Jay Jones' question about the nature of foods fed by birds who are 
victims of brood parasitism to their involuntary "children" is a darn 
good one.  However, I could not find an answer to it in my usually 
helpful resource, "The Birdwatcher's Companion to North American 
Birds" by Christopher Leahy.

After reporting a couple of days ago to MDOsprey that our local Song 
Sparrows seem not to have raised any Cowbirds this year, I realize I 
spoke too soon.  One was feeding a voracious young Cowbird on the 
deck just yesterday.  I do note from Leahy's book (op.cit.) that in 
most cases of parasitism by Brown-headed Cowbirds, the host is able 
to fledge some of its own young as well as  the cowbird.  One of our 
most visible Song Sparrows is, I think, young of the year.  So there 
is some positive news.  Next year I must work harder at locating the 
nest so as to watch the drama unfold.

Mike Bowen
Bethesda


At 04:54 PM 8/6/2006 +0000, you wrote:
>Recent emails about Song Sparrows and others feeding young Cowbirds 
>got me thinking and wondering about something....
>I assume that hosting parents of Cuckoos feed them what they 
>instinctively feed their own young.  I can't imagine a seed-eating 
>parent fulfilling the nutritional needs of Cuckoo nestlings when 
>adults (I understand) feed almost exclusively on insect fare, 
>primarily caterpillars.  Do adult Cuckoos, or Cowbirds for that 
>matter, seek the nests of species that feed their young the proper diet?
>To the extent that fledged Cuckoos learn gleaning techniques from 
>observing their parents, how is it that they successfully feed 
>themselves as adults without that example?
>I'm sure I'm not the first to wonder about this.  Answers, anyone?

D. H. Michael Bowen (Mike)
8609 Ewing Drive
Bethesda MD 20817-3845
Tel/Fax: (301) 530-5764
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