The Bicknell’s Thrush

Catharus bicknelli

By: Liza

Scientific Classification:


Kingdom:
Animalia
Phylum:
Chordata
Class: Aves
Order: Passeriformes
Family: Muscicapidae
Genus: Catharus
Species: bicknelli



Natural History

On June 15, 1881, the Bicknell’s thrush was first discovered by the 21 year-old amateur ornithologist, Eugene P. Bicknell. He had hired a local guide, and with the guide’s help, climbed the summit of Slide Mountain in the Catskills, which are located in up-state New York. At the top of the summit, they came to a small opening in the fir forest and heard an unfamiliar bird call, which sounded similar to the Verry’s (a member of the thrush family). The next moment, a thrush-sized bird flew into the opening. Eugene caught the bird as it flew by, and with a closer look, he thought it to be a gray-cheeked thrush.

Confused about his findings, Eugene Bicknell sent the bird to Dr. Robert Ridway of the American Museum of Natural History. There, based upon physical characteristics, it was determined to be a new subspecies of the gray-cheeked thrush and was named the Bicknell’s thrush.

After that, the issue of the Bicknell’s thrush’s classification was ignored until the 1930’s when Dr. George Wallace reviewed the case in the hope that he could prove that the Bicknell’s thrush was indeed its own species. He discovered that the Bicknell’s thrush was quite a bit smaller than the gray-cheeked thrush and had a yellower lower bill. In the end, though, Dr. Wallace had to conclude that it was indeed a subspecies.

Once again the issue was put to rest until it was reexamined again by Dr. Henri Ovellet, who published his own findings in 1993. Dr. Ovellet found that the gray-cheeked thrush and the Bicknell’s thrush had different breeding and winter ranges, and different songs and calls. Along with that, the Bicknell’s thrush wouldn’t respond to any of the gray-cheeked thrush’s calls. Another scientist, Dr. Gilles Seutin, examined the DNA of both birds and found them to be very different. This led him to believe that they had been separated from a common ancestor 1 million years ago.

Because of the new information provided by the two men, the American Ornithological Union’s Committee on Classification and Nomenclature made the Bicknell’s thrush a full species and gave it the scientific name Catharus bicknelli.

Habitat

Since the Bicknell’s thrush is such a shy bird, it is not a surprise that it prefers to stay hidden in thick, tangled underbrush or stunted stands of balsam fir and red spruce for the majority of the day. This species of bird not only enjoys the scrubby northern forests in which these shrubs are found, but also likes to live in the second growth industrial forests located in Canada. Basically, the Bicknell’s thrush loves to be surrounded with dense, regenerating growth.

During the summer, the Bicknell’s thrush has a breeding range that goes from New York and Connecticut to the Gaspay Peninsula and the highlands of New Brunswick, Cape Breton, and Nova Scotia, Canada. In these places, the Bicknell’s thrush is found to like nesting in highly elevated areas and occasionally on coastal ones. It feels right at home in heights from 450 meters (1450 feet) to 965 meters (3000 feet). At these semi-high altitudes the Bicknell’s thrush tends to be attracted into making its home near ski slopes and mountain roads.

Every year in September, many birds may be seen migrating south for the winter, following the eastern U.S. coast to Florida and then over to the Caribbean where it makes what will be its home for the next 8 months or so until it returns in late May. Outside of the Dominican Republic’s highly elevated broadleaf forests, very few groups of these species of birds can be found.

Present Status:

The Bicknell’s thrush is listed as a species of concern by the State of Maine.

Physical Describtion

The Bicknell’s thrush is an elusive and secretive bird which stays hidden most of the time. With its subtle markings and colors you will be lucky to tell it apart from the surrounding trees and bushes. With a quick glance, some might even mistake this bird for a large sparrow. Like a sparrow, its back is olive brown in color which eases into a chestnut on the upside of its tail. This bird’s underside is a smooth gray to white and is spotted black on its flanks and chin.

The Bicknell’s pinky-beige throat supports the head on which two black, beady eyes are found. A thin, pale, yellow-based bill extends from the head, with the lower part of the beak taking on a darker hue.Two small, pink legs support this warmblooded vertebrate’s body, the length of which is around 6.25 inches (16 cm). Both the females and the males have similar characteristics.

Overall, the Bicknell’s thrush is quite like its close relative, the gray-cheeked thrush, distinguishable most easily by the Bicknell’s beautiful song.

Diet and Feeding Habitats

When the Bicknell’s thrush is still young, the only food it is fed is insects. As it grows older, its diet expands to include a larger variety of insects and other arthropods like caterpillars, ants, wasps, beetles, and flies, and fruit (also known as producers; green plants that produce their own food and food for others) such as blueberries, bunchberries, snowberries, red berried alder, and wild grapes.

The Bicknell’s thrush is a forager, meaning that in order to find its food, it searches the surface of the forest floor. During the breeding season, it mainly searches for beetles and ants to eat. When it is migrating south, it regularly indulges in fruit as well. And, in the winter, it tries to eat a little of both, though the types of fruit it likes to eat are normally scarce so it must content itself with the insects that it can find.

Being an omnivore, the Bicknell’s hrush preys upon insects and in turn it is preyed upon by its predators the sharp-shinned hawk, long-tailed weasel, and northern saw-whet owl. The eggs and young of the Bicknell’s thrush are prey for none other than the red squirrel.

Causes of Endangerment

The Bicknell’s thrush, like so many other species, is on the species of concern list mainly because of human development and disturbance, and because of nest predators.

Not all animal populations decrease because of something humans do; sometimes other animals play a part as well. In the Bicknell’s thrush’s case, the blue jay, common raven, eastern chipmunk, deer mouse, and the weasel all help to reduce their numbers. These particular animals take over the Bicknell’s thrushes’ nests, forcing them to abandon their homes. But this is not the only reason for the declining numbers of the Bicknell’s thrush; we are also at fault.

When people are whizzing down the ski slopes, they probably aren’t thinking about the species of bird that happens to make its home along the ski slopes and roads. They probably aren’t aware that the expansion and development of ski slopes and the building of communication towers and wind power turbines are destroying the habitat where the Bicknell’s thrush lives. Furthermore, they probably don’t know that the more business they give to the ski industries, the more habitat loss the Bicknell’s thrush undergoes.

However, the list of threats does not end here. Acid precipitation (the polluted rain that results when large amounts of certain chemicals combine with rainwater) has been damaging the Bicknell’s thrushes’ forest homes for years, maybe as early as the 1960’s or 1970’s. Agricultural conversion, logging and charcoal production, as well as the clearing and fragmenting of their winter environment makes the situation even more desperate for the Bicknell’s thrush. Even in Quebec, Canada, the widespread practice of thinning is making the Bicknell’s thrush forest habitat useless.

Personal Essay

For the Children

Gary Snyder

The rising hills, the slopes

of statistics

lie before us.

the steep climb

of everything, going up,

up, as we all

go down.

In the next century

or the one beyond that,

they say,

are valleys, pastures,

we can meet there in peace

if we make it.

To climb these coming crests

one word to you, to

you and your children:

stay together

learn the flowers

go light.

The wilderness is very important, something that should be cherished and protected, but isn’t. In this poem, Snyder talks mainly about the destruction of the natural world; how while the economy may soar, the pollution and destruction caused by it ends up hurting the natural world and in turn ourselves.

Because of the web of life, the death of one species of animals (no matter how insignificant their niche is) causes a ripple affect, making it so that other species also are hurt or weakened. As John Muir put it, “When one tugs at a single thing in nature, he finds it attached to the rest of the world.”

One such example is the Bicknell’s thrush. If it were to become extinct then it would cause its predators’ numbers to decline and its prey to increase, upsetting the balance. Of course, the creatures who depend on the Bicknell’s thrush (like the insects it eats or the saw-whet owl that eats it) would adapt to the situation because of the diversity in our ecosystem, but it would still weaken it. And as more and more ‘links’ in the food chain disappear from the face of this earth, the more and more likely it is that the ecosystem as we know it will crumble.

Gary Snyder also mentions that if we try to protect the wilderness by learning more about it and by being more conservative, then we still can save it. The wilderness is a beautiful thing and provides much for us. It not only provides a home, water, food, oxygen; it also is extremely beautiful and without it our race would perish and our lives would be without beauty.

So next time you think that what you do to the natural world and it’s animals won’t affect you, think again.

Bibliography :

1. A species is born. 2003. http://www.tantramar.com/bicknell/species_is_born.html.(March 16, 2003)

2. Mountain Culture Festival 2002. 2001. http://www.catskillmtn.org/past/mfc2002/children_species.php.(March 24,2003)

3. Species of concern list. Maine department of Inland Fisheries & Wildlife. Augusta, ME. 1996.

4. Species Factsheet. 2001. http://www.birdlife.net/species/threatened_species.cfm. (Febuary 26, 2003)

5. ITTS report. Febuary 27, 2003. http://www.mbr-pwrc.usgs.gov/Infocenter/i7571id.html(Febuary 28, 2003)



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