Point Blue Conservation Science: Monthly Banding Summary, June 2019
August 14, 2019
This summary was compiled by Point Blue’s Palomarin banding interns Sam Snowden, Sophie Noda, Sarah Mueller, and Olivia Wang with help from Mark Dettling, Banding Supervisor.
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Exciting Captures and Observations:
Throughout the month there were several reports of rare bird sightings around Marin County, including Northern Parulas, a Common Redpoll, and a Black Vulture in or near Point Reyes National Seashore. On rare occasions a species shows up in our area that is completely outside of its normal geographic range or during a time of year that it is usually found elsewhere. We call birds that are found outside their normal range “vagrants.” These migratory birds that unexpectedly turn up in California might normally be found as far away as the East Coast, the Midwest, Canada, Alaska, or even eastern Asia. It is not always clear what causes these vagrants to end up so far outside of their normal range. It is possible that they are blown off course by bad weather during migration, or simply get lost due to an error in their internal navigation system.
In June, the Palomarin interns were very lucky to catch American Redstarts at Redwood Creek (in the Golden Gate National Recreation Area) not once, but twice! Redstarts normally breed from the East Coast to the Midwest and north to Western Canada, and migrate to South America, Central America and Mexico for the winter. They occur in California as vagrants, and more so in the fall season. The first capture was a male on June 17th, after the interns heard the bird singing nearby. On June 27th, the interns caught the male again, and this time caught a female as well! Amazingly, both birds were in breeding condition, meaning that they were likely a pair, despite the odds. In addition to the male singing, the birds were observed carrying nesting material, which is a very good sign that they have a nest nearby. The interns have yet to locate the nest, but remain hopeful that juvenile redstarts may be the next surprise visitor at the banding station. It looks like the closest area where they regularly breed is far northeast Oregon.
In addition to the redstarts, the interns caught a male Rose-breasted Grosbeak at Redwood Creek on June 27th. Rose-breasted Grosbeaks typically breed only in the northern parts of the Midwestern and Eastern US and in Canada, but are annually recorded as vagrants in California. Interestingly, our grosbeak also showed breeding condition, so he could be attempting to breed outside its normal range much like the redstarts!
At Palomarin on June 13th, we caught a Varied Thrush. This species is common here in winter, but migrates north for the summer to breed in far northern California, Oregon, Washington, Canada, and Alaska. Varied Thrushes typically depart Palomarin by the end of April and do not arrive again until September, so they are a very unusual summer capture.
Of course, we also captured many individuals of our more common species. The breeding season continues in Marin, and this month we caught even more juveniles, including a Black Phoebe, Oregon Junco, Swainson’s Thrushes, and Brown Creepers. In addition, the Barn Swallow nest under the eaves of the bunkhouse at Palomarin successfully fledged three young!
Let’s Do the Numbers:
In 28 days (12978.51 net hours) of mist-netting at Palomarin in June, we captured 164 new birds and recaptured 147 previously banded birds. A total of 312 birds of 30 species were caught. Approximately 11 birds were caught per banding day.
At our other West Marin banding sites, we captured 184 new birds and recaptured 150 previously banded birds. A total of 355 birds of 33 species were caught over 11 banding days in June (3011.46 net hours), an average of approximately 32 birds per day.
The highest capture rate at Palomarin was on June 14th with a total of 24 birds. The highest capture rate at our other West Marin banding sites was June 17th at Redwood Creek with a total of 64 birds!
At Palomarin, the following species were caught in the highest numbers: Wilson’s Warbler (87), Swainson’s Thrush (49), Allen’s Hummingbird (36), Wrentit (18), and Pacific-slope Flycatcher (16).
Across all off-sites, the highest numbers of captures by species were: Wilson’s Warbler (75), Swainson’s Thrush (65), Song Sparrow (63), Orange-crowned Warbler (26), and Allen’s Hummingbird (16).
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.
Our Palomarin Field Station is open to the public. Consider visiting us! Learn how on our contact & visit us web page.