San Francisco Bay Bird Observatory - Notes from the Station

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Anna's Hummingbird

9/29/2022

Species: Anna's Hummingbird
Most recent capture date: 9/4/2022
Age: less than one year old
Sex: male

Notes: You can see the outermost tail feather here, R5, has a patch of white with a black spike pointing down through it. That black spike indicates that this not-very-pink Anna's Hummingbird is a young male rather than a female. (You can also see a foot in this picture: hummingbirds do have legs and feet! They're just very small.)

Common Yellowthroat

9/26/2022

Species: Common Yellowthroat
Most recent capture date: 9/4/2022
Age: less than seven months old
Sex: male

Notes: The black mask says "male;" the speckles on the black mask say "baby."

Willow Flycatcher

9/24/2022

Species: Willow Flycatcher
Most recent capture date: 8/31/2022
Age: less than 7 months old

Notes: The Willow Flycatcher can be distinguished (on the west coast) from "Western" Flycatchers by their lack of an eyering. ("Western" Flycatchers are either Pacific-slope or Cordilleran Flycatchers, which are hard to tell apart.) East coast Willow Flycatchers are trickier, and closely resemble Alder Flycatchers to the point that those two species also have an umbrella name for the both of them, "Traill's" Flycatcher, to use when you can't distinguish them. There is a reason that Empidonax flycatchers have a reputation among birders...

Bushtit

9/21/2022

Species: Bushtit
Most recent capture date: 8/31/2022
Age: at least 1 year old
Sex: female

Notes: We put birds in light cloth bags to transport them the short distance between the nets and where we take their data. The bags allow the birds to sit however they like; many cling to the fabric or climb up the inside of the bag. Bushtits tend to call to their flockmates from inside the bag, so if you catch a flock of Bushtits, you will have many bags all cheeping to each other.

Lesser Goldfinch

9/18/2022

Species: Lesser Goldfinch
Most recent capture date: 8/31/2022
Age: at least 1 year old
Sex: female

Notes: The size of white patches on the wing and tail, and the amount of black on the crown, help us identify the age and sex of these little birds.

Black-headed Grosbeak

9/15/2022

Species: Black-headed Grosbeak
Most recent capture date: 8/28/2022
Age: less than 6 months old

Notes: Yes, grosbeaks bite.

Swainson's Thrush

9/12/2022

Species: Swainson's Thrush
Most recent capture date: 8/21/2022
Age: less than 6 months old

Notes: What a difference a molt makes! Compare this slick-looking kid to the speckled Swainson's Thrush from a few posts back: this bird has replaced their body feathers in the preformative molt and now looks all grown up.

Anna's Hummingbird

9/8/2022

Species: Anna's Hummingbird
Most recent capture date: 8/20/2022
Age: over 1 year old
Sex: female

Notes: Did you know that hummingbirds are small? Hummingbirds are SMALL. This one has more pink in the gorget than we generally expect to see in a female; we can tell she is female by the pattern of white and black on her outer tail feather.

Pacific-slope Flycatcher

9/5/2022

Species: Pacific-slope Flycatcher
Most recent capture date: 8/17/2022
Age: less than 5 months old

Notes: We call these Western Flycatchers, since it is difficult to distinguish Pacific-slope from Cordilleran Flycatchers in the hand, but detailed measurements of this bird and his location make it highly likely that he is a Pacific-slope. Western Flycatchers, or WEFLs (pronounced like "waffles" but with an E), are the defining species of our fall migration, showing up in great numbers just for this one brief period. Their big eyes, long "whiskers" (technically, rictal bristles), and flat boat-shaped bills give them lots of charisma.

Song Sparrow

9/1/2022

Species: Song Sparrow
Most recent capture date: 8/07/2022
Earliest capture date: 6/15/2022
Age: less than 5 months 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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