Vole

“ The minute weasel is on the track of a vole or a wood-mouse and cannot harm the birds. Yes, he can take the nestlings from the robin's and willow-wren's nests, and from other nests built on the ground, but what has the chaffinch to do with it all? Can it be that there is some fatal weakness in birds, in spite of their wings, in this bird especially, such as exists in voles, and mice, and rabbits, and in frogs and lizards, which brings them down to destruction, and of which they are in some way conscious? ”

“ If the vole was at the sap when the hornet came he was at once driven off, and when the hornet was there first the vole was never allowed to feed, although on every occasion he tried to do so, stealing to his lower place in the {10} gentlest way in order not to give offence, and after beginning to feed affecting not to see that the other had left off eating, and with raised head was regarding him with jealous eyes.
Rarely have I looked on a prettier little comedy in wild life. ”

“ Although voles were a common item of prey for many species of predators on the Reservation, no marked effect on the density of the population of this vole could be attributed to predation pressure. Only when densities reached a point that caused many voles to expose themselves abnormally could they be heavily preyed upon. ”

“ Even the drone of the drowsy beetle, swinging over the ripples of the shadowed stream or from tuft to tuft of grass beside the woodland path, had ceased. But at times the cheery dipper still sang from the boulder whence the vole had dived to escape the big brown owl; and, when other birds had gone to sleep, the robin on the alder-spray and the wren among the willow-stoles piped their glad vespers to assure a [Pg 108] saddened world that presently the winter's gloom would vanish before the coming of another spring. ”

“ In such a habitat, vole runways are poorly developed, and are difficult to find. Voles in grasslands feed in runways, as attested by the piles of cuttings found in the runways and the nibbled grass which borders them. Voles in clover or alfalfa feed at the bases of the plants wherever the plants may grow. ”

“ At first, each vole is intimidated by movements of the other, and as a result, the original occupants huddle in their established corner while the newcomer cowers in the most remote part of the container. Gradually the voles become less timid and one may approach another slowly and cautiously, to sniff at it. The vole approached may react with a show of hostility which is largely defensive. In the characteristic posture of threat for defense, the vole crouches, or rears back on its haunches, with snout elevated and incisors prominently displayed. ”

“ Voles were trapped in runways of the cotton rats, but no cotton rat was caught in a typical runway of a vole.
The burrows of the prairie vole are 40 to 50 mm. in diameter, and the shallowest part is usually 50 to 100 mm. below the surface of the ground. Burrows leading to nests or food chambers may descend deeper than the others. Some prairie voles were trapped in tunnels of the common mole (Scalopus aquaticus) . The voles make their own burrows, and are especially active at this task when a hard rain has loosened the previously hard, dry soil. ”

“ Only those voles captured at least four times were used for the home range studies. Individuals which included the edge of the trap grid in their range were excluded unless a barrier existed (see description of habitat) confining the seeming range to the study area. ”

“ Though the young voles, in the tunnelled buttress of the river-bank, lived under the care of experienced parents ever ready and resolute in their defence, and became as shy and furtive as the wood-mice dwelling in the hollows of the hedge beside the pond, they were not always favoured by fortune. The weakling of the family died of disease; another of the youngsters, foraging alone in the wood, was killed by a bloodthirsty weasel ”

“ No intolerance of other voles exists and, in laboratory cages, groups of voles lived together peaceably from the time they are placed together. Crowding does not seem to be harmful directly, therefore, and high densities will develop if food and cover resources permit. ”

“ Nine other species of small mammals occur in the same habitat with the prairie vole, and frequently use its runways. The vole makes a network of paths through the grass, and constructs its own burrows which lead to its nests and food stores. Each of fifteen nests found were underground. Most, if not all, of the underground tunnels are dug when the soil is moist, not when the soil is dry.
The commonest flea on the prairie vole is Ctenophthalmus pseudagyrtes; it averages 1.9 (for subadult voles) to 3.4 (for adult voles) per individual vole. ”

“ In those districts where the over-zealous efforts of the gamekeeper have resulted in the partial extermination of the Weasel and the Owls, the increase of the Field Vole is so enormous and so rapid that they have at times become a plague. ”

“ Wood, meadow, and hedgerow were bathed in liquid blue. The very tree trunks stood out as indigo against the sky. Daisy and marigold, hyacinth and clover were attuned to the same soothing minor chord. The work-a-day world was at rest, but the sleep-a-day world was holding high revel.
Before he was halfway down the stump he had caught the glint of twenty pairs of eyes. The voles and wood-mice had waited, like himself, until the owl had passed. Before each tuft of grass now stood its latest tenant. From beneath the root of a neighbouring hazel came a stealthy procession of five bank voles. ”

“ In a few days the whole field became swarming with these pretty voles; at the same time white and blue foxes made their appearance, and snowy owls and many species of hawks became abundant. My dogs, too, were annoyed by the rash courage of the new-comers, which would jump at their noses even when slowly drawing on game, so that they never spared a lemming, though they never ate them till last year, when I observed that they would eat their heads only, rejecting the body, although they devoured the common field-mouse to the end of his tail. ”

“ The cuttings that have accumulated at the base of the plant may be eaten, but frequently they remain as evidence of the vole's feeding activity.
On May 12, 1946, an analysis was made of the cuttings found in an area of alfalfa, grasses, and weeds. From table 1 it may be seen that quackgrass, alfalfa, wild lettuce, and cleavers were common. In three nights 70 traps caught 8 prairie voles and 3 deer mice; no pine mice or cotton rats were caught on the area. The stomachs of the voles and the deer mice were examined, and only the stomachs of the voles contained green material. ”

“ I stood and watched these playful gambols, and soon discovered that the little animals were short-tailed field-mice, or voles, as I believe they ought to be called. Some differences in structure separate the voles from the true mice and rats; they also differ in their food, the voles being almost entirely vegetable feeders. ”

“ A shortening of the tail is seen in the voles, to which the common meadow mice of various species belong, and still more in the lemmings, in the Old World mole rats, and in our pouched gophers. All these are not only ground-keeping kinds, but burrowers, and have no use for a long tail, save in the case of the muskrat, which is really a big vole that has taken to an aquatic life, and needs an oar to scull himself through the water; for muskrats swim more by means of their tails than by their feet. ”

“ Figs. 2, 5, and 8 show length and weights of voles whose ages in days were definitely known because they were born in the laboratory, or in a live-trap after the female was caught there. Young voles marked at birth and released with the female were rarely recovered in the period of suckling, as they ordinarily remain in the nest burrow when the female ventures out to forage. Litters retained in the laboratory therefore have provided most of the records of growth in suckling young. Growth varied greatly between litters. ”

“ Over-all length plotted against weight in young prairie voles, from newborn to the minimum size at breeding maturity. The range of variation increases as development proceeds, especially after the age of weaning is attained. ”

“ As many as five adults have been caught in a trap simultaneously at times when the population density was high. At such times, the meadow habitat is crossed by a maze of interconnecting surface runways and one runway may be traced continuously for 100 yards or more. Because each individual vole normally confines its activity to a small area, only a fraction of an acre, it is evident that individuals living at different places overlap in their home ranges, and also in the trailways followed in foraging. ”

“ A relationship between the condylobasilar length of the skull and the age of a vole was discovered and, with further study, may yield a method of aging voles more accurately than has been possible heretofore. Other characteristics, varying with age, were described. The most reliable indicator of age seemed to be the prominence of the temporal ridges.
Runway systems and burrows are used by groups of voles rather than by individuals. Most of the activity of voles is confined to these [411] runways and an exposed individual is seldom seen. ”

“ A home range may include several runway systems, and the ranges of individuals overlap extensively. Both home ranges and patterns of runway systems change constantly. Runways seem to be primarily feeding trails, and are extended or abandoned as the voles change their feeding habits. Groups of adult voles using a system of runways seem to have no special relationship. Juveniles tend to stay near their mothers, but as they mature, they shift their ranges and are replaced by other individuals. Males wander more than females, and shift their ranges more often. ”

“ Young are able to stand erect, with bodies held clear of the ground, and they can even run, but the gait is slow and clumsy, and the forequarters and hind quarters are poorly co-ordinated, so that the voles tend to fall on their sides. The fur averages approximately 3 mm. ”

“ Although the amount of growing tissue of plants probably is at least as important to voles as the total amount of vegetation, some correlation seemed to exist between the density of grassy vegetation and the density of populations of voles. A mixed stand of grasses, with an obvious weedy component, can support a larger population of voles than can either a nearly pure stand of grass or the typical early seral stages dominated by weeds. ”

“ As a group, voles are characterized by being more heavily built than rats and mice, and by their less brisk movements. They have very small eyes, blunt snouts, inconspicuous ears and short limbs and tails, in all of which points they are markedly contrasted with true rats and mice. In common with lemmings and other representatives of the Microtinae, voles are, however, broadly distinguished from typical rats and mice by the structure of their three pairs of molar teeth. ”

“ Size distribution of prairie voles in a year-around sample, including all the measurements of voles taken over a three-year period. Young are not represented in their actual ratio to the total population in this sample, because they are less attracted to the bait, and range less widely than adults. The higher ratios of males than of females in the three largest size groups is well shown, as is the higher ratio of females among those voles of small adult size.
Table 5. Average Growth (in Over-all Length) in Young Voles of Several Sizes.
[Pg 153] ”

“ Voles, living in clover and alfalfa, do not make runways as distinct as they do in grasslands. The clover and alfalfa plants are branched and of a spreading growth form, whereas the grasses have leaves which are appressed to the main stem. The individual grass plants grow close together, and a vole cannot run through grass without trampling some of it. As voles use the same paths repeatedly, the grass in their runs becomes flattened and dies. There is sufficient room between the stems of the clover and alfalfa plants to allow the voles to pass through without treading on the stems. ”

“ The mean number of embryos per female was higher than the mean number of young per litter delivered in captivity and the mean number of young per litter delivered in traps was lower than in those delivered in captivity. The differences were not statistically significant. In some instances females that delivered young voles in traps may have delivered others prior to entering the trap or the mother or her trapmates may have eaten some of the newborn voles before they were discovered. ”

“ A very prolific rodent of the amphibious class obtained from Canada and the United States, similar in habit to the English vole, with a fairly thick and even brown underwool and rather strong top dark hair of medium density. It is a very useful fur for men’s coat linings and ladies’ driving or motoring coats, being warm, durable and not too heavy. If the colour were less motley and the joins between the skins could be made less noticeable, it would be largely in demand for stoles, ties and muffs. ”

“ Whilst still quite blind, the young voles, if placed on a table, would invariably creep backwards and continue a retrograde movement, until at last they would have fallen over the edge of the table if I had allowed them to do so.
I imagine nature teaches this evolution so that, in their native burrow, these defenceless weak young creatures may invariably retreat as far back as possible out of the reach of danger. ”