Notes from the Station

Species: American Robin
Most recent capture date: 3/18/2023
​Sex: Female

Notes: Robins come in a variety of shades. Compare this pale bird to the dark bird from two posts ago! Males are generally darker than females, but there is a lot of overlap in the middle, so we generally can’t determine the sex of intermediate birds. These two are sufficiently extreme in their coloring that we can determine their sex.

Species: Nuttall’s Woodpecker
Most recent capture date: 3/5/2023
Age: almost one year old
​Sex: Female

Species: American Robin
Most recent capture date: 2/25/2023
​Sex: Male

Notes: This has been a banner robin winter for us. Usually if we catch robins at all, it’s just for a day or two as the flock moves through; but this winter we have been catching them for months now. We aren’t the only ones: lots of people in the Bay Area have reported seeing more robins than usual.

Species: Yellow-rumped Warbler
Most recent capture date: 2/25/2023
Age: almost one year old

Notes: Don’t be alarmed: this bird is perfectly healthy. Yellow-rumps tend to get sticky stuff on their faces while foraging. We don’t know if this is while they are actively eating sap (which they are known to do) or while foraging for insects on sticky trees like the invasive eucalyptus, but either way, they end up with their faces in sticky stuff. Their feathers get stuck together in clumps and even pulled out, as you see in this individual. They don’t seem to have any health issues with this; the damage is purely aesthetic.

Species: Yellow-rumped Warbler (Myrtle Warbler subspecies)
Most recent capture date: 2/25/2023
Earliest capture date: 3/30/2019
Age: at least 4 years old
​Sex: Male

Notes: We don’t get across-year recaptures for Yellow-rumped Warblers very often. Getting one across four years is pretty amazing.

Species: Lesser Goldfinch
Most recent capture date: 2/18/2022
Age: at least one year old
​Sex: female

Species: Downy Woodpecker
Most recent capture date: 2/15/2023
Age: almost one year old
​Sex: male

Notes: When bird banders talk about some species being “grippy,” we mean that they like to clutch at things with their feet. This can be counterproductive when we are trying to get them out of our net: they clutch at the net, at our fingers… One approach for mitigating this is to give them something else to hold. We gave this young woodpecker a stick so that he would let us extract him from the net.

Species: Hutton’s Vireo
Most recent capture date: 2/4/2023
Earliest capture date: 5/18/2022
Age: almost one year old

Notes: This bird was first banded at CCFS as a fledgling, captured in the company of another fledgling vireo – almost certainly their sibling. 2022 was the first year that we were certain we had Hutton’s Vireo’s breeding at CCFS. It’s delightful to see that at least one of this batch of babies has survived and stayed local. (The vireo is on the left in this photo, being fluffy; on the right is a Ruby-crowned Kinglet, a bird very similar in plumage. The two species are often confused for each other.)

Species: Red-breasted Sapsucker
Most recent capture date: 2/1/2023
Age: at least two years old

Notes: We know these handsome woodpeckers are around CCFS in the winter because we see their signature feeding marks on the trees, but we rarely catch them. In the past five years we have only caught one Red-breasted Sapsucker besides this one. Despite their bright plumage, we can’t tell the sex of this bird: in this species both males and females are equally decorated.

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

Notes: Another one of these treat sparrows! (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?