Effects of forest edge on populations of white‐footed mice Peromyscus leucopus

Abstract

Several studies have reported higher densities of white‐footed mice in small fragments than in large fragments of eastern deciduous forests. The edge hypothesis states that higher densities in smaller fragments reflect an increase in relative amount of edge habitat, which supports higher densities of mice because of its higher quality. To test this hypothesis we live trapped white‐footed mice along edge‐to‐interior gradients in forest fragments of east‐central Illinois. Our results indicated a greater abundance of mice in the forest interior than near the edge, which did not support the edge hypothesis. This pattern could occur because dominant adults hold larger territories of higher quality habitat, thereby reducing density and increasing fitness near the edge (an ideal despotic distribution). We found some evidence of increased reproductive success (juveniles per female) at the edge, but this could reflect density‐dependent demographic processes rather than habitat quality. Furthermore, other indicators of dominance (body weight, and reproductive activity) did not show an increase at the edge, and other studies indicate higher prevalence of natural enemies at edges, which could account for lower densities there. Reduced competition from larger rodents and reduced predation could cause higher densities in small fragments but the distributions of competitors and predators do not strongly support these hypotheses. We suggest two additional hypotheses that could account for greater densities in smaller fragments: 1) estimates of high densities could be artifacts of the large effect that a few captures can have on density estimates for very small fragments, and 2) densities in smaller fragments are overestimated because mice use a relatively larger area of surrounding habitat as fragment size decreases.

Edge effects on nest predators in two forested landscapes

“…However, other studies found contrasting results to those reported here. For example, a study of the whitefooted mouse determined that abundance was greatest in the forest interior rather than in the edge in an agricultural landscape (Wolf and Batzli 2002). Abundance of small mammals may be affected by variables at the microclimate scale, such as resource availability, abundance of predators and parasites, and presence of understory woody debris (Bellows et al 2001;Wolf and Batzli 2002).…”

Annual changes in structural complexity of understory vegetation and relative abundance ofPeromyscus leucopus in fragmented habitats

“…Al though other fac tors could con trib ute to vari a tion in the rel a tive abun dance of P. leucopus in for est patches (eg, com pe ti tion, pre dation, ac cess to ma trix; see Mac Ar thur et al 1972, Nupp and Swihart 1998, Wolf and Batzli 2002, our re sults strongly sup port the hy poth e sis that greater struc tural com plex ity of understory vege ta tion re sults in a greater rel a tive abun dance of P. leucopus. This ap pears to be in con trast to Wolf and Batzli (2004) who found that for est "edge" hab i tat was of rel a tively poor qual ity; however, they de fined "edge" hab i tat as be ing 5 times wider in their study.…”

Efectos de la fragmentación de hábitats y pérdida de conectividad ecológica dentro de la dinámica territorial

“…Los diversos procesos asociados que inciden sobre las dinámicas y condiciones que tienen lugar en los fragmentos son conocidos como "efecto borde" (MURCIA, 1995;LAURANCE, 1997;WOLF Y BATZLI, 2002;DESROCHERS ET AL., 2003;SCHTICKZELLE Y BAGUETTE, 2003).…”