Semi-Daily Journal Archive

The Blogspot archive of the weblog of J. Bradford DeLong, Professor of Economics and Chair of the PEIS major at U.C. Berkeley, a Research Associate of the National Bureau of Economic Research, and former Deputy Assistant Secretary of the U.S. Treasury.

Sunday, October 08, 2006

We Have at Least One Small Grey Fox...

A new addition to the charismatic fauna we see on our (250 yard long) driveway:

GRAY FOX: (Urocyon cinereoargenteus): The grey fox, or tree fox, is distributed from northern Ontario, Canada, throughout the central and southwestern US to Venezuela. That foxes figure as the wily character in the popular tales of many lands, reflects both their distribution and and their resourceful behavior. Standing about 12-16 inches at the shoulders, weighing up to 16 pounds and having an overall body length of up to 47 inches, the grey fox is an agile canid able to scurry up and down trees with relative ease. The pelage is coarse when compared to other foxes with the face, upper part of the head, flanks, back and most of the tail grey. The throat and undersides are whitish with the ventral surface of the tail tending to a rusty brown. The individual hairs along the middle of the back and top of the tail are are heavily tipped with black which gives the apperance of a black mane. A consealed mane of black-tipped bristles occurs on the top of the back and tail which stand erect during body posturing displays.

Mostly nocturnal and crepuscular, this canid frequents the wooded and brush country, and often rocky and broken terrain of the arid southwestern US, to forested woodlands bordering pastures and fields. Opportunistic foragers, using hunting techniques which vary from stalking to dash-and-grab, the grey fox's diverse diet is made up of birds, invertebrates, fruits and berries, rodents, small mammals, small ungulates, fish, small reptiles and eggs. Best known of the capture techniques, is the "mouse pounce," which is completed by jumping up to three feet above the ground and diving, front paws first, onto the prey. The impact of the aerial descent stuns the prey, or effectively flushes it from its hiding place, allowing the fox to catch it.

The normal grey fox social unit is composed of an adult pair and their young. Being quite territorrial, grey foxes mark their territorial boundaries with feces and urine left on conspicuous landmarks like tufts of grass and prominent structures. These scent marks are distributed throughout the range, but especially in places often visited. The paired anal sacks, located on either side of the anus, can be evacuated voluntairly, or the secretion mat be coated onto feces. Both males and females may raise their leg while urinating. A pungent odor, quite similar to that of the skunks, is evident in areas where grey foxes frequently scent mark. Like other canids, foxes communicate by means of sound as well as scent markings and body posturing. These vocalizations includ an agressive yapping, a resonant howl, barks, soft whimpers and screams. Grey foxes generally breed once a year, maiting from December through April, resulting in litters from two to eight young, after a gestation of about 62 days. The "kits", as they are called, are born weighing about 100 grams, their eyes closed and the body covered with a blackish colored coat. Their eyes open in 10--14 days, they have begun to eat solid foods by six weeks and begin to forage independentally at four months.

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