Age- and sex-specific responses of the gray-tailed vole, Microtus canicaudus, to connected and unconnected habitat patches

Abstract

We monitored demography, movement, and reproductive behavior of gray-tailed voles, Microtus canicaudus, in experimental habitat patches with and without corridors to test the hypotheses that more individuals would move among patches in corridor than in control unconnected habitats, and that individuals would distribute themselves more evenly among patches if corridors were present than if they were not. We predicted that more males than females would move among patches in both treatments and that juveniles in control habitats would exhibit delayed sexual maturation if their dispersal was delayed and opposite-sex relatives remained in proximity to each other. All experiments were conducted in eight 0.2-ha enclosures planted with alfalfa that was fragmented into four patches (each 156 m 2 ) separated by 12.5 m of bare ground. In four of the enclosures, patches were connected by 1 m wide habitat corridors. Corridors facilitated movements, with males moving more than females. However, corridors did not result in an even distribution of animals in the four patches. Unconnected habitat patches resulted in female-biased juvenile dispersal, and females dispersed at a lower body mass than males in both connected and unconnected habitats. Males that did not disperse from their natal patch grew at a slower rate than those that did disperse. We conclude that movement was deterred in patchy environments, enhanced by corridors, and differentially affects males and females. Behavioral factors that affect an individual's dispersal or reproductive pattern should be considered in landscape design.Résumé : Nous avons étudié la démographie, les déplacements et le comportement reproducteur chez le campagnol Microtus canicaudus dans des parcelles d'habitat expérimentales comportant ou non des corridors, dans le but d'éprouver l'hypothèse selon laquelle plus d'individus sont susceptibles de se déplacer d'une parcelle à l'autre dans les parcelles réunies par des corridors que dans les parcelles témoins non reliées, et selon laquelle aussi la répartition des individus risque d'être plus uniforme dans les parcelles avec corridors que dans les parcelles non reliées. Nous avons prédit que plus de mâles que de femelles se déplaceraient d'une parcelle à l'autre dans les deux formes de traitement et que les juvéniles présents dans les parcelles témoins verraient leur maturation sexuelle retardée si leur dispersion était retardée et si les individus apparentés du sexe opposé restaient près les uns des autres. Toutes les expériences ont été faites dans huit arènes de 0,2-ha contenant des plants de luzerne, arènes fragmentées en quatre parcelles (chacune de 156 m 2 ), séparées par 12,5 m de sol nu. Dans quatre des arènes, les parcelles étaient reliées par des corridors de 1 m de largeur. Les corridors facilitaient les déplacements et les mâles se déplaçaient plus que les femelles. Cependant, la présence de corridors n'a pas donné lieu à une répartition uniforme des campagnols dans les quatre parcelles. Dans les parcelles d'habitat non reliées, le...

Effect of Corridors and Habitat Edges on Dispersal Behavior, Movement Rates, and Movement Angles in Roesel's Bush‐Cricket (Metrioptera roeseli)

“…When moving toward the edge, individuals' turning angles decreased and they moved back to the center. When they encountered the habitat edge they showed avoidance behavior, a reaction also reported in earlier studies (Mauremooto et al 1995; Davis‐Born & Wolff 2000). It may be that this behavior is caused by an interest in investigating the area beyond the central habitat and an aversion to the open, cut vegetation (Soulé & Gilpin 1991).…”

“…The individuals thus demonstrated an avoidance of the matrix, and the corridor proved to be a preferred alternative for dispersal. This behavior has been recorded in both mammals (Davis‐Born & Wolff 2000) and insects ( Haddad 1999). The effect of matrices on an individual's movement behavior may differ for several reasons.…”

Patterns and processes of dispersal behaviour in arvicoline rodents

“…Despite good evidence for distance-limited dispersal in all species at spatial scales ranging from 100 to 1000 m (see Fig. 2), demographic effects of habitat fragmentation were modest in five independent experimental studies (La Polla & Barrett 1993;Diffendorfer et al 1995;Wolff et al 1997;Davis-Born & Wolff 2000;Andreassen & Ims 2001). This result must however be interpreted with caution because most experiments were conducted at short spatial scales (approximately 50-100 m) relative to the dispersal capacity of microtine rodents and lasted only for one breeding season, while some demographic effects are only seen after several years of fragmentation (Robinson et al 1992).…”

“…1995; Wolff et al. 1997; Davis‐Born & Wolff 2000; Andreassen & Ims 2001). This result must however be interpreted with caution because most experiments were conducted at short spatial scales (approximately 50–100 m) relative to the dispersal capacity of microtine rodents and lasted only for one breeding season, while some demographic effects are only seen after several years of fragmentation (Robinson et al.…”

Use of Riparian Corridors and Vineyards by Mammalian Predators in Northern California

“…The value of corridors is much debated among conservation biologists, in large part because empirical data on the subject are lacking (e.g., Noss 1987; Simberloff & Cox 1987; Perault & Lomolino 2000; Puth & Wilson 2001). Few studies have been conducted at large spatial scales and on area‐sensitive species (such as carnivores) that would be relevant to wilderness management and land‐use planning (e.g., Joyce et al 1999; Danielson & Hubbard 2000; Davis‐Born & Wolff 2000). In addition, little is known about the factors that influence corridor use, such as corridor width and habitat quality, making it difficult to advise land managers and planners.…”