jueves, 18 de octubre de 2012

An example of endurance in an old Wolf, Canis lupus. L. David Mech (1997)

Lobo ártico portando una liebre ártica. 
Foto de L. David Mech. Fuente: Arctic. Noaa
An 11 to 13-year-old Arctic Wolf (Canis lupus arctos) was observed chasing a young Arctic Hare (Lepus arcticus) for 6 to 7 minutes and catching it. This provides an example of the degree of endurance of which an old wolf is capable.

Many descriptions of Wolves {Canis lupus) hunting have been published. However, none has provided a specific example of the endurance of which a known-old Wolf is capable. The observation of a female Wolf chasing, following, and tracking a White-tailed Deer (Odocoileus virginianus) for 21 km over a 130-minute period provides some insight, but that pursuit did not take place at high speed, and it involved a 2.5-year-old Wolf.

I describe here a chase by an 11 to 13-year-old, male Arctic Wolf (C /. arctos) of an Arctic Hare (Lepus arctos) that gives new insights into Wolf endurance. Wolves rarely live > 13 years in the wild and 16 in captivity (Mech 1988). I first observed the Wolf in this account on Ellesmere Island, Northwest Territories, Canada, during 1986 as a member of a pack that I habituated to my close presence (Mech 1988, 1995). The Wolf was distinguishable by a large wound on his left shoulder during 1986 and 1987 and by his behavior toward me from 1986 through 1996 as I observed him at distances of < 2 m.

In 1986, this Wolf must have been at least 1-year old because of his size, and his behavior seemed to be mature enough for a 2 or 3 -year- old animal, but he was not the dominant male of the pack. Because it is unlikely for a Wolf to remain in a pack more than three years, unless it assumes the breeding role (Gese and Mech 1991), this Wolf was probably not more than 3-years old in 1986.

In 1988, this Wolf which I called "Left Shoulder" became the breeding male in the pack, and he maintained that role through summer 1996; the only other males in the pack from 1988 to 1996 were his offspring (Mech 1995). In 1996, Left Shoulder's lower canine teeth were broken or worn to 1/3 to 1/2 their normal length. I made the following observation of this Wolf through binoculars from about 200 m away on 25 July 1996.

The terrain consisted primarily of lowhills covered by snow-free, bare soil and scree,  withlow hummocks in valleys. No vegetation was higher than a few cm. The Wolf and his mate had been hunting young hares intermittently from 0045 to 0250 when the  female headed back toward their den some 8 km away. The male slept from 0312 to 0535 and then arose. He walked NW approximately 100 m and suddenly veered E toward a crouching leveret about 10 m away and more-or-less upwind of him. He walked by the hare, passing 3-7 m by it and got about 7 m beyond, turned, and went back toward it. The hare then jumped up, and the chase began. The Wolf chased the hare for 6-7 minutes and almost caught it several times, but the hare's ability to make quick turns helped it elude the Wolf since the Wolf could not turn so sharply. The chase went back and forth, up and down gently sloping hills covering a distance with a maximum radius of an estimated 300 m. At times, the hare was as far as an estimated 30 m ahead of the Wolf. Finally at 0544 the hare seemed to tire and slow down, and the Wolf pounced on it.

The Wolf then rested, standing and panting from 0544 to 055 1 , when he lay down. He continued to lie and pant until 0606 when an associate of mine inadvertently disturbed him. The Wolf arose, carried the hare off, and cached it. He then slept from 0632 to 0712, and then left the area. I later dug up the cache and found that the leveret weighed 1 .45 kg.

This observation indicates that even an old Wolf can persist in a long pursuit at high speed for several minutes. That such a chase taxed the Wolf was evidenced by the animal's 22-minute rest before caching his quarry and his 40-minute sleep after that. In comparison, a yearling female Wolf observed chasing a young Arctic Hare on 10 July 1993 for 3 minutes rested 11 minutes before she began eating the hare. 

Mech, L. David. 1997. An example of endurance in an old Wolf, Canis lupus. Canadian Field-Naturalist 111(4): 654-655. http://bit.ly/OBH1s2 (Publicado en internet por http://www.biodiversitylibrary.org/http://archive.org/  )

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