Metabarcoding reveals striking dietary variation in a reintroduced mesocarnivore

Area of Science:

• Conservation biology
• Wildlife ecology
• Molecular ecology

Background:

• Carnivore populations rely on prey availability, making foraging ecology crucial for conservation.
• Mesocarnivore conservation status is influenced by access to energy-efficient prey.
• Reintroduction programs benefit from understanding diet dynamics for population trajectory assessment.

Purpose of the Study:

• To assess fisher (Pekania pennanti) diet variation across two Washington state reintroduction sites using DNA metabarcoding.
• To investigate correlations between DNA metabarcoding data and prey biomass consumption.
• To evaluate the relationship between diet composition and reintroduction success metrics.

Main Methods:

• Collected 300 fisher scats and gastrointestinal tracts via telemetry and scat detection dogs.
• Employed high-resolution DNA metabarcoding to characterize diet profiles.
• Validated metabarcoding results against captive feeding trials to assess prey biomass correlation.

Main Results:

• A moderate correlation (r=0.47) was found between relative read abundance and approximate prey biomass in individual samples.
• Stronger correlation (r=0.72) observed between relative read abundance and prey biomass in aggregated diet profiles.
• Hares and rabbits were prevalent prey in both sites, but South Cascades fishers had limited prey diversity (19 taxa) compared to North Cascades fishers (71 taxa).
• Diet composition in the South Cascades resembled fishers in the central/eastern US, while the North Cascades diet was similar to fishers in the southern extent of their range.

Conclusions:

• Dietary variation between adjacent reintroduction sites is significant.
• DNA metabarcoding is a valuable tool for assessing resource availability and reintroduction success.
• Understanding diet composition is critical for informing management interventions and ensuring adequate resources for reestablishing fisher populations.