Spring Banding Summary 2024

July 9, 2024

This summary was compiled by Palomarin banding apprentices Ananke Krishnan, Sarah Needles, Fen Conway, and Sam Eberhard, along with banding supervisor Larissa Babicz.

Exciting Captures and Observations:

Capture rates were relatively low in late March and early April, which is typical for this time of year because many wintering birds have already left, while the birds that spend the summer months here have only just started to arrive and for the most part haven’t yet produced young. Spring is also the windiest season in west Marin, and we had several days with gusts over 20 miles per hour, resulting in many shortened or canceled banding days (we do not mist net in inclement weather). The slower days coincided with the arrival of a new apprentice cohort, who did appreciate the reduced activity as a blessing in disguise as they began learning the ropes of the station.

The beginning of April generally marks the arrival of significant numbers of neotropical migrants in the area. These species spend the cooler months in Central and South America and in the spring either pass through our area on their way further north or settle down for the summer to breed locally. These birds started to show up in early April, but unseasonable rains seemed to hamper migration along the California coast. Though numbers seemed to initially be lower than expected for these migrants, many found their way back to their breeding territories, and by late April, even the later-arriving species like Swainson’s Thrush and Olive-sided Flycatcher were singing away at Palomarin. On March 17th, we caught our first Wilson’s Warbler and our first Swainson’s Thrush, which winters in western Mexico (see this blog post on SpringerNature for a summary of our study that helped determine that) was captured on April 30th; both eventually constitute two of our most common captures in the spring and summer. Birds started being captured in breeding condition (with a brood patch for incubating eggs or brooding young, or a cloacal protuberance for mating) around mid-March as well, heralding the beginning of nesting season, egg incubation, and spring at last! 

Spring was also a great time for a birding trip for the Palo banders and Point Blue’s Spotted Owl monitoring crew. We began a brisk morning at the Bolinas Lagoon and enjoyed good looks at several wintering species that had yet to head off to their breeding grounds. We took care to note diagnostic field marks on the Clark’s and Western Grebes, as well as on the Greater and Lesser Scaups that were rafting on the lagoon. Other highlights from the lagoon were Elegant Terns, a Black-crowned Night-Heron, and an adult Bald Eagle. At Five Brooks Pond in Point Reyes National Seashore we were rewarded with some good looks at Wood Ducks and four species of swallow. At Giacomini Wetlands at the south end of Tomales Bay, we saw three species of teal, and at the Bear Valley Earthquake Trail in Point Reyes National Seashore we carefully counted six Bald Eagles – together! One of these eagles was leucistic, a rare condition where melanin (the dark pigment that gives color and strength to feathers) is lacking in a bird’s feathers. 

 

In the spring, Palomarin banders also monitor four banding sites away from the field station (we call these “offsites”), three of which are in a riparian habitat and are generally busier. We were glad to have some of the wintering species, such as Fox Sparrows, still hanging around during the early part of the season. The affectionately nicknamed “butter-butts” (Yellow-rumped Warblers) were especially exciting, and we were able to differentiate the Myrtle and Audubon subspecies in the hand! It was a fun learning opportunity for new banders.

At Pine Gulch, a riparian study site at the Bolinas Lagoon Preserve, we had a cool diversity of sparrows, and one banding day produced five different species (Song, Fox, Swamp, Lincoln’s, and even a White-throated)! Other notable captures, that are around but not commonly caught, included a Marsh Wren, a gorgeous adult male Western Bluebird, and a female Lesser Goldfinch!

 

 

At our nearest offsite, located just a few minutes’ hike from our field station in the Point Reyes National Seashore, we were lucky enough to catch a Sharp-shinned Hawk! These tiny birds of prey are fast and agile, experts at weaving through forests to hunt small songbirds. Sharp-shinned Hawks look very different in their first year of life than they do as adults, with a streaky brown plumage and yellow eye. We were able to use these criteria and the wing length to call this individual a second-year male, meaning that it hatched last year!

In late April, we finally began seeing the first juveniles of the season! The first young bird was an Allen’s Hummingbird caught on April 12th at Muddy Hollow, another riparian study site in the Point Reyes National Seashore. By this time in mid-April, many of the birds we caught were showing breeding condition, foreshadowing of the many young birds to come…

 

Let’s Do the Numbers: 

In 30 days (3,256.04 net hours) of mist-netting at Palomarin in March and April, we captured 51 new birds and recaptured 70 previously banded birds. A total of 121 birds of 23 species were caught. Approximately 4 birds (!) were caught per banding day.

At our other West Marin banding sites (“off-sites”), we captured 90 new birds and recaptured 83 previously banded birds. A total of 173 birds of 31 species were caught over 16 banding days during March through April (811.83 net hours), an average of approximately 11 birds per day.

The highest capture rate at Palomarin was on April 9th with 11 birds, and at our off-sites was on April 22nd at Muddy Hollow with 24 birds.

Between March 1st and April 30th, at Palomarin, the species caught in the highest numbers were: Wilson’s Warbler (23), Orange-crowned Warbler (15), and Oregon Junco (12).

In that same time period, across all off-sites, the highest numbers of captures by species were: Song Sparrow (50), Wilson’s Warbler (20), and Common Yellowthroat (16).

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. Learn more about our seasonal apprenticeships by visiting the careers page on our website. 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.

The Palomarin Field Station is open to the public. Consider visiting us! Learn how on our contact & visit us web page.

Bird-Safety Statement

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. All birds were captured and handled with appropriate training and permitting.