Monthly Archives: October 2018

Great horned owl reigns as ‘feathered tiger of the night’ among birds

 

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Photo by Alexas-Fotos/Pixabay • A great horned owl is capable of almost silent flight, which helps the predatory bird take prey by surprise. Many myths and superstitions surround the world’s owls, but the truth about owls is often more fascinating.

I’ve been so focused on migrating warblers and other songbirds of late that I felt some surprise when outside near dark on Oct. 10 when I heard the low hoots of a feathered phantom from the woodlands on the ridge behind my home.

The hooting of a great horned owl is an instantly recognizable sound and always sends shivers traveling along the spine. The after-dark calls of this large predatory bird also got me to thinking about previous encounters with this owl, such as watching one glide silently over wetlands in Shady Valley, Tennessee, many years ago. I had traveled to the bogs in Shady Valley maintained by The Nature Conservancy in the hope of witnessing the mating displays of the American woodcock. Before those avian rituals began, a great horned owl kicked off the evening in style. I still remember the large owl passing like a dark shadow only a couple of feet over my head. The wings did not even appear to flap as the owl’s silent flight propelled the bird out of sight within seconds.

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Photo by Flickr on Pexels.com

I also remembered another occasion while driving on a wet and stormy night, rounding a curve, and finding an owl, upright in the road, standing over fresh roadkill. The owl’s eyes reflected the beams of my headlights before it seized its meal in powerful talons and flew off into the darkness. I’ve always wondered if the owl had killed something in the road or came along at just the right moment to scavenge a meal after some creature had been killed by a passing car.

Owls have been around for a long time, according to “Owls: The Silent Hunters,” an episode of National Geographic’s series, “Wildlife Wonders.” The narrator for the episode reveals that the first recognizable owls first showed up in the fossil record about 40 million years ago. Since that time, owls have evolved into a fantastic, widespread and diverse group of about 135 different species. North America is home to several species, including the far-ranging great horned owl, which ranks as one of continent’s largest owls. It’s not the largest owl in North America, but it is the most widespread of the continent’s large owls. The snowy owl — popularized in J.K. Rowling’s fiction as Harry Potter’s loyal companion owl, Hedwig — is one of the largest owls in the Northern Hemisphere, bigger than such large owls as great horned owl and barred owl. The aptly named great gray owl is larger in body size than the great horned owl, but the snowy owl is heavier and more massive than either of these two contenders.

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Photo by U.S. Fish & Wildlife Service • A captive snowy owl educates the public about owls and some of the perils they face in an environment shared by humans.

Nevertheless, the great horned owl is large enough, ferocious enough, and lethal enough to have been described by many ornithologists as a “feathered tiger of the night.” The great horned owl lives and hunts in the woodlands of northeast Tennessee, southwest Virginia and western North Carolina. They thrive in rural areas, but these adaptable owls have also learned to make their way in the suburbs and even city parks. Not by any stretch of the imagination, however, is this owl confined to the southern Appalachians. These owls also make their home in the wetlands along the southern Atlantic coast, as well as arid deserts of the American southwest.

During a September vacation many years ago to Fripp Island, South Carolina, a solitary great horned owl provided several days of entertainment for my parents and me. We took a golf cart at dusk each evening to park at a spot that offered a good view of the marshes and tidal creeks in the interior of the island. For several consecutive days, the owl flew to a perch on a piece of driftwood as the sun sank below the horizon. We would wait patiently for only a brief interval before the owl entertained us with its low hoots that resonated across the marsh.

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Photo by Pixabay on Pexels.com

The great horned owl is capable of taking a wide variety of prey, including many rodents ranging in size from mice and voles to rabbits and squirrels. Although various mammals form the most part of its diet, the great horned owl will kill adult birds as large as a Canada goose, wild turkey and great blue heron. This owl also preys on fish, reptiles, amphibians and even insects. The great horned owl is one of the few predators that preys regularly on skunks. Lacking a well-defined sense of smell, owls aren’t bothered in the least by the skunk’s powerful arsenal of stink. That ability to fly and glide using almost completely silent wings has given this nocturnal predator an enormous advantage over many of its prey species.

A wild great horned owl’s longevity peaks at around 13 years of age. Captive owls, however, have been reported reaching ages of more than 30 years old.

Various Native American tribes have held owls in high respect. Dwight G. Smith, author of “Great Horned Owl,” a book in the “Wild Bird Guides” series, noted that members of the Zuni tribe of the southwestern United States often hold owl feathers in their mouths to impart the owl’s ability to hunt silently onto their own hunting abilities.

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Photo by Pixabay on Pexels.com

The main fascination humans hold for owls rests in their mystery. Owls, being mainly nocturnal creatures, rarely cross paths with humans. These predatory birds have many adaptations that help them stake out their claim on the night hours. Owls possess large eyes with binocular vision and extremely accurate depth perception — which also make them seem more expressive to human observers and perhaps helped establish the reputation of the “wise” owl.

Owls cannot completely rotate their heads, but they come close. Owls are flexible enough, however, to be able to turn their heads in a 270-degree arc, or three-quarters of the way around. Owls have keen hearing to go with their excellent eyesight. In fact, owls don’t even need to see their prey to capture it. Tests with barn owls in total darkness have shown that they are capable of catching mice by hearing alone. An owl’s prominent facial disk directs sounds toward their ears. The “ear tufts” on the great horned owl and some other relatives are ornamental feathers, and not actual ears.

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Photo by Bryan Stevens / A great horned owl perches on a post during its part in a wild bird show at Callaway Gardens in Pine Mountain, Georgia.

Around the world, the world’s owls have earned some rather descriptive common names. Examples include pharoah eagle-owl, vermiculated fishing owl, fearful owl, pearl-spotted owlet, chestnut-backed owlet, spectacled owl, black-and-white owl, crested owl, cinereous owl, tawny owl, whiskered screech owl, greater sooty owl and desert owl.

Americans will observe Halloween on Wednesday, Oct. 31, which brings me to one other piece of owl trivia. There’s an ancient Chinese belief that owls snatch the souls of incautious people — just something I thought you might want to know if you find yourself out and about after dark on Halloween night and hear the hoots of a nearby owl.

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Photo by George Gentry/U.S. Fish and Wildlife Service • A great horned owl is shown on the nest with one of her chicks.

Thrushes epitomize the spirit of fall migration

 

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Photo by U.S. Fish & Wildlife Service • The Wood Thrush often sings its flute-like song from deep under cover in dense woodlands.

While many migrant birds take wing in the autumn, a recent event reminded me that, in many respects, fall is the season of the thrush.

Taking part in the recent Fall Bird Count conducted by members of the Elizabethton Bird Club afforded me the opportunity to see some amazing birds, including large flocks of migrating broad-winged hawks, playful pileated woodpeckers and some often hard-to-see thrushes.

I usually feel lucky to be able to find one thrush in a single day of birding. On Saturday, Sept. 29, migration must have brought these birds out in full force, because I saw three different species — wood, gray-cheeked and Swainson’s — in the span of a few hours.

I found the Swainson’s thrush during the morning while walking the trails at Sycamore Shoals State Historic Park along the Watauga River in Elizabethton, Tennessee. I flushed the bird from cover and got a good look at the bird. The Swainson’s thrush is a model of subtle beauty with a plumage that consists of warm olives and browns and a beige wash across the upper half of an otherwise white breast dotted with a faint brown spots. The beige wash extends into a prominent eye-ring.

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Photo by Bryan Stevens • After striking a window, this Swainson’s thrush was given time to recover in a box in a dark, quiet place before being released to continue its migration.

I usually see more Swainson’s thrushes in autumn than spring. Named for William John Swainson, the thrush doesn’t spend the summer months in the region, but is a fairly common spring and fall migrant. The thrushes that do nest during the summer in the region include wood thrush and veery, as well as the hermit thrush, which is also a winter resident.

The namesake of the Swainson’s thrush was a famous English naturalist living in the 19th century. Swainson, who grew up in London but spent much of his adult life in New Zealand, excelled as an English ornithologist, malacologist, conchologist, entomologist and artist. Besides the thrush, eight other species of birds are named in his honor.Swainson_William_1789-1855

Two of the other birds — Swainson’s warbler and Swainson’s hawk — are resident in the United States for at least the spring and summer months.

The other six species include Swainson’s francolin, Swainson’s sparrow, Swainson’s antcatcher, Swainson’s fire-eye, Swainson’s flycatcher and Swainson’s toucan.

Swainson never visited the United States of America, but in 1806 he accompanied the English explorer Henry Koster to Brazil in South America. Swainson and his family emigrated to New Zealand in 1841. Swainson settled near the New Zealand city of Wellington only to have earthquakes in 1848 and 1855 devastate the shoreline near his estate, which he called Hawkshead. He found the pioneer life in New Zealand difficult, especially when a native Maori chief pushed his own claims to Swainson’s estate. Swainson died of bronchitis on Dec. 6, 1855, at the age of 66.

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Gray-cheeked Thrush Photo by Dave Menke/U.S. Fish and Wildlife Service • A gray-cheeked thrush sits tightly on its nest on Kodiak Island in Alaska. More than other members of the thrush family, the gray-cheeked thrush nests in remote regions and only passes through Tennessee and Virginia during a limited period every spring and fall.

The recent Fall Bird Count also offered me an opportunity to see a gray-cheeked thrush for the first time in almost 18 years. The species is aptly named. The gray-cheeked thrush lacks an eye ring, and its most prominent feature is the grayish plumage around the bird’s face. No evidence of brown or buff coloration intrude into the face region.

Gray-cheeked thrushes nest far from Tennessee and Virginia. In fact, they nest almost to the very edge of the tundra region in the far north. Because of this tendency to nest in remote regions, experts have had difficulty determining population trends for this species.

I know that I hadn’t seen one of these thrushes since back in 2000. I didn’t get a very good look during my recent encounter. I saw a bird fly from a tree branch into thicker cover. I relied on other members of the count party who got a better look to make the identification. The gray-cheeked thrush is not a common migrant in the region, but they do make some sporadic appearances. It’s possible they are also overlooked. Their migration actually takes place at night. The daytime observations of this bird involve individuals that have stopped for a brief respite to refuel and rest.

A shy personality contributes to the ease with which the bird can be missed even by a sharp-eyed observer. Like some of its relatives, but perhaps even more so, the gray-cheeked thrush would rather slip into concealing cover than reveal itself on an exposed perch to human observers. Both the gray-cheeked thrush and Swainson’s thrush belong to the genus Catharus, a term derived from Ancient Greek that can be described as “pure” or “clean” in reference to the plumage of some of the members of the genus.

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The other two Catharus thrushes in North America include the veery, Bicknell’s thrush and hermit thrush. Some members of this genus are colorful birds with descriptive names, including the orange-billed nightingale-thrush, black-headed nightingale-thrush and slaty-backed nightingale-thrush. The incorporation of the name “nightingale” is no accident. Like the famous nightingale of folklore and fairytales, many members of the genus are remarkable singers capable of producing ethereal and flute-like songs.

In the final days of September and early days of October, wood thrushes returned to prominence in the woodlands around my home. I have wood thrushes nesting in the woods around my home every spring, but it is still always a treat to see the largest of the brown thrushes that call North America home during at least half of the year.

The wood thrush is not a member of the Catharus genus of thrushes, but instead is the sole representative of the genus Hylocichla. While not exactly a official state bird, the District of Columbia has made the wood thrush its official bird. The popularity of the wood thrush is probably helped by its own beautiful song, which has often been described as one of the most beautiful of all North America’s birds. Widespread in the United States and Canada during the summer nesting season, wood thrushes withdraw in winter to spend the cold season in southern Mexico through to Panama in Central America.

Right now, migration of thrushes is proceeding at a somewhat leisurely pace. Soon, though, most of this family of talented singers will depart the borders of the United States until next spring. When they get ready to leave, most thrushes will make a remarkable non-stop journey that will take them to the region where they will wait out the cold winter months.Enjoy them before they depart.

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Photo by Jean Potter • The wood thrush is a common summer resident of woodlands in Northeast Tennessee, Southwest Virginia and Western North Carolina.

 

 

Tennessee warbler visits Volunteer State only a few weeks each year

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A Tennessee warbler as painted by early naturalist and painted John James Audubon. Because the first of these warblers was found in Tennessee, the bird was given a rather inappropriate name. At most, they spend a few weeks each year in the Volunteer State during migration.

This fall has been a good time to see warblers. Some of the more common ones I have noticed in the yard so far have included American redstart, chestnut-sided warbler and black-throated green warbler. Of course, these two species nest in the region during the summer.

One of fall’s first true migrants showed up on Sept. 17 when a rambunctious Tennessee warbler made its debut by chasing a male Northern cardinal from the blue spruce near the creek.

The pioneering American ornithologist Alexander Wilson gave the Tennessee warbler its name, which, unfortunately, is not an accurate moniker.

Here’s some trivia for you should you ever find yourself competing on the game show “Jeopardy” and the category is “Warblers.” Four of our warblers — Kentucky Warbler, Louisiana waterthrush, Connecticut warbler and Tennessee warbler — bear common names that honor states. The Kentucky warbler and Tennessee warbler are named for the states where they were first found and described by Wilson in 1811. Neither the Tennessee warbler or Kentucky warbler are particularly affiliated with the states for which they were named. In fact, the Tennessee warbler passes through the Volunteer State only for a few weeks each year during spring and fall migration. Its closest breeding range is in the boreal forests of Michigan, and these warblers spend the winter in Mexico or farther south. Wilson got lucky and found his Tennessee warbler along the Cumberland River during migration.

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Tennessee Warbler Photo by Paul Spark/Adobe Stock • The Tennessee warbler, while named for the Volunteer State, spends very little time within Tennessee. These warblers migrate through the region each spring and fall but nest much farther north in the boreal forests.

 

Don’t blame Wilson too harshly for the mistake. Even after he “discovered” the first Tennessee warblers back in 1811, it would be almost another century before scientists finally located the bird’s nesting grounds in Canada in 1901. The remote and inaccessible nature of the the region helped prolong this mystery about the Tennessee warbler’s life cycle.

In almost 25 years of birding, I’ve never seen a Tennessee warbler during spring migration. I see many of these birds every autumn as they stage their fall migration through the Volunteer State to reach destinations farther south. The appearance of the Tennessee warbler varies greatly depending on the season. In autumn, most Tennessee warblers are greenish-yellow birds with whitish-gray underparts. In the spring, the basic green and white pattern remains evident, but both males and females sport a gray head and a black line that runs through the eye and along the side of the bird’s face. The plumage — at least in illustrations and photographs — is shown as more crisp and distinct with spring birds.

Some experts have floated the opinion that the Tennessee warbler should be named named “coffee warbler,” since wintering individuals are attracted to coffee plantations in Central America. According to the website, “Birds of North America,” recent studies demonstrate the importance of shade coffee plantations for Tennessee warblers during their time spent outside North America every winter. Other warblers, such as the black-throated blue warbler, are also closely associated with coffee plantations during the wintering season.

Some years find Tennessee warblers in great abundance, probably thanks to a feast of caterpillars infesting the spruce trees in the boreal forests where these warblers nest during the summer months. In years of famine when the caterpillars are less rampant in the forests the Tennessee warbler calls home, the birds raise fewer young, and the population grows less dramatically.

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Photo by Bryan Stevens • Tennessee warblers are nectar thieves, punching holes in the sides of flowers to get nectar without contributing to the pollination process.

The Tennessee warbler is not strictly an eater of caterpillars and insects. This warbler has a bit of a sweet tooth — or should that be sweet beak? They visit flowers to partake of nectar; however, the Tennessee warbler is not a good example of an avian pollinator. Tennessee warblers cheat by poking holes in the flower with their bills to steal the nectar without having to let the flower’s pollen accumulate on their bills and heads. The Tennessee warbler will also come to sugar water feeders put out on their wintering grounds to attract hummingbirds. The Tennessee warbler also supplements its diet with fruit and berries.

Here’s something that might also come in handy in a test of your knowledge of trivia some day: Not only is the Tennessee warbler named for the state, but the capital city of Nashville also has its name linked another member — the Nashville warbler — of the warbler clan. Once again, Wilson provided a rather inaccurate name, as the bird in question is only a visitor to Nashville during a limited window of time each year.

While the briefly visiting Tennessee Warbler already pays tribute to our state with its common name, the Northern mockingbird was selected in 1933 as the official bird for Tennessee. This relative of the brown thrasher and gray catbird also serves as the state bird for Arkansas, Florida, Mississippi and Texas. At my home, Northern mockingbirds are usually evident only during the winter months. I haven’t seen one at home so far this year. Gray catbirds were scarce this summer, but a pair of brown thrashers provided much entertainment as they raised young in my yard and gardens.

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Photo by Bryan Stevens • The Northern Mockingbird has been the official state bird for Tennessee since 1933.

For now, I think Tennesseans will probably stick with the mockingbird, rather than the Tennessee warbler, when it comes to offering one of our feathered friends the accolade of official state bird. That’s not to say we can’t enjoy observations of this warbler during its brief forays through the state. Don’t wait too long, though. The window of opportunity usually closes by mid-October.

Mother Nature’s whims can produce major impacts on birds

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Photo by U.S. Fish and Wildlife Service/Duncan Wright The sooty tern, pictured, nests mainly in Hawaii, but some also nest on the islands of the Dry Tortugas, west of the Florida Keys. In 2004, Hurricane Frances blew one of these tropical birds to Holston Lake in Bristol. Severe storms also present devastating obstacles for other birds.

With Hurricane Florence dominating the headlines in recent weeks, it’s only natural to speculate on whether such storms can impact birds in a negative way.

According to a 2011 blog post made on the National Wildlife Federation website, hurricanes can be bad news for some birds. Naturally enough, sea birds and waterfowl are most exposed to the forces of a hurricane. Some birds will move inland to avoid the incoming storm. The birds that inhabit our yards and gardens will ride out the storm using special adaptations. Songbirds will automatically tighten their toes around their perches, riding out the winds of a hurricane by holding onto a branch with a death grip. It’s the same adaptation that lets them sleep on a branch without letting go and falling off during the night.

The blog points out that the news often covers the appearance of rare species after a major storm. Some of these birds transported to unusual locations are probably younger or weaker birds. Once transported far from their usual range by a hurricane, it can take weeks to return home — if they can find the right foods on their way back.

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Early naturalist and accomplished artist John James Audubon painted Bachman’s warbler without ever seeing a living one. A friend sent him some skins of the warbler collected near Charleston, South Carolina. A hurricane may have contributed to the extinction of Bachman’s warbler.

In a worst case scenario, hurricanes may have dealt fatal blows to some bird species. For instance, a hurricane may have delivered the knock-out blow to a species of warbler that went extinct last century, according to the website, Field Guide to Extinct Birds. A hurricane that slammed into Cuba in the 1930s when most of the Bachman’s warbler population was wintering on the island might have wiped out enough of the population to make the survivors too rare and far-flung to find each other to breed. The warbler, sensitive to habitat destruction from logging and already in a steep decline, never seemed to recover. It was the ultimate example of keeping all of one’s eggs — or birds — in one unlucky basket.

Discovered in 1832 near Charleston, South Carolina, by the Reverend John Bachman, this warbler attracted little attention for the first half century after its discovery. Bachman sent some skins of the bird to his friend, the artist and early naturalist John James Audubon. Subsequently, Audubon painted this warbler by using those skins and Bachman’s description of the bird’s habits for inspiration. Ironically, considering he described the species for science, Audubon never actually laid eyes on an actual living Bachman’s warbler.

The last specimens of Bachman’s warbler were collected in Mississippi in the early 1940s. The last strongholds for breeding Bachman’s warblers in the United States were Fairfax County, Virginia, in the 1950s and South Carolina’s I’on Swamp in the early 1960s. The last photograph documenting a Bachman’s warbler was taken in 1954. in Charleston, South Carolina, bringing the story of this warbler full circle from its discovery in the same vicinity back in 1832. No Bachman’s warbler sightings have been confirmed since 1961, despite reports in the 1970s and 1980s, as well as reports made in the spring of 2000 and 2001 in the Congaree Swamp National Monument in Richland County, South Carolina. None of those sightings could be confirmed.

Like the ivory-billed woodpecker and Eskimo curlew, Bachman’s warbler is another bird likely to be labeled for the near future with the tag “likely extinct” associated with its name. Like the large woodpecker and the shorebird with a penchant for long-distance migration, the Bachman’s warbler went out with a whimper, not a bang, with most of its viable population snuffed out by an October hurricane just as the species returned to Cuba for the winter season.

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Photo by Bryan Stevens • Ruby-throated Hummingbirds make a non-stop crossing of the Gulf of Mexico. A hurricane in the Gulf during migration could have serious consequences for this small bird.

More recently, experts worried Hurricane Irma might have delivered a knockout blow to the population of another tiny species of warbler. The Barbuda warblers on the tiny Caribbean island of Barbuda were feared exterminated in the wake of Irma. When the storm hit the island in September of 2017, its path affected more than 90 percent of the island and nearly wiped out the available habitat for the warbler, which already had a Near Threatened status. After the passage of the storm, participants in searches for the warbler turned up sightings of the bird. Nevertheless, the population status and ability to fully recover remains uncertain.

Science keeps adding to its knowledge of how birds are affected by hurricanes and other storms. A 2017 study showed possible consequences for a seabird known as the sooty tern in relation to hurricanes.

The study, published in the peer-reviewed open-access journal PeerJ, is the first to map the birds’ annual migratory path and demonstrate how its timing and trajectory place them in the direct path of hurricanes moving into the Caribbean after forming over the Atlantic.

Climate change threatens to bring about more frequent and powerful hurricanes, which could be bad news for the terns. Migration is a stressful undertaking for birds. If they encounter a strong storm in a weakened state, the results could be catastrophic. The study revealed a strong relationship between the numbers and locations of bird deaths and the numbers and locations of hurricanes. The study also showed that it isn’t just monster storms with the potential to cause devastation. Tropical Storm Delia, a small storm in the Gulf of Mexico in 1973, killed a lot of sooty terns. Essentially, the terns were in the wrong place at the wrong time.

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Photo by Bryan Stevens • A mixed flock of Short-billed and Long-billed Dowitchers and a Ruddy Turnstone at Huntington Beach State Park in South Carolina. Hurricanes can interrupt the migrations of even these long-distance migrants.

Of course, the sooty tern is not a rare bird. About 80,000 or more of these terns are estimated to breed in the Dry Tortugas each year. That’s the entire point, however; Bachman’s warbler was also once considered a common bird.

All of these examples point to the resilience of birds, but there’s also a lesson to learn. We should never take any of our feathered friends for granted. While the winds and rains from a hurricane can decimate human lives, wildlife is not immune. Sadly, birds can weather many a storm, but sometimes they get swamped.