DOI: 10.5061/dryad.1g1jwsv9v
title: Mammals with large home ranges, low reproductive rates, and small body sizes are most vulnerable to roads: A meta-analysis

description: In a previous meta-analysis, mammals with large home ranges, low
 reproductive rates, and large body sizes were found to respond most
 negatively to roads. However, due to correlations among these traits, it
 is not known whether these responses were due to a subset or all three
 traits. We conducted a multiple meta-regression of the effects of species
 traits on mammal responses to roads, using data from 92 studies, to
 determine whether an analysis with a larger sample size and controlling
 for correlations among traits will support the previous findings. The
 results reinforce the findings that mammals with larger home ranges and
 lower reproductive rates respond more negatively to roads. Surprisingly,
 we found that when controlling for the effects of home range size and
 reproductive rate, larger mammals respond less negatively to roads than
 smaller mammals. We speculate that the positive effect of body size is due
 to driver avoidance of collisions with larger mammals and/or differences
 in road attraction and car avoidance behaviors of larger vs. smaller
 species that allow larger mammals to extract benefits of roads while
 avoiding oncoming vehicles. We also found high variability of individual
 responses to roads, above what could be explained by the species traits
 model, most likely due to site and/or species-specific characteristics.
 Synthesis and applications: Road mitigation for mammals should ideally be
 informed by site level knowledge and generally involve prioritizing
 species with the combination of larger home ranges, lower reproductive
 rates, and smaller body sizes. To protect these vulnerable mammals from
 roads, we should maintain low road densities and install small-mesh
 mitigation fencing along roads. This differs from current road mitigation
 efforts which are typically targeted towards large mammals (e.g.,
 large-mesh fencing along roads) and are often ineffective for smaller
 mammals.
description: # Mammals with large home ranges, low reproductive rates, and small body
 sizes are most vulnerable to roads: A meta-analysis Dataset DOI:
 [10.5061/dryad.1g1jwsv9v](10.5061/dryad.1g1jwsv9v) ## Description of the
 data and file structure We conducted a meta-analysis of the effects of
 species traits on mammal population responses to roads. We first updated
 the literature search by Rytwinski and Fahrig (2012) with recent
 literature that quantified a relationship between roads and mammal
 population abundance. Following screening at title/abstract and at
 full-text, we extracted the information needed to calculate an effect size
 from all included studies. We adjusted sample sizes to allow for a
 comparable weighting of effect sizes across the studies included in the
 meta-analysis. We reduced multiple non-independent effect sizes from the
 same study. We then collected information on species traits (home range
 size, reproductive rate, body mass) for all species for which a road
 effect could be calculated. ### Files and variables #### File:
 Full_Mammal-Responses-to-Roads.xlsx **Description:** In this file, we
 provide the full dataset used to conduct the global meta-analysis. Please
 note that cells with ‘n/a’ represent that the information was not
 available, e.g., when no information could be found for a species trait
 because the trait value was missing from the species trait database, and
 the information could not be found when searching additional online
 resources. ##### Variables * Dataset_ID: Individual road impact on mammal
 population abundance * STUDY_ID: An independent publication * Study_Name:
 Citation of publication * Country: The name of the country in which the
 study was conducted * Biome: The biome in which the study was conducted *
 TemperateTropical: The study was conducted in a temperate or tropical
 region * Species_Name: The scientific name of the species * Study_Design:
 The study design of the dataset, coded here as: (1) Landscape or region,
 (2) Home range vs. random, (3) Presence plot vs. random, (4) Distance from
 road (multiple distances), (5) Road near vs. far, (6) Road present vs.
 absent * Road_Category: Road category of the road exposure evaluated,
 coded as: (1) 4-lane or more, paved, divided highways, (2) 2-lane paved
 roads, (3) 1-lane paved roads or unpaved roads, and (4) a combination of
 multiple road categories * ESr: The correlation coefficient (effect size)
 * ES_Zr: The z-transformed correlation coefficient * SE: The standard
 error of the effect size * V: The variance of the z-transformed
 correlation coefficient * N: The adjusted sample size * W: The inverse
 variance weight  * N_Minimum: Sample size was set to the minimum for
 inclusion in the meta-analysis (Y = yes; N = no) * Order: The taxonomic
 order of the species * Family: The taxonomic family of the species *
 Repro_Rate: Reproductive rate; the median number of offspring per litter
 per female multiplied by the median number of litters per female per year
 * Repro_Rate_Extrapolated: Reproductive rate estimated (by averaging
 across closely taxonomically related species) for species with missing
 values * Mobility_km2: Home range size (km2); the median area within which
 daily movements of individuals of both sexes occur *
 Mobility_km2_Extrapoloated: Home range size (km2) estimated (by averaging
 across closely taxonomically related species) for species with missing
 values * Mass_g: Body mass (g); the median body mass of adult individuals
 of both sexes. * Mass_g_Extrapolated: Body mass (g) estimated (by
 averaging across closely taxonomically related species) for species with
 missing values * Complete_LH: Values for all species traits (reproductive
 rate, home range, body mass) were available (Y = Yes; N = No) *
 Trophic_Group: Trophic group classification as herbivore (1), omnivore
 (2), or carnivore (3) #### File: Subset_Mammal_Responses-to-Roads.xlsx
 **Description:** In this file, we provide the subset of data for species
 for which complete species trait information could be collected, used to
 conduct the species traits meta-regressions. ##### Variables * Dataset_ID:
 Individual road impact on mammal population abundance * STUDY_ID: An
 independent publication * Study_Name: Citation of publication * Country:
 The name of the country in which the study was conducted * Biome: The
 biome in which the study was conducted * TemperateTropical: The study was
 conducted in a temperate or tropical region * Species_Name: The scientific
 name of the species * Study_Design: The study design of the dataset, coded
 here as: (1) Landscape or region, (2) Home range vs. random, (3) Presence
 plot vs. random, (4) Distance from road (multiple distances), (5) Road
 near vs. far, (6) Road present vs. absent * Road_Category: Road category
 of the road exposure evaluated, coded as: (1) 4-lane or more, paved,
 divided highways, (2) 2-lane paved roads, (3) 1-lane paved roads or
 unpaved roads, and (4) a combination of multiple road categories * ESr:
 The correlation coefficient (effect size) * ES_Zr: The z-transformed
 correlation coefficient * SE: The standard error of the effect size * V:
 The variance of the z-transformed correlation coefficient * N: The
 adjusted sample size * W: The inverse variance weight  * N_Minimum: Sample
 size was set to the minimum for inclusion in the meta-analysis (Y = yes; N
 = no) * Order: The taxonomic order of the species * Family: The taxonomic
 family of the species * Repro_Rate: Reproductive rate; the median number
 of offspring per litter per female multiplied by the median number of
 litters per female per year * Mobility_km2: Home range size (km2); the
 median area within which daily movements of individuals of both sexes
 occur * Mass_g: Body mass (g); the median body mass of adult individuals
 of both sexes. * Complete_LH: Values for all species traits (reproductive
 rate, home range, body mass) were available (Y = Yes; N = No) *
 Trophic_Group: Trophic group classification as herbivore (1), omnivore
 (2), or carnivore (3) #### File: Articles-Excluded-at-Full-Text.xlsx
 **Description:** In this file, we provide a list of all articles excluded
 during the full-text screening or data extraction stage of the
 review. Please note that cells with ‘n/a’ represent that the information
 was not available, e.g., when no date for the article was published could
 be found. ##### Variables * Full citation: The article's full
 reference * Title: The article's title * Author: The author(s) of the
 article * Year: Year of publication * Language: Language in which the main
 text is written * FT Screening Outcome: Reason for the article being
 excluded at full-text screening