Flocks of robins‏ Alan Fritz/Nancy Taylor 2/27/14

Adding to Adena Mooers South Hill observation, I observed it seems like 100s of robins here and there on my loop walk of South Hill Tuesday while enjoying the bright views of snow on Lummi and Orcas Islands. Are migratory robins on their way through?

Alan

Dear birders who are more knowledgeable than I am,

Like Alan, I wondered about the flocks of robins we have been seeing. Are they from our area and getting ready to migrate, or did they just arrive from the north, or are they passing through? I have never heard of a radio tagged robin, so there may be no way to know for sure.

Does anyone know?

Nancy Taylor

Could it be that the snow is causing large congregations of robins in bare spots around houses and bushes, and in berry-bearing shrubbery, where there is food?

John Stark

I rode my bike through a flock of at least 200 robins on and around the grass at Roosevelt Park this morning. Last night, the communication tower in the Public Works yard on Pacific was covered in an equal number of raucous Red-winged blackbirds. NW

I, too, had a flock of robins... not in the hundreds, but far more than I've ever seen before, all at once, in my yard (Alabama hill). They were "digging" in the snow to get at berries on shrubs. Pat Buhl




I do think it's the snow that causes Robins to flock up. Though I didn't see that in my neighborhood this time around, I have seen it in the past. They are probably concentrating on places where food is accessible.

True to style, yesterday I saw the first Varied Thrushes close to home this winter. Snow usually brings them here.

Barry Ulman

I saw 3 large flocks of robins the week before we had snow, so I'm not convinced that the flocking is related to weather. It could be related to day length, which I suppose is a big factor of migration.
Nancy

I suspect that the flocks of Robins are resident birds concentrated bysnow. 

In past springs i had Robins fall out at the muhlberry bushes at the clinic and feed in frenzies on over winter berries- same behavior in the falls.
Fredrick R. Sears

Why couldn't it be both things happening at once: The snow focusing the robins on limited feeding areas, while at the same time there is a migrational thing going on...? JS



John and Whatbirders,



I think you are right  in that both migration and snow concentrates the robins. I wondered, though, if flocks of robins that we see (outside of a weather event) are getting ready to leave, are passing through, or have just arrived. Without study (and I doubt there is much research money for robins), we may not know. I always presumed that flocks of robins that are seen later in the spring are stopping off on their way north, or possibly some or all are staying here. We may never know for certain, but it's fun to surmise.



Now I will go look at my feeders and enjoy the robins' cousins,  Varied Thrushes.

Nancy




John,



I think you are bang on.



A few (!!) years ago, when I was doing field work for my master’s thesis on urban birds at the University of British Columbia, I found that the majority of American Robins arrived in the spring during the last 2 weeks of February. Although Robins are fairly common in the winter, 80% or 90% of those which breed in the residential areas of Vancouver arrive in late February and early March. They are one of the earliest of all spring migrants.



In good weather during the early spring, Robins tend to take up breeding territories, and do much of their feeding on lawns. However, during foul weather, they may abandon their breeding territories and gather into flocks which feed on fruit, much as Robins do in the winter. However, in late spring (from late March onward), even foul weather will not cause Robins to abandon their territories--  there is too great a risk of losing it to another Robin!



I think this explains what is happening with the recent snow in Bellingham and Vancouver. Yes, I noted sizable flocks of Robins in Bellingham myself on Wednesday while looking for the Western Scrub-Jays, which are still near Grant and Connecticut in Bellingham (well, at least one of them is!)



Wayne C. Weber