Comparing wildlife habitat suitability models based on expert opinion with camera trap detections.

Expert knowledge is used in the development of wildlife habitat suitability models (HSMs) for management and conservation decisions. However, the consistency of such models has been questioned. Focusing on 1 method for elicitation, the analytic hierarchy process, we generated expert-based HSMs for 4 felid species: 2 forest specialists (ocelot [Leopardus pardalis] and margay [Leopardus wiedii]) and 2 habitat generalist species (Pampas cat [Leopardus colocola] and puma [Puma concolor]). Using these HSMs, species detections from camera-trap surveys, and generalized linear models, we assessed the effect of study species and expert attributes on the correspondence between expert models and camera-trap detections. We also examined whether aggregation of participant responses and iterative feedback improved model performance. We ran 160 HSMs and found that models for specialist species showed higher correspondence with camera-trap detections (AUC [area under the receiver operating characteristic curve] >0.7) than those for generalists (AUC < 0.7). Model correspondence increased as participant years of experience in the study area increased, but only for the understudied generalist species, Pampas cat (ß = 0.024 [SE 0.007]). No other participant attribute was associated with model correspondence. Feedback and revision of models improved model correspondence, and aggregating judgments across multiple participants improved correspondence only for specialist species. The average correspondence of aggregated judgments increased as group size increased but leveled off after 5 experts for all species. Our results suggest that correspondence between expert models and empirical surveys increases as habitat specialization increases. We encourage inclusion of participants knowledgeable of the study area and model validation for expert-based modeling of understudied and generalist species.

Comparación entre los modelos de idoneidad de hábitat basados en la opinión de expertos y la detecciones con cámaras trampa Resumen El conocimiento de expertos se usa en el desarrollo de modelos de idoneidad de hábitat (MIH) para la gestión y la toma de decisiones en conservación. Sin embargo, se ha cuestionado la coherencia de dichos modelos. Utilizamos un solo método, el proceso de jerarquización analítica, para generar MIH para cuatro felinos: dos especies especialistas de bosque (Leopardus pardalis y L. wiedii)) y dos generalistas de hábitat (Leopardus colocola y Puma concolor). Usamos estos MIH, la detección de las especies mediante censos de cámaras trampa y modelos lineales generalizados, para analizar el efecto de dichas especies y las características de los expertos sobre la correspondencia entre los modelos expertos y las detecciones con cámaras trampa. También analizamos si la agregación de las respuestas de los participantes y la retroalimentación iterativa mejoran el desempeño del modelo. Analizamos 160 MIH y encontramos que los modelos para las especies especialistas mostraron una correspondencia mayor con las detecciones de cámarastrampa (ABC [área bajo la curva de la característica operante receptora] >0.7) para las especies generalistas (ABC < 0.7). La correspondencia del modelo incrementó conforme incrementaron los años de experiencia de los participantes en el área de estudio, pero sólo para Leopardus colocola, una especie generalista y poco estudiada (ß = 0.024 [SE 0.007]). Ninguna otra característica de los participantes se asoció con la correspondencia del modelo. La retroalimentación y la revisión de los modelos aumentaron la correspondencia y la agregación de opiniones de múltiples participantes aumentó la correspondencia sólo para las especies especialistas. La correspondencia promedio de las opiniones agregadas incrementó conforme creció el tamaño grupal, aunque se niveló después de cinco expertos para todas las especies. Nuestros resultados sugieren que la correspondencia entre los modelos de expertos y las evaluaciones empíricos incrementan conforme aumenta la especialización del hábitat. Promovemos la inclusión de participantes conocedores del área de estudio y la validación del modelo para el modelado de expertos de especies generalistas y poco estudiadas.

How do habitat amount and habitat fragmentation drive time-delayed responses of biodiversity to land-use change?

Land-use change is a root cause of the extinction crisis, but links between habitat change and biodiversity loss are not fully understood. While there is evidence that habitat loss is an important extinction driver, the relevance of habitat fragmentation remains debated. Moreover, while time delays of biodiversity responses to habitat transformation are well-documented, time-delayed effects have been ignored in the habitat loss versus fragmentation debate. Here, using a hierarchical Bayesian multi-species occupancy framework, we systematically tested for time-delayed responses of bird and mammal communities to habitat loss and to habitat fragmentation. We focused on the Argentine Chaco, where deforestation has been widespread recently. We used an extensive field dataset on birds and mammals, along with a time series of annual woodland maps from 1985 to 2016 covering recent and historical habitat transformations. Contemporary habitat amount explained bird and mammal occupancy better than past habitat amount. However, occupancy was affected more by the past rather than recent fragmentation, indicating a time-delayed response to fragmentation. Considering past landscape patterns is therefore crucial for understanding current biodiversity patterns. Not accounting for land-use history ignores the possibility of extinction debt and can thus obscure impacts of fragmentation, potentially explaining contrasting findings of habitat loss versus fragmentation studies.

The lion in West Africa is critically endangered.

The African lion has declined to <35,000 individuals occupying 25% of its historic range. The situation is most critical for the geographically isolated populations in West Africa, where the species is considered regionally endangered. Elevating their conservation significance, recent molecular studies establish the genetic distinctiveness of West and Central African lions from other extant African populations. Interventions to save West African lions are urgently required. However formulating effective conservation strategies has been hampered by a lack of data on the species' current distribution, status, and potential management deficiencies of protected areas (PAs) harboring lions. Our study synthesized available expert opinion and field data to close this knowledge gap, and formulate recommendations for the conservation of West African lions. We undertook lion surveys in 13 large (>500 km²) PAs and compiled evidence of lion presence/absence for a further eight PAs. All PAs were situated within Lion Conservation Units, geographical units designated as priority lion areas by wildlife experts at a regional lion conservation workshop in 2005. Lions were confirmed in only 4 PAs, and our results suggest that only 406 (273-605) lions remain in West Africa, representing <250 mature individuals. Confirmed lion range is estimated at 49,000 km², or 1.1% of historical range in West Africa. PAs retaining lions were larger than PAs without lions and had significantly higher management budgets. We encourage revision of lion taxonomy, to recognize the genetic distinctiveness of West African lions and highlight their potentially unique conservation value. Further, we call for listing of the lion as critically endangered in West Africa, under criterion C2a(ii) for populations with <250 mature individuals. Finally, considering the relative poverty of lion range states in West Africa, we call for urgent mobilization of investment from the international community to assist range states to increase management effectiveness of PAs retaining lions.

Population genetic structure of the cyclic snowshoe hare (Lepus americanus) in southwestern Yukon, Canada.

Spatial population structure has important ecological and evolutionary consequences. Little is known about the population structure of snowshoe hares (Lepus americanus), despite their ecological importance in North American boreal forests. We used seven variable microsatellite DNA loci to determine the spatial genetic structure of snowshoe hares near Kluane Lake, Yukon during a cyclic population peak. We sampled 317 hares at 12 sites separated by distances ranging from 3 to 140 km, and used 46 additional samples from Alaska and Montana. The level of genetic variation was high (13.4 alleles/locus, 0.67 expected heterozygosity) and the distribution of alleles and genotypes was not homogeneous across the sites. The degree of differentiation was low among Yukon sites (FST = 0.015) and between Yukon and Alaska (FST = 0.012), but the Montana site was highly differentiated (FST = 0.20). A weak pattern of isolation by distance was found over the Yukon study area, with an indication that local genetic drift may be important in shaping the regional genetic structure. Landscape barriers expected to influence gene flow did not consistently affect genetic structure, although there was evidence for a partial barrier effect of Kluane Lake. The high level of inferred gene flow confirms that snowshoe hare dispersal is widespread, successful and equal between the sexes. A stepping-stone model of gene flow, potentially influenced by the synchronous density cycle, appears to best explain the observed genetic structure. Our results suggest that despite their dramatic fluctuations in density, snowshoe hares in the northern boreal forest have a large evolutionary effective population size and are not strongly subdivided by either physical or social barriers to gene flow.