Redpolls at TTPBRS
This morning at TTPBRS saw quite a scene! We had gone down to the station to wrap up the season by packing up the last of the equipment, and in preparation for inventorying and taking down the nets, we had our remaining nets open - the last week at the station has been so quiet, we didn't expect any birds to get caught. Well, what a surprise we were in for, then, when we walked around the corner of net 7 to discover a flock of 47 redpolls caught in a single net!
We banded 70 redpolls this morning. In the group were 13 much chunkier birds, with noticeably darker plumage. These birds are of the "Greenland" subspecies of Common Redpoll, and average about 10% larger than the "mainland" populations. Our "mainland" birds were mostly 11-13 g in weight, while the "Greenland" birds were generally 16+ g, with one weighing in at over 19 g!
Also among the flocks of redpolls were two Hoary Redpolls. Hoarys are difficult to distinguish from Common Redpolls in that they overlap in size and plumage characteristics, especially in their first-winter (hatch-year) plumage. The two best criteria for identifying Hoary Redpolls are the size and shape of the bill, and the patterning of the undertail coverts. The bill of the Hoary is noticeably shorter and stubbier, with a resultingly sharper angle to the upper mandible. The undertail coverts are sparsely streaked, with little to no markings over most of the feathers. The birds are also slightly paler overall, and show narrower, less diffuse streaking. Only the adult males are the really "snowy" birds one tends to think of for the species. Both of the birds we captured were hatch-year females.