Point Blue's Palomarin Blog

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

Monthly Banding Summary, April 2014

05.22.14
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This summary was compiled by Palomarin banding interns Janelle Chojnacki and Asya Rahlin with help from Renée Cormier, Banding Supervisor.

Exciting Captures and Observations:

April is an exciting time at the field station, with the later spring migrants returning from southern winter grounds for the breeding season, including Olive-sided Flycatchers and Swainson’s Thrushes. A few exciting April captures of uncommonly-captured species for us included Tree Swallow, Hermit Warbler, and Swamp Sparrow! The nest searching interns (aka “gridders”) continued to find nests, with 45 new nests located in April. Gridders and banders also banded the first nestlings of the year: Wrentits and Orange-crowned Warblers.

A Tree Swallow is safely removed from a mist net. Photo by Janelle Chojnacki.

A Tree Swallow is safely removed from a mist net. Photo by Janelle Chojnacki.

In addition to searching for nests throughout the study area to monitor reproductive success each year, Palomarin interns also monitor a few nest boxes at the field station. So far, we have observed partially built nests in several boxes. We found eggs in two of the boxes: one nest box is occupied by a Chestnut-backed Chickadee pair and the other box by a pair of Western Bluebirds! Both of these breeding bird pairs failed in their first nesting attempt, but second attempts have been made and more eggs have been laid.. The Western Bluebird box, as shown by the photo below, is being fought over by two pairs. Interns watched in awe as the already established male confronted the intruding male with the females following suit. We saw periods of intense chase, fighting, and rest as the four birds battled right outside our kitchen window.

Western Bluebirds fighting over a nest box at Palomarin. Photo by Janelle Chojnacki.

Western Bluebirds fighting over a nest box at Palomarin. Photo by Janelle Chojnacki.

The Visitors’ Center is home to roosting bats. Identified as California myotis, or Myotis californicus, this small brown bat flew consecutive circles around the field station, apparently trying to find its roosting spot. In the breeding season, California myotis bats will form maternity groups of roosting mothers who will each eventually give birth to one pup, born sometime in May through July.

California myotis emerging from roost above the Visitors’ Center.  Photo by Janelle Chojnacki.

California myotis emerging from roost above the Visitors’ Center. Photo by Janelle Chojnacki.

The calls of Western Gulls fill the air. The photo below was taken on Southeast Farallon Island, which lies approximately 20 miles south of Point Reyes. Palomarin interns periodically assist Point Blue biologists with a bi-monthly food delivery to the island, including last month! Thousands of breeding gulls cover the Farallones in April. Point Blue biologists have been studying wildlife on the islands, including Western Gulls, Common Murres, Rhinoceros Auklets, Black Oystercatchers, and Ashy Storm-Petrels, year-round for over four decades. 

Western Gulls have established territories on the Farallones. Photo by Asya Rahlin.

Western Gulls have established territories on the Farallones. Photo by Asya Rahlin.

Let’s Do the Numbers:

In 15 days (1387.93 net hours) of mist-netting at Palomarin in April, we captured 39 new birds and recaptured 50 previously banded birds. A total of 89 birds of 25 species were caught this month. Approximately 6.83 birds were caught per banding day.

At our other West Marin banding sites (“off-sites”), we captured 78 new birds and recaptured 98 previously banded birds. A total of 176 birds of 30 species were caught over 12 banding days this month (601.91 net hours), an average of approximately 15.27 birds per day.

The highest capture rates at Palomarin and our other West Marin banding sites were on April 29 at Palomarin with 11 birds and April 21 and 28 at Muddy Hollow and Pine Gulch with 18 birds each.

At Palomarin the highest numbers were captured for the following species: Wilson’s Warbler (15), Chestnut-backed Chickadee (9), Song Sparrow (8), Orange Crowned Warbler (8), and Oregon Junco (7).

Across all off-sites, the highest numbers of captures by species were: Wilson’s Warblers (31), Song Sparrows (23), Fox Sparrows (15), Golden-crowned Sparrows (12), and Swainson’s Thrushes (11).

About these Summaries:

In an effort to share our science with the public, Point Blue interns and staff at our Palomarin Field Station (Palomarin or “Palo”) in Point Reyes National Seashore near Bolinas, CA produce these monthly bird-banding summaries. Our science interns create these summaries as part of their science outreach training.

Our Palomarin Field Station is open to the public.  Consider visiting us!  Learn how by visiting our mist-netting demonstrations web page.

 

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