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, January 2014

02.28.14
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This summary was compiled by Palomarin banding interns Hummingbird Baber and Lindsay Wagner with help from Mark Dettling, Banding Supervisor.

Exciting Captures and Observations:

On the 18th of January, we had a very lucky capture of a juvenile Cooper’s Hawk.  This species is rather large to get caught in our nets and it was a right-place, right-time situation, as we arrived at the net just as the hawk flew in. This species is sexually dimorphic, with the males being smaller than the females.  With a wing measurement, we were able to determine this individual’s sex to be male.  This measurement also helped us confirm that this bird was a Cooper’s Hawk, rather than the very similar yet smaller Sharp-shinned Hawk.  Other characteristics we use to tell the two species apart include tail shape (Cooper’s = rounded, Sharp-shinned = squared), leg size (Cooper’s large legs take a larger sized band than the pencil-like legs of a Sharp-shinned) and juvenile plumage (Coopers = thin streaks, Sharp-shinned = coarse streaks).

Juvenile Male Cooper’s Hawk. Photo by Max “Hummingbird” Baber

Juvenile Male Cooper’s Hawk. Photo by Max “Hummingbird” Baber

Juvenile Male Sharp-shinned Hawk. Photo by Jenny Phillips

Juvenile Male Sharp-shinned Hawk. Photo by Jenny Phillips

Here at Palomarin, the long-time staff have been saying that this is a particularly busy winter, with high capture rates.   So, out of curiosity, we looked up some numbers! While this has, indeed, been a busy January with 15 birds per day on average, it is not an extraordinary month (see graph).  Though to the staff’s credit, they did get the trend right for the past 5 years.

The average bird capture rates for January at Palomarin over the past decade.  Excluded were incomplete banding days (due to rain or wind) to reduce the influence of variable weather conditions and net hours.  This January (15 birds/day) proved to be the most productive since 2008 (17 birds/day) and the second most in the past 10 years.

The average bird capture rates for January at Palomarin over the past decade. Excluded were incomplete banding days (due to rain or wind) to reduce the influence of variable weather conditions and net hours. This January (15 birds/day) proved to be the most productive since 2008 (17 birds/day) and the second most in the past 10 years.

As we advance through the winter season, our recapture rate (the percentage of all captures which are already banded) has increased.  The reason for this change is likely due to a number of different factors. As fall migration slows and birds have flown south, we began banding our wintering birds.  These wintering birds are at the end of their migration and will remain here until spring.  Every bird that we band is expected to remain in the area and thus as we continue through this season, we are catching more of the birds that we have already banded.  Check out the figure below to see our increasing recapture rates!

Recapture rates (the percentage of all captures which are already banded) from fall migration to January, 2013-14.

Recapture rates (the percentage of all captures which are already banded) from fall migration to January, 2013-14.

Let’s Do the Numbers:

In 15 days (1561.16 net hours) of mist-netting at Palomarin in January, we captured 84 new birds and recaptured 120 previously banded birds. A total of 204 birds of 16 species were caught this month. Approximately 15 birds were caught per banding day.

At our other West Marin banding sites, we captured 93 new birds and recaptured 98 previously banded birds. A total of 191 birds of 20 species were caught over 11 banding days this month (551.50 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 January 25th at Palomarin with 27 birds and January 21st at Pine Gulch with 40 birds.

At Palomarin the highest numbers were captured for the following species: Fox Sparrow (78), Oregon Junco (47), Golden-crowned Sparrow (18), Hermit Thrush (14) and tied for 5th: Varied Thrush and Rub-crowned Kinglet (9).

Across all off-sites, the highest numbers of captures by species were: Fox Sparrow (59), Golden-crowned Sparrow (32), Song Sparrow (20), Hermit Thrush (12) and tied for 5th: Ruby-crowned Kinglet and Pacific Wren (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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