Banding report - Sunday, January 10 - Any Hepburn's?

[Rosyfinch]

The latest report from the Rio Grande Bird Research banding team:

Hi all,

We banded 12 birds today (9 Brown-capped, 2 Gray-crowned - Interior, 1 Black).  We estimated the flock size to be about 75 birds.

We also recaptured 2 Rosy-Finches from previous seasons.  One was a Gray-crowned (interior) that we originally banded in January 2007. It is now a 5 year old bird.  The other was a Brown-capped that we banded in February 2009.  It is now a 3 year old.

The road is in great condition.  The only snow of concern is between the parking lot and the Crest House.

Nancy & Steve


I have been reviewing the tabular and spreadsheet data compiled by the banding team over the past seven years. You may view it at:
http://www.rosyfinch.com/RosySightings.html

The banding team's recapture rate, as expected, is increasing each year. During all of the winter of 2008-2009, the team recaptured a total of 35 rosy-finches that had been banded in prior winters. This winter they have already recaptured 52.

This appears to be shaping up as a lean winter for the Coastal (Hepburn's) subspecies of the Gray-crowned Rosy-Finch.  Except for the winter of 2006-2007, when only 8 of the Brown-capped species were newly banded, the Gray-crowned species has been least numerous.

That same winter of 2006-2007, Coastal (Hepburn's) Gray-crowns were mysteriously abundant, outnumbering the Interior subspecies, and accounting for 104 (over 13%) of newly banded birds. The next winter, nearly half of the Gray-crowns were still Hepburn's: 29, or over 6% of all rosy-finches banded that season. In other winters they varied from 0 to about 2.5% of newly banded Rosies, and the Interior subspecies outnumbered Hepburn's by a 7:1 ratio.

This winter, observers have not reported seeing any more than one or two Hepburn's at once, and only one has been newly banded so far.

What natural forces (biologic, climactic or other environmental) account for these fluctuations? Do they correlate with local abundance or scarcity of other montaine finches? Does eBird or other data suggest an answer? Rosy-finches depend less upon tree seeds than other northern finches, whose irruptions have been tied to the location, timing, success and failure of seed production in various species of conifers and other trees.

Please, when you visit Sandia Crest, enter your  sightings in the Rosy-Finch Sightings Log (not to be confused with the Visitor Log, both of which are located on the desk near the lower (east) entrance of the Crest House. Your observations supplement the banding information. Also, report them to eBird, which contains surprisingly sparse reporting of Sandia Crest sightings, given the large number of birders who visit the feeders.

(On that note, when I first reported sighting Black Rosy-Finches, eBird got back to me and challenged the entry, saying it was outside the species' usual range! Unfortunately, eBird does not consider Sandia Crest to be a "Hot Spot," so you cannot obtain location-specific counts. However, the Bernalillo County listings are presumably all from Sandia Crest. I am a bit troubled by this, as I fear that "citizen scientists" may be reporting them as feeder birds in their Albuquerque back yards. eBird appears to weed out any summer reports, if received, but as an interpreter at the Rio Grande Nature Center I sometimes had visitors say they had them, until they were shown pictures of House Finches.