Point Blue Conservation Science: Monthly Banding Summary, August 2018
October 22, 2018
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This summary was compiled by Point Blue’s Palomarin banding interns Michael Mahoney and Nicole Gaudenti with help from Renée Cormier, Banding Supervisor.
Exciting Captures and Observations:
In August we said “see you soon” to our four spring/summer banding and three nest searching interns, and welcomed back two former banding and nest searching interns as the new fall banding crew. Due to the reduced number of interns this fall, we are only operating one off-site (Pine Gulch, in the Bolinas Lagoon Open Space Preserve) in addition to banding six days a week (Tuesday through Sunday) at the Palomarin Field Station. On the bright side, the reduced number of interns provides an opportunity for some “celebrity banders” – previous Palo interns, many who are now Point Blue staff – to come band while one of the two current interns catches a break from the busy fall schedule. Along with the new crew, we welcomed the many fall migrants that pass through coastal central California on their journey from their northern summer breeding grounds to their wintering grounds.
The Palomarin Field Station is an exciting place to band during the fall months, as many young birds take a more coastal migration route on their journey. Additionally, the peninsular coastline in Point Reyes National Seashore funnels migrants along the bay, and hopefully, into our nets!
Exciting first of fall captures included two Hermit Warblers captured on August 1, a Band-tailed Pigeon on August 9, multiple Cassin’s Vireos at Palo and Pine Gulch, a Blue-gray Gnatcatcher on August 12, an Olive-sided Flycatcher on August 14, an American Goldfinch on August 21, a Rufous Hummingbird on Aug 29, and a Western Tanager on Aug 30. While many of these species breed in Marin (Rufous Hummingbird being the only exception), and some even breed here at Palo (e.g., Band-tailed Pigeon and Olive-sided Flycatcher), we do not often get opportunities to see these birds in the hand!
Another exciting capture included a female Sharp-shinned Hawk on August 17. From analysis of the banding data at Palo (see Culliney and Gardali 2011, published in the Journal of Raptor Research) we learned that we don’t catch as many female Sharp-shinned Hawks as we catch males of this species (92% male vs 7% female!). This could be due to the fact that female ‘Sharpies’ are larger than their male counterparts, so they may get caught less often in our mist nests (which are designed for small songbirds), or because the males and females spend their winters apart from one another. Interestingly, we have had an increase in capture of Sharp-shinned Hawks at Palo from 1979 to 2006, potentially due to the banning of DDT or local changes in the habitat at Palo from a coastal scrub/ riparian oak woodland to a Douglas fir Forest.
As mentioned before, not only is Marin County a great place to find the expected migrants, it’s also well-known for the number of vagrant birds that pass through. A vagrant bird is any bird found outside of its expected range, and on the West Coast, the term typically refers to East Coast birds or East-Asian species that are, for whatever reason, off their typical course. This fall we caught a Canada Warbler at Palo on August 29, an unexpected East Coast vagrant. Canada Warblers typically spend their summers breeding in southern and central Canada and migrate to their wintering grounds taking an eastern migratory route. This was the 5th capture of a Canada Warbler at the Palomarin Field Station, and if you can’t tell, we were very excited about it!
Let’s Do the Numbers:
In 27 days (3,117 net hours) of mist-netting at Palomarin in August, we captured 226 new birds and recaptured 115 previously banded birds. A total of 341 birds of 37 species were caught. Approximately 13 birds were caught per banding day.
At Pine Gulch, the only off-site being operated this fall, we captured 59 new birds and recaptured 18 previously banded birds. A total of 78 birds of 19 species were caught over 3 banding days in August (153 net hours), an average of approximately 26 birds per banding day.
The highest capture rates at Palomarin and Pine Gulch were on August 9th at Palomarin with 27 birds and August 13th at Pine Gulch with 33 birds.
At Palomarin the highest numbers were captured for the following species: Wrentit (50), Pacific-slope Flycatcher/Western Flycatcher (likely all Pacific-slope Flycatchers, but some aren’t reliably separable from Cordilleran Flycatcher in the hand, 43), Wilson’s Warbler (36), Oregon Junco (30), and Swainson’s Thrush (22).
At Pine Gulch, the highest numbers of captures by species were: Song Sparrow (15), Pacific-slope Flycatcher/Western Flycatcher (19), Wilson’s Warbler (9), Warbling Vireo (5), and Common Yellowthroat (5).
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.