Sp. Jensen et P. Honess, THE INFLUENCE OF MOONLIGHT ON VEGETATION HEIGHT PREFERENCE AND TRAPPABILITY OF SMALL MAMMALS, Mammalia, 59(1), 1995, pp. 35-42
The trappability of small mammals was compared between moonlit and ove
rcast nights, and between clear and overcast nights, and between clear
and overcast days, for different heights of vegetation. Regardless of
moonlight, all species captured showed a preference for traps in tall
vegetation (approximate to 60 cm), and although wood mice and common
shrews were occasionally captured in short vegetation (approximate to
4 cm), bank voles and field voles were not captured there. Bank voles
are thought to rely on vegetation cover to avoid predators and by rema
ining in tall vegetation had no need to respond to cloud cover on moon
lit nights. Wood mice, which are thought to rely on speed and agility
to avoid predators, were captured in short vegetation, but only when t
he sky was overcast. Two types of camouflaging trap-covers (cut grass
and wooden board) were tested to control for differences in trap visib
ility that might have contributed to the observed avoidance of short g
rass on moonlit nights. Wood mice preferred uncovered traps when the s
ky was overcast but their preference was not affected by vegetation he
ight. The proportion of captures of voles and shrews in covered, as op
posed to uncovered, traps was not affected by either cloud cover or ve
getation height. It was concluded that the animals were genuinely usin
g plots with short grass less, as opposed to merely avoiding very visi
ble traps.