Winter weather has a major effect on activities at bird feeders. Cold, snowy conditions invariably increase visits to feeders. Last week's record cold spell brought more birds to my feeders than I've seen in months.
Ice storms can be particularly catastrophic for wild birds. When ice covers everything for several days, birds starve because they cannot break through the ice to get to food. This is an important reason to be sure feeders are filled during ice storms.
Sometimes habitat changes cause bird numbers to increase or decrease. Recent activity by the natural gas industry in parts of Pennsylvania, Ohio, and West Virginia has wreaked havoc on the landscape. Well pads and spider webs of pipelines riddle the countryside. And the truck traffic that accompanies these activities certainly takes a toll.
Furthermore, unless numbers of birds are somehow measured every year, it's difficult to accurately detect population changes. For example, there may have been a few cold snowy days last winter when two dozen cardinals visited feeders, and that's what's remembered and compared to this year.
This is a good reason to record your observations in a field journal. That enables you to compare estimates of bird numbers from year to year. Another option is to participate in Project FeederWatch, a citizen science exercise sponsored by Cornell's Lab of Ornithology. Not only do participants get an annual record of their own observations, they also can compare their results to volunteers from across the country.
To get a broader perspective on this year's winter bird populations, I checked with Emma Grieg, director of Project FeederWatch. "So far this year, there's nothing to suggest any widespread problem with winter birds," she said. "And though we also get letters about fewer birds in some places, it's no more this year than other years."
So, if you think wild bird numbers are down this year, be patient. And be sure feeders are hilled during periods of severe winter weather.