Reproductive rate and body size predict road impacts on mammal abundance

Abstract

It has been hypothesized that mobile species should be more negatively affected by road mortality than less-mobile species because they interact with roads more often, and that species with lower reproductive rates and longer generation times should be more susceptible to road effects because they will be less able to rebound quickly from population declines. Taken together, these hypotheses suggest that, in general, larger species should be more affected by road networks than smaller species because larger species generally have lower reproductive rates and longer generation times and are more mobile than smaller species. We tested these hypotheses by estimating relative abundances of 17 mammal species across landscapes ranging in road density within eastern Ontario, Canada. For each of the 13 species for which detectability was not related to road density, we quantified the relationship between road density and relative abundance. We then tested three cross-species predictions: that the slope of the relationship between road density and abundance should become increasingly negative with (1) decreasing annual reproductive rate; (2) increasing home range area (an indicator of movement range); and (3) increasing body size. All three predictions were supported in univariate models, with R2 values of 0.68, 0.50, and 0.52 respectively. The best overall model based on AICc contained both reproductive rate (P = 0.008) and body size (P = 0.072) and explained 77% of the variation in the slope of the relationship between road density and abundance. Our results suggest that priority should be placed on mitigating road effects on large mammals with low reproductive rates.

Roadside Abundance of Anurans within a Community Correlates with Reproductive Investment

“…However, if the relationship between life history and roadside abundance does hold on a smaller scale, roads could have a strong influence on community composition. Rytwinski and Fahrig (2011) investigated the relationship between mammal body size, mobility, and reproductive rate and traffic density within a landscape and found that reproductive rate is an explanatory factor in roadside community structure, echoing the global trend seen in the metaanalysis. Here, we investigate whether the community-level correlation between reproductive rate and roadside abundance also holds for anurans.…”

Synthèse des connaissances relatives aux impacts des routes sur l’écologie du caribou

“…Parmi les facteurs permettant d'expliquer la vulnérabilité d'une espèce face aux routes, notons la mobilité et la taille du domaine vital qui augmentent la probabilité d'entrer en contact avec une route, mais également la longévité, un faible taux de reproduction et de faibles densités à l'échelle du paysage (Gibbs et Shriver, 2002 ;Fahrig et Rytwinski, 2009 ;Rytwinski et Fahrig, 2011). Ces caractéristiques, communes à plusieurs espèces de grands mammifères, représentent bien le cas du caribou dont les différentes populations présentent généralement de faibles taux de croissance, notamment en raison d'un faible taux de recrutement lié à la mortalité d'une proportion élevée des faons (Pinard et collab., 2012).…”

Effect of paved road density on abundance of white-tailed deer

“…It is important to determine which species or species groups are most susceptible to negative road effects so that mitigation measures can be targeted to those species. For mammals, Rytwinski and Fahrig (2011) showed that, in a cross-species comparison, mammal species with lower reproductive rates are much more likely to show negative population-level effects of roads than are species with higher reproductive rates. They suggested that populations of mammals with low reproductive rates are less able to rebound from road mortality.…”

“…Like other large mammals, the reproductive rate of white-tailed deer, 1-1.5 fetuses per female per year (Mundinger 1981;Kie and White 1985;Garroway and Broders 2007), is low relative to the reproductive rates of smaller mammals. Therefore, based on Rytwinski and Fahrig's (2011) analysis we might expect to see negative effects of road mortality on population abundances of white-tailed deer.…”