Efficiency in conservation: Comparable genetic and population data from one and two noninvasive sampling rounds in <i>Tetrao urogallus</i> (Western Capercaillie)

ABSTRACT Noninvasive genetic sampling is often used in conservation biology to assess population genetic parameters and population size of rare and elusive species. However, this sampling method poses some challenges, such as identifying an appropriate approach to sampling in the field, the optimal number of samples to be analyzed, and the number of sampling rounds. In this study, we compare the influence of 1 (OneRound) vs. 2 (TwoRounds) noninvasive sampling rounds on drawing population genetic inferences on Tetrao urogallus (Western Capercaillie) to create a framework for future development of grouse-related genetic studies. We identified unique genotypes using microsatellite markers and compared population genetic parameters and population size estimations for OneRound vs. TwoRounds. Under the premise that fieldwork is conducted at the same sampling sites during lekking season, we found that the decreased fieldwork effort of OneRound results in overall similar conclusions as TwoRounds for population genetic indices. In our study area, both approaches indicated a well-connected T. urogallus population with no signs of inbreeding or isolation. Population size estimations were slightly higher when based on OneRound of sampling, with high overlaps (86%) for males with TwoRounds. The largest discrepancy between the 2 datasets OneRound and TwoRounds became evident when comparing the data on females, indicating a sex bias. We conclude that 1 sampling round is more cost-, time- and personnel-efficient sampling approach, as highly similar results for various important population parameters can be obtained with half the fieldwork effort compared with 2 sampling rounds. When deciding about the number of sampling rounds, the weather dynamics of the target area as well as the likelihood to obtain sufficient numbers of samples should be considered.