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# A roads meta-analysis found an average wildlife cost—and big uncertainty
- URL: https://intelligence.wildlandseco.com/2026-10-14-road-wildlife-impacts-meta-analysis-heterogeneity/
- Published: 2026-10-14T13:52:23.000Z
- Updated: 2026-10-14T13:52:23.000Z
- Description: A synthesis of 160 studies found a roughly 32% reduction on one effect scale, while other effect metrics were uncertain and site results varied greatly.
- Author: Benjamin Worlund
- Tags: roads, meta-analysis, fragmentation, Wildlife, Infrastructure, Connectivity, Methods, #ecological-intelligence, #brief-2026-10-14, #priority-read, #peer-reviewed, #geo-global

Evidence

Peer-reviewed

Geography

Studies spanning multiple world regions

System

Road corridors; terrestrial wildlife communities

## WHAT THE EVIDENCE SAYS

Reviewers fitted three-level models to 643 effect estimates from 160 studies. On the log-response-ratio scale, wildlife outcomes near roads averaged about 32% lower, but the standardized mean difference and correlation estimates had confidence intervals crossing zero. Prediction intervals spanned positive and negative responses; traffic volume was reported for only 91 effects.

## WHY IT MATTERS / OUR READ

An average road effect is not an adequate crossing-location or mitigation design. Species, outcome type, traffic exposure and nearby habitat all matter; mixed effect scales should not be silently collapsed into a single universal loss percentage.

## CAVEATS / UNCERTAINTY

Effects were heterogeneous and most studies did not supply standardized traffic-volume information. This synthesis is observational across studies and does not prove a single causal road response for all taxa or habitats.

## SOURCE

Frontiers in Ecology and Evolution — primary systematic review and meta-analysis  
[View original evidence ↗](https://doi.org/10.3389/fevo.2026.1940830?ref=intelligence.wildlandseco.com)

From the Morning Brief · 2026-10-14

[Read the full Morning Brief →](https://intelligence.wildlandseco.com/morning-brief-2026-10-14/)