Good site Bel, this part, in particular, is right down my alley...

Quote:

Where Have All the Robins Gone?
What happened to all the robins? I’m not seeing them any more.

Each year in late summer and fall, robins leave the territories where they’ve raised their young. They spend fall and winter in flocks, traveling to places where they can find more food. In fall, we receive questions from people in some areas who are wondering where the robins have gone, and questions from people elsewhere who are incredulous because they’ve been inundated with large flocks of robins.

By flocking, the robins benefit by having more eyes to look out for predators and to find food. You probably won’t see individual robins again until spring when the demands of finding and defending a territory cause them to leave the flock and strike out on their own.

Although robins are one of the most familiar and widespread birds in North America, their patterns of movement are poorly understood. In fall, their migrations are often influenced by the availability of fruit, but in spring they move in response to the availability of soil invertebrates, such as earthworms. Their numbers in particular places may vary from year to year.

Robin sightings reported by participants of the Great Backyard Bird Count show that robins tend to avoid areas with deep snow cover. This makes sense, since they often search for food in the soil.



In Feburary I was amazed to see several hundred robins flocking about in the trees and grounds of the Huntsville Alabama library. At first I mistook them for Red-breasted Blackbirds (which, in a taxonomic way, that's what they are) but I was told that Red-breasted Blackbirds are particular to the western states so I guess they were robins.

No, Bel, I can't well sex flocking winter birds but it is known that some bands of crop destructive blackbirds are made up of only young unattached males.

I will elaborate later.

Thanks for your interest.