Lagomorph Ladders: Disease Spillover Risk in Alpine Habitats

Project Overview

Emerging infectious diseases pose significant threats to wildlife populations, particularly for climate-sensitive species already facing environmental challenges. This project investigated the potential for Rabbit Hemorrhagic Disease Virus type 2 (RHDV2) to spread from lower-elevation rabbits and hares up into alpine American pika populations at Great Sand Dunes National Park and Preserve.

The research addressed a critical conservation question: could rabbits and hares act as "ladder fuels"—ecological bridges that allow disease to reach higher-elevation species? Understanding these transmission pathways is essential for protecting alpine mammals already threatened by climate change.

Study System: RHDV2

Rabbit Hemorrhagic Disease Virus type 2 (RHDV2) is a highly contagious and often fatal calicivirus that affects lagomorphs. First detected in North America in 2018, RHDV2 has spread rapidly across the western United States, causing significant mortality in wild rabbit and hare populations.

While American pikas are susceptible to RHDV2, their isolated alpine habitats have historically provided natural protection from lowland diseases. However, if lower-elevation leporids serve as disease reservoirs in overlapping habitats, they could facilitate transmission to pika populations—creating an additional stressor for a species already constrained by climate warming.

Field Methods

During the summer field season, our team conducted systematic surveys across Great Sand Dunes National Park and Preserve, spanning elevation gradients from montane forests through subalpine zones to alpine talus fields. We established 115 survey plots stratified across habitat types and elevations to characterize the spatial distribution of both pika and leporid populations.

At each plot, we recorded:

• Species presence/absence through visual surveys and sign detection
• Habitat characteristics (vegetation, substrate, elevation)
• GPS coordinates for spatial modeling
• Environmental variables relevant to disease transmission

Analytical Approach

We used spatial modeling techniques in GIS to map the distribution patterns of pika and leporid habitat use. By analyzing occupancy patterns across elevation gradients and habitat types, we identified areas where the two groups' ranges overlap—potential "contact zones" where disease transmission could occur.

Our models incorporated:

• Occupancy detection data for both taxonomic groups
• Elevation and habitat type variables
• Movement corridor analysis

Conservation Significance

This research provides critical baseline data for understanding how emerging wildlife diseases might compound existing threats to climate-sensitive alpine species. American pikas serve as sentinel species for climate change impacts in mountain ecosystems, and understanding their disease risk profiles is essential for comprehensive conservation planning.

The "ladder fuel" concept—where intermediate-elevation species facilitate disease transmission between lowland and alpine zones—has broad implications for wildlife disease management in mountainous regions. As climate change pushes species ranges upward, these transmission pathways may become increasingly important.

By identifying high-risk contact zones, this work enables park managers to implement targeted monitoring strategies and early detection protocols. The methodology also provides a framework for assessing disease spillover risk in other multi-host systems across elevation gradients.

Collaborators

This project was conducted in collaboration with the National Park Service, Great Sand Dunes National Park and Preserve, and represents a partnership between academic research and applied conservation management.

Project Team

Principal Investigator: Airy Peralta
Publication Collaborators: Chris Ray, Jessica Castillo Vardaro, Erin Borgman
Funding: Department of Interior
Field Season: August 2022