Integrating niche and occupancy models to infer the distribution of an endemic fossorial snake (Atractus lasallei)

TL;DR

This study combines niche and occupancy models to understand the habitat and distribution of a rare, burrowing snake in Colombia, showing it's vulnerable due to habitat fragmentation.

Contribution

The study integrates niche and occupancy models to estimate both potential and realized distributions of an understudied endemic snake species.

Findings

Atractus lasallei prefers low slope areas with high annual precipitation and herbaceous/shrubby vegetation.

The species' realized distribution is only 935 km², indicating high vulnerability due to habitat fragmentation.

The snake's potential distribution spans the Central and Western Cordilleras in Colombia.

Abstract

Understanding species distribution and habitat preferences is crucial for effective conservation strategies. However, the lack of information about population responses to environmental change at different scales hinders effective conservation measures. In this study, we estimate the potential and realized distribution of Atractus lasallei, a semi-fossorial snake endemic to the northwestern region of Colombia. We modelled the potential distribution of A. lasallei based on ecological niche theory (using maxent), and habitat use was characterized while accounting for imperfect detection using a single-season occupancy model. Our results suggest that A. lasallei selects areas characterized by slopes below 10°, with high average annual precipitation (>2500mm/year) and herbaceous and shrubby vegetation. Its potential distribution encompasses the northern Central Cordillera and two smaller centers along the Western Cordillera, but its habitat is heavily fragmented within this potential distribution. When the two models are combined, the species’ realized distribution sums up to 935 km2, highlighting its vulnerability. We recommend approaches that focus on variability at different spatio-temporal scales to better comprehend the variables that affect species’ ranges and identify threats to vulnerable species. Prompt actions are needed to protect herbaceous and shrub vegetation in this region, highly demanded for agriculture and cattle grazing.

Figures