Scavenging patterns of generalist predators in forested areas: the potential implications of increase in carrion availability on a threatened capercaillie population

The increases in ungulate populations and hunting bags throughout Europe and North America have resulted in higher carcass numbers available for mesocarnivore species in temperate and boreal forests. The increase in food resources can sustain denser predator populations, potentially affecting prey species such as the threatened western capercaillie Tetrao urogallus. We investigated the ungulate population trends in recent decades and the carrion use by facultative scavengers in areas of the Pyrenees occupied by capercaillie to assess the potential effects on predation of nests and adult birds, and on its population trend. We found a significant increase in the number of ungulates harvested during the period of sharp capercaillie population decline. Carrion was provided experimentally in forested areas occupied by capercaillie showing that remains were mainly consumed by red fox Vulpes vulpes, followed by wild boar Sus scrofa and marten species (Martes sp.). Season (cold or warm) was the most important factor determining scavenging activity in most species. Main predators of capercaillie nests and adults were martens and red fox, with no predation by wild boar. Our data show that main predators of capercaillie are the same species that mainly consume carrion, especially in winter, and that plentiful carrion resources could maintain higher populations of these species, potentially increasing predation pressure on the capercaillie population. This study shows that managing carrion arising from hunting activity in areas of capercaillie distribution is a necessary management action to reduce the available carrion biomass and so reduce the impact of mesocarnivores on capercaillie conservation.We acknowledge the forestry rangers of Generalitat de Catalunya for field work. The comments of two anonymous reviewers improved the previous version. This work was funded by the Spanish Ministry of Science, Innovation and Universities (RTI2018-099609-B-C22) and the Spanish Ministry for the Ecological Transition and the Demographic Challenge

Integrating opportunistic and structured non-invasive surveys with spatial capture-recapture models to map connectivity of the Pyrenean brown bear population

International audienceConnectivity, in the sense of the persistence of movements between habitat patches, is key to maintain endangeredpopulations and has to be evaluated in management plans. In practice, connectivity is difficult to quantifyespecially for rare and elusive species. Here, we use spatial capture-recapture (SCR) models with an ecologicaldetection distance to identify barriers to movement. We focused on the transnational critically endangeredPyrenean brown bear (Ursus arctos) population, which is distributed over Spain, France and Andorra and isdivided into two main cores areas following translocations. We integrate structured monitoring from cameratraps and hair snags with opportunistic data gathered after depredation events. While structured monitoringfocuses on areas of regular bear presence, the integration of opportunistic data allows us to obtain information ina wider range of habitat, which is especially important for ecological inference. By estimating a resistanceparameter from encounter data, we show that the road network impedes movements, leading to smaller homeranges with increasing road density. Although the quantitative effect of roads is context-dependent (i.e. varyingaccording to landscape configuration), our model predicts that a brown bear with a home range located in anarea with relatively high road density (8.29 km/km2) has a home range size reduced by 1.4-fold for males and1.6-fold for females compared to a brown bear with a home range located in an area with low road density (1.38km/km2). When assessing connectivity, spatial capture-recapture modeling offers an alternative to the use ofexperts’ opinion when telemetry data are not available

Sedation of Wild Pyrenean Capercaillie (Tetrao urogallus aquitanicus) Using Intramuscular Midazolam

Global Positioning System (GPS) tracking offers key information in the study of movement ecology of threatened species. Nevertheless, the placement of GPS devices requires animal capture and handling, which may represent a challenge to the individual's survival after release, mainly due to capture myopathy. The Pyrenean Capercaillie (Tetrao urogallus aquitanicus) is a threatened galliform especially sensitive to handling, extremely elusive, and challenging to capture. Our goal was to adapt a sedation protocol for Pyrenean Capercaillies undergoing GPS tagging, in order to increase their welfare and safety during the procedure. From 2018 to 2021, 23 wild Pyrenean Capercaillies were captured and sedated for GPS tagging as part of a European conservation project of emblematic Pyrenean avian species. The birds received intramuscular (IM) sedation with midazolam (ranging from 1.9 mg/kg to 8.08 mg/kg) and were handled for 20 to 40 min. Sedation was reversed with flumazenil (0.1 mg/mL IM). The sedated capercaillies were less responsive to stimuli (i.e., closed eyes and recumbency), showing discrete to no response to handling (i.e., placement of the GPS device, physical examination, cloacal temperature measurement, or reflex tests). Such response was compared in birds with sedation doses above and below the average dose (5.17 mg/kg). Only one clinical sign showed statistically significant differences between the two groups ("open-mouth breathing" sign, p = 0.02). A mortality rate of 4.35% was registered (one individual died during handling). Sedation facilitated the handling of the birds and faster interventions in the field, without increasing mortality when compared to handling without sedation. Therefore, sedation was shown to be a useful tool to reduce stress related to capture and handling of the threatened Pyrenean Capercaillie.Peer reviewe

Estimating abundance of a recovering transboundary brown bear population with capture-recapture models

International audienc