How do over-wintering birds survive?
As mentioned above, food is the primary concern for over-wintering birds. If food is present in sufficient quantities through the winter in a bird’s “summer” range, then the expense of migration is not biologically justified. Anything, then, that will increase total food supply or even increase the ease by which food is found will greatly influence the survival of over-wintering birds. One very interesting behavior that can be observed in the many of the winter birds of the Nature Trail is the formation of mixed species flocks. The chickadees, titmice and downy woodpeckers in particular join together into large, complex flocks for the winter. At first glance this flocking behavior would seem to be disadvantageous to all of the species and to all of the individuals concerned. Food is in short supply in the winter Nature Trail ecosystem, how could the clustering of many individuals that all eat approximately the same prey items (primarily insect larvae) do anything but decrease the survi
