Summer is slipping away fast at the Lesser Slave Lake Bird Observatory. By the time August is over, we will have seen the last of most of our long-distance migrants that arrived only a few months ago for a hurried breeding season in the boreal forest.
Their long journeys seem to have been worth every mile as our nets have been filled with young birds hatched a month or two ago and already heading out on their own migrations south. Capture rates for our Fall Migration Monitoring have picked up with August 7 capturing 127 birds and August 4 capturing a whopping 269 birds – 58 of which had to be released at the net since almost all of these birds were captured in the last net check of the day and there was no way we could get them all banded within a reasonable amount of time.
Among the 614 birds banded this week was our fourth ever Blackburnian Warbler! This species breeds east of central Saskatchewan. While the males are a striking orange and black, we caught a drab young bird that had us jumping through every hoop to confirm our identification before banding.
Another interesting recent capture was a common bird, but with an unusual look – a leucistic American Robin. Leucism is a mutation that can happen in any species which causes otherwise colourful feathers to go white. While adult American Robins normally have a whitish throat, this bird had extensive white throughout the head, a few flecks on the back and breast, and even one of the feathers in its wing was completely white.
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- Partially leucistic American Robin captured this fall
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- Leucistic American Robin with completely white wing feather
While I have never personally seen such a bird, some birds may have every feather on their body turn white and they are often mistaken for albinos. Unlike albinism which affects every cell in a birds’ body leading to diagnostic red eyes, leucism only impacts the feathers on the bird so other parts of the body, such as the legs or eyes, are coloured in a way that is typical for that species.
Slightly melanistic young American Robin caught this week
Although our robin had already made it through at least a year with this odd colouring, birds with extensive amounts of white caused by leucism are at a disadvantage. Not only can white plumage stick out to predators in the green and brown forest, but it also experiences more sun damage. As white feathers degrade more quickly, having many white feathers in the wing may eventually impair the bird’s flight.
On the opposite side of the “oddly coloured” spectrum is melanism which causes birds to appear darker than the standard member of their species. There is also xanthochroism where feathers may become yellowish or orange instead of red (common in House Finch), or erythrism where some individuals are more red overall (common in Ruffed Grouse). All these colour differences can be due to diet, genetics, or both.
If you are keen to learn more about birds and our operations, please drop in to one of our Bird Observatory Tours every Wednesday and Saturday with good weather through August.
By Robyn Perkins, LSLBO Bander-in-Charge
