San Francisco Bay Bird Observatory - Notes from the Station

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White-throated Sparrow

1/27/2023

Species: White-throated Sparrow
Most recent capture date: 12/28/2022

Notes: Another one of these treat sparrows! (The range map on Birds Of The World notes below its range map, discouragingly: "Species is present only at very low densities in the western wintering range shown.") Someone told this bird that any outfit should have an attention-grabbing element and he went for four of them just to be safe: chestnut head stripes, white throat, gold on the forehead, and yellow at the wrists (yes, they seem like they should be shoulders but they are the bird's wrists). Doesn't that white throat look like a bowtie?

Bewick's Wren

1/24/2023

Species: Bewick's Wren
Most recent capture date: 12/24/2022
Earliest capture date: 5/15/2022
Age: about 8 months old

Notes: This youngster's bill is Not Right: instead of the upper and lower mandibles meeting at one point, the lower mandible is too short and the upper mandible is too long and slightly decurved. His bill has been like this since we first saw him in May, which is a good sign: clearly he has figured out how to use it well enough to survive, so as long as it doesn't get any stranger, he should be okay. We have caught him about once a month since May, and I'm always a little surprised he's survived - but on this latest capture he was quite fat, so I can probably stop worrying about him!

House Finch

1/21/2023

Species: House Finch
Most recent capture date: 12/24/2022
Sex: Male

Notes: Our third House Finch from that date, sporting the least-common of the colors we see: gold!

House Finch

1/20/2023

Species: House Finch
Most recent capture date: 12/24/2022
Sex: Male

Notes: The second of our three House Finches on that date, this one showing off a classic dusty rose hue. (This color could easily show up on a Purple Finch, but several traits including bill length assure us that this is a House Finch.)

House Finch

1/19/2023

Species: House Finch
Most recent capture date: 12/24/2022
Earliest capture date: 1/19/2022
Age: at least one year old
Sex: Male

Notes: We caught three male House Finches on 12/24, nicely spanning the range of male House Finch colors we see in our area. This fellow is a nice reddish-orange. I'll post the other two in the following posts.

Yellow-rumped (Audubon's) Warbler

1/16/2023

Species: Yellow-rumped Warbler, Audubon's subspecies
Most recent capture date: 1/4/2023
Age: at least two years old

Notes: The banding station is located next to Coyote Creek, and includes a managed floodplain that catches creek overflow to prevent flooding in less-convenient places. This means that when we get lots of rain, we flood, and banding has to be put on hold for the safety of both birds and people. So far in 2023 we have managed to band for only one half-morning, during which we processed just five birds, including this warbler. Yellow-rumped Warblers of both subspecies are a late winter staple bird for us, and we're especially excited to see them this year because we recently secured a grant to fund a research project about them.

Bushtit

12/26/2022

Species: Bushtit
Most recent capture date: 11/26/2022
Earliest capture date: 11/20/2019
Age: at least three years old
Sex: Male

Ruby-crowned Kinglet

12/23/2022

Species: Ruby-crowned Kinglet
Most recent capture date: 11/27/2022
Age: about six months old
Sex: Male

American Goldfinch

12/20/2022

Species: American Goldfinch
Most recent capture date: 11/20/2022
Age: about six months old
Sex: Male

Notes: American Goldfinches used to be one of the most common captures at CCFS, but they have declined precipitously, to the point where we captured none of them at all in 2018-2021. The cause for that decrease is an ongoing mystery. We have plenty of their favorite seeds growing, which our local Lesser Goldfinches enjoy eating. The Breeding Bird Survey has found that American Goldfinch populations are decreasing overall, but not nearly as quickly as the local drop we have seen.

Golden-crowned Sparrow

12/17/2022

Species: Golden-crowned Sparrow
Most recent capture date: 11/26/2022
Earliest capture date: 11/23/2019
Age: three years old

Notes: Most Golden-crowned Sparrows that we see in the winter have understated, golden-brown and dark brown crowns. This bird's striking black and gold regalia would be a clue that they are an older bird even if we didn't have our capture history information to tell us that they are three years old.

About

You never know who you'll catch when you're bird banding! We wanted to share that sense of surprise, so we'll be posting here some of the birds we catch in the course of our research. Some birds will be here because they are unusual in some way; others just because they took a nice photo.

Authors

We are biologists who study landbirds in the south San Francisco Bay Area through bird banding at Coyote Creek Field Station. We have extensive training (and official permits) for our bird handling, and we prioritize bird safety over all else.

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