Outdoor recreation is often a key reason for the establishment of and continued support for protected areas, and it is commonly assumed that recreation is compatible with wildlife conservation. Despite increasing evidence that recreation has negative effects on animal communities, questions remain about the consistency and magnitude of its effects. The results of individual studies on the effects of recreation vary widely among ecosystems, species, and types of impact. We conducted a meta-analysis to synthesize evidence across individual studies, identify overall trends, and compare types of recreation effects on various taxonomic groups. From an existing database of 274 articles on the effects of recreation on wildlife, we selected articles that measured recreation effects on vertebrate abundance or species richness and used a categorical measure of recreation. From each article, we recorded attributes of the study and the means, variances, and sample sizes for the “control” (no/low recreation) and “treatment” groups (high recreation), and converted these to Hedges’ g, a measure of effect size that compares pairs of means. We used meta-analytic random effects models to estimate a summary effect of recreation on species richness and abundance, and mixed effects models to compare effects among taxonomic groups.
Results/Conclusions
The meta-analysis dataset consisted of 12 articles investigating species richness and 26 examining abundance, with a combined total of 89 results. Most of the abundance results measured relative abundance (e.g., numbers of detections). Articles studying effects on birds were the most common (n=13), followed by mammals (n=8), fish (n=4), and reptiles (n=4). We found that recreation negatively affected vertebrate species richness and abundance, with summary effect sizes of Hedges’ g > 0.35; species richness was more strongly affected than abundance. Negative effects on bird and mammal species richness were similar in magnitude, with greater precision for bird richness, while recreation did not significantly affect fish species richness. Negative effects on mammal abundance were 2.4 times greater than those on bird abundance. Effects on fish and reptile abundance varied greatly and group-level effects were not significant. Our analysis provides quantitative evidence of negative effects of recreation on animal communities, despite limited research on this topic.