- Established 1982 -


23-31 August 2021

Installment #750---Visitor #visitor counter

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On 28 August 2021 we rose early at Hilton Pond Center with the intent of deploying mist nets to catch hummingbirds for banding. We got held up because of household chores--which turned out to be a very good thing. Fifteen minutes later as we got ready to go out the door of the old farmhouse we stopped in our tracks to see on the ground just off the back deck four Black Vultures--three of them visible in our photo above.

All text, maps, charts & photos © Hilton Pond Center

We watch Black Vultures (BLVU, above) soaring overhead nearly ever day and occasionally see them perched in trees around the property, but seldom have we observed them on the ground--and NEVER this close to the house. Despite our indoor movement, the big black birds never spooked; reflection on the windows probably impaired their view at least a little, but meant our photos through the glass weren't as sharp as we'd have liked.

All text, maps, charts & photos © Hilton Pond Center

We're not positive what brought in the BLVU--there wasn't anything dead lying around--but suspect the sound of moving water in our garden fountain was an attractant. (Two of the birds eventually jumped onto the fountain and appeared to drink.) In any case, the vultures were in no hurry to move on and spent more than 45 minutes walking around or just standing or sitting on the ground (above). This latter behavior was new to us and may have allowed the cool ground to lower the vulture's body temperature on a warm August day.

All text, maps, charts & photos © Hilton Pond Center

Two of the vultures exhibited another activity we'd never observed as they scooted along on their bellies while flapping their wings. We guessed this was begging behavior--borne out when our telephoto lens revealed brownish feathers on the napes of two birds (above); this meant they were immatures hatched in 2021. Based on behaviors and appearances, we speculate our Black Vulture quartet was a family unit, with two parents still putting up with antics of two fully grown offspring.

All text, maps, charts & photos © Hilton Pond Center

The two head shots above were made possible when three of the Black Vultures hopped up to the deck railing, giving us super-close views of their naked heads. The bird in the photo just above was one of the adults. It lacked the brownish hackles and had much wartier skin on its head. Note also the "nail" on the tip of its decurved bill was whiter than that of the immature--likely because it had hardened further.

All text, maps, charts & photos © Hilton Pond Center

With vultures perched just eight feet away on the deck railing we were able to see additional details--as when the immature above temporarily covered its eyeball with a semi-transparent "third eyelid." This nictitating membrane moistens the eye without blocking out light--an adaptation that apparently allows a bird to maintain orientation, especially when in flight. (Typical upper and lower eyelids close down to block light during sleep.)

The ear canal is at right--not usually visible in birds with feathered heads--while at lower left one can see through the bird's bill because of its perforate nostril. (In most birds, the nostrils are separated by a septum.) Incidentally, Black Vultures apparently have no sense of smell, whereas Turkey Vultures--which have good olfaction--use their nostrils to locate decaying food while more aggressive Black Vultures watch before swooping in to commandeer the carcass.

All text, maps, charts & photos © Hilton Pond Center

Vultures on the nearby railing also revealed their stout, scaly legs and feet (above) whose relatively small and non-raptorial claws seem more adapted to walking than to tearing open carrion. (The foot is anisodactyl, with three toes in front and the hallux behind.) We should point out that legs of the two adult vultures were much whiter than those of the two immatures. We suspect this is because the white stuff--uric acid crystals released as the vulture voided waste--had more time to accumulate on the scales. Yes, Black Vultures DO defecate on their legs; it's called "urohidrosis," an adaptation that supposedly allows otherwise black legs to reflect the sun's rays during the heat of summer. Sounds like a strange way to stay cool, but it may indeed work for vultures. An alternative hypothesis says Black Vultures urinate/defecate on their legs in an antiseptic attempt to kill bacteria and parasites they might acquire when tromping around in dead, decaying animal matter. This also sounds plausible.

(NOTE: We're not sure anyone has experimentally tested either the leg-cooling or sanitizing aspects of defecating on one's own legs--so who knows?--perhaps there's some other explanation entirely. Maybe mate-seeking Black Vultures find white legs attractive, or maybe they just have an incontinence problem when they get excited near rotten food items. In any case, urohidrosis sounds like worthwhile focus for a doctoral dissertation that would make a great ice-breaking topic at grad student get-togethers.)

All text, maps, charts & photos © Hilton Pond Center

Two days after our first encounter with the Black Vultures, two immatures returned to the Center and spent the better part of an afternoon perched on the farmhouse roof just above our office. At such close range we could hear them walking around and vocalizing occasionally--kind of a cross between a hiss and a growl. It's nice to hear and see these big scavengers up close, but we have mixed feelings about their recent house-perching behavior--especially since we've heard tales about Black Vultures pecking at and eating roofing material and weather stripping (as well as windshield wipers or sunroof seals on cars). We hope there are enough roadkills in our area to keep them from snacking on our residence as they perch instead in trees (above) around the property. We're just glad we didn't have our delicate hummingbird mist nets open that morning when the Black Vulture family of four came to visit at Hilton Pond Center.

All text, maps, charts & photos © Hilton Pond Center

(from our on-going series)

All text, maps, charts & photos © Hilton Pond Center

Sunset over Hilton Pond (above), 24 August 2021
Sun rays occur where light passes between
shadow cracks in the clouds.

All text, maps, charts & photos © Hilton Pond Center

Sunset over Hilton Pond (above), 27 August 2021
Clear skies to the west so we turned east with the pond behind
us and gazed across the road from our property. Only a few clouds there--one very far distant--and no wind, but the image offers a
view of undisturbed layers of water vapor, dust, smog, and
other pollutants.

Photoshop image post-processing for this page employs
DeNoise AI, Sharpen AI, and other Topaz Lab tools

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York SC 29745

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Don't forget to scroll down for Nature Notes & Photos,
plus lists of all birds banded or recaptured during the period

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

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We're pleased folks are thinking about the work of the Center and making donations. Those listed below made contributions received during the period. Please join them if you can in coming weeks.

Gifts can be made via PayPal (; credit card via Network for Good (see link below); or personal check (c/o Hilton Pond Center, 1432 DeVinney Road, York SC 29745). You can also donate through our Facebook fundraising page.

The following donors made contributions to Hilton Pond Center during the period 23-31 August 2021:

  • Fred Schroyer (repeat supporter; via Network for Good)
  • Frank Voelker (on-going major supporter; via Network for Good)
  • The following friends contributed via the "Donate" button on one of the Center's Facebook postings or fund-raisers; some may be repeat contributors. Several have set up through Facebook to make a recurring monthly donation to benefit the Center.
    Bill Pennington, Cliff Tune, Marcia Power

    * = past participant in Operation RubyThroat Neotropical Hummingbird expedition)
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23-31 August 2021

Ruby-throated Hummingbird--
American Redstart--1
American Goldfinch--
Northern Cardinal--2
Carolina Wren--2
Downy Woodpecker--1

* = new banded species for 2021

6 species
29 individuals

55 species (40-yr. avg. = 63.7)

2,249 individuals
(40-yr. avg. =

166 Ruby-throated Hummingbirds

(Banding began 28 June 1982; since then 172 species have been observed on or over the property.)
127 species banded
74,051 individuals banded

6,810 Ruby-throated Hummingbirds banded since 1984

(with original banding date, verified sex, and current age):
Ruby-throated Hummingbird (0)
None this week.

American Goldfinch (1)
02/03/19--after 4th year female

Northern Cardinal (1)
10/26/20--2nd year female

* New longevity record for species
(none this week)

--August banding continues at a slow pace, with no fall migrants as yet and most of the local birds avoiding nets and traps--perhaps in part because many of them are going through energy-intensive molt and are spending much of their time back in the bush.

--As of 31 Aug, the Center's 2021 Yard List stood at 82--about 47% of 172 avian species encountered locally since 1982. (Incidentally, 80 of those species so far this year have been observed from the windows or porches of our old farmhouse! Best year so far was 111 species in 2020. If you're not keeping a
Yard List for your own property we encourage you to do so, and to report your sightings via eBird,
where y
ou, too, can be a "citizen scientist!") New species observed locally during the period 23-31 Aug: Scarlet Tanager

--Our immediate past installment of "This Week at Hilton Pond" was about milkweed pollinators. It's archived and always available on our Web site as Installment #749.

All text & photos © Hilton Pond Center

Please report your spring, summer &
fall sightings of
Ruby-throated Hummingbirds

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