Sampling
We sampled fecal pellets of white-tailed deer in 2016 and 2017. The
study area in southwestern Finland (central coordinate: 60° 51’ 56” N,
22° 49’ 26” E (WGS84)) is forest, surrounded by agricultural fields,
which is a typical landscape for the region. Sampling followed the
protocol of Poutanen et al. (2019) but with small changes to the
sampling design. We used a cluster design with 23 clusters with four
sampling plots in each for a total of 92 plots. We modified the sampling
of Poutanen et al. (2019) so that the distances between the clusters
were decreased from 500m to 300m and distance between the plots was
reduced from 100m to 60m in order to obtain more spatial recaptures. In
order to sample a closed population, sampling was conducted in the
autumn before the white-tailed deer hunting season, when migration is
also limited and fawns of the year remain with their mothers. In 2016,
we sampled in September, but in 2017 sampling was initiated in August,
due to the earlier timing of the hunting season. In 2016, we visited
sampling plots weekly for three visits and in 2017 every four days for a
total of six visits. During the first visit, the plots were cleared of
feces, which were then discarded and not used in the subsequent
analysis. Therefore, there were two sampling occasions in 2016 and five
in 2017. In 2017, plots were visited more frequently than in 2016
because the results of the earlier study of the authors suggested that
decreasing the sampling interval would allow collection of scats more
frequently, reducing environmental exposure and DNA degradation, thus
improving genotyping success rates (Poutanen et al. 2019).