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GOLDFINCHES AND THISTLE SOCKS

As always, lots of things happened this week in the natural world around Hilton Pond Center, but due to yet another (and even more invasive) retinal surgery on the executive director, not many nature observations were made and recorded. Meanwhile, volunteers have been maintaining our all-important bird feeders, keeping them well-stocked with black sunflower seeds that are the favorite choice of many avian visitors to Hilton Pond.

Good numbers of American Goldfinches, House Finches, and Purple Finches have been chowing down on sunflower, but goldfinches are equally adept at taking tiny thistle (niger) seeds one at a time from white mesh bags we hang from tree branches. For goldfinches, these "thistle socks" are real magnets; they're available pre-filled at most discount and feed stores and can be reloaded with loose thistle after finches pick them clean. In the photo above left (taken through double-pane window glass), the top two and bottom birds are MALE American Goldfinches, as indicated by black forehead feathers--remnants (or precursors) of black caps that are part of their summer breeding plumage. Males also have black wing feathers edged with white, while those of females are brownish-black with duller white. (NOTE: You can see the shadowy image of a band on the leg of the bird at lower left.)

Thistle seeds are indeed tiny--scarcely a quarter-inch long by less than a sixteenth of an inch wide--and much smaller than a kernel of corn or a black sunflower seed (above). The alternate name of "niger" or "nyger" was used because at one time nearly all the seed was imported from Africa--although Ethiopia, rather than Nigeria, was the country of origin. The seeds are produced by Guizotia abyssinica (below right), which is not really a "thistle" (Carduus spp. or Cirsium spp.) but a composite more closely related to sunflowers. Thistles, by the way are also in the Sunflower Family--the Asteraceae (formerly Compositae)--but most botanists place them in a separate tribe (Cynareae) from typical sunflowers (Heliantheae). The niger plant has been cultivated for perhaps a thousand years in eastern Africa, India, China, and Myanmar (Burma)--primarily as an oil source for human consumption and, more recently, as food for cage and wild birds. Attempts to grow niger commercially in North America have largely met with failure, so shipping fees still lead to its relatively high cost; at least 70 million pounds are imported annually. An "EarlyBird" strain developed in Minnesota shows some promise as a domestic crop. Niger is also grown in the U.S. in small quantities as an ornamental under the name "Ramtilla" and has escaped from cultivation in several states.

In past winters, thistle seed at Hilton Pond Center attracted impressive numbers of heavily streaked and pointy-billed Pine Siskins (below left), but this species has declined significantly at our feeders; the last one seen locally was on 17 April 2002--even though 486 siskins were banded in the winter of 1986-87. Back then they consumed thistle we offered primarily via special thin-slit tube feeders that dispensed seeds one at a time.

Thistle retails at a dollar or more per pound, but it doesn't spoil in wet weather like most foods we offer wild birds, and few thistle seeds go uneaten at Hilton Pond Center. Thus, it's well worth the expense to pour a cup or two of thistle seed into a mesh sock that, across most of the U.S., is almost guaranteed to bring hungry American Goldfinches--or even elusive Pine Siskins--to your own backyard feeding station.

All text & photos © Hilton Pond Center
Flower photo courtesy www.nyger.com

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SPECIES BANDED THIS WEEK:
American Goldfinch--10
Brown-headed Nuthatch--1 *
Downy Woodpecker--1 *
Purple Finch--3

* = New species for 2005

WEEKLY BANDING TOTAL
5 species
15 individuals

YEARLY BANDING TOTAL (2005)
7 species
43 individuals

BANDING GRAND TOTAL
(since 28 June 1982)
124 species
45,350 individuals

All text & photos © Hilton Pond Center

NOTABLE RECAPTURES THIS WEEK
(with original banding date, sex, and current age)