Variation in space and time: a long-term examination of density-dependent dispersal in a woodland rodent

Abstract

Dispersal is a fundamental ecological process that can be affected by population density, yet studies report contrasting effects of density on propensity to disperse. In addition, the relationship between dispersal and density is seldom examined using densities measured at different spatial scales or over extensive time series. We used 51 years of trapping data to examine how dispersal by wild deer mice (Peromyscus maniculatus) was affected by changes in both local and regional population densities. We examined these patterns over both the entire time series and also in 10-year shifting windows to determine whether the nature and strength of the relationship changed through time. Probability of dispersal decreased with increased local and regional population density, and the negative effect of local density on dispersal was more pronounced in years with low regional densities. In addition, the strength of negative density-dependent dispersal changed through time, ranging from very strong in some decades to absent in other periods of the study. Finally, while females were less likely to disperse, female dispersal was more density-dependent than male dispersal. Our study shows that the relationship between density and dispersal is not temporally static and that investigations of density-dependent dispersal should consider both local and regional population densities.

To go or not to go: variable density-dependent dispersal in small mammals

“…The decision of an individual to both leave one area and settle into another can be influenced by several phenotypic traits and environmental characteristics (Lena et al 1998; Baguett et al 2011; Jack et al 2012). Differences in conspecific density between pre- and post-dispersal sites is one such environmental factor demonstrated by both theoretical and empirical studies to be a proximate cause of dispersal (Rodrigues and Johnstone 2014; De Bona et al 2019; Baines et al 2020; Denomme-Brown et al 2020). Intraspecific competition with increasing population density can result in increased emigration and an increase in distanced traveled during transience (positive density dependence; Altwegg et al 2013; Mabry 2014).…”

Bottom–up trophic effects on fisher Pekania pennanti harvest age structure: associations with mast, voles and owls

“…3). The Algonquin Small Mammal Project is the longest running continuous mammal survey in North America and has been described in several published articles (Fryxell et al 1998, 1999, Falls et al 2007, Denomme‐Brown et al 2020). We used 23 years (1994–2016) of this dataset for the purposes of our study.…”

Gene drives for vertebrate pest control: Realistic spatial modelling of eradication probabilities and times for island mouse populations

“…Density‐dependent dispersal is ubiquitous in nature (Amarasekare, 2004 ; Matthysen, 2005 ; Travis & French, 2000 ), but the relationship between density and dispersal is not always positive (Matthysen, 2005 ; Travis & French, 2000 ). Dispersal rate often decreases with increasing abundance in various taxa (Matthysen, 2005 ; Travis & French, 2000 ) including small rodents (Denomme‐Brown et al, 2020 ; Diffendorfer, 1998 ; Ims & Andreassen, 2005 ; Lambin, 1994 ; Lin & Batzli, 2001 ; Rehmeier et al, 2004 ; Smith & Batzli, 2006 ; Van Hooft et al, 2008 ). Moreover, dispersal distances tend to be longer when densities are low (Boonstra, 1989 ; Jones et al, 1988 ; Russell et al, 2005 ; Sandell et al, 1990 ).…”