Variations in Microclimate in a Conifer Swamp Deeryard in Northern Michigan

Abstract

Wide differences in winter microclimate were found in 1965 and 1966 among six habitat types within a single conifer swamp used by white-tailed deer (Odocoileus virginianus) as a winter area in Upper Michigan. No compartment of cover provided both optimal shelter and adequate food. A densely stocked even-aged stand of mature swamp conifers offered deer the best protection from cold weather and the least hazardous snow conditions. This site exhibited the narrowest thermal ranges, warmest average temperatures during the coldest weather, highest and most stable relative humidity, least amount of wind flow, minimal snow depths, and best snow support conditions. The other habitat types consisted of pole-size and sapling conifers, mixed hardwood-conifers, northern hardwoods, and upland opening. Since deer normally seek the best shelter available from adverse climatic factors, management of conifer swamp deeryards should strive to maintain blocks of even-aged mature timber as prime winter cover, interspersed in an ideal pattern near younger stands providing abundant food. With the advent of inclement winter 1953). This so-called yarding is obweather white-tailed deer seek heavy cover viously a behavior pattern vital to the overthat provides them the maximum physical winter survival of whitetails that face secomfort, apparently having little regard for the availability of food (Severinghaus 1 A contribution from Federal Aid in Wildlife Restoration Project W-70-R, Michigan, and the Cusino Wildlife Research Station. Field work was also supported by a grant from the Society of the Sigma XI. vere winter climate at the northern edge of their range. While conifer swamps are preferred wintering areas in much of northern Michigan, Verme (1965) has shown that wide differences in shelter quality occur among swamps of different composition and stocking, and that deer usually avoid This content downloaded from 207.46.13.134 on Fri, 23 Dec 2016 04:50:50 UTC All use subject to http://about.jstor.org/terms VARIATIONS IN DEERYARD MICROCLIMATE * Ozoga M Swamp hardwoods 9 Balsam fir, block spruce, tamarack ,-l.. _ _ I ., 900-L_ Northern white cedar