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DUML; Re: house sparrows



Hi Carolinabirders,

Took the biodiversity class down to the Duke University Marine Lab on
Saturday. The trip included a few hours on Carrot Island/Bird Shoal/The
Rachel Carson National Estuarine Reserve. Virtually no land-related
migrants; the only one I can recall offhand was a dragonfly, Black
Saddlebags, several of which were lurking around the island. Many more
shorebirds, highlighted by a Piping Plover amid half a dozen
Semipalmateds. Also a Marbled Godwit, a Willet, a Ruddy Turnstone, a few
Sanderlings, and lots of Yellowlegs and Semipalmated-lookin' Sandpipers.

Back here in Durham, the migrants are mostly avoiding me. Or I am them.
Was grading midterms outdoors yesterday and heard a chip note from the
nearby Red Cedar thicket; pished out an immature American Redstart. This
morning, heard what sounded ominously like Yellow-rumped Warblers across
the street from my house, but had no binocs and saw nothing...

On Sun, 28 Sep 2003, Etemun wrote:
>
> I wonder if one day all the house sparrows disappeared,
> whether another bird would fill the niche, ie. hanging out
> so close to people and in crowded urban areas.  Are they
> known to have actually replaced other species in places
> they have moved into in America?
>
> Any thoughts?

Well, they have two niches, really. As feeders, they're eating seeds in
open habitats. But they're cavity nesters; virtually no other granivores
do this. I think it has been pretty clearly shown that, in the absence of
human intervention, they can exclude bluebirds from an area by
monopolizing nest cavities. It's quite possible that, if House Sparrows
disappeared, species like Great Crested Flycatcher (which I've seen
nesting in streetlamps and other human constructs) might spread further
into and become more common in urban environments. And they'd almost
certainly increase in agricultural areas. If the Starlings didn't beat
them to it...

I'm not sure that anything would take over the feeding turf. House
Sparrows seem to feed on superabundant, surplus resources like garbage,
bird feeder seed, and agricultural waste. I don't think competition is
nearly as strong for these items as it is for good, safe nesting cavities.

Good birding,

Josh


Joshua S. Rose
Duke University
Department of Biology (Zoology, R.I.P.)

jsr6@duke.edu
http://www.duke.edu/~jsr6/