Bird count

There are many field methods available for conducting avian ecological research. They can be divided into three types: counts, nest monitoring, and capturing and marking.

Basic bird counts are a good way to estimate population size, detect changes in population size or species diversity, and determine the cause of the changes if environmental or habitat data is collected as well. Basic bird counts can be completed fairly easily and inexpensively, and they provide general information about the status of a bird population.

Birds can be directly counted on breeding colonies, and at roosts, flocks, or Leks. Large diurnal migrants, like many raptors, can be counted as they pass through migration bottlenecks. Small nocturnal migrants are harder to count, but many advances have been made in the use of radar and microphone arrays to identify and count them.

Perhaps the simplest method of counting birds is called a "point count", in which a trained observer records all the birds seen and heard from a point count station for a set period of time. A series of point counts completed over a fixed route can then be compared to the results of the same point counts in other seasons or years. A similar method, called an area search, involves searching throughout a fixed area for a set amount of time and recording the number of birds seen and heard.

Nest monitoring is essential for measuring the reproductive success of a population, which is important for identifying changes in a population’s birth rate. Nests can be found either through systematic searching of the birds’ preferred habitat or by watching birds for behavioral clues. A researcher can then track the success of each nest by regularly checking nests for signs of hatching, fledging, or predation.

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Wikipedia