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Posted by Paul-the-other on 10:22:16 08/10/07
From Kirby Storter location comes this bluebird photographed in the Spring. John Boyd has indicated that there is a difference between the residents and the visitors.
"Distinguishing between the two can be difficult in the field. The non-migratory resident birds (Sialia sialis grata) are larger-billed than the northern Sialis sialis." (JBoyd)
So three questions emerge here. First, is this large bill or small and 2nd (more important) what would account for our resident birds having a larger bill?; and third if the ENP is releasing bluebirds into the Park will the cross-breeding change the bill appearance of the resident bluebirds?
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