DEMOGRAPHY OF THE SPRING DECLINE IN POPULATIONS OF THE VOLE, MICROTUS TOWNSENDII

摘要: SUMMARY (1) Population densities of small rodents typically decline in the spring at start breeding season. Eighteen declines Microtus townsendii were monitored by mark-recapture methods on undisturbed grasslands near Vancouver, British Columbia. (2) The duration and size is highly variable: sometimes there virtually no decline, other times more than 90% population may be lost a that last for 12 weeks after begins. (3) Males usually disappear rapidly females. (4) closely related to rate loss. (5) In light-to-moderate most this loss due emigration; severe death rather movement. (6) males, amount rump wounding correlated with decline. (7) We suggest both sexes M. are produced spacing behaviour, but we do not know if differences behaviour sufficient explain all variations declines.