- Established 1982 -


16-31 August 2023

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Mary Kimberly and Gavin MacDonald--long-time friends and Top Tier supporters of Hilton Pond Center--came from Georgia to visit this week, giving us ample time to reminisce about the SEVEN Operation RubyThroat expeditions they made with us to study Ruby-throated Hummingbirds in the Neotropics. As might be expected, both are inveterate birders, so on the morning of their departure for an extended trip north we took a walkabout to see what birds might be active in summer heat. We did pretty well in 90 minutes or so, tallying 31 species in fields and woods around Hilton Pond.

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

Of special interest were numerous large birds of prey we saw circling overhead. There were the usual Black Vultures and Turkey Vultures--the Center less than two miles from the county landfill--joined by a half-dozen other raptors we took to be immature Red-shouldered Hawks, based on barred tails and dark breast streaking (above). Thus, Mary added six RSHA to our eBird list and we sauntered further to see what else might appear.

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

There definitely WERE a couple of red-shoulders high in the skies above, but something didn't quite feel right about some of their companions. Despite their tail barring some of those birds' wings were too pointed (above) and it finally struck us--they weren’t Red-shouldered Hawks, they were immature Mississippi Kites!

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

We've had precious little experience with Mississippi Kites (MIKI). Our "lifer" came in early August 1984 when with Russ Rogers (a student from our Fort Mill High days) we spied a dark brown immature (above) perched in a fence row below Hilton Pond. More than 30 years later Ernesto Carman came to visit from Costa Rica one summer and found with spotting scope a trio of MIKI circling above a field almost a mile west of the Center. In three other years, we had brief May flyovers of MIKI--not long enough to actually study the birds--so until this week our involvement with Mississippi Kites was indeed limited.

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

During our field day with Mary and Gavin we had ample time to observe and photograph a half-dozen Mississippi Kites whirling and soaring above an overgrown cattle pasture adjoining Hilton Pond Center. There appeared to be one full adult with distinctive light head and belly and dark gray wings and tail; we were unable to get a photo of it. The others were individuals with heavily barred tails; some with pale heads and lighter brown breasts we took to be sub-adults, and others with darker heads and heavily blotched undersides we supposed were young of the year. Regardless of age, these raptors were masterfully aerobatic as they wafted on a light breeze above the fallow field.

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

Frequently one of the kites would stop its wing flaps and spread and drop its tail, coming to a temporary full stop in the air. The bird in our photo above shows tail barring and that lighter areas in the tail are actually spots that don't go all the way across each feather.

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

While photographing the MIKI that had come to a mid-air stop we managed a second later to capture another image, just above. It revealed what this stationary kite was actually doing: Hovering at the approach of a large dragonfly buzzing in front of it. The kite went after the insect and deftly grabbed it with its talons.

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

We didn’t get a good shot of that particular kite actually eating its prey, but a different bird gave us opportunity later in the morning. In the photo above you can see the kite grasping a dragonfly with its right foot and biting the insect with its bill, chowing down while in full flight.

What an exciting opportunity we had that day with Mary and Gavin at Hilton Pond Center (below with Susan and Bill Hilton Jr.) --watching a small flock of Mississippi Kites patrol the skies for dragonfly prey. For nearly a week thereafter we saw a few kites over the same field, but all appeared to be migrating through rather than taking extended time to feed.

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


Our Ruby-throated Hummingbird research season has been especially productive in 2023 at Hilton Pond Center, with 243 banded by the end of August. This is nearly a week ahead of the earliest we've reached that number in 40 years. Interestingly, the tally of new adult males is well below average but adult females are present in record numbers; immature males and females become more abundant with every passing day.

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

Along with all these "normal" ruby-throats, this week we caught a few notably different. Three were adult females (above) with numerous throat and upper breast feathers that were dark instead of white; scattered among that darker plumage were several narrow quills that enclosed developing feathers--plus a couple of pure white feathers just unsheathed. We'd never encountered this before and examined the dark feathers with a hand lens, revealing they appeared to be soiled.

This late in the season it was quite likely these were not "local" adult female RTHU and were passing through from further north. With that thought in mind, we wondered if these hummers might be from Canada, where widespread wildfires charred countrysides this summer. Perhaps the discolored throat feathers showed soot from those conflagrations.

When we posed our speculation to a hummingbird bander listserv, we heard from a couple of U.S. banders who reported discoloration on female ruby-throats that had been probing in ash piles, probably in pursuit of minerals that help make eggshells developing in the birds' oviducts. We can't know for sure, of course, but soot-staining seems like a reasonable explanation for the appearance of these three dark-throated female ruby-throats.

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

Also unusual this week was another adult female Ruby-throated Hummingbird we captured on 19 August. In this individual the #4 primary in the right wing was pure white (above and below)--an albinistic feather among others that were normal. This feather was also worn and poorly formed, with sparse barbs emanating from the central vane. It's hard to say exactly what caused this aberration, but it is known that damage to a feather follicle can result in an abnormal feather.

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

Non-iridescent feathers get their color from pigments laid down during feather growth. These pigments--especially melanin--are deposited into the feather as it develops in the feather follicle. If the follicle is damaged, malformed, or unable to produce normal amounts of pigment, the new feather that grows in may lack pigmentation and be white. Follicular damage can come from physical trauma, infections, malnutrition, and genetic mutations.

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

Follicle damage seemed like a plausible explanation--until we noticed the bird also had two white back feathers (above) AND two white covert feather on the opposite (left) wing. It seems unlikely physical damage would have occurred during feather development on three different areas of the hummer's plumage, so that led us to consider other possible causes, including the following:

--Random mutation: Genetic mutations can sometimes disrupt pigment production in just one feather follicle, leading to a single white feather.
--Partial albinism: In rare cases, a bird can have localized albinism that impacts only small regions or a single feather. This causes a lack of melanin production.
--Nutrient deficiency: Deficiencies in certain nutrients needed for pigment production could affect a single feather.

There's no way of knowing which of these scenarios, if any, caused the white feathers in this week's Hilton Pond hummer, and we hesitate to speculate further. We'll just chalk up this as yet another unanswered mystery in the fascinating world of Ruby-throated Hummingbirds. We welcome your own white-feather hypotheses at INFO.

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

(from our on-going series)

"Never trust a person too lazy to get up for sunrise
or too busy to watch the sunset."

Sunset over Hilton Pond, 24 August 2023

This was the hottest day of the year so far on the Center's digital thermometer: 95.4°. And don't let those late afternoon clouds in our photo fool you; it didn't rain even though we need it badly.

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

Don't forget to scroll down for lists of Hilton Pond supporters and of all birds banded and recaptured during the period.

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"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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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, among other things, to continue writing, photographing, and sharing "This Week at Hilton Pond" with students, teachers, fellow scientists, and the general public. Please scroll below to the blue section if you'd like to make a gift of your own.

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/Vimeo (; 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 16-31 August 2023.

  • Mim Eisenberg (via PayPal)
  • The friends below contributed via the "Donate" button on one of the Center's Facebook postings or fundraisers; some are repeat contributors. Several have set up through Facebook to make a recurring monthly donation to benefit the Center. Many are much-appreciated long-time and/or repeat donors.
    --Bj Berquist, Lynn Biasini McElfresh, J. Drew Lanham, Sara S. Duncan, Bill Pennington, Richard Barnett, Carla Girten

    * = Past participant in Operation RubyThroat Neotropical Hummingbird expedition

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The Piedmont Naturalist--Vol. 1--1986 (Hilton Pond Press)
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16-31 August 2023

Ruby-throated Hummingbird--59
Blue-gray Gnatcatcher--1
White-eyed Vireo--1
Hooded Warbler--1
Tufted Titmouse--1

* = new banded species for 2023

5 species
63 individuals

62 species (42-yr. avg. = 66.0)

1,572 individuals
(42-yr. avg. =

243 Ruby-throated Hummingbirds

(Banding began 28 June 1982; since then 173 species have been observed on or over the property.)
128 species banded
78,638 individuals banded

7,433 Ruby-throated Hummingbirds banded since 1984

(with original banding date, verified sex, and current age):
Carolina Chickadee (1)

04/02/22--after 2nd year male

Northern Cardinal (1)
11/21/21--after 3rd year female

** Notable local longevity for species
*** Longevity record for Hilton Pond

--As of 31 Aug Hilton Pond's 2023 Yard List stood at 89--about 51% of 173 avian species encountered locally since 1982. Our record for one calendar year is 111, reached in 2020 & 2021. (Incidentally, all species so far this year have been observed from windows, porches, or the yard around our old farmhouse!) 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 you, too, can be a "citizen scientist!") New species observed locally during the period 16-31 Aug: Mississippi Kite.

--Our immediate past installment of "This Week at Hilton Pond" was about hummingbird banding, late bluebirds, and Peace Lilies and is archived and always available on our Web site as Installment #811.

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.