Tuesday, September 7, 2010

Northern Parula

Although I have enjoyed listening to this warbler's trill at the Lower Basswood Falls in the Boundary Waters Canoe Area of northern Minnesota, I have always considered this warbler to be a denizen of the southeast.  Actually, it is both.  Indeed, the northern and southeastern ranges may not be contiguous.  I wondered if northern and southern birds might be distinct subspecies.  The American Ornithologists' Union considers the Northern Parula to be monotypic--not dividable into distinct races.  Researchers have noticed, however, that many eastern birds are heavier than western ones and, furthermore, sing distinct songs.  DNA evidence, on the other hand, does not support these two populations as being different.

Increasing air pollution has reduced the numbers of epiphytes (plants that hang on trees) that Northern Parulas use for nesting.  Old Man's Beard, a lichen that hangs from the boughs of many northern conifers, is an example of an epiphyte. This decimation of epiphytes is especially severe in the northeast United States, where Northern Parulas are now very rare, if not extinct.  Elsewhere in North America, deforestation threatens this species.  Most of this information is from Moldenhauer and Regelski (1966).  I banded this bird on 4 September and caught it again on the 7th.

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