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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: Monthly Banding Summary, March 2020

May 31, 2020

This summary was compiled by Point Blue’s Palomarin banding interns Mary De Aquino, Mary Kate Lisi and Bernarda Vasquez with help from Mark Dettling, Banding 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:

March was an eventful month at the Palomarin Field Station.  As banding interns Hannah Roodenrijs and Samantha Chavez entered their final month, four new banding interns began their training for the spring and summer seasons! The new banding interns are Brandon Dunnahoo from Texas, Mary Kate Lisi from New Jersey, Mary De Aquino from California, and Bernarda Vasquez all the way from Ecuador!  In addition, three nest searching interns (known here at the field station as “gridders”), arrived at the station in mid-March.  The gridders are Oliver Nguyen from Massachusetts, Evan Lipton from Rhode Island, and Sarah Stewart from South Carolina.

All interns spent the first month of their internship learning to identify the local species by sight and sound. While banding interns learned how to operate the mist-net stations, gridders began to familiarize themselves with their study plots or “grids” and locate study species and their territories. Palomarin’s study species are monitored closely, and gridders diligently track their territory boundaries and search for their nests. Our study species are Song Sparrow, Wrentit, Wilson’s Warbler, California Scrub-Jay, Spotted Towhee, White-crowned Sparrow, and Swainson’s Thrush. Some of the individuals of these species are banded with a combination of brightly colored bands (in addition to their 9 digit silver band) which aides the gridders in identifying individual birds in the field and tracking their movements.

Unknown sex Wrentit. Wrentits are another one of our study species, and you can see some of the color bands in this photo!  In most passerines species, only females incubate the eggs.  This is facilitated through the development of a brood patch, a bare area on their belly that allows for better heat transfer to the eggs. Wrentits are unique in that males and females share the responsibility of incubation, and thus both develop brood patches. This makes determining the sex of Wrentits near impossible by sight alone.  Photo by Mary De Aquino.

 

Unknown sex California Scrub-Jay. This bird is one of our study species, and was color banded when captured. You can see one of the blue plastic color bands on the bird’s leg here! Photo by Mary Kate Lisi.

 

Pine Siskins. These four individuals were captured in the same net at the same time at one of our offsites, Muddy Hollow. The differences in the yellow color on their wings were used to age and sex the birds. Brighter, bigger yellow marks on the wings are characteristic of older males, while younger males and adult females have duller yellow plumage. Photo by Sam Chavez.
Male Anna’s Hummingbird. Similar to the Rufous Hummingbird (see below), this Anna’s Hummingbird is a male with a big, bright gorget! Compared to the orange/red gorget of the Rufous Hummingbird, the male Anna’s can be identified by its vibrant pink gorget.

 

Due to COVID-19, a shelter-in-place order was assigned to Marin County in mid-March, limiting our work to the Palomarin Field Station and nearby offsite, Palomarin Grid Uppers. Despite only working at Palo, there were several exciting captures at the field station with spring and summer migrants arriving in the area! Orange-crowned Warblers arrived earlier in the month, with Wilson’s Warblers arriving a few weeks later. Other exciting captures included Rufous Hummingbirds, Hermit Thrushes, a Red-breasted Nuthatch, and a Downy Woodpecker.

Male Wilson’s Warbler. This is a photo of the first Wilson’s Warbler we captured this season! We measure the crown of every captured individual and use the length, along with other characteristics, to age and sex this species. Both males and females have a black crown, but differ in crown length and percent of green feathers present. Photo by Bernarda Vasquez.
Male, Rufous Hummingbird. This bird was easily identified as a male due to the full, bright gorget of feathers on the head and throat. How beautiful! Unlike Allen’s or Anna’s Hummingbirds, Rufous Hummingbirds do not breed in the Palo area, but travel farther north to their breeding grounds. Photo by Bernarda Vasquez.

 

Male, Red-breasted Nuthatch. This bird was aged as an “after second year,” meaning it was born in 2018 at the earliest! Photo by Mary Kate Lisi.

 

The Allen’s Hummingbird nest that was found along the net trail last month was successful! From the trail we were able to see 2 nestlings in the nest. After a week or so, we did not notice any more activity and we believe the nestlings have fledged.

We also began to see our first fledglings of the year with several Allen’s Hummingbirds. Gridders began to locate territories and nests, and we expect to band plenty of nestlings in the next few weeks!

Let’s Do the Numbers:

In 19 days (1719.74 net hours) of mist-netting at Palomarin in March, we captured 32 new birds and recaptured 41 previously banded birds. A total of 73 birds of 21 species were caught. Approximately 5 birds were caught per banding day.

At our other West Marin banding sites, we captured 62 new birds and recaptured 52 previously banded birds. A total of 114 birds of 21 species were caught over 8 banding days in April (396.83 net hours), an average of approximately 19 birds per day.

The highest capture rates at Palomarin and our other West Marin banding sites were on March 31st at Palomarin with 11 birds, and March 6th and 12th at Muddy Hollow, tied with 27 birds each.

At Palomarin, the following species were caught in the highest numbers: Orange-crowned Warbler (11), Oregon Junco (10), Pacific Wren (8), Song Sparrow (5), and Anna’s Hummingbird (5).

Across all off-sites, the highest numbers of captures by species were: Song Sparrow (23), Ruby-crowned Kinglet (20), Wrentit (9), Fox Sparrow (9), and Hermit Thrush (6).

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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