Conservation & Ecology
A wood mouse meets his maker!
is the only UK mouse that hibernates, giving rise to the sleepy dormouse of Alice in Wonderland fame.
The average dormouse litter size is four and these are typically born in July or August, but litters may be born as early as late May or early June. Young dormice are weaned after about one month, but remain with the mother as juveniles before they become independent and disperse. They must reach a weight of between 15‐18g to survive the winter hibernation. Dormice usually just have a single litter, but those that breed in early May be able to have a second.
The UK population is unknown, but there has been a long term decline in both number and range; recently there is an indication that the decline is slowing and, as part of an ongoing dormouse reintroduction programme, the current range is slowly being extended. The current dormouse range is Southern England, South Wales and along the border between England and Wales. Even where dormice are considered present, their distribution is patchy. During the winter, they hibernate and are not normally active again until April or May. Thus, dormice may spend three‐quarters of their year “asleep”.
VOLES
Two of the UK voles ‐ bank and field ‐ maintain above‐ground runways, which expand like a railway‐system through their entire home range. Voles are seldom seen
Conservation Status:
Wood, yellow‐necked and house mice have no legal protection and conservation does not seem necessary as recolonisation after mortality is often rapid.
Dormice are strictly protected by law under the 1981 Wildlife & Countryside Act and may not be intentionally killed, injured or disturbed in their nests, collected, trapped or sold, except under licence.
Harvest mice are listed as a BAP (Biodiversity Action Plan) Species because they are thought to have become much scarcer in recent years and they require conservation plans to reverse the decline.
Changes in habitat management and agricultural methods are thought to be the
116 I PC DECEMBER/JANUARY 2018
main cause for the loss of populations from certain areas, although there have been no reliable studies to quantify this change.
Field voles are very widespread and are currently thought to be the most common British mammal; a recent population estimate put the number of field voles in Britain at 75,000,000. Therefore, they have no legal protection.
Bank voles are similarly widespread and, likewise, have no legal protection.
Water voles are legally protected in Britain. Recent evidence indicates that they have undergone a long term decline in Britain, disappearing from 94% of their former sites. Predation by the introduced American mink
has had a severe impact on water vole populations, even causing local extinctions. Habitat degradation and pollution are also thought to have contributed to their decline.
Shrews are protected under the 1981 Wildlife & Countryside Act. As with all shrews, they may be trapped only under licence. In any trapping study on small mammals, care is necessary to avoid killing shrews, which are extremely susceptible to death by starvation due to their small size and correspondingly high metabolic rate. Traps should be provided with suitable food (e.g. mealworms, meat) and/or visited at least every two hours. The main habitat requirements are vegetation cover and invertebrate food.
Vole runways in drought conditions
outside these runways, which allow for a faster and safer journeys to and from the nest. Their climbing ability is very poor. Underground nests are dug from anywhere from just under the surface to, in the case of the field vole, 30 to 40cm deep into the ground. Nests are used for food storage, offspring raising and as a place for rest and sleep. Nests can be shared and defended by up to five females, with juveniles that are related in most cases. Females are territorial and an overlap of occupied areas does not occur. As voles have a polygynous mating system, the males do not maintain territories and move as so‐ called ‘floaters’ between several females’ territories in order to mate as often as possible. They can show overlap in territories. Males predominantly conduct dispersal, being most often caused by the competition for mates.
Water voles have been discussed in a previous issue of Pitchcare.
SHREWS
Shrews belong to the family Soricidae in the order Insectivora. They have a very high metabolic rate and seem to be on ‘fast forward’ all the time! They have an insatiable appetite for insects and worm and can devour their own body weight in a day. They will die within twelve hours if deprived of food.
The Water shrew is the largest of the three species with a distinctive dark grey coat and white belly. They are capable of
Bank vole (Myodes glareolus)
delivering venom to their prey via grooves in their teeth. The poison is used to paralyse their prey and not as a form of defence. Outside the breeding season, both male and female water shrews maintain a territory but, during the breeding season, only the females do so. At this time, the males wander about visiting various female territories which indicates a promiscuous mating system without pair bonding. On the whole, they are solitary animals that seem to mutually avoid each other and there is no social hierarchy.
Three to four litters of between four to eight young are produced each year. The common and pygmy shrews look, on casual inspection, to be very similar, but the chestnut brown of the larger common shrew sets it apart from the smaller grey coated pygmy shrew. However, the latter’s longer tail gives them an appearance of being of similar size to the common shrew. Active by day and night, they are very territorial and aggressive for their size and can sometimes be heard fighting, their high pitched squeaks particularly noticeable during the summer months.
The breeding season lasts from April to September, but peaks during the summer months. After a gestation period of about twenty‐four days, the female gives birth to a litter of five to seven babies. A female rears two to four litters each year. The young are weaned and independent within twenty‐five days.
Young shrews often form a caravan
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