Bird Nests of May – Part II
“Although it is easier to find the nest in early winter, nest finding in spring is more of a challenge and infinitely more rewarding, since the nests are in use.” —John Hanson Mitchell from “A Field Guide to Your Own Back Yard.”
Step outside in The Last Green Valley National Heritage Corridor and you will almost certainly hear the forest drumming of woodpeckers. Various woodpecker species call our region’s woods home. The fast drumming we hear in spring is their way to attract a mate and communicate with one already found. The effort is also about finding food and creating a home.
Woodpeckers use cavities to nest. From the small downy to the large pileated, woodpeckers use their sharp chisel-like bills to make nesting cavities for rearing their young, usually in dead trees. Seeing pileated woodpeckers at work is particularly impressive. They are about the size of a crow, and their deep crimson red cap stands out as they fly through the woods in swooping motions. The male will select a tall, usually dead tree and after several test taps to check the density of the wood, will select a softer, more rotted section and begin to chisel his way into the tree. It may take a week of work, but he’ll create a hole big enough for three to five white, almost round eggs. Both adults will incubate the eggs, which will hatch after 15-18 days.
The nesting habits of birds reveal a lot about them, which is why I am dedicating a second column this month to the various nests we can find here in the Heritage Corridor. Last week I wrote about ground nests (eggs laid right on the bare ground or in a slight depression), platform nests (piles of sticks laid and heaped together in trees or on ledges) and burrow nests (nesting holes dug into the earth). For those who didn’t read the first column it is available on the TLGV website at: https://thelastgreenvalley.org/category/read-reid/
In addition to cavity nests (nests built in holes in trees), today I will write about cup nests (woven nests attached to trees or bushes), pensile nests (suspended nests hanging from above like a hammock woven into the fork of a twig), pendulous nests (hanging woven pouches suspended from thin twigs at the ends of a branch) and no nests (parasitic birds who don’t build a nest, but instead lay their eggs in the nest of another species).
My favorite book on bird nests is the informative “Secrets of the Nest: The Family Life of North American Birds,” by Joan Dunning. The book describes in exceptional detail the nests and breeding habits of a variety of bird species and includes beautiful illustrations by the author. Dunning’s book is the inspiration for this two-part column, and information gleaned from it as well as my own observations provide the source material for this column.
You can attract a cavity nesting bird by using wood boxes. At my house I put up wood boxes for my favorite cavity nesting bird, the eastern bluebird. One year we had more bluebirds than boxes, and I discovered a pair successfully using a small hole in a long sugar maple branch that had probably been made by a woodpecker. I am pleased to report that as of this writing, there is a bluebird nest in one of my boxes, and it already has 5 or more eggs. Other birds rely on cavities in trees to make their nests, as well. Some like the tufted titmouse don’t have a beak strong enough to excavate their own cavities and rely on old cavities made by woodpeckers.
My guess is most readers have seen the cup nest of a robin in a nearby shrub or bush in their backyard. Perhaps you have a barn swallow who has taken up residence and built its mud-lined cup nest firmly attached to an overhead beam in your garage or porch. Late last month an eastern phoebe pair built its mud and stick nest under an eve of our barn.
The cup nest I have never had the pleasure of discovering is that of the ruby-throated hummingbird. The nest of a hummingbird is tiny — only an inch across and an inch deep — and made of the most remarkable materials, such as leaf bud scales bound together with spider web. The nest is lined with milkweed fluff and thistledown and is then covered with green and gray lichens bound with spiderweb and the web of tent caterpillars. Inside the female lays two tiny white eggs the size of peas, which will hatch in 11-14 days.
In my office I have a tiny nest built by a red-eyed vireo. It is perfectly round, barely two-inches wide at the opening and two-inches deep. Into a fork of a twig, it has been carefully woven together with thin strands of reddish bark stripped from wild grape vines, bits of grass and thin roots. Dunning calls these pensile nests, which hang and are suspended from above. The beauty of the red-eyed vireo nest is its weight. It’s so light it can be built at the ends of smaller exterior branches and twigs where most predators cannot go. The red-eyed vireo will lay two to four white eggs with tiny brown and black spots. Incubation is by the female and takes 12-14 days for the eggs to hatch.
The most unwelcome of birds is the parasitic cowbird. It doesn’t build a nest of its own, but instead lays a single egg in the nest of another bird, leaving the incubating and rearing to its unsuspecting host. Unfortunately for the host bird, the cowbird egg typically hatches before the host eggs and quickly outgrows its nest mates, beating them out for the available food.
Cowbirds are the most common and widespread “brood parasite” in North America and a fascinating story of evolution and adaptation. They are native to the United States and are found in grasslands, open farmland, urban and suburban gardens and lawn habitats. They prefer areas where cattle or horse-disturbed soil is available for feeding on ground insects. Historically, they followed bison herds and fed on the insects and bugs kicked up by the passing herds.
It is speculated this association with moving herds of bison may be why the cowbird developed the breeding strategy of parasitism. Perhaps by leaving their eggs in the nests of other birds they could keep up with moving herds, or their innate breeding instincts gave them the freedom to do so. The 18th and 19th-century cutting of the eastern forest for agricultural lands allowed the cowbird to expand eastward beyond its original range of plains and prairie. By mid-19th century, Connecticut was 80 percent cleared land, predominately field and pasture for livestock, and provided perfect cowbird habitat. It is also believed this expansion provided the cowbird with access to bird species who had not developed defensive strategies against cowbird parasitism.
To find a pendulous nest in our region means you have discovered the nest of a Baltimore oriole. It is a woven pouch made of plant fibers, bark, bits of yarn and hair lined with soft plant fiber. The one I discovered was hanging from the tip of a downward swinging branch high up in an elm tree. Inside would have been four to five white eggs with brown blotches. The female incubates the eggs for 12-14 days. The first Baltimore orioles are already arriving in our Heritage Corridor, and as May slides towards June and the Summer Equinox, we will see more of these migrators, and I’ll listen for their distinctive “hew li” and rattled call. I’ll scan the green foliage for the flash of bright red orange heralding the arrival of summer.
We live in a beautiful place called The Last Green Valley National Heritage Corridor. I hope you’ll join me and together let us enjoy it, care for it and pass it on.
Bill Reid is the Chief Ranger of The Last Green Valley National Heritage Corridor. He can be reached at 860-774-3300 or email@example.com
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