Every winter I get letters ands e-mails from readers asking why they are seeing fewer birds at their feeders.
For example, Sheryll Jameson from Parkersburg, W.Va. writes, "I enjoy reading your column and wondered if you could answer a question for me. I have been feeding birds for several years and am disappointed by the lack of cardinals and blue jays this year. Do you have an explanation for this?
Similarly, Frank Abruzzino e-mailed his worries about blue jays, "We are long-time readers of your columns and enjoy them very much. We have noticed very few blue jays in recent years, in fact, we do not recall seeing any the last two years. We maintain several feeders year-round. Do you have any thoughts why we no longer have them?
And Don and Belva Spung from Waterford, Ohio report, "We are avid bird feeders, year round. In September, we had 15 pairs of cardinals and now we have just one pair. We wonder what could have happened to them."
Answering such questions with confidence is difficult because many factors could be responsible, and I am not familiar with the specific situation. It may be just a matter of using a poor quality birdseed mix that attracts fewer birds. Or maybe a neighbor offers more attractive foods such as sunflower kernels, nyjer, nuts, suet, and/or mealworms.
Another possibility is that disease can spread rapidly at feeders where birds congregate. This is why feeders and the ground beneath them should be cleaned regularly.
The most likely explanation for fluctuations in wild bird populations is that it's normal variation. Bird numbers rise and fall from year to year due to factors such as nesting success, predator abundance, weather, changes in habitat quality, and increased road traffic. Few wildlife populations remain stable from year to year.
A cold wet spring, for example, can reduce nest success and fall population sizes. Sometimes a Cooper's hawk or a few hungry, outdoor cats can hammer bird populations.