Wildlife cameras have emerged over the recent years as an effective research tool for collecting various types of data on wild animals, and they are used increasingly also in avian studies. However, choosing the best method to collect data depends on the aim of the research and the characteristics of the target species and its habitat. Here, we compared the performance of game cameras taking images by passive infrared motion sensitive (PIR) and time-lapse triggering in gathering occurrence and relative abundance data of the taiga bean goose (Anser fabalis fabalis) in peatlands across Finland in 2020-2021. We found the time lapse trigger mode to be more efficient in collecting data on goose presence than PIR triggering. However, there was no significant difference in the goose numbers between the two trigger modes. We also found the capture probability and relative abundance to vary between years, but this could be attributed to random inter-annual variation. In general, we find time lapse to be a more suitable method to study elusive ground dwelling birds like the taiga bean goose due to fewer required visits to camera sites compared to motion triggered cameras that may produce a lot of empty images due to false triggering. This reduces the disturbance to the geese and other wildlife during the sensitive breeding period.

Host-specialist parasites of endangered large vertebrates are in many cases more endangered than their hosts. In particular, low population densities and reduced among-host transmission rates are expected to lead to inbreeding within parasite infrapopulations living on single host individuals. Furthermore, spatial population structures of directly-transmitted parasites should be concordant with those of their hosts. Using population genomic approaches, we investigated inbreeding and population structure in a host-specialist seal louse (Echinophthirius horridus) infesting the Saimaa ringed seal (Phoca hispida saimensis), which is endemic to Lake Saimaa in Finland, and is one of the most endangered pinnipeds in the world. We conducted genome resequencing of pairs of lice collected from 18 individual Saimaa ringed seals throughout the Lake Saimaa complex. Our analyses showed high genetic similarity and inbreeding between lice inhabiting the same individual seal host, indicating low among-host transmission rates. Across the lake, genetic differentiation among individual lice was correlated with their geographic distance, and assignment analyses revealed a marked break in the genetic variation of the lice in the middle of the lake, indicating substantial population structure. These findings indicate that movements of Saimaa ringed seals across the main breeding areas of the fragmented Lake Saimaa complex may in fact be more restricted than suggested by previous population-genetic analyses of the seals themselves.