Comparative efficacy of sign surveys, spotlighting and audio playbacks in a landscape-scale carnivore survey

Many carnivores are difficult and labour-intensive to detect, often leading to prohibitively high effort and cost in large-scale surveys. However, such studies provide information that is important for effective management and conservation. Here, we evaluate the suitability of three survey methods for landscape-scale multi-species monitoring. We compare sign surveys, spotlighting, and audio playbacks in terms of detection efficiency, precision, effort, and cost. Sign surveys out-performed the other methods in all comparison criteria, although supplementary methods were needed for some species and sites. We found that using established analysis techniques, robust landscape-scale abundance estimates would require unrealistically high effort and cost. Occupancy estimation required considerably lower sample sizes and was therefore more economical. We conclude that sign-based occupancy estimates constitute a versatile and efficient option for future large-scale, multi-species carnivore surveys

Life and death in wolverines

Developing trustworthy conservation planning for endangered species requires a deep understanding of the variations of their populations in both space and time. I used individual-based long-term location and demographic data on wolverines (Gulo gulo) in Northern Sweden, and data on reproductions from the national monitoring systems of Norway and Sweden, to analyze how wolverine demography in Scandinavia is affected by variation in habitat and management policies. Wolverines showed agerelated patterns of reproduction and reproductive costs, which were influenced by seasonal resources. The top predator Eurasian lynx (Lynx lynx) increase scavenging opportunities on reindeer (Rangifer tarandus) carrion, and wolverines and lynx selected for the same habitats when sharing prey base and sources of adult mortality. Illegal killing was a main source of adult mortality in brown bears (Ursus arctos), lynx and wolverines in northern Sweden, and the risk of being illegally killed was in general higher in national parks and on reindeer calving grounds, and lower in forest and steep terrain. At population level, the reproductive range of wolverines was set by latitude and elevation; presence of reindeer and lynx, rugged terrain and higher primary production had a positive effect; whereas human dominated habitats negatively influenced the frequency of reproductions. Different management policies influenced the frequency of wolverine reproductions; in Sweden this was 2 times higher than in Norway. Finally, I show that in Sweden, adult female wolverines were illegally killed at lower rates than males. Thus, the Swedish carnivore conservation payment system, which pays for wolverine reproductions, protects the demographic segment that is most important for population growth. Carnivores impose negative impact on rural economies and herding cultures in Scandinavia, and there will be need for continued monitoring combined with economic incentives to ensure carnivore-human coexistence. The approach of linking life histories to habitat has the potential for in-depth studies of mechanisms shaping spatial and temporal variation in populations, and should be implemented in future adaptive management for species persistence

Density estimations of the Eurasian lynx (Lynx lynx) in the Swiss Alps

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 are

Limitations to recording larger mammalian predators in savannah using camera traps and spoor

Traditionally, spoor (tracks, pug marks) have been used as a cost effective tool to assess the presence of larger mammals. Automated camera traps are now increasingly utilized to monitor wildlife, primarily as the cost has greatly declined and statistical approaches to data analysis have improved. While camera traps have become ubiquitous, we have little understanding of their effectiveness when compared to traditional approaches using spoor in the field. Here, we a) test the success of camera traps in recording a range of carnivore species against spoor; b) ask if simple measures of spoor size taken by amateur volunteers is likely to allow individual identification of leopards and c) for a trained tracker, ask if this approach may allow individual leopards to be followed with confidence in savannah habitat. We found that camera traps significantly under-recorded mammalian top and meso-carnivores, with camera traps more likely under-record the presence of smaller carnivores (civet 64%; genet 46%, Meller’s mongoose 45%) than larger (jackal sp. 30%, brown hyena 22%), while leopard was more likely to be recorded by camera trap (all recorded by camera trap only). We found that amateur trackers could be beneficial in regards to collecting presence data; however the large variance in measurements of spoor taken in the field by volunteers suggests that this approach is unlikely to add further data. Nevertheless, the use of simple spoor measurements in the field by a trained field researcher increases their ability to reliably follow a leopard trail in difficult terrain. This allows researchers to glean further data on leopard behaviour and habitat utilisation without the need for complex analysis

Rapid biodiversity assessment of arthropods for monitoring average local species richness and related ecosystem services

Rapid biodiversity assessment (RBA) is proposed as an affordable indicator for monitoring local species richness of arthropods and sustainability of related ecosystem services. The indicator is based on strictly standardised sampling procedures and the identification of parataxonomic units (morphospecies) instead of species identification. The collection of arthropods was optimized with regard to trap types, time and length of collecting period, selection of four out of seven weekly samples, and choice of counted taxa and trophic guilds. By measuring arthropod activity, RBA is an indicator for functional diversity. Over a period of 8years, average yearly numbers of morphospecies were assessed in Switzerland in 15 agricultural habitats, 15 managed forests, and in 12 unmanaged habitats ranging from protected lowland wetlands to Alpine meadows. The yearly RBA-trend in unmanaged habitats is used for assessing the influence of climate and weather on biodiversity, and as a reference for measuring the relative influences of recent management changes in agriculture and forestry. The average number of morphospecies per sampling station per year depends on temperature, and was only marginally significantly increasing over time in agriculture, but not in forestry or unmanaged areas. Three RBA indices considered to be relevant for maintaining ecosystem services were calculated from the average number of morphospecies per location per year: (1) indicator for ecological resilience and sustainability (all morphospecies); (2) indicator for pollinator diversity (taxa with a majority of pollinators) and (3) indicator for biocontrol diversity (ratio between carnivore and herbivore guilds

Assessing genetic structure in common but ecologically distinct carnivores: the stone marten and red fox

The identification of populations and spatial genetic patterns is important for ecological and conservation research, and spatially explicit individual-based methods have been recognised as powerful tools in this context. Mammalian carnivores are intrinsically vulnerable to habitat fragmentation but not much is known about the genetic consequences of fragmentation in common species. Stone martens (Martes foina) and red foxes (Vulpes vulpes) share a widespread Palearctic distribution and are considered habitat generalists, but in the Iberian Peninsula stone martens tend to occur in higher quality habitats. We compared their genetic structure in Portugal to see if they are consistent with their differences in ecological plasticity, and also to illustrate an approach to explicitly delineate the spatial boundaries of consistently identified genetic units. We analysed microsatellite data using spatial Bayesian clustering methods (implemented in the software BAPS, GENELAND and TESS), a progressive partitioning approach and a multivariate technique (Spatial Principal Components Analysis-sPCA). Three consensus Bayesian clusters were identified for the stone marten. No consensus was achieved for the red fox, but one cluster was the most probable clustering solution. Progressive partitioning and sPCA suggested additional clusters in the stone marten but they were not consistent among methods and were geographically incoherent. The contrasting results between the two species are consistent with the literature reporting stricter ecological requirements of the stone marten in the Iberian Peninsula. The observed genetic structure in the stone marten may have been influenced by landscape features, particularly rivers, and fragmentation. We suggest that an approach based on a consensus clustering solution of multiple different algorithms may provide an objective and effective means to delineate potential boundaries of inferred subpopulations. sPCA and progressive partitioning offer further verification of possible population structure and may be useful for revealing cryptic spatial genetic patterns worth further investigation

Estimating carnivore community structures

'Juan de la Cierva' research contract from the Spanish Ministry of Economy and Competitiveness [JCI-2012-13066

A spatially explicit approach for estimating space use and density of common genet

Un método espacialmente explícito para estimar el uso del espacio y la densidad de la jineta común Muchas especies que se presentan en bajas densidades no se estiman con precisión utilizando métodos de captura y recaptura, puesto que tales técnicas suponen que las poblaciones están bien definidas en el espacio. Para resolver este sesgo, recientemente se han elaborado modelos de captura y recaptura espacialmente explícitos (SECR). Estos modelos incorporan el movimiento y pueden determinar las zonas en la que es más probable que los individuos concentren su actividad. En el presente estudio, utilizamos datos obtenidos con cámaras de trampeo en estudios sobre la jineta común (Genetta genetta) en Serra da Malcata (Portugal) concebidos para comparar las estimaciones de abundancia producidas por los modelos de SECR y los modelos tradicionales de captura para una población cerrada. Utilizando los modelos de SECR, observamos la existencia de heterogeneidad espacial en la distribución de la jineta y las estimaciones de la densidad fueron aproximadamente dos veces inferiores a las obtenidas en los modelos para poblaciones cerradas. Las estimaciones del modelo no espacial se limitaron al tamaño de la cuadrícula de muestreo y probablemente infravaloraron los movimientos, lo que conllevaría que se sobreestimara la densidad. Los estudios futuros deberían sopesar la incorporación de modelos de carga–distancia que puedan incluir hipótesis explícitas sobre la forma en que las variables medioambientales influyen en la métrica de la distancia.Un método espacialmente explícito para estimar el uso del espacio y la densidad de la jineta común Muchas especies que se presentan en bajas densidades no se estiman con precisión utilizando métodos de captura y recaptura, puesto que tales técnicas suponen que las poblaciones están bien definidas en el espacio. Para resolver este sesgo, recientemente se han elaborado modelos de captura y recaptura espacialmente explícitos (SECR). Estos modelos incorporan el movimiento y pueden determinar las zonas en la que es más probable que los individuos concentren su actividad. En el presente estudio, utilizamos datos obtenidos con cámaras de trampeo en estudios sobre la jineta común (Genetta genetta) en Serra da Malcata (Portugal) concebidos para comparar las estimaciones de abundancia producidas por los modelos de SECR y los modelos tradicionales de captura para una población cerrada. Utilizando los modelos de SECR, observamos la existencia de heterogeneidad espacial en la distribución de la jineta y las estimaciones de la densidad fueron aproximadamente dos veces inferiores a las obtenidas en los modelos para poblaciones cerradas. Las estimaciones del modelo no espacial se limitaron al tamaño de la cuadrícula de muestreo y probablemente infravaloraron los movimientos, lo que conllevaría que se sobreestimara la densidad. Los estudios futuros deberían sopesar la incorporación de modelos de carga–distancia que puedan incluir hipótesis explícitas sobre la forma en que las variables medioambientales influyen en la métrica de la distancia.Many species that occur at low densities are not accurately estimated using capture–recapture methods as such techniques assume that populations are well–defined in space. To solve this bias, spatially explicit capture–recapture (SECR) models have recently been developed. These models incorporate movement and can identify areas where it is more likely for individuals to concentrate their activity. In this study, we used data from camera–trap surveys of common genets (Genetta genetta) in Serra da Malcata (Portugal), designed to compare abundance estimates produced by SECR models with traditional closed–capture models. Using the SECR models, we observed spatial heterogeneity in genet distribution and density estimates were approximately two times lower than those obtained from the closed population models. The non–spatial model estimates were constrained to sampling grid size and likely underestimated movements, thereby overestimating density. Future research should consider the incorporation of cost–weighed models that can include explicit hypothesis on how environmental variables influence the distance metric