Comparison of 2 methods to estimate density of an endangered lagomorph

We estimated densities of the endangered Lower Keys marsh rabbit (Sylvilagus palustris hefneri) at 5 habitat patches on Boca Chica Key, Monroe County, Florida, using pellet counting and direct enumeration from livetrapping. We compared density estimates from these 2 methods to an independent estimation of population size based on radiotracking data to determine which method would be best for long-term population monitoring. Density estimates were made 3 times per year for 2.5 years from March 1991 to July 1993. Significant correlations were found between pellet counting and radiotelemetry estimates (r(2) = 0.89, p < 0.0001) and between the livetrapping and radiotelemetry estimates (r(2) = 0.99, p < 0.0001). Pellet-counting estimates took 80% less time to perform than livetrapping estimates. Although livetrapping may have a higher correlation with actual population density, pellet counting provides an economic and efficient estimate that is well suited to long-term population monitoring.