11-21 September 2010
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John James Audubon's rendering of Summer Tanagers (above)


With the autumnal equinox occurring on 22 September at 11:09 p.m., summer's final FULL day in 2010 fell on the 21st. It was a terrific day filled with blue skies, a few puffy clouds, and an occasional light breeze, so it only seemed appropriate our last birds banded on summer's last full day turned out to be SUMMER Tanagers. Although we're likely to net a few more of these colorful birds before fall migration is over, they were a welcome and appropriate way to end the season.

All text & photos © Hilton Pond Center

These two Summer Tanagers caught on 21 September were in the same net at the same time but were just about as different in appearance as Summer Tanagers ever get. One--a brilliant adult male (above)--had intense red plumage; the other was a greenish-yellowish-orangeish individual (below) we initially suspected to be an immature male but that required a bit more scrutiny before we finally confirmed its age and sex.

All text & photos © Hilton Pond Center

Two tanager species occur at Hilton Pond Center: The Summer Tanager, Piranga rubra, that breeds here, throughout South Carolina, and north to about the Mason-Dixon Line; and the Scarlet Tanager, P. olivacea, that passes through in spring and fall. (Although scattered Scarlet Tanager nesting records exist from South Carolina's Upcountry, this species more typically breeds north of the Palmetto State up to New England and south central Canada.) We've never found a Summer Tanager nest at the Center but through the years have banded several recent fledglings and females with well-developed brood patches--both sure signs the species is breeding on or very close to our 11-acre site. And even though we see (and hear) Summer Tanagers early May through late September, we've banded only 181 since 1982--possibly because they seem more inclined to hang out in the subcanopy or higher and seldom come down to ground level for capture in our eight-foot-tall mist nets.

All text & photos © Hilton Pond Center

There is some variation in color intensity among adult male Summer Tanagers in full breeding plumage; the one just above from 2004 has a slight yellowish cast while this week's bird at the top of the page is more crimson. Professional artists probably have a name for each of these various hues, but we're at a loss to describe them with mere words. Adult male Summer Tanagers, by the way, are the only completely red birds in North America; male Northern Cardinals come close but sport a black mask, and male Scarlet Tanagers have black wings.

All text & photos © Hilton Pond Center

Some second-year male Summer Tanagers look like patchwork quilts, such as one (above) we caught during spring migration several years ago at Hilton Pond Center. This individual seemed 'way behind in his molt sequence but by his third year likely would have replaced all his green feathers with red. Whether these calico birds are vocal and aggressive enough to attract a female and mate successfully during their second year is anybody's guess. It seems ornithologists know little about the breeding biology of Summer Tanagers and even less about their behavioral ecology on wintering grounds from central Mexico to the northern countries of South America. (NOTE: We banded four Summer Tanagers at Crooked Tree during our March 2010 hummingbird expedition to Belize; we suspect all were soon to be northward bound.)

All text & photos © Hilton Pond Center

That adult-looking male we caught this week did have one secret up his sleeve, or--more accurately--on his wings: Two primary feathers on each side were yellow-orange (above) rather than red like all the rest of his plumage. Some ornithologists report these two non-red feathers indicate he is a second-year bird, while other experts caution that he actually could be in his third year. Confusing, no?

Even more perplexing in Summer Tanagers is the similar appearance of females and immature males. Generally speaking, females of any age are more greenish and lack any true red feathers (as shown in Audubon's rendering at the top of the page), but the same can be said of many young males. In our novice banding years back in the last century, we were taught to look at a tanager's crissum--undertail coverts that overlap the bases of the tail feathers. The guideline was that a young male Summer Tanager has a bright yellow or yellow-orange crissum that contrasts strongly with paler yellow belly plumage--which is the case in the above photo of this week's bird. Some studies, however, have shown older females can have orange-tinted crissa--so we were understandably hesitant to call our bird-in-hand a young male.

All text & photos © Hilton Pond Center

Because knowing our mysterious Summer Tanager's age might be a clue to determining its sex, we carefully examined the bird's tail feathers. Fortunately, we had photographed the rectrices of this week's adult male (above), so we had a good basis for comparison. In many bird species, the adults--those in at least their second year--have tail feathers that are truncate (more or less flat-tipped) or broadly rounded without sharp points. That certainly is the case in the adult male above.

All text & photos © Hilton Pond Center

In contrast, the tail of the mystery tanager was a classic representation of immature plumage: Weakly formed, acute (pointed) rectrices that already were beginning to wear. There was no question about the bird's age--it was a youngster that hatched in 2010--but we still weren't sure of its sex and had to resort to the bird bander's ultimate strategy: When in doubt, measure!

Based on measurements of many museum specimens--whose sex was determined via dissection of the dead birds' internal gonads--ornithologists concluded wing chords in male Summer Tanagers typically range from 90-101mm, with tails 63-72mm, while females have wings of 86-96mm and tails 62-70mm. Careful measurement of our in-hand bird showed an inconclusive wing chord of 92mm, but its tail was 72mm. Thus, because of its bright yellow crissum, its pointed rectrices, and the length of its tail, we FINALLY felt confident in calling this week's puzzling hatch-year Summer Tanager a male!

All text & photos © Hilton Pond Center

We really like Summer Tanagers--not because their fledglings are so challenging to age and sex, but because we find their lifestyles fascinating. We once watched an adult male zip out repeatedly from a tree limb grabbing insects just like flycatchers do, except what the tanager was catching was paper wasps. These social insects had built a nest in the eaves of a house and each time a wasp would leave on a foraging mission the tanager would snatch it out of the air. Returning to its perch the bird would whack the wasp against the branch a few times, subdue it, and then swallow it whole. (Some observers report the tanager wipes the bee or wasp on a branch to remove its stinger, but we didn't observe this.)

Such wasp- and bee-eating habits put Summer Tanagers in poor stead with beekeepers and pollination enthusiasts, but these colorful "Beebirds" also take important agricultural pests such as grasshoppers, beetles, and caterpillars too big for many birds to handle. We suspect a distinctive little "tooth" midway along the edge of the Summer Tanager's upper mandible (above and below) comes in quite handy when crunching down on wasps and oversized insects--something we had plenty of at Hilton Pond Center on the last full day of summer.

All text & photos © Hilton Pond Center

Comments or questions about this week's installment?
Please send an E-mail message to INFO.

Be sure to scroll down for an account of all
birds banded or recaptured during the period,
plus other nature notes of interest.

Thanks to the following fine folks for recent gifts in support of Hilton Pond Center for Piedmont Natural History and/or Operation RubyThroat: The Hummingbird Project. Your tax-deductible contributions allow us to continue writing, photographing, and sharing "This Week at Hilton Pond." (Please see Support if you'd like to make a gift of your own. You can also contribute by ordering an Operation RubyThroat T-shirt.)

Using Network for Good via Facebook's "Causes," some of the following individuals this week made contributions to "Help the Hummingbirds" in honor of Bill Hilton Jr.'s 64rd birthday on Costa Rica Independence Day (15 Sep). You, too, can still help by going to FaceBook. (Donations are still coming in and will be acknowledged in later installments of "This Week at Hilton Pond.") Your generosity is greatly appreciated and goes a long way in helping us implement the Center's education, research, and conservation activities.

  • Laura Neath Black (via Facebook Causes)
  • Ellis Carter (via FaceBook Causes)
  • Alexis Dandretta (alumna of the Operation RubyThroat expedition to Costa Rica in 2008; via FaceBook Causes)
  • Cindy Hilton Farver (via FaceBook Causes)
  • Anne Florenzano (via Network for Good)
  • Shirley Ann Jackson (via FaceBook Causes)
  • Mary Kimberly & Gavin MacDonald (alumni of Operation RubyThroat expeditions to Costa Rica in 2009 and Belize in 2010; via FaceBook Causes)
  • Brenda Piper (alumna of the Operation RubyThroat expedition to Costa Rica in 2010)
  • Carol Phillips (via Network for Good)
  • Sean Sands (via FaceBook Causes)
  • Tommye Schneider (via PayPal)
  • Lisa Schuermann (alumna of the original Operation RubyThroat expedition to Costa Rica in 2004 and Belize in 2010; via FaceBook Causes)
  • Laura Thomas (via FaceBook Causes)
  • Gail & Tom Walder (alumni of Operation RubyThroat expeditions to Costa Rica in 2008 and Belize in 2010; via Facebook Causes)
  • plus five Anonymous donors (via Network for Good or FaceBook Causes)

"This Week at Hilton Pond" is written & photographed
by Bill Hilton Jr., executive director of
Hilton Pond Center for Piedmont Natural History.

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11-21 September 2010

Ruby-throated Hummingbird--51
American Redstart--5

Chestnut-sided Warbler--1
Brown-headed Nuthatch--1
Common Yellowthroat--1
Acadian Flycatcher--1
Red-eyed Vireo--3
Gray Catbird--1
Summer Tanager--3
Northern Cardinal--2
Eastern Towhee--1
House Finch--1
Eastern Bluebird--1
Swainson's Thrush--1
Brown Thrasher--1

* = New species for 2010

16 species
75 individuals

39 species
923 individuals
Ruby-throated Hummingbirds
(since 28 June 1982, during which time 170 species have been observed on or over the property)
124 species (29-yr avg = 67.8)
54,565 individuals
(29-yr avg = 1,882)
4,267 Ruby-throated Hummingbirds (27-yr avg = 158)

(with original banding date, sex, and current age)

Ruby-throated Hummingbird (1)
07/14/08--after 3rd year female

Carolina Chickadee (2)
06/26/08--3rd year male
12/31/09--after hatch year unknown

Northern Cardinal (2)
09/17/09--2nd year female
12/31/09--2nd year male

Operation RubyThroat has teamed with EarthTrek so citizen scientists--like YOU--can contribute observations about hummingbird migration and nesting behavior. Membership is free for this great new opportunity to help increase scientific understanding of Ruby-throated Hummingbirds. Data entry forms for 2010 are on-line, so please register today at EarthTrek.

NOW is the time to report your 2010 RTHU spring arrival dates for the U.S. & Canada, and spring departure dates for Mexico & Central America.
Please participate.

All text & photos © Hilton Pond Center


--After being pleased all spring and most of the summer with high water levels in Hilton Pond, the ever-widening expanse of muddy banks along its perimeter indicates a near-absence of rain in late August and September. (Uprecedented highs in the 90s nearly every day from mid-Jul through mid-Sep haven't helped, either, with heat-enhanced evaporation taking its toll.) As of this week, the depth gauge reads two feet below full pond, and tree stumps submerged when the impoundment was built in about 1955 are beginning to reappear. Nonetheless, pond depth at summer's end is still greater than it has been the past several years.

--Thus far, fall migration of songbirds has been a less than fulfilling at Hilton Pond Center (see list upper left). With day after day of sunny skies, high temps, and no cold fronts to speak of, the birds--especially "confusing fall warblers"--so far have passed us by. Or, more accurately, they've passed us over.

--An adult male Ruby-throated Hummingbird (above) newly banded on 13 Sep this year was the second-latest of his age/sex class at Hilton Pond Center; the latest was on 14 Sep 2002. Adult females linger a bit longer, with the latest on record locally occurring on 27 Sep 2003. Immatures are around as late as mid-October.

--An after-third-year female Ruby-throated Hummingbird banded on 14 Jul 2008 and re-trapped on 14 Sep this year was of interest because she was our latest fall encounter of a RTHU banded in a previous year at the Center. Most of our "old" hummers are long-gone by the end of Aug; since 1984 we've recaptured only four of them in Sep.

--On 17 Sep we caught our 200th new Ruby-throated Hummingbird of 2010--the sixth time in the past seven years we've reached the "two century" mark at the Hilton Pond Center. We doubt we'll tie our record of 230 from 2008, but considering this year was our second-slowest spring in 27 years of banding hummers, we're more than pleased. Through 21 Sep we've caught 218 new RTHU and had 16 returns from past years. Now if you could just help us encounter one of our banded Hilton Pond RTHU on its wintering grounds in the Neotropics . . . .

Please report your
sightings of
Ruby-throated Hummingbirds

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Hilton Pond Center for Piedmont Natural History is a non-profit research & education organization in York, South Carolina USA; phone (803) 684-5852. Directed by Bill Hilton Jr., aka The Piedmont Naturalist, it is the parent organization for Operation RubyThroat. Contents of this Web site--including all articles and photos--may NOT be duplicated, modified, or used in any way except with the express written permission of Hilton Pond Center. All rights reserved worldwide. To obtain permission for use or for further assistance on accessing this Web site, contact the Webmaster.

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