Spring songbird migration is underway
With April comes loads of blossoms, leafing trees and pollen. Pollen irritates throats and eyes even in allergy-free people. The good news is that pollen should lessen by the end of April. The bad news is there are three weeks to go yet.
With hundreds of species of wild flowers in bloom even to the highest peaks, Western North Carolina’s mountains are rich in biodiversity.
As you travel up these ancient mountains you find birds that you usually see in Canada. Rather than make the long trip to northern breeding grounds, Ruffled Grouse, Saw-Whet-Owl, Raven, Brown Creeper, Winter Wren, Golden Crown Kinglet, Veery, Hermit Thrush, Blue-Headed Vireo, Black-Throated Green Warbler, Canada Warble, Dark Eyed Junco, Red Crossbill and Pine Siskins migrate up the mountains to nest. Others make the long trip north to breed and nest.
Tree Swallows returned in mid-March, about two weeks early this year. Just about any house that looks like a blue bird house is fair game for them. And any cavity in a dead tree, including woodpecker holes, looks good to the Tree Swallow. Some are already laying eggs.
Tree Swallows are the hardiest of all the swallow species that call WNC their breeding grounds. They can feed on leftover berries and seeds during cold snaps. Their iridescent greenish blue upper parts catch the sun and glisten. The underparts are clean white with a dusky brown wash across the breast. They are small and chunky, with a shallow forked tail. With their broad-based triangular shaped wings, they glide more than they fly.
The Tree Swallows’ nesting season coincides with the best availability of insects to eat and feed their young. They winter farther north than any other American swallow, and return to the breeding grounds long before others do. They eat plant foods along with their normal insect diet, an adaptability that helps them survive the harsh cold snaps of early spring. The handsome little aerialists are familiar sights throughout northern North America during the summer months.
Tree Swallows feed from dawn to dusk in sheltered areas with large insect populations. Usually they forage for insects no higher than 40 feet off the ground. They consume all kinds of insects, including dragonflies, damselfies, mayflies, caddisflies, sawflies, bees, ants, wasps, beetles, stoneflies, butterflies, and moths and spiders, and roundworms. Some of their prey is as small as a grain of sand. They also eat high-calcium foods like crayfish, fish bones, exoskeletons, clam shells and eggshells of ducks and birds.
The female builds the nest, an endeavor that can take a few days or a couple of weeks. Swallows can often be seen chasing feathers floating in the air. Their nests always have feathers from other birds in them.
Courtship rituals revolve around the male showing off his expertise in flying with twists, twirls, and skimming the water. This shows his skills in hunting insects.
Swallows are very sensitive to pesticides on manicured lawns. Pesticides poison the bugs, and the bugs in turn poison the birds when they eat them. The baby birds die of pesticide poison when the parents feed them poisoned bugs.
The female Tree Swallow is the only North American passerine (perching bird) that retains her immature plumage into her first breeding season (and sometimes into the second). Her immature plumage is brownish but often shows some blue-green on the back and wings.
The natural predators of Tree Swallows include rat snakes, raccoons, black bears, chipmunks, mink, weasels, deer mice and feral cats. Kestrels, Grackles, Crows and Flickers also prey on them. Outside the nest, adults are hunted by Falcons, Great Horned Owls, and Sharp-Shinned Hawks. As a defense, Tree Swallows usually swarm and dive-bomb predators while making alarm calls.
They bathe by skimming the water and then, while rising, they shake off the droplets. Tree Swallows nest in isolated pairs. They will nest close to a Bluebird’s nest and keep other birds away from it, so they make good neighbors for a nesting pair of Bluebirds.
Competition with House Sparrows and Starlings has impacted Tree Swallow populations.
Purple Martins are arriving daily at nesting sites at Givens-Highland Farms in Black Mountain. About a dozen of the scouts are on site, with more arriving daily.
Dragonflies are out.
Toad frogs are beginning to call.
Flickers are busy establishing territories.
House wrens nest. Carolina Wrens are nesting.
White tail deer begin to grow antlers.
Canada geese are nesting, with some babies already hatching.
Wintering sparrows have headed north.
Raccoons continue to give birth in April and May.
Black bear females with cubs are up and about.
Tree frogs continue to call from dusk through the night into early June.