A single Pine Siskin started visiting my feeders in late September. Seven Evening Grosbeaks visited last Sunday. Does the appearance of these birds mark the beginning of a strong season of winter finches?
The Pine Siskin is one of the "irruptive" winter finches, meaning they periodically move south during the winter in search of food. These irruptions tend to follow a two-year cycle. For example, if you had large numbers of finches visiting your feeders during the winter of 2005-2006, chances are you had few or none visiting in the winter of 2006-2007.
Here's a link from the Great Backyard Bird Count (GBBC) showing Pine Siskin group sizes from the year 2000 to 2007. It shows a pattern that roughly follows a 2-year cycle. There were few Pine Siskins reported in New York for the February 2007 GBBC. Following a typical biennial cycle, we can expect higher numbers of irruptive species such as Pine Siskins and Common Redpolls this coming winter. Other irruptive winter finches seen in our area are Common Redpolls, Evening Grosbeaks, and Purple Finches.
A DC Birding Blog recently posted a summary of the Winter Finch Forecast out of Ontario Canada. Overall, poor food supplies in Canada further suggest that we may have good numbers of these winter finches at our feeders this year. Good news!