Today on the bike trail around Sheldon Lake in Fort Collins City Park I did a lap to see how the bird word was coping with the cold. The usual white-cheeked geese and mallards were sitting on the ice or in open water made by bubblers. They were joined by a young male common goldeneye hunting crayfish, a male northern shoveler and three common mergansers.
Most interesting was a flock of at least 20 bushtits busily feeding in both large willows and Scots pines. I was able to figure out what they were eating in the pines: Cinara aphid adult cadavers and eggs, plus pine needle scales. I suspect giant willow aphid (Tuberolachnus salignus) eggs and adult cadavers were the targets in willow. Bushtits are the ultimate “free pest control”. During the ten minutes I watched, the number of individual aphids they prevented from sucking pine and willow sap had to be in the several hundreds. Who says you can’t be an insectivore in CO in the winter. Then, on some mysterious signal like they always do, it was off to another tree, then another, then another. They are quite the clean-up crew.
From left to right: adult aphid cadaver (Cinara sp.), aphid eggs (Cinara sp.) and pine needle scales (Chionaspis pinifoliae)
Dave Leatherman
Fort Collins
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