Warblers feeding on joe-pye

A male Cape May Warbler (Setophaga tigrina) shifts position in a Red Elm (Ulmus rubra). I encountered a mixed foraging flock of warblers this morning not far from where I live, in Franklin County, Ohio. Co-dominant in the flock were Cape May and Tennessee warblers. The site was a deciduous woodland bordering bisected by a broad powerline cut. Red and White oaks, elms, cherry and other caterpillar-rich trees were plentiful and unsurprisingly that's where the birds were focused.

A female Cape May Warbler works the densely flowered inflorescence of Sweet-scented Joe-pye (Eutrochium purpureum). The powerline cut was full of this statuesque plant. Even though the joe-pye was mostly done flowering, it was full of insects. Several Cape May and Tennessee warblers worked the senescing flowers, yanking what mostly appeared to be orthopterans (crickets, katydids, etc.) and spiders out.

A Tennessee Warbler (Leiothlypis peregrina) peers intently into joe-pye flowers. It was interesting to watch them rustle about the flowers, sometimes spending a minute or more in the same spot, seizing early instar crickets and spiders.

I'm going to pay more attention to the joe-pyes in fall migration.

Frugivorous birds plundering southern trees

 

A Fringe-tree (Chionanthus virginicus) heavily laden with ripe fruit. This shrubby (small treelet, at best) member of the Olive Family (Oleaceae) is a close relative of ashes. It flowers in spring, and produces pleasing bouquets of stringy white-petaled flowers. Come fall, the blue drupes (as the fruit are called) also create an aesthetically pleasing appearance. With the added - and more important - benefit of feeding long-haul migratory songbirds.

While the somewhat similar Chinese Fringe-tree (C. retusus) is sometimes used in landscaping, the one featured here is the native. In the interior, it occurs as far north as southern Ohio. The trees in my images were planted at Inniswood Gardens, a metropark in Westerville, Ohio, only 15 minutes from where I live. This site is probably about 80 miles north of Fringe-tree's native range, but who are we to split hairs. The tastiness of its drupes are certainly well known to songbirds engaged in long migrations between Neotropical wintering regions and northern breeding grounds. These birds have undoubtedly long known and utilized this plant's autumnal bounty.

A Swainson's Thrush (Catharus ustulatus) with a freshly plucked drupe. Larger birds like this swallow the drupes whole. Many of these speckle-bellied thrushes were present on this mid-September day. Swainson's Thrush is the most common of our highly migratory thrushes, and they breed across the great expanse of North American boreal forest, from Alaska to Newfoundland, and south at high elevations in the west. Most birds winter from Central America south to western South America, all the way to Peru.

A Cape May Warbler (Setophaga tigrina) perches briefly in a nonnative Norway Spruce (Picea abies) near the Fringe-trees. This warbler is another boreal breeder, and intimately linked to spruce on the breeding grounds. Even migrants seek out spruce, including the nonnative species. Cape Mays breed in a fairly narrow belt of boreal forest, from Alberta to Nova Scotia, and most winter in the Caribbean and the western coast of Mexico and Central America.

Come fall, Cape Mays often become frugivorous, plundering the bonanza of berries to be found in autumn in the eastern deciduous forest region that blankets much of eastern North America, as far north as southern Canada. Unlike the larger thrushes, warblers such as this typically puncture the skin of fruit with their sharp bills. They then drink the juices and perhaps eat some of the pulp. Many Cape May Warblers regularly visited this small Fringe-tree planting.

The most frequent frugivorous warbler at the Fringe-trees was the Tennessee Warbler (Leiothlypis peregrina). This one strikes a pose amongst some drupes, all of which bear the tell-tale evidence of feeding warblers.

While warblers are highly insectivorous during the breeding season, some add much vegetable matter in migration and winter. Tennessee Warblers winter throughout the Caribbean, much of Central America, and well into South America. I have seen them by the score in winter in Guatemala, where they avidly take nectar from the flowers of various trees. So much so that their faces are often stained bright colors courtesy of the nectar.

As a bonus, a stone's throw away was a gorgeous Sweetbay Magnolia (Magnolia virginiana) loaded with ripe fruit. Birds galore were taking advantage, including many Swainson's Thrushes, occasional thrushes of other species, especially American Robins (Turdus migratorius), Gray Catbirds (Dumetella carolinensis), and most surprisingly to me, lots of Red-eyed Vireos (Vireo olivaceus, pictured).

Vireos are notorious for the number of caterpillars they take. The raptor-like hook at the bill tip is an adaptation for seizing and tearing open larvae, or so I assume. Vireos are closely related to shrikes, which are highly predatory songbirds and sport even more of a hooked raptor-type bill. In the case of the vireo, this bill also works well when plucking fruit.

A Red-eyed Vireo, caught in the act of fruit plundering. This does not take long. As soon as a bird freed one, it quickly swallowed it. Something about Sweetbay Magnolia fruit is very attractive to this species, which I did not know prior to this experience. At times there would be perhaps a half-dozen vireos in the tree together, and a few times they were joined by a Philadelphia Vireo (Vireo philadelphicus). As with the Fringe-tree, Sweetbay is a southerner not occurring until 100 miles or south of central Ohio. But in the south and in the Atlantic states it can be common and birds have undoubtedly long used it as a food source.

A juvenile Red-eyed Vireo (brown eyes) watches a pugnacious Ruby-throated Hummingbird (Archilochus colubris). A number of hummingbirds had staked claim to the nearby gardens and flowering plants. When they weren't trying to drive each other away, they'd occasionally fly high into the magnolia to have a go at the vireos.

The Red-eyed Vireo is a true long-haul migrant. They breed over a massive swath of eastern North America and extend into northwest Canada and the U.S., mostly using caterpillar-rich deciduous forests. The wintering grounds encompass most of the northern half of South America. Some vireos probably fly 5-6,000 miles, one way. It is fascinating, to me at least, to learn about the intimate connection migrant songbirds have with plants, and to think about the role of native plants and their fruit in helping to stoke these long, hazardous journeys.

Cape May Warblers, and the Friends of Magee Marsh

A fabled place, especially at this time of year. Tens of thousands of birders make the peregrination to western Lake Erie, especially Ohio's Lucas and Ottawa counties, and stop #1 is a mile-long boardwalk that bisects a lakefront patch of swamp woods.

Owned and managed by the Ohio Division of Wildlife, the Magee Marsh Bird Trail can be akin to birding in an open-air zoo aviary. Scores of warblers and other songbirds fill the woods, and can often be seen at arm's length. Fixated on feeding to fuel the long flights ahead, and replenish fat deposits lost in the long migration to reach this point, the birds are little concerned with the throngs of human admirers.

I was up there over the weekend, and the birds put on a heckuva show. At least 29 warblers species were seen, most in large numbers. The rarity highlight among that crowd was a vagrant black-throated gray warbler - one of relatively few Ohio records.

Many visitors commented on the sparkly new look to the boardwalk. We can thank the Friends of Magee Marsh (FOMM) for that. This nonprofit exists to provide support and help make improvements to the marsh and its infrastructure. FOMM embarked on an ambitious two-year fundraiser to replace the aging boardwalk, ultimately pulling in several hundred thousand dollars and seeing to the complete replacement of the boardwalk's planking. That work benefits scores of people who visit Magee Marsh from all over North America, and far beyond. Support the Friends of Magee Marsh - details on the organization RIGHT HERE.

This spring, the stars of the warbler parade have been Cape May warblers. Here, a male forages in a patch of American black currant, Ribes americanum. A male Cape May warbler is a thing of great beauty; a colorful dynamo packaged in an 11-gram bundle of chestnut, yellow, black and green feathers. Charcoal tiger streaks complete its exotic appearance.

It is no coincidence that the bird in the photo above is in a patch of currant. And, once again, we have the Friends of Magee Marsh to thank for this. Read on...

A week or so after the first male Cape May warblers return from their Caribbean and Central American wintering haunts, they are joined by the females. The lass in this photo perches on an elderberry, Sambucus canadensis, another native plant found along the boardwalk.

Over time, the woods along the Bird Trail became choked with nonnative flora, as happens to so many of our habitats. Two of the worst botanical offenders were bush honeysuckle, Lonicera morrowii and others, and garlic mustard, Alliaria petiolata. These species are highly aggressive and crowd out the native flora. Not only that, they are also allelopathic - the plants produce growth-inhibiting enzymes from their rootstocks that impedes or eliminates the growth of competitors.

The upshot was a sea of nasty invasives along the trail, and very little native flora other than the overarching trees. Until the FOMM began an orchestrated and labor-intensive project to eradicate the nonnative flora. This work began about five years ago, and FOMM members keep on top of things with regular eradication sweeps.

Their work has been highly successful. There's hardly a weed to be seen these days, and the response of native flora - the species vanquished by the nonnative invaders - has been astonishing. Spring wildflowers have returned, along with jewelweed, native nettles (they play host to red admiral butterfly caterpillars!), and many other kinds of indigenous flora. Along with the major spike in botanical diversity has come a marked increase in value to birds and other wildlife.

Back to the American black currant and Cape May warblers. While the currant had nearly been eliminated when the invasives were at their worst, it has bounced back with a vengeance. Everyone who birds the trail can't help but to notice it. A small shrub, the currant is bedecked with dangling clusters of small yellowish flowers and is showily conspicuous.

What nearly everyone this spring has also noticed is the fixation of Cape warblers with the currant flowers. In this photo, a male plumbs the depths of a blossom with its slender bill, drawing out nectar with its semi-tubular tongue. Cape May warblers are big consumers of flower nectar, and the proliferation of currant plants along the boardwalk has given them back a large and important food source at a critical place and time in their long migratory trek to the boreal forests of the extreme northern U.S. and Canada. Once there, they specialize on spruce budworm caterpillars and I assume last summer saw large outbreaks of those caterpillars. The number of Cape May warblers seen this spring in migration has been astounding, likely due to high breeding success triggered by abundant food crops on the breeding grounds last year.

Cape May warblers aren't the only beneficiaries of currant blooms. Other warbler nectar-feeders include Nashville and Tennessee warblers, along with northern parula. This tale is an excellent and clearcut example of the value of native plants, and the often ornate ecology that binds plants and animals. Working to eradicate nonnative invasive plants is tough and time-consuming, but obviously can bear rich fruit.

Thanks once again to the Friends of Magee Marsh for their hard work, and I'm sure the warblers send their thanks, too. Again, for information about FOMM, GO HERE.

Cape May Warbler in November!

Photo: Tom Sheley

Tom Sheley, who is the proprieter of the Wild Birds Unlimited store on Riverside Drive in northwest Columbus, brightened my email inbox by sending along two photos of an unexpected November feeder visitor.

This male Cape May Warbler, Setophaga tigrina, is visiting feeders in a Worthington, Ohio backyard well after most of his compadres are back in their Caribbean wintering haunts. Given that the weather here today was in the 40's and rainy, I would think this little tiger-striped beauty may be lamenting his decision to linger, if he is still about.

Photo: Tom Sheley

Tom made these images on November 8, and normally the last straggling Cape May Warblers are gone from Ohio by mid-October. It'll be interesting to see how long this bird toughs it out.

In spite of their primarily insectivorous diet - although Cape Mays do eat lots of fruit in fall and winter - these warblers can be surprisingly hardy. There are probably 15-20 early winter records, and a few Cape Mays have toughed it out at feeders well into January.

Out of the norm birds often show up at feeders, such as Tom's beautifully photographed Cape May Warbler. If you ever spot anything that seems out of the ordinary at your feeders, such as a warbler in winter, please let me or another birder know.