Field Guide to Animal Tracks and Scat of California. Lawrence Mark Elbroch
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Название: Field Guide to Animal Tracks and Scat of California
Автор: Lawrence Mark Elbroch
Издательство: Ingram
Жанр: Биология
Серия: California Natural History Guides
isbn: 9780520951648
isbn:
This variation of the walk can also be altered by adding or subtracting speed. Look at each pair of tracks, and note where in relation to the front track the hind track registers. When raccoons walk slowly the hind track falls behind the front track, and when they walk quickly the hind track falls beyond the front track in each pair. The distinctive fast walk of the raccoon is trotlike in speed and unique to this species.
Trotting
Faster trots are easily differentiated from slower walks, in that a front and hind leg on opposing sides move together, as if joined by a cable. Rather than each foot moving independently, two legs move simultaneously, and there is a moment during each cycle of footfalls when the animal becomes airborne, completely losing contact with the ground. This vertical component is easily seen in any canid, from foxes to Domestic Dogs; there is a little bounce in their common gait. This means that as the right hind foot shifts forward in the air, so does the left front foot. Just before the right hind and left front are placed down, the right front and left hind feet push off, maintaining forward momentum. Then, just before the right front and left hind touch down, the animal pushes off with the right hind and left front feet. The cycle begins all over again. Rhythmically, the beat is a continuous, unbroken 1, 2, 1, 2, 1…, where each number is two diagonally placed feet landing simultaneously.
The common gait of canids (members of the dog family) and many voles is the trot. Many other species also use trots as a travel gait, including badgers, Mule Deer, American Black Bears, and members of the cat family. Bighorn Sheep tend to trot on flat ground, where they are at greater risk of predation.
The classic 2 × 2 pattern created by a walking raccoon is a distinctive character that aids in their identification.
A trotting wolf.
A Domestic Dog illustrates the side trot.
Direct-register trots, in which hind tracks are superimposed on front tracks of the same side of the animal, are common in many species. Hind feet land exactly upon the recently made front tracks, as the front foot and opposite hind pick up just before the alternate pair touches down. The forward momentum of the animal carries the hind foot directly over the track just made by the exiting front foot on the same side of the body.
The perfect straight line created by a trotting Coyote—moving away from the photographer.
As with walking, speed estimates can be inferred by the position of the hind foot in relation to the front track. Direct-register trots are theoretically slower than overstep trots, in which hind tracks in a given pair register beyond the fronts. Overstep trots are achieved by species in different ways. The hind foot can only move forward so far before it collides with the front foot of the same side. Animals typically overcome this obstacle in two ways. Canids tend to use the side trot, or crab, and trot with their entire body at an angle; they kick out their rear end to one side. In this way the hind feet pass to one side of the front feet so as to move at a faster pace. When an animal is using a side trot, all the front tracks appear on one side of the trail, and all the hind tracks on the other side; the hind tracks are also slightly forward of each front track in each pairing. This unique gait and track pattern is easy to find along Coyote, Wolf, and Red Fox trails; Gray Foxes very rarely side trot.
The side trot of a Red Fox in light snow. On the left side of the trail are all of the hind tracks, and on the right are all of the front tracks.
A Caribou illustrates the straddle trot.
Another option is to kick each hind leg out to either side of the front legs, and this is called a straddle trot. All the canines use this gait, but it tends to be for short sections of trail and most often is a transition from a direct-registering trot to a side trot. However, Gray Foxes use this gait very often, as do Mule Deer and several shrew species. The final option to successfully overstep trot involves a longer airborne time, allowing the hind feet to glide over the front tracks with forward momentum, as seen in lizards and occasionally other animals. This last option is rare in mammals but is sometimes incorporated into dominance displays and aggressive interactions.
Some lizards can trot in the technical sense, and achieve high speeds, while other reptiles and amphibians use a gait that simultaneously exhibits characteristics of both trotting and walking. Most turtles and tortoises are so wide and heavy that they move each foot independently, as described under walking above, so as to benefit from tripod support from their remaining three legs. Others, including salamanders, walk with their opposing (diagonal) front and hind limbs in synch—as described under trotting above. However, unlike trotting animals, they never leave the ground when moving in this manner, and their movements often appear exaggerated as they curve their spines side to side to increase speed. Note, this is why it is impossible for a salamander to completely direct-register walk; the right front foot is still on the ground when the right hind comes in behind, and therefore blocks it from moving any farther forward. For this slower gait, we suggest the term diagonal walk to differentiate it from trotting. In a diagonal walk the animal remains in contact with the ground yet is propelled forward by diagonal limbs moving simultaneously.
Lopes, Gallops, Hops, and Bounds
Lopes and Gallops
Lopes and gallops are very similar gaits, and the fastest gaits for mammals. During lopes and gallops, each foot lands independently of the others but in rapid succession. During both gaits the animal becomes momentarily airborne, just after pushing off with the front legs, but during gallops there is a second point at which the animal is in the air, just after pushing off with the hind legs. Not only is it difficult to catch this second, short flight when watching an animal move, but it is also challenging to distinguish between lopes and gallops when interpreting track patterns on the ground.
A Caribou in a slow lope.
A loping Wolverine–also called a 3 × 4 lope.