[Tweeters] Re: Peregrine feeding post fledging ?

Martin Muller martinmuller at msn.com
Wed Jun 8 21:10:12 PDT 2016


Barb, Tweeters,

I receive Tweeters in digest mode, hence the slow response. I didn’t see any responses other than Rob S’s wonderful story, so I guess I’ll pipe up.

Just like in less urban locales, city-dwelling peregrines try to maximize their offspring survival. So yes, they will feed their offspring for a number of weeks after fledging. In the city, a noisy landscape, if youngsters land in awkward locations, the adults may not be able to find them. Recall many years ago one youngster from our downtown site ended up on the sidewalk of 5th Avenue. With the din of traffic, I’m not sure the adults could have heard its food begging calls (but even if they had would they have come down that low?). The youngster “solved” the problem by walking into the UPS store and after getting boxed it was shipped off to a rehabilitation center for some strengthening and flight training (I picked it up and met the Sarvy van at Northgate). If memory serves me well, it was later successfully released back to its parents for some additional training and feeding.

I know I’ve seen youngsters downtown still receiving food from its parents a month after fledging, sometimes till August (especially some immature females appeared to have good luck with receiving food from their dad). As you (Barbara) found, in the Birds of North America account it mentions that the adults will feed young in migratory populations for 5 - 6 weeks post fledging, 9 - 10 weeks in non-migratory populations. But since the birds are rather mobile, it becomes quite difficult to monitor these events in our urban setting. For instance, one year the whole downtown peregrine family ended up hanging out at the grain terminal north of downtown (lots of pigeons!). Then they all flew across Elliott Bay to West Seattle. Had I not seen that, I could have interpreted their disappearance as dispersal.

A few years ago on a field trip we observed a young bird successfully begging for food from an adult. In January. And that youngster was not even related to the adult. Because all of this adult’s young had been banded and this youngster was un-banded we know this for a fact. That was probably a rare event (an unrelated adult feeding a seven-month-old youngster), but it illustrates that outliers occur. And this was not some early courtship feeding, the youngster acted like a chick food-begging. Not the wailing calls females give soliciting food from a (prospective) mate.

Since you (Barbara) checked the peregrine BNA account, I assume you checked the accounts for the other species you asked about as well? Just to summarize: American Kestrels fledglings are dependent on adults for food some 3 weeks post-fledging. Prairie Falcons about 5 weeks. Gyrfalcons 4 - 6 weeks. Peregrines (as stated before) 5 - 10 weeks (depending on migration status). For Merlins the period is up to 4 weeks. So your estimate of “a few days” is probably an underestimation. But again, it is hard to track this in our urban setting.
At least for peregrines the period mentioned in the literature seems pretty accurate for urban nesting birds as well.

Cheers,
Martin MUller, Seattle




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