Pesenti E.,University of Lausanne |
Journal of Mammalogy | Year: 2013
Use of photographic capture-recapture analyses to estimate abundance of species with distinctive natural marks has become an important tool for monitoring rare or cryptic species, or both. Two different methods are available to estimate density: nonspatial capture-recapture models where the trap polygon is buffered with the half or full mean maximum distance moved by animals captured at more than 1 trap (1/2 MMDM or MMDM, respectively); or spatial capture-recapture (SCR) models that explicitly incorporate movement into the model. We used data from radiotracked Eurasian lynx (Lynx lynx) in the northwestern Swiss Alps (NWSA) during a low (1.0 lynx/100 km2) and a high (1.9-2.1 lynx/100 km2) lynx population density to test if lynx space use was density dependent. Second, we compared lynx density estimates resulting from these 2 different methods using camera-trapping data collected during winters 2007-2008 and 2009-2010 in the NWSA. Our results indicated lynx space use was negatively correlated with density. Lynx density estimates in all habitats using MMDM (0.86 and 0.97 lynx/100 km2 in winters 2007-2008 and 2009-2010, respectively) were significantly lower than SCR model estimates, whereas there was no significant difference between SCR model (1.47 and 1.38) and 1/2 MMDM (1.37 and 1.51) density estimates. In the NWSA, which currently harbors the most abundant lynx population in Switzerland, 1/2 MMDM and SCR models provided more realistic lynx density estimates compared to the MMDM, which lies in the lower range of densities. Overall, the SCR model is preferable because it considers animal movements explicitly and is not biased by an informal estimation of the effective sampling area. © 2013 American Society of Mammalogists.
Mavrot F.,University of Bern |
Zimmermann F.,KORA |
Vilei E.M.,University of Bern |
Ryser-Degiorgis M.-P.,University of Bern
European Journal of Wildlife Research | Year: 2012
Infectious keratoconjunctivitis (IKC) caused by Mycoplasma conjunctivae is a widespread ocular affection of free-ranging Caprinae in the Alpine arc. Along with host and pathogen characteristics, it has been hypothesized that environmental factors such as UV light are involved in the onset and course of the disease. This study aimed at evaluating the role of topographic features as predisposing or aggravating factors for IKC in Alpine chamois (Rupicapra rupicapra rupicapra) and Alpine ibex (Capra ibex ibex). Geospatial analysis was performed to assess the effect of aspect (northness) and elevation on the severity of the disease as well as on the mycoplasmal load in the eyes of affected animals, using data from 723 ibex and chamois (583 healthy animals, 105 IKC-affected animals, and 35 asymptomatic carriers of M. conjunctivae), all sampled in the Swiss Alps between 2008 and 2010. An influence of northness was not found, except that ibex with moderate and severe signs of IKC seem to prefer more north-oriented slopes than individuals without corneal lesions, possibly hinting at a sunlight sensitivity consequent to the disease. In contrast, results suggest that elevation influences the disease course in both ibex and chamois, which could be due to altitude-associated environmental conditions such as UV radiation, cold, and dryness. The results of this study support the hypothesis that environmental factors may play a role in the pathogenesis of IKC. © 2012 Springer-Verlag.
Revue Suisse de Zoologie | Year: 2011
In 2005, a male and a female otters escaped from the zoo of Bern, and settled in the nearby River Aar. The number of otters present in the area increased to 5 individuals after the adult pair reproduced. A monitoring was launched in 2007 in order to examine how these otters live in this suburban environment. Food habits notably were investigated. Fish constituted the staple prey (91.5%) with salmonids being the most frequently eaten prey category (43.1%). Seasonal dietary variation occurred but was not marked. The results and the perspective of a long-term survival of otters are discussed with regards to the overall decrease in fish numbers recorded in the Swiss waters.
Rovero F.,Sezione di Biodiversita Tropicale |
Rovero F.,Udzungwa Ecological Monitoring Center |
Zimmermann F.,KORA |
Berzi D.,Canis lupus Italia |
And 2 more authors.
Hystrix | Year: 2013
Automatically triggered cameras taking photographs or videos of passing animals (camera traps) have emerged over the last decade as one of the most powerful tool for wildlife research. In parallel, a wealth of camera trap systems and models has become commercially available, a phenomenon mainly driven by the increased use of camera traps by sport hunters. This has raised the need for developing criteria to choose the suitable camera trap model in relation to a range of factors, primarily the study aim, but also target species, habitat, trapping site, climate and any other aspect that affects camera performance. There is also fragmented information on the fundamentals of sampling designs that deploy camera trapping, such as number of sampling sites, spatial arrangement and sampling duration. In this review, we describe the relevant technological features of camera traps and propose a set of the key ones to be evaluated when choosing camera models. These features are camera specifications such as trigger speed, sensor sensitivity, detection zone, flash type and flash intensity, power autonomy, and related specifications. We then outline sampling design and camera features for the implementation of major camera trapping applications, specifically: (1) faunal inventories, (2) occupancy studies, (3) density estimation through Capture-Mark-Recapture and (4) density estimation through the Random Encounter Model. We also review a range of currently available models and stress the need for standardized testing of camera models that should be frequently updated and widely distributed. Finally we summarize the "ultimate camera trap", as desired by wildlife biologists, and the current technological limitations of camera traps in relation to their potential for a number of emerging applications. © 2013 Associazione Teriologica Italiana.
McCarthy J.L.,University of Massachusetts Amherst |
Belant J.L.,Mississippi State University |
Breitenmoser-Wursten C.,KORA |
Hearn A.J.,University of Oxford |
Ross J.,University of Oxford
Raffles Bulletin of Zoology | Year: 2013
Tropical carnivores often occur at low densities and non-invasive techniques may be inadequate to meet research and monitoring goals. Live capture allows researchers to gather information such as movement and habitat use, that they would not have access to using other techniques. However, for most tropical carnivore species there have been few live trapping studies, and hence no development of cohesive protocol. For effective project design to live trap tropical carnivores, we present a review of trapping techniques from literature and personal experience. When developing a live capture study, it is important to clearly identify study goals and ensure that live trapping will provide ample data for useful inference. It is also important to increase effi cacy and effi ciency of the technique so the capture rate is maximised and the risk of negative side effects is minimised. To meet these needs it is important to assess different methods of live capture. The benefi ts and detriments of each method must be considered for applicability to the study site and target species. Once the capture method is implemented it is important to reduce the time that the animal spends in the trap, and increase effi ciency of the immobilisation process to reduce stress and improve general welfare of the captured individual. To maximise the capture rate, the spatial and temporal placement of traps and the use of baits and lures should be given careful consideration. Through review of tropical carnivore capture methods and discussion of improved effi cacy and effi ciency, researchers can better develop successful live capture projects. © National University of Singapore.