# Exposure of western United States bird communities to predicted high severity fire

## TL;DR

This study identifies bird communities in the western US most at risk from high severity fires, which could threaten biodiversity.

## Contribution

The study combines fire forecasting and species modeling to map bird biodiversity exposure to altered fire regimes.

## Key findings

- 55-58% of biodiversity hotspots are in low-severity fire areas ('refugia'), while 24-30% are in high-severity areas ('areas of concern').
- Over half of 'areas of concern' are in regions with historically low-severity fires, suggesting a fire regime mismatch.
- Birds preferring dense vegetation and with shallow beaks are most exposed to high severity fires.

## Abstract

Fire is a pervasive biogeographic process that shapes biodiversity globally and is now experiencing unprecedented changes. Despite well documented impacts of fires on biodiversity, we do not know where biodiversity might be most vulnerable to changing fire regimes. We leverage recent advancements in fire forecasting and species distribution modeling to assess the exposure of bird species richness, community uniqueness, and functional richness to altered fire regimes in the western United States. We find that 55-58% of biodiversity hotspots are classified as “refugia”, where high biodiversity intersects with predicted low severity burn areas. In contrast, 24-30% of biodiversity hotspots are classified as “areas of concern”, where high biodiversity intersected with predicted high severity burn areas. Over half (52-60%) of “areas of concern” occur in geographies with historically low-severity fire regimes; a fire regime mismatch indicating a potential threat to biodiversity. We find that species with a preference for high-density vegetation and with shallower beak depth are most likely to be exposed to high severity fire, indicating a potential for habitat losses for species with these traits. Our findings reinforce calls for targeted management to reduce impacts of future fire where it is predicted to be outside the historical range of variation.

Changing fire regimes, leading to higher likelihood of high severity fire, are having unknown impacts on biodiversity. This study identifies regions of high avian biodiversity and individual bird species predicted to be highly exposed to future high severity.