The biology of the stoat (Mustela erminea) in the national parks of new zealand v. moult and colour change

Abstract

Moult and colour change were recorded independently from the flat skins of 1298 stoats. A moult cycle begins when hair follicles enter the anagen phase and begin to accumulate melanin (visible on the ‘skin’ side as black patches) and ends when the old hair is shed. Growth of the hair was inferred from the disappearance of the anagen follicles, and shedding was inferred from colour change. On average in New Zealand, the spring moult begins in August and ends in December and the autumn moult begins in November and ends in July (the moult periods will be shorter at any given locality). The spring moult is later in the south (44- 45°S) than in the north (39-40°S), and is synchronised with the breeding season, but is not later at higher altitude. The autumn moult is earlier in the south. The proportion of male stoats turning white is significantly related to minimum temperatures and to numbers of days with ground frosts, but not to mean temperature, number of days with snowfall, or duration of snow-lie. Both altitude and latitude influenced whitening. These data are consistent with hypotheses developed from experimental work on animals in captivity that moult and breeding are controlled by daylength (i.e., latitude but not altitude) but that winter whitening is controlled by temperature (i.e., latitude and also altitude). Three anomalous specimens were possible examples of pituitary malfunction. © 1982 Taylor & Francis Group, LLC.