Winter Bird Banding

This winter, as in the last few years, I have been banding birds by the feeders in my backyard. Due to the lousy weather this season, I have had unusually few opportunities to do so. While cold, windy, snowy weather elicit the highest visitation rates to the feeders, such conditions discourage banding. Not only do wind and snow make netting ineffective, but much more importantly, harsh weather poses added stress. As a bander, I find that capturing the same individuals week after week and even year after year generates a particular attachment to all birds I have banded, and while I enjoy the views of the local Cooper's Hawks, I do not like the thought that they are eating "my" birds.

One focus to the banding has been comparing counts of birds visiting the feeders at any one time to actual numbers of local birds. These are my most common species this winter:

Dark-eyed Junco - peak count of 26 (on Jan 14); 88 banded so far this season

American Goldfinch - peak count of 21 (on Feb 9); 10 banded

Black-capped Chickadee - peak count of 2; 8 banded

Northern Cardinal - peak count of 11 (Jan 28); 10 banded

The low banding total for goldfinch can be explained by the distance of my net from the feeders; all birds are caught as they move between available cover. Because I have only been able stay open for 57 hours all season, most capture totals have been correspondingly low. However, juncos have been particularly numerous this year.

I have also been interested in age and sex breakdowns of those species captured. This year, males account for 65% of the junco total -- a figure consistent with previous winters. Also, 64% of the juncos represent immature birds. While good fecundity and juvenile survival last summer would seem to explain the higher junco total this winter, the ratio is actually slightly lower than past seasons, so better annual survival of adults (thus, a greater breeding pool) appears more logical. However, this is not reflected in a high recapture rate from past years, and it seems that juncos, like finches but unlike American Tree Sparrows, woodpeckers, chickadees, and cardinals, have fairly poor site fidelity on the winter grounds.

Finally, I pay close attention to health. Despite their densities, the juncos appear to be in great shape. Recaptures have been prevalent, most of the birds have been very fat, and diseases have not been evident. For some reason, the immature cardinals never completed their feather molt last fall. Generally, young cardinals replace all their juvenal feathers. Goldfinches have been problematic. Based on the birds that I have watched at the feeders and those that I have captured, several either have appeared sluggish or have obviously displayed swollen eyes (mycoplasmal conjunctivitis).

Banding would seem to benefit from mild, sunny days. However, clear skies make the net more visible, and nice weather brings fewer birds to the feeders. Male titmice and nuthatches appear to be more interested in singing than feeding, and other birds are likely roving further around the neighborhood -- probably using the opportunity to seek alternate food sources. While capture rates drop, interesting birds are likely. A male Purple Finch and a male Brown-headed Cowbird have each made one-day visits this winter. On the other hand, irruptive finches have been notable by their absences. Finally, the bird pictured below was captured during the pleasant afternoon of Feb 18.

This is the first Chipping Sparrow that I have ever seen during the winter in Muskegon County.

- Brian Johnson