How do lemmings adapt?

Answer 1

Most small rodentsp rovide at least some paternacl are when

confined to small cages, but there is only anecdootar li ndirect

evidence of this behaviour in the wild (Manning, 1954;

Tuchscherer, 1990). Therefore, some researchers (e.g., Daly

and Wilson, 1978; Hartung and Dewsbury, 1979; Xia and

Millar, 1988) have argued that many examples of paternal

care are artifacts of the close confinement of laboratory cages.

Male collared lemmings (Dicrostonyx richardsoni)provide

extensive paternal care in small cages (Shilton and Brooks,

1989) but generally do not appear to do so in the wild

(Tuchscherer, 1990). Summer research on collared lemmings

suggests that the mating system is polygamous (R.J. Brooks,

1993).

In this study, we test the hypothesis that paternal care is

not a behaviour only performed uncdleors e confinement and

in very simple environments. We examined the effects of

increased space and the presence of alternative activities

on paternal care in collared lemmings under laboratory

conditions. Three predictions were made: 1) Male collared

lemmings would continue to provide paternal care when in

larger enclosures. 2) Relative to a control, males would

maintain equal levels of paternal care when they had access

to a running wheel. 3) Relative to a control, males would

decrease their attendance to the pups when a strange male

was present due to the uncertainty of paternity. If paternal

care persisted when the male was provided with a large

enclosure and outlets for alternative activities, then the

hypothesis that male collared lemmings provide paterncaal re

in the wild would be supported.

METHODS

A metal rack held fou7r3 cm X 137 cm X 30 cm varnished

plywood enclosures, each enclosure having glass on one

137 cm side (Fig. 1). A wire-mesh barrier was fixed 16 cm

behind the glass front. The area enclosed by the barrier and

the glass formed a compartmeinnt which strange males were

housed. The remainder of each enclosure housed the pairs

with litters. Physical separation prevented the pair from

attacking and potentially killing the strangmea le. In the pair's

portion of each enclosure, a doorway allowed passage to a

running wheel 30 cm in diameter. A running wheel was

placed on an extension of the metal rack behind each

enclosure. Access to the running wheel was provided by a

plastic tube. A dark plastic door allowed control of access

to the running wheel. The mated pair's portion of the

enclosure was partially divided by a wooden wall perpendicular

to the barrier, providing an area in which the male

could be separated visually from the female and the litter.

Food and water were provideadd libitum.Enclosures were

bedded with Grit-O-Cob and shredded paper.