UNPRECEDENTED RED-BELLIED WOODPECKER INVASION

 

During the fall of 2004 an unpredicted event began unfolding across northern New England and the Maritime Provinces of Canada. First one out-of-range Red-bellied Woodpecker was reported to a list serve where it was considered a rarity worth chasing. Soon this single report was followed by another, then another, then another--and not just in one area but across a region extending from the Adirondacks of New York eastward to New Brunswick and Nova Scotia . Soon it was clear that this was not just the normal handful of fall wanderers of the species but rather the largest and most widespread invasion of Red-bellied Woodpeckers ever documented.

 

At least 250 out-of-range birds were reported across the region including a minimum of 200 from Maine , 20 from Nova Scotia , and 22 from New Brunswick . While more than 50 of the reported Red-bellies occurred more than 100 miles from the nearest previous breeding area, the record for long distance travel goes to a bird found in New Glasgow, Nova Scotia that was 450 miles from the range edge. Of course, as in most invasion events like this one, we know nothing about the origin of these individuals. The assumption is that they are birds born this past summer who are making their first dispersal movement to find new, unoccupied places to set up territories. The massive number of individuals involved in this Fall 2004 movement likely indicates that there was a highly successful breeding season in some portion of the species range. A second hypothesis is that the movement was the result of a major decline in food availability (perhaps a decline in acorn abundance) in a portion of the range.

 

Of particular interest will be to see whether the species permanent breeding range now leaps northeastward as a result of the invasion or if birds slowly drift southward or die over the winter. In a number of locations multiple birds have been recorded nearby suggesting that it is possible that some of the invaders may find mates in the coming spring.

 


FIGURE CAPTION: Red-bellied Woodpecker reports from beyond the established breeding range limit in Fall 2004. Reports were taken from state and provincial listserves. Some reports were not included because of difficulty in establishing exact locations and some locations had more than one individual present.