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Taking the Long View: An inside look at the goings-on at the longest running avian ecology field station west of the Mississippi.

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Point Blue Conservation Science: Palomarin Field Station Spring Season Update – April & May, 2020

May 31, 2020

This summary was compiled by Point Blue’s Palomarin banding interns Mary De Aquino and Bernarda Vasquez with help from gridding interns Oliver Nguyen and Sarah Stewart, and Hilary Allen, Gridding Supervisor.

About Point Blue: Our mission is to conserve birds, other wildlife, and ecosystems through science, partnerships, and outreach.

Our Vision: Because of the collaborative climate-smart conservation work we do today, healthy ecosystems will continue to sustain thriving wildlife and human communities well into the future.

Explore Point Blue’s website to learn more.

Exciting Captures and Observations:

April and May were exciting months at the Palomarin Field Station. With spring migrants continuing to arrive and the breeding season in full swing, the banding interns and nesting searching interns were kept busy. In addition to some of our commonly caught local species, such as Song Sparrows, Spotted Towhees, and Wrentits, our most common captures have begun to change with the the arrival of spring and our neotropical breeding migrants.  The mist nets were kept busy with Orange-crowned Warblers, Wilson’s Warblers, and Swainson’s Thrushes, as well as a very enthusiastic Pacific Wren family that had quite the knack for showing up in our nets.

Juvenile Pacific Wren: In the past couple of months we began catching some “hatch-year” (hatched this year) birds. You can see that this Pacific Wren is a juvenile by its gape, the wide yellow portion at the base of its beak.  Other characteristic features of juveniles in many species include streaky coloration and loose plumage compared to adults. Photo by Bernarda Vasquez

 

In addition to our more common captures, we got a few species that don’t often end up in the nets, including a Northern Flicker, Steller’s Jay, two California Quail, and a Western Bluebird, the first one since 2015. Near the end of May, exciting captures included a nine-year old Swainson’s Thrush, a MacGillivray’s Warbler, and a Brewer’s Sparrow, the fourth one ever caught at Palomarin!

Male MacGillivray’s Warbler. Although we hear the occasional MacGillivray’s Warbler in the area surrounding the Field Station, it was quite a surprise when this after-hatch-year male ended up in our nets.  The white crescents above and below the eye are not only charming, but also a key feature for identifying this species. Photo by Brandon Dunnahoo
Female Red-shafted Flicker: This bird was a surprise for everyone! From the photo you can see that it is a very large and colorful bird, with wonderful black circles in its plumage and orange on the underside of its tail feathers. We can tell this individual is a female because it does not have the red mustache present in males.  It is a bird with a great personality and a strong bill. Photo by Bernarda Vasquez
A male California Quail. This is the first male California Quail we captured this season! Photo by Bernarda Vasquez
A male Purple Finch. Here you can see the beautiful purple color for which these finches are named.  Only male Purple Finches have this bright raspberry coloration, which they achieve only after their second year, allowing us to identify this individual as an after-second-year male.  Females remain drab brown throughout their life.  In the hand, another diagnostic feature of this species is that they love to bite fingers.  Ouch! Photo by Bernarda Vasquez

 

With some changes to shelter-in-place restrictions in the second half of May, banding interns were able to resume banding at two more of our other study sites or “off-sites”: Muddy Hollow (in Point Reyes National Seashore) and Redwood Creek (in Golden Gate National Recreation Area). Compared to Palomarin, our capture rates were much higher at off-sites, which gave the interns lots of great practice processing birds.  On our first visit to Redwood Creek we caught 63 birds, 10 of which were hummingbirds!  It was fun to get some unusual species at the off-sites, including Warbling Vireos, a Brown-headed Cowbird, and even a Black-headed Grosbeak.

A foggy morning on the grids. Photo by Sarah Stewart.

 

In April and May the gridders continued to spend their days following birds and locating their expertly hidden nests. Nest searching requires a lot of patience and countless hours spent crawling through swaths of poison oak and other thick vegetation, waiting to catch glimpses of birds and gather small clues that will help lead us to finding a nest. Paying such close attention to, and spending day after day with individual birds out on the plots, allows gridders to have a very unique window into the birds’ lives. Gridders come to know some individual birds quite intimately, learning which birds are particularly unfazed by their presence, which birds are quick to come and scold them for being in their territory or near their nest, and which birds are infamously elusive and tricky to follow.

Despite some rainy days, the gridders found many new study species’ nests, especially those belonging to Wrentits, Wilson’s Warblers, and Song Sparrows.  In addition, they noted quite a few non-study species’ nests, including Oregon Junco, Allen’s Hummingbird, Band-tailed Pigeon, and even a Hermit Thrush nest, only the second one ever found on our study plots!

A Wrentit parent on a nest. Photo by Oliver Nguyen
A Wrentit nest with three blue Wrentit eggs. Photo by Sarah Stewart
A California Scrub-Jay nest with nestlings. These California Scrub-Jay nestlings are about 10 days old. They will spend another 10 days in this nest while they continue to be fed by their parents before taking a brave step out of their cozy nest and into the world. Photo by Oliver Nguyen.

 

When they locate a nest, gridders monitor its progress through the building, incubating, and nestlings stages of the nest. When nestlings of the study species hatch, gridders pay extra close attention to their development in order to determine when they sufficiently mature and can be safely banded.

A Song Sparrow nestling. We band Song Sparrow nestlings when they are just 7 days old. This little nestling will continue to grow and be ready to leave the nest in just two or three more days! Although it may look pretty different from an adult, this nestling’s legs have reached their full girth and the nestling is ready to be banded. Photo by Oliver Nguyen.
A Wrentit nestling. We band Wrentit nestlings when they are 10 days old. Wrentits are abundant on our study plots. In April alone we banded 26 Wrentit nestlings! Photo by Sarah Stewart.
A Wilson’s Warbler nestling. We band Wilson’s Warbler nestlings when they are 7 days old. Hard to believe that this little half naked nestling will be making the journey to Central America this fall! Photo by Hilary Allen

 

About these Summaries:

Point Blue interns 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.

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