Thursday, June 14, 2012

Black Tern

John H. and I canoed Sprague Lake in southwestern Rice County, Minnesota, on Tuesday. We found breeding Black Terns on this relatively pristine lake. Four pairs allowed us relatively close approach. We were surprised that they nested near the public access to the lake. Black Terns are known to nest "semicolonially." Since the 1960s, the numbers of this species declined by about 3.1% per year (Heath et al. 2009). Factors contributing to this decline include loss of wetlands and adverse affects of agricultural insecticides. This tern eats both minnows and flying insects, both of which can be adversely affected by the poisons.

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