- Established 1982 -


1-15 July 2023

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Except for noticeable increase in Ruby-throated Hummingbirds as their newest chicks take flight, by mid-July things start to slow down at Hilton Pond Center after a busy spring season. The vernal wildflower bloom is long since over and initial tree leaves are completely unfurled, casting welcome shade on hot mid-summer days that seem even hotter than usual--and apparently are.

Courtship and nesting are already done for many songbirds, although some avian species like Northern Cardinals and Eastern Bluebirds may be working on a second or even third set of eggs. When dusk falls and temperatures cool a little, activity increases for some organisms--evidenced by a loud mixed nocturnal chorus of Bush Katydids, Field Crickets, and ever-boisterous Green Tree Frogs. (Lightning Bugs also put on a show, but their blinking doesn't make much noise.)

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

Despite sweltering July heat, some critters do remain active by day--including a few spring/summer butterflies. Perhaps most obvious this week at the Center were several large black and white lepidopterans with long appendages on their hindwings. Among the most easily identified butterflies, these were Zebra Swallowtails, aptly named and not to be confused with Tiger Swallowtails that are yellow and black. Note also those red antennae.

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

Zebra Swallowtails, Eurytides marcellus, are native to the eastern U.S. and southern Canada and are Tennessee's state butterfly. The species' yellow-banded caterpillars (above) are highly selective, munching exclusively on foliage of Pawpaws, Asimina triloba. It's not coincidental we've seen an increase in Zebra Swallowtails through the years at the Center, what with the appearance of many Pawpaw sprouts planted--we suppose--in the droppings of fruit-loving Raccoons and Virginia Opossums that ate the tasty ripened fruit.

Zebra Swallowtail adults are long-lived and survive in large part because those Pawpaw leaves their larvae eat contain annonaceous acetogenins that are highly distasteful to birds and other potential predators. These compounds are sequestered by the caterpillars and carry over in metamorphosis to adult butterflies. The latter don't eat Pawpaws but take nectar from Eastern Redbuds, Viper's-bugloss, and various blackberries--all of which are common at Hilton Pond Center.

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


The latest bird fledglings were indeed out and about this week at Hilton Pond Center, mostly on their own by now but a few still begging for one last handout from exhausted parents. In some cases the father was tending to his offspring while mom was back at a nest brooding another batch of siblings.

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

We captured a trio of Northern Cardinals in early July, distinguishable as immature by their drab plumage and brownish black mandibles that will turn orange as they age. One (above)--judged to be a male because he already had bright red feathers coming in on his wings and back--seemed a little extravagant with his headgear. Those towering crest feathers in our photo will be lost sometime soon, replaced by deep red feathers in the somewhat more refined cone shape of an adult male.

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

A Tufted Titmouse snared in one of our nets reveal its juvenility because of a soft pinkish-yellow gape that served as a target area when it was in the nest. It's easier for food-bearing parents to find the chicks' gaping maws when they're brightly colored. Like the cardinal just mentioned, this little titmouse had a poorly formed crest that will be more tightly tufted in adult plumage, and the fledgling will lose that fluffy patch of neck feathers that are found in baby birds of many species.

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


And speaking of fledgling birds, during the past few weeks at Hilton Pond Center we have captured for banding several immature House Finches with mild signs of mycoplasmal conjunctivitis, also known as "Winter Finch Eye Disease." To avoid further spread of this highly contagious and possibly fatal ailment, we immediately ceased offering sunflower seeds in tube-style feeders like the one at right. When finches stick their heads through those round feeding ports they may rub against them and release mucus from their eyes--thus transmitting Mycoplasma gallisepticum bacteria to other birds.

Obviously, conjunctivitis is NOT just a winter ailment and can occur year-round. Our research indicates young House Finches can acquire the disease even while still in the nest, likely from carrier parents that had conjunctivitis but survived. Watery, swollen eyes (see photo below) are just a symptom; the bacteria also invade lungs and in worst cases kill the bird.

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

We encourage you to watch your feeders carefully for any signs of conjunctivitis, remembering that House Finches are not the only carriers or victims. If you see ailing birds, stop feeding for at least a week and sterilize ALL your feeders with a mild 10% water-bleach solution. Although tube feeders are prime suspects, any type of feeder might facilitate disease spread--including platform feeders at which birds pick through seeds (and their own contaminated droppings). Thus, if disease is detected you might also spray the bleach solution on soil and seed shells under your feeders; bird baths should likewise be decontaminated.

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

NOTE 1: Mycoplasmal conjunctivitis is not the only visible disease to infect wild birds. Young House Finches, in particular, seem especially susceptible to various strains of avipoxviruses that give rise to a condition known as "avian pox." The dry (cutaneous) form of this disease is marked by wart-like growths on featherless areas such as toes, legs, and base of the bill, and sometimes around the eyes. This week at the Center we caught a young HOFI (above) with a more typical wart on its upper mandible. Although these lesions usually subside on their own, they sometimes leave body parts disfigured.

Avian pox sometimes can be spread via contaminated feeders, female mosquitoes are the true villains as vectors that feed on an infected host bird and transmit the virus while biting a new one. Mosquitoes thrive in standing water, so one way to help control avian pox is by frequent cleaning of bird baths.

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

NOTE 2: It's worth mentioning House Finches (and many other species) do visit hummingbird feeders (above). While there's some evidence hummingbirds can become infected with mycoplasmal bacteria in laboratory situations, controlled studies in natural settings would be needed to conclusively demonstrate hummers can acquire the disease from finches at feeders or transmit it directly to other hummingbirds. Of course, if you happen to see an infected House Finch stealing sugar water, it would be prudent to wash and sterilize that feeder--and to keep it down for several days.

In any case, frequent cleaning of hummingbird feeders eliminates mold growth and assures your tiny guests of fresh food. In the heat of summer here at Hilton Pond Center we never put out more 4:1 sugar water than our ruby-throats can consume in three days max.

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."

Sunrise over Hilton Pond, 12 July 2023

A little ground fog gilded the view from the pond at dawn.
Good morning, World!

Sunset over Hilton Pond, 14 July 2023

Rained .hard a mile from here today--for a minute or two--but
not on Hilton Pond.

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.

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

"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 1-15 July 2023.

  • Anonymous (recurring $17 monthly donation via PayPal)
  • Ken Baerwalde (repeat donor)
  • Anita Clemmer (via PayPal)
  • Liz Layton* (long-time supporter)
  • Carol Williams (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.
    --Gretchen Locy
    * = 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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1-15 July 2023

Ruby-throated Hummingbird--36
Acadian Flycatcher--1
Hooded Warbler--1
Chipping Sparrow--1
White-eyed Vireo--2
American Goldfinch--2
Black-and-white Warbler--1

Northern Cardinal--3

Carolina Wren--2
House Finch--15
Tufted Titmouse--2
Blue Grosbeak--1
Downy Woodpecker--1
Brown Thrasher--1

* = new banded species for 2023

14 species
69 individuals

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

1,410 individuals
(42-yr. avg. =

98 Ruby-throated Hummingbirds

(Banding began 28 June 1982; since then 173 species have been observed on or over the property.)
128 species banded
78,476 individuals banded

7,288 Ruby-throated Hummingbirds banded since 1984

(with original banding date, verified sex, and current age):
Ruby-throated Hummingbird (3)

08/02/22--2nd year male
08/21/22--2nd year female

08/24/22--2nd year female

Northern Cardinal (1)
10/03/20--4th year male

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

--Ruby-throated Hummingbirds were again big news at Hilton Pond Center this week as we continued our record-breaking pace for new bandings AND recapture of returning birds banded in previous years. By mid-July we had 98 new RTHU, far above our previous high of 73 by that date (average is 36). Our 58 returns were ahead of the previous record pace of 53(average 23).

--As of 15 Jul, Hilton Pond's 2023 Yard List stood at 87--about 50% 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 1-15 Jul: Yellow-billed Cuckoo.

--Our immediate past installment of "This Week at Hilton Pond" was about far-off encounters of two Purple Finches banded at the Center and is archived and always available on our Web site as Installment #808.

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.