Monthly Banding Summary, August 2024
December 5, 2024
This summary was compiled by Point Blue’s Palomarin banding interns Adlai Herrera, Jackie Quinones, and Ariana Vélez with help from Mike Mahoney, Banding Supervisor.
Exciting Captures and Observations:
August was an exciting month for the Palomarin Field Station as it marked the end of the summer breeding season and the start of fall migration. In addition to welcoming early season migrating songbirds, we also welcomed the new Fall Bird Banding Apprentices, who were grateful to come in this unique time filled with late-season fledgling birds and early fall migrants.
During spring through fall, Palomarin banders monitor bird populations through constant effort mist-netting efforts at up to five banding sites including the Palomarin Field station and four additional sites that we refer to as “offsites” across coastal Marin County, California. The offsites generally have higher capture rates than the banding station at the Palomarin Field Station (Palo) because of differences in habitat. Many of these sites offer exciting opportunities to see species our banders normally wouldn’t see at Palomarin; for instance at our banding site along Pine Gulch Creek, banders have the opportunity to see Marsh Wrens, Common Yellowthroats, and a variety of shorebirds. However, for this fall, we transitioned in the middle of August from monitoring four offsites in addition to the nets at Palo to just one, Muddy Hollow, a riparian habitat located in Point Reyes National Seashore.
To start the month off strong, on August 1st Palomarin had an exciting capture, Nuttall’s White-crowned Sparrow, a subspecies of White-crowned Sparrow that breeds in the area! This was particularly memorable, because White-crowned Sparrow captures have declined over the years due to the decline of coastal scrub habitat at the field station. The Nuttall’s subspecies of White-crowned Sparrow is one of the station’s focal species, but one that has declined significantly at Palomarin due to habitat succession, so banders don’t catch them too often anymore. As a focal species, in addition to giving them the standard 9-digit aluminum band, we also put color bands on them. When Point Blue biologists are territory spot mapping, these bands help us identify individuals when they are in their natural habitat and gather data on their breeding territories. This data has been used for many publications at Point Blue revolving around nesting behavior, and you can read more about the changes in community composition and habitat change at the Palomarin Field Station on the Palomarin Data Explorer.
The new banders were thrilled to catch the local residents species like Red-breasted Nuthatch, Anna’s Hummingbird, Oregon Junco, Brown Creeper, Chestnut-backed Chickadee, and Wrentit.
Male Anna’s Hummingbird (left) and a Red-breasted Nuthatch (right) at the Palomarin Field Station. Photos by Adlai Herrera and Jackie Quinones / Point Blue
Muddy Hollow had an uncommon capture on August 6th: a Brown-headed Cowbird! Rather than these birds building their own nests, female Brown-headed Cowbirds lay their eggs in other species’ nests such as American Goldfinch, as documented by Palomarin nest searching apprentices. When a young Brown-headed Cowbird hatches, they can push out the other species from the nest to gain more attention from the host parent. A relatively common species in the region, these are rarely caught in our mist nets.
A Brown-headed Cowbird captured at Muddy Hollow. Photo by: Jackie Quinones / Point Blue
Fall migration is arguably one of the most exciting times of the year at the station, and the Palomarin banders always look forward to catching migrants passing through or possible vagrants species- birds that are found outside of their expected range.
On August 14th we caught our first Rufous Hummingbird! As these birds migrate from their breeding grounds British Columbia, Canada and the Pacific Northwest of the United States to their wintering sites in Mexico, like many other species in fall, they pass through our area during their southern migration to warmer climates. These birds look extremely similar to Allen’s Hummingbirds, a species that breeds locally. When we catch these birds, we must take extra measurements on the shape and width of their tail feathers, to ensure that we identify them to the correct species.
An Allen’s Hummingbird, identified with caution, with pollen on its bill, captured at the Palomarin Field Station. Photo by: Ariana Vélez / Point Blue.
Lazuli Buntings are always an exciting capture in the fall. While they breed in Marin, they are relatively uncommon to catch at our sites; however, we were lucky enough to catch one on August 25th.
A Lazuli Bunting showing off it’s pale red breast, captured at the Palomarin Field Station. Photo by: Mike Mahoney / Point Blue
In August, warblers have also started to move through! On August 22nd, we caught our first Black-throated Gray Warbler of the season (featured below). Just a few days later, on August 25th, we captured our first Yellow Warbler of the fall. Yellow Warblers are a bright dashing yellow, sometimes with reddish streaking. Finally, on August 28th, we celebrated two first captures: a Townsend’s Warbler, a species we’re excited to welcome as some stay all fall and winter here, and a Hermit Warbler, some of which may choose to winter here but many will make their way south (see this Institute for Bird Populations blog post for more information about Hermit Warbler migratory patterns).
A female Townsend’s Warbler, a Hermit Warbler, and a Black-throated Gray Warbler, all captured at the Palomarin Field Station. Photos by: Sam Eberhard / Point Blue.
While we had many exciting captures, we also encountered some species that slipped past our nets but were spotted at our field stations. This included Blue-gray Gnatcatchers and Western Tanagers at Palomarin and an Ash-throated Flycatcher and an American Redstart, American Redstart, a vagrant whose typical range does not include most of California, at Muddy Hollow!
Let’s Do the Numbers:
In 27 days (2958.24 net hours) of mist-netting at Palomarin in August, we captured 182 new birds and recaptured 60 previously banded birds. A total of 242 birds of 26 species were caught. Approximately 8 birds were caught per banding day.
At our other West Marin banding sites (“offsites”), we captured 128 new birds and recaptured 38 previously banded birds. A total of 166 birds of 26 species were caught over 7 banding days in August (351.99 net hours), an average of approximately 23 birds per day.
The highest capture rates occurred at Palomarin on August 10th and 30th, tying for 17 birds caught, and at our offsites on August 6th at Muddy Hollow, with 52 birds.
At Palomarin, the following species were caught in the highest numbers: Western Flycatcher (45), Oregon Junco (33), Wilson’s Warbler (28), Brown Creeper (27), Swainson’s Thrush (18).
Across all offsites, the most commonly captured species were as follows: Song Sparrow (44), Wilson’s Warbler (26), Swainson’s Thrush (21), Oregon Junco (11).
About these Summaries:
Point Blue apprentices and staff at our Palomarin Field Station share these blog posts in an effort to further engage the public in our science. We are grateful to our partners at the Point Reyes National Seashore and to our surrounding Bolinas and West Marin County community for their support of our work.
Early-career bird banders are part of a rigorous training program at Point Blue’s Palomarin Field Station, where they learn to capture birds safely using mist nets and record data on each bird caught. The information collected allows us to better understand how populations of birds are doing and in turn gives us insight into the health of the systems we research. Learn more about our seasonal apprenticeships by visiting the careers page on our website.
All banding, marking, and sampling is being conducted under a federally authorized Bird Banding Permit issued by the U.S. Geological Survey’s Bird Banding Labratory.
Our Palomarin Field Station is open to the public. Consider visiting us! Learn how on our contact & visit us web page.