ELSEVIER 0006-3207(94)00036-0 Biological Conservation 71 (1995) 269 274 © 1995 Elsevier Science Limited Printed in Great Britain. All rights reserved 0006-3207/95/$09.50+ .00 INFLUENCES OF CORRIDOR CONTINUITY AND WIDTH ON SURVIVAL AND MOVEMENT OF DEERMICE Peromyscus maniculatus Bonnie Ruefenacht & Richard L. Knight Department oJ Fishet3' and Wildlife Biology, Colorado State l/niversity, Fort Collins, Colorado 80523, USA (Received 28 May 1993; revised version received 29 December 1993; accepted 29 December 1993) Abstract We investigated the effects of corridor gaps and corridor width on the survival and movement of resident and non- resident deermice Peromyscus maniculatus. Trans- planted non-resident deermice were used to simulate dispersing mdivMuals, and resident deermice served as controls. The study design was a completely randomized 2-" Jilctorial with width (narrow or wide) and continuity (with or without a lO-m-wide corrMor gap) as factors of interest. Vegetation variables were more significant with movement and number oJ crossings than were width and continuity. Survival was unafJected by corridor width and continuity, as well as vegetation variables. Keywordsv Medicine Bow National Forest, Peromyscus maniculatus, corridors, corridor width, corridor conti- nuity. INTRODUCTION Corridors are strips of land that differ from the sur- rounding habitat matrix (Forman & Godron, 1986) and are often considered to be useful components of landscapes because they can facilitate wildlife dispersal (Inglis & Underwood, 1992). Use of corridors in land- scape management is of considerable interest, but few data exist on how corridor parameters such as length, width, continuity, and shape affect animal movement and survival through landscapes (Inglis & Underwood, 1992; Simberloff et al., 1992). Such information is needed for development of effective corridors in land- scape design (Noss, 1987; Harrison, 1992). Gaps within corridors may serve as obstacles and cause greater mortality to dispersing individuals because of the openness and altered abiotic factors such as heat and wind patterns caused by changes in vegetation (Harris & Scheck, 1991). Some species are reluctant to cross open areas (Wegner & Merriam, 1979; Henderson et aL, 1985; Lovejoy et al., 1986; Szacki, 1987; Klein, 1989; Henein & Merriam, 1990; Merriam & Lanoue, 1990), and others tend to remain within similar habitat when dispersing (Holekamp, 1984; Garrett & Franklin, 1988; Wiggett & Boag, 1989). Thus, gaps may reduce movement and elevate mortality rates of dispersing indi- viduals, allowing for population differentiation. 269 Corridor width may also determine the utility of cor- ridors for dispersing wildlife. Narrow corridors may consist of all edges where animals experience high mor- tality rates (Ambuel & Temple, 1983). Alternatively, wide corridors may increase travel time and decrease effectiveness of corridors for movement (Soul6 & Gilpin, 1991). We investigated the effects of corridor gaps and cor- ridor width on the survival and movement of non- resident and resident deermice Peromyseus maniculatus. Non-resident deermice simulated dispersing animals unfamiliar with the habitat through which they were moving (Merriam & Lanoue, 1990). Resident deermice served as controls for non-resident deermice. We hypothesized for both non-resident and resident deer- mice that corridor gaps would reduce movement and elevate mortality rates, and that movement and sur- vival would be greater in wide than in narrow corridors STUDY AREA AND METHODS The study was conducted from 18 May to 31 July 1992 in 12 linear aspen Populus tremuloides stands, which represented corridors, surrounded by sagebrush Artemesia sp., in the Medicine Bow National Forest, southeastern Wyoming. The study design was a com- pletely randomized 22 factorial with three replications (Ott, 1988). Corridor gaps and corridor width were the two factors of interest. Corridors were either continu- ous and wide, discontinuous and wide, continuous and narrow, or discontinuous and narrow. Wide corridors were 20-27 m wide and narrow corridors 10-16 m wide. Discontinuous corridors had a 10-m-wide gap in the middle of the corridor. Gaps (i.e. treatments) were created using a brush cutter and were assigned ran- domly to six of the 12 corridors. All vegetation _< 7 cm diameter breast height was removed in the gaps. Movement and survival of deermice were determined by live trapping within corridors. Trap grids consisted of 24 (narrow corridors) or 36 (wide corridors) Sher- man live traps, baited with a mixture of peanut butter and rolled oats were placed 5 m apart. Three rows of traps were placed on each side of the gaps. For corridors without gaps, 10-m-wide areas were measured in the middle of the trap grid so that trap grids were similar