement in a species's fortunes. Here is a graph showing numbers of wild turkeys counted on CBCs in Maryland and DC over the past 50 years.
You can see how the population of wild turkeys was virtually non-existent in Maryland and DC through the middle of the 20th century, then took off with re-introduction programs in the 1970s. Wild turkeys would appear to be one of the more successful species in terms of adapting to new conditions in the area.
