Ημερολόγιο της/του swampster

Here in Athens, GA, the Winged Elm trees (Ulmus alata) are now starting to fruit. The number of species I've observed dining on these samaras over the past few days is truly awe inspiring. But this is not the first time I've been struck by the truly awesome power of native plants to feed local wildlife (see this eBird checklist where 46% of the species I observed that day were seen dining on the fruit of Virginia Creeper vines, Parthenocissus quinquefolia).

This has inspired me to start a journal series that I am calling "Native Plants Make the Best Bird Feeders". The books of Doug Tallamy have been truly eye-opening to the necessity of incorporating native plants into our "home and office" landscaping. Supplemental bird feeding is widely poplar, but if we really want to support bird and other wildlife populations, native plants are far superior. In addition to providing food directly to wildlife in the form of berries, seeds, flowers, etc., native plants support arthropod populations that are absolutely vital for most songbird nestlings and many other life forms.

Here is the list of species I have observed eating Winged Elm samaras over the past few days:
Blue-headed Vireo (Vireo solitarius), Carolina Chickadee (Poecile carolinensis), Tufted Titmouse (Baeolophus bicolor), Ruby-crowned Kinglet (Corthylio calendula), Golden-crowned Kinglet (Regulus satrapa), Cedar Waxwing (Bombycilla cedrorum), American Goldfinch (Spinus tristis), Chipping Sparrow (Spizella passerina), Field Sparrow (Spizella pusilla), White-throated Sparrow (Zonotrichia albicollis), Orange-crowned Warbler (Leiothlypis celata), Pine Warbler (Setophaga pinus), Yellow-rumped Warbler (Setophaga coronata), Northern Cardinal (Cardinalis cardinalis), and Eastern Gray Squirrel (Sciurus carolinensis).

Ulmus alata is a medium-sized tree native to the southeastern United States (range map here). The name Winged Elm comes from the corky "wings" that form on each side of the young branches (see second photo in the associated observation). Like other North American native elms, it is susceptible to Dutch elm disease and elm yellows, two accidentally introduced diseases. Elms are the host plant for a number of butterfly and moth caterpillars.

Today I photographed two Eastern Tiger Swallowtails, one light/standard morph and a dark morph. I was fairly certain both were females, but I could not find any photos of male dark morphs to compare. After posing the question to the iNat Forum, I found out it's because they don't exist!

Unlike humans, females are the heterogametic sex in butterflies. Males have ZZ chromosomes while females have ZW chromosomes. The dark morph is a sex-linked trait that occurs on the W chromosome, so only females can have the trait.

For the past few weeks at work, I have been watching an Eastern Phoebe. The running joke is that it's a vegetarian since we see it gorging itself on Winged Sumac berries more than we see it flycatching insects.

Yesterday, I was admiring a swarm of Tree Swallows. The flock was composed of at least 5,000 birds. While not quite the intricate murmurations of starlings, this flock was forming interesting shapes and patterns, flying as a shifting mass only to descend and flatten over a shrubby section of marsh. I asked my coworker, "how often do you think an individual bird in that flock actually gets an insect?" A large flock suddenly descending on the marsh might flush up a few more insects than a single bird, but I couldn't imagine it was enough to compensate for the competition an individual swallow would have to catch those few insects.

On my lunch break, I decided to look up the diet of Tree Swallows on Birds of the World. I was curious to know what size insects the swallows prefer. Are they eating mosquitoes or primarily larger insects? What I was surprised to discover is Tree Swallows regularly eat Wax Myrtle berries in the winter. Suddenly, it all made sense. They weren't eating insects at all. Those shrubs out in the marsh were Wax Myrtles!

While I already knew that Eastern Phoebes will eat berries in the winter when insects are scarce, I never suspected it with Tree Swallows. Further reading revealed that Tree Swallows' unique ability to digest the waxy coating on the berries is what allows them to winter much farther north than other swallow species that are more reliant on insects. It was fascinating to learn something new about a species that I originally thought I knew so much about!

I had one final revelation when I googled to see what other species feed on Wax Myrtle berries. Listed were Yellow-rumped Warblers and Gray Catbirds. That came as no surprise; I regularly see both foraging in the Wax Myrtle thickets. What finally clicked for me was the eastern subspecies name for Yellow-rumped Warbler, Myrtle Warbler! I knew they ate Wax Myrtle berries sometimes, and I knew they were called Myrtle Warblers, but I had never associated the two. Yesterday certainly exemplified the adage, you learn something new every day.

My ebird checklist for the day can be found here.

I discovered a nest on the a beam of my sister's porch. Because a Carolina Wren flew away when I first found it, I assumed it was a Carolina Wren nest. However, while watching from a distance in my hammock, I noticed that both a pair of Carolina Wrens and a pair of Eastern Phoebes were bring food to the nest and removing fecal sacs.

I decided to get a closer look. The nest indeed had at least 3 Carolina Wren chicks, looking developed enough to be fledging soon by my guess. The base of the nest did look very much like a phoebe nest, with the "hood" characteristic of a wren nest.

I decided to set up a game camera on the beam facing the nest. I kept a close eye on the nest, because I did not want the presence of the camera to prevent the parents (both biological and adopted) from feeding the chicks. The first wren came and fed the chicks with no concern for the camera. Next came one of the phoebes, who reacted much more to the camera. It called his/her mate, and both phoebes scolded the camera. Next came another wren and upon seeing the phoebes scolding the camera, also called his/her mate. With all four parents scolding the camera, I quickly removed it, so as to not stress them any further.

So...I am assuming that a pair of Carolina Wrens built their nest on top of a Eastern Phoebe nest. I am very curious as to how the nest construction and incubation was carried out, but I suppose I may never know.