[SBB] BCSP continues ... and BTPI thoughts

[Mike Rogers <[[email protected]]>]

All,

It has been a week since Garth first heard the singing Black-chinned 
Sparrow at Hidden Villa, so I decided to head out there over lunch today 
5/31/06 to see whether I could upgrade the breeding status from 
"POssible breeder-singing in suitable breeding habitat" to "PRobable 
breeder-singing for at least a week to maintain a territory". Almost as 
soon as I started up the Hostel Trail, I heard the singing BLACK-CHINNED 
SPARROW, although it was best heard from a viewpoint a hundred yards or 
so below the trail junction to Toyon Hill. It was still audible from the 
Hostel Trail past the Toyon Hill trail junction, but sounded like it was 
over the ridge and likely not visible. Scanning the hillside from across 
the canyon failed to locate the bird visually, but my impression was 
that the bird did not move around much. The perceived location of 
singing Black-chinned Sparrows can vary significantly depending on which 
direction the bird turns its head while singing and it seemed to me that 
the variation in song volume was due to this rather than significant 
movement of the bird.

BAND-TAILED PIGEONS were still streaming overhead (22 total), but with 
most heading to the hills at this time of day (from about 1:00pm to 
1:45pm) instead of towards the valley floor as Bill noted yesterday. 
Bill raised the interesting question of whether birds that breed in the 
hills could forage widely in lowland areas, perhaps returning 
infrequently to their nests. I have been toying with this idea as well, 
based on birds that are present virtually daily in Sunnyvale, often near 
Knickerbocker and Mary. These birds are apparently attracted to backyard 
feeding stations, mostly in the morning (when seed is put out?), 
sometimes in fairly large numbers (e.g. 15 on 9 May), but disappear 
later in the morning, often leaving to the southwest towards the hills. 
This species caused real headaches for our county breeding bird atlas 
because urban sightings during the breeding season were hard to 
interpret. Were they local breeders? Birds that had already completed 
their breeding? Birds not yet involved in breeding? (Breeding can occur 
early or late in the season for this species.) Or widely foraging 
breeding birds as discussed above? Any insight based on known nests, 
recently fledged young, or other breeding evidence would be most welcome!

Mike Rogers


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