| dc.description.abstract | In the UK, the water vole is usually found associated with water; in rivers, canals, ditches,
streams, lakes and ponds. Now listed as a UK Biodiversity Action Plan priority species for
conservation it receives partial protection under UK legislation. The current study used various
techniques to investigate aspects of the ecology of water voles at five sites in the southern
England.
Live-trapping techniques examined aspects of social organisation, such as population size,
structure, distribution and Observed Range Lengths. Capture rates, weight differences and
survival were also examined. Water voles became extinct from two study sites most likely due
to American mink predation. Densities of water voles at three sites were generally higher than
those recorded elsewhere, suggesting density may be dependent on type of habitat or other
variables. Water voles were distributed along almost the entire length of these study sites. All
populations peaked in size (as a result of juveniles entering the populations) and adult weights
peaked in the spring and summer, declining in the autumn. Adult weights were generally lower
than found in previous studies with no difference between adult male and female weights at any
site. High rate of ear tag loss meant individuals could not be reliably followed between months,
therefore the population estimates based on Minimum Number Alive (MNA) may have been
significantly underestimated. The highest period of activity was between 22: 00hrs and 06: 00hrs
corresponding with published studies.
The relationship between water vole numbers and latrines was examined and compared with
published literature. Seasonal patterns in the production of latrines were examined to gain
further information on their function and the bearing that this may have upon any relationship
between latrines and water vole numbers. Further examination considered the number of
latrines per individual water vole and compared these with the published literature. Rainfall
rendered many counts invalid as rising water levels or the act of the rain itself washed latrines
away. Numbers of latrines per water vole were generally lower than published attributable to
differences in the physical character of sites. Three sites showed a broadly similar trend in the
numbers of latrine counts across months. Latrine numbers generally fell over winter which is
likely to correspond with low water vole numbers and above ground activity. Peaks in latrine
numbers in March and April were attributed to the onset of the breeding season whilst peaks
seen in August were attributed to large population sizes. Relationships were found between
latrines and the total number of water voles captured, MNA, adult females and all adults;
latrines and adult females; all adults during the breeding season at two of the sites. The
resultant predictive equation for the number of water voles from the number of latrines was not
significantly different from the published relationship.
Water voles were radio-tracked at one study site to examine overwinter behaviour. Home range
sizes, movements, activity patterns and interactions were investigated. Due to time constraints
and difficulty of intensive radio-tracking during cold conditions some sessions were done in
August and September and some continued into March and April. Three of the tracked voles
died during the study, two assumed to be through predation, probably by foxes, and one due to
unknown causes. There was no difference between the area of male and female home ranges,
however, male home ranges appeared to be longer than female ones. Increases in mean range
length were seen in January, February and April likely to correspond to the onset of the
breeding season. In many cases the majority of activity was centred on one or two points,
identified as nest sites. A number of male water voles, and one female, dispersed to `new'
home ranges. Activity occurred within discrete blocks of time, 1.5hrs to 4hrs with rest periods
of 0.5hrs to 4.5hrs. Home ranges of a number of males and females overlapped and positive
associations only occurred towards the end of the breeding season. | en_US |
