Notes from the Station

Species: Black-headed Grosbeak
Most recent capture date: 5/23/2021
​Earliest capture date: 5/13/2018
Sex: Male
Age: 4 years old

Notes: You don’t often get to see a Black-headed Grosbeak’s secret yellow underwing. Our scientific understanding of bird coloration suggests that yellow/orange/red colors are costly to produce, so there must be some reason the grosbeaks bother to produce this patch of bright yellow, even if it’s usually hidden.

Species: Bushtit
Most recent capture date: 6/13/2021
Sex: probably female
Age: less than two months old

Notes: In adult Bushtits, the sexes can be distinguished by eye color: males have brown eyes while females have pale eyes. Juvenile Bushtits, however, all have brown eyes. Therefore, the eyes of female Bushtits must at some point transition from brown to pale. This appears to be happening in this young bird, whose eyes are dark at the bottom but pale at the top.

Species: Yellow-breasted Chat
Most recent capture date: 6/10/2021
Sex: Female
Age: 2 years old

Notes: This bird, captured at one of our satellite banding locations, is really special. Not only is she an unusual species for us; when we examined her, we found a brood patch, meaning that she was breeding – the first record of a breeding Yellow-breasted Chat in the county! Here’s hoping her nest is successful and we have more of these beautiful chats around in the future.

Species: Nuttall’s Woodpecker
Most recent capture date: 6/6/21
Sex: Male
Age: less than 6 weeks old

Notes: More babies! You can see in this picture how fluffy he is – that’s actually a real attribute of young birds that we can use to distinguish them from adults. In official bird banding terminology it’s called “loosely-textured plumage”. You can also see here the trait that lets us distinguish this species from the similarly-sized Downy Woodpecker: Nuttall’s Woodpeckers have striped backs, while Downy Woodpeckers have white backs.

Species: Yellow Warbler
Most recent capture date: 5/29/21
Sex: Male
Age: at least 1 year old

Notes: Male Yellow Warblers have variable amounts of red streaking on the breast. We usually get individuals with very little streaking, so this fellow’s moderate streaking was fun to see.

Species: Chestnut-backed Chickadee
Most recent capture date: 6/4/21
Age: 3-5 weeks old

Notes: It’s baby season! This grumpy-looking fellow was caught with three same-aged juvenile chickadees and a male-and-female pair of adults: the whole family, probably. When we catch possible families we take care to release them all at the same time so they don’t lost track of each other.

Species: Downy Woodpecker
Most recent capture date: 5/29/21
Earliest capture date: 12/27/17
Sex: Male
Age: 4 years old

Notes: In most bird species, only females incubate the eggs, so only females develop brood patches, an anatomical feature that develops during the breeding season to help them better transfer heat to the eggs. However, in woodpeckers, males also incubate. This guy had a brood patch when we caught him this year, and also had one in 2018 and 2019. (We didn’t catch him in 2020.) He could have great-great-grandchildren by now!

Species: Yellow Warbler
Most recent capture date: 5/23/21
Sex: Female
Age: at least one year old

Notes: This Yellow Warbler had a brood patch, indicating that she’s breeding. That’s quite exciting: Yellow Warblers were a target species when strips of riparian habitat at CCFS were restored from pear orchard in 1987 and 1993, but we haven’t seen them breeding here, just passing through on migration. A breeding population here would be a long-delayed but lovely success.

Species: Song Sparrow
Most recent capture date: 5/29/2021
​Earliest capture date: 5/9/2020
Sex: Female
Age: at least 2 years old

Species: Western Tanager
Most recent capture date: 5/7/21
Sex: Male
Age: slightly less than 1 year old

Notes: Sometimes you watch a bird dart about in the trees and think, “Please fly into the net… please…” – and then sometimes a bird shows up in the net that you didn’t even know was in the area. This Western Tanager was a gilded, fiery surprise when he turned up at one of our satellite banding sites.