1. Preliminary investigations of the stomach contents of moles
in 1967/68 winter showed that earthworms were the main food of moles
and that the percentage weight of earthworms in the diet might
vary in different localities.
2. The distribution, population densities and biomass of earthworms were determined in Boghall glen and the results were related
to the habitat and the distribution and abundance of moles. The
distribution and abundance of earthworms were found to be directly
influenced by the habitat particularly soil and soil conditions.
Moles lived in the areas with the highest populations of earthworms
and the abundance of moles was influenced by the abundance of
earthworms.
3. The population densities of insect larvae and slugs were
determined in Boghall glen and the results were related to the
distribution of moles. The results showed that the distribution
of moles was not related to those of insect larvae and slugs.
4. A study of the distribution and abundance of moles in relation
to the habitat at Boghall glen showed that the habitat had no
direct effect on the distribution of moles but the abundance of
moles was directly related to the habitat.
5. Studies on the distribution and abundance of moles and
earthworms in relationship to soil and soil conditions showed that
soils which were suitable for earthworms were also suitable for
moles, and that the abundance of earthworms, and as a result that
of moles, were influenced by soil and soil conditions.
6 . Results of investigations of the diet showed that
invertebrates were the only food eaten by moles and that moles
did not have any major preferences for particular items of food.
The composition of the diet reflected mainly the distribution and
relative abundance of the moles' potential foods in the soil.
7. The monthly variations in the body weight, weight of stomach
contents, weight of stomach contents expressed as a percentage of
body weight and the composition of the diet of moles were studied
from March to August 1969. The body weight did not undergo any
major monthly fluctuations except in the breeding season. Males were
significantly heavier in May than in March and July and females
were significantly heavier in each of April, May and June than in
March. There were no significant monthly differences in the
weight of stomach contents and the weight of stomach contents
expressed as a percentage of body weight in males. The food consumption of females was significantly higher in May than in March
and the weight of stomach contents expressed as a percentage of
body weight (less the weight of stomach contents) was significantly
higher in May than in March and July and in June than in July.
The relative weight of earthworms in the diet did not undergo any
major monthly variations but insect larvae contributed relatively
more weight to the diet than earthworms in May to July.
Males were significantly heavier than females both as adults
and as juveniles. Juveniles were lighter than adults in June but
they grew to adult sizes in July though they were still sexually
distinguishable from adults. There were no significant differences
between males and females and adults and juveniles in the weight
of stomach contents, weight of undigested food in the stomachs
and the .weight of stomach contents expressed as a percentage of body
weight. The weight of full stomachs (stomach contents + empty
stomachs) and the weight of empty, stomachs of males were significantly
higher than those of females, on average and in January 1970. There
were no major differences in the qualitative composition of the diet
of males and females and of adults and juveniles.
8. The body weight and feeding habits of moles collected in
pastures at different localities in January 1970 were compared.
There were no significant differences in the body weight, stomach
weight, weight of stomach contents, weight of stomach contents
expressed as a percentage of body weight and the relative weight of
earthworms in the diet of moles in the different pastures. Slight
differences in the composition of the diet were observed between
localities.
9. Four moles were each fed in captivity for 10 weeks. Males
ate 73 -75% of their body weights and females ate 85-89% of their
body weights daily when fed on earthworms.
10. Investigations carried out on wild and captive moles showed
that captive moles stored earthworms from mid-September to end of
November and wild moles stored earthworms probably from after mid-October to mid-January.
11. Three methods were used to estimate the population density
of moles in Boghall glen. Only 23% of moles built fortresses and
only L|_3% built nests that could be located from surface evidences.
Reliable estimates of the number of moles present were obtained in
the spring when all mole-hills and ridges were flattened on two
areas and the number of areas with fresh diggings were counted on
the second and third days.
12. The age of moles was assessed by measuring the length of
the second upper molar teeth. The age structure of a mole
population depends on the history of the population. The maximum
life span of a mole was found to be four years but only 3 moles
(1*7%) in the populations studied (N = 181) was of this age.
The age distribution was similar in both males and females.
13- Investigations carried out on a small population of moles
on Leip field from July 1969 to January 1970 showed that the sex
ratio in an undisturbed population in July was 1:1. Evidence was
obtained which suggested that moles were usually solitary and
aggressive in the presence of other moles. Only one of six moles
marked on Leip field in mid-August 1969 survived till January 1970.
The other moles probably died during the severe drought and soil
desiccation at the end of August to early September and in
October 1969.
13- Investigations carried out on a small population of moles
on Leip field from July 1969 to January 1970 showed that the sex
ratio in an undisturbed population in July was 1:1. Evidence was
obtained which suggested that moles were usually solitary and
aggressive in the presence of other moles. Only one of six moles
marked on Leip field in mid-August 1969 survived till January 1970.
The other moles probably died during the severe drought and soil
desiccation at the end of August to early September and in
October 1969.
