Close-kin mark-recapture informs critically endangered terrestrial mammal status.

Area of Science:

• Conservation Biology
• Population Genetics
• Wildlife Management

Background:

• Accurate population size is crucial for managing threatened species.
• Mark-recapture methods are standard for estimating abundance in wild populations.
• The Christmas Island flying-fox (CIFF) is critically endangered and the last native terrestrial mammal on the island.

Purpose of the Study:

• To apply the close-kin mark-recapture (CKMR) method to a terrestrial species for the first time.
• To estimate demographic parameters for CIFF management, overcoming challenges posed by their elusive nature and habitat.
• To provide robust population estimates for informing conservation efforts.

Main Methods:

• Utilized genetic data from 450 CIFFs captured between 2015 and 2019.
• Detected kin pairs within the genetic data.
• Implemented a novel CKMR model to estimate sex-specific abundance, trend, and mortality, incorporating male reproductive skew and mate persistence.

Main Results:

• Estimated total adult female CIFF abundance at approximately 2050 individuals (95% CI: 950–4300).
• Revealed that only 23% of adult males contributed to annual reproduction on average.
• Provided strong evidence for between-year mate fidelity in wild Pteropus species.

Conclusions:

• CKMR is a powerful tool for estimating demographic parameters in cryptic and mobile species.
• The study provides the most robust population status assessment for the critically endangered CIFF.
• Findings will directly inform immediate and future conservation strategies for the CIFF.