Monitoring, Immobilizing & Capture

Abstract
The ongoing wolf’s recolonization of continental Europe at the beginning of the 21st century recently reached many regions where wolves were absent for centuries, including several areas on the Czechia’s borders. We observed the process of wolf recolonization across the Bohemian Forest Ecosystem from 2015 until April 2023. We adopted a multifaceted approach, based on systematic tracking surveys, camera traps, telemetry, and provoked howling. The first breeding pair with permanent occupation was detected in 2016, connecting two major European wolf populations – Alpine and Central European. We observed increasing amounts of confirmed wolf occurrence data from 2015 to April 2023, with camera trap pictures and scats being the most abundant data sources. The implications of intensive population expansion were confirmed by locating six activity centres in the wolf year 2022/2023, reflecting six existing packs in the Bohemian Forest Ecosystem. Although those wolf packs spread practically across the whole study area in eight wolf years, the intense phase of recolonization is probably finished, and only continuous small changes in population density are expected. Further observations on the population dynamics are essential, focusing on the transitions between existing packs and the establishment of new territories within the existing social structure.

Monitoring the abundance of rare carnivores is a daunting task for wildlife biologists. Many carnivore populations persist at relatively low densities, public interest is high, and the need for population estimates is great. Recent advances in trail camera technology provide an unprecedented opportunity for biologists to monitor rare species economically. Few studies, however, have conducted rigorous analyses of our ability to estimate abundance of low-density carnivores with cameras. We used motion-triggered trail cameras and a space-to-event model to estimate gray wolf (Canis lupus) abundance across three study areas in Idaho, USA, 2016–2018. We compared abundance estimates between cameras and noninvasive genetic sampling that had been extensively tested in our study areas. Estimates of mean wolf abundance from camera and genetic surveys were within 22% of one another and 95% CIs over-lapped in 2 of the 3 years. A single camera with many detections appeared to bias camera estimates high in 2018. A subsequent bootstrapping procedure produced a population estimate from cameras equal to that derived from genetic sampling, however. Camera surveys were less than half the cost of genetic surveys once initial camera purchases were made. Our results suggest that cameras can be a viable method for estimating wolf abundance acrossbroad landscapes (>10,000 km2).