Aim:We test a new species distribution modelling (SDM) framework, while comparing results to more common distribution modelling techniques. This framework allows for the combination of presence-only (PO) and presence-absence (PA) data and accounts for imperfect detection and spatial bias in presence data. The new framework tested here is based on a Poisson point process model, which allows for predictions of population size. We compared these estimates to those provided by experts on the species. Species and Location: Presence data on Baird's tapir (Tapirus bairdii) throughout its range from southern México to northern Colombia were used in this research, primarily from the years 2000 to 2016. Methods: Four SDM frameworks are compared as follows: (1) Maxent, (2) a presenceonly (PO) SDM based on a Poisson point process model (PPM), (3) a presence-absence (PA) SDM also based on a PPM and (4) an Integrated framework which combines the previous two models. Model averaging was used to produce a single set of coefficient estimates and predictive maps for each model framework. A hotspot analysis (Gi*) was used to identify habitat cores from the predicted intensity of the Integrated model framework. Results: Important variables to model the distribution of Baird's tapir included land cover, human pressure and topography. Accounting for spatial bias in the presence data affected which variables were important in the model. Maxent and the Integrated model produced predictive maps with similar patterns and were considered to be more in agreement with expert knowledge compared to the PO and PA models.Main conclusions: Total abundance as predicted by the model was higher than expert opinion on the species, but local density estimates from our model were similar to available independent assessments. We suggest that these results warrant further validation and testing through collection of independent test data, development of more precise predictor layers and improvements to the model framework.
Baird´s tapir (Tapirus bairdii) is one of the most emblematic mammalian species from Mesoamerica. Due to its level of evolutionary distinctiveness and anthropogenic threat this species was recently ranked in 34th position, in terms of its urgency for conservation, among more than 4,000 species of mammals assessed by experts from the Zoological Society of London. Despite its evolutionary and conservation relevance there remain important gaps in knowledge of the basic ecology of this species. Based on camera-trapping data, we estimated Baird´s tapir abundance and analyzed its patterns of daily activity and preference for different altitude intervals in El Triunfo Biosphere reserve, one of the last strongholds for this species in southern Mexico. We also applied a recently developed method (Random encounter model) to estimate tapir density without the need of individual identification. Tapir relative abundance was: 1.3 events/100 camera-trap days and density: 0.12 ind./km 2 . Tapir activity concentrated around dusk (χ 2 = 21.18, P<0.01) and use of mid-altitude areas was preferred (χ 2 = 49, P < 0.001). This study provides data on the ecology of the species and insights on study methods that can have a direct positive impact on its management and conservation.Keywords: density estimation, camera-trapping, cloud forest, mammal threat, daily activity Resumen El Tapir o Danta centroamericana (Tapirus bairdii) es una de las especies de mamífero más notables de Mesoamérica. Debido al grado de amenaza que experimenta y a que representa una línea evolutiva muy distintiva, esta especie fue recientemente colocada en el lugar 34, en términos de la prioridad de su conservación, entre más de 4,000 especies de mamíferos evaluados por expertos de la Sociedad Zoológica de Londres. A pesar de esto, persisten importantes vacíos en el conocimiento de la ecología básica de esta especie. Con base en un estudio de foto-trampeo estimamos la abundancia de T. bairdii y analizamos sus patrones de actividad, a lo largo del día, y de uso de sitios a lo largo de un gradiente altitudinal en la Reserva de la Biosfera de El Triunfo, uno de los últimos refugios de la especie en el sureste de México. Asimismo, aplicamos un método recientemente desarrollado (Modelo de encuentros aleatorios) para estimar la densidad del tapir sin la necesidad de realizar identificación individual. Los valores estimados de abundancia relativa de la especie y densidad fueron: 1.3 eventos/100 días cámara-trampa y 0.12 ind./km 2 . La actividad del tapir se concentró alrededor del anochecer (χ 2 =21.18, P<0.01) y en la zonas de altitud media (χ 2 = 49, P < 0.001). Este estudio presenta información sobre la ecología básica de la especie y sobre aspectos metodológicos de su estudio que pueden impactar de manera positiva las prácticas para su manejo y conservación.Palabras clave: estimación de densidad, foto-trampeo, bosque de neblina, mamíferos amenazados, actividad diaria.
Conservationists recognize the value of protected area (PA) systems, with adequate coverage, ecological representation, connection, and management to deliver conservation benefits. Yet, governments primarily focus on coverage, disregarding quantification of the other criteria. While recent studies have assessed global representation and connectivity, they present limitations due to: (1) limited accuracy of the World Database of Protected Areas used, as governments may report areas that do not meet the IUCN or CBD PA definitions or omit subnational PAs, and (2) failure to include human impacts on the landscape in connectivity assessments. We constructed a validated PA database for Tropical Andean Countries (TAC; Bolivia, Colombia, Ecuador, Perú, and Venezuela) and used the existing Protected-Connected-Land (ProtConn) indicator—incorporating the Global Human Footprint as a spatial proxy for human pressure—to evaluate TAC ecoregions’ representation and connectivity. We found that just 27% of ecoregions in the TAC are both protected and connected on more than 17% of their lands. As we included human pressure, we conclude that previous global ProtConn studies overestimate PA connectivity. Subnational PAs are promising for strengthening the representation of PA systems. If nations seek to meet Aichi target 11, or an upcoming post-2020 30% target, further efforts are needed to implement and report subnational conservation areas and appropriately evaluate PA systems.
The rapid expansion of avocado cultivation in Michoacán, Mexico, is one of the drivers of deforestation. We assessed the degree of fragmentation and functional connectivity of the remaining temperate forest within the Avocado Belt and prioritized patches that contribute the most to connectivity using a network-based approach and modelling different seed and pollen dispersal scenarios, including two types of patch attributes (size and degree of conservation). As landscape transformation in the region is rapid and ongoing, we updated the land-use and land-cover maps through a supervised classification of Sentinel-2 imagery, improving the reliability of our analyses. Temperate forest is highly fragmented within the region: most patches are small (<30 ha), have a reduced core-area (28%), and irregular shapes. The degree of connectivity is very low (0.06), dropping to 0.019 when the degree of conservation of patches was considered. The top 100 ranked patches of forest that support the connectivity of seeds and pollen have different characteristics (i.e., size and topology) that may be considered for implementing conservation and management strategies. Seed dispersal seems to be more threatened by fragmentation than pollen dispersal, and patches that are important for maintaining seed connectivity are embedded in the denser zone of avocado orchards.
Climate change, habitat loss and fragmentation, invasive species, and resource over-exploitation are among the major factors driving biodiversity loss and the current global change crisis. Maintaining and restoring connectivity throughout fragmented landscapes is key to reduce habitat isolation and mitigate anthropogenic impacts. To date, few connectivity approaches seek to identify corridors along climate gradients and least transformed natural habitats despite its importance to facilitate dispersal of organisms, as species' ranges shift over time to track suitable climates. In this study, we identified least-cost climatic corridors in Mexico between 2027 old-growth vegetation patches incorporating evapotranspiration as climatic variable, Euclidean distances, and human impact. We identified old-growth vegetation patches using the land use and vegetation map of 2011 (scale 1:250 000) by the National Institute of Statistics and Geography (INEGI). Moreover, we calculated a human impact index based on the theoretical framework of the Global Biodiversity Model (Alkemade et al. 2009) but adapted for Mexico (Mexbio, Kolb 2016), and includes the impact of land use, road infrastructure and fragmentation based on the land use and vegetation map of 2011 and a road map by the Mexican Institute of Transportation. We modeled corridors for a baseline period (1980-2009) and under three future time periods (2015-2039, 2045-2069 and 2075-2099), corresponding to four Global Circulation Models (MPI-ESM-LR, GFDL-CM3, HADGEM2-ES and CNRMCM5) each under two emission scenarios (RCP 4.5 and 8.5) The historical and future evapotranspiration values were calculated using the climate surfaces from Cuervo-Robayo et al. 2019 and from the Center of Atmospheric Sciences of the National Autonomous University of Mexico*1, respectively. The historical and future evapotranspiration values were calculated using the climate surfaces from Cuervo-Robayo et al. 2019 and from the Center of Atmospheric Sciences of the National Autonomous University of Mexico, respectively. We used the Turc evapotranspiration equation (Turc 1954) to estimate actual evapotranspiration. Least cost climatic corridors using future climate projections were used to test the assumption that climatic gradients are maintained in the future. We then prioritized climatic corridors using a multicriteria analysis guided by expert knowledge, incorporating factors such as indicators of human impact, vulnerability and exposure to climate change, and priority sites for biodiversity conservation and restoration. On average, more than 4,500 least cost climatic corridors were identified for each scenario. There is a high spatial coincidence in the geographical location of current and future climatic corridors (overlap > 90%). Fewer corridors were identified in the northern part of the country where natural vegetation is less fragmented, whereas in central and southern Mexico landscape fragmentation is greater, resulting in an increased number of corridors (Fig. 1). The use of open spatial data was key in identifying climatic corridors in order to support decision-making. The results provide a spatial guide to implement conservation and restoration actions to promote connectivity, in particular among climatic stable areas, thus supporting the achievement of Aichi Targets and Sustainable Development Goals. Also, it informs multiple stakeholders and sectors in land-use planning decisions and to promote the alignment of existing incentives to reduce habitat loss, degradation and fragmentation in key areas needed to maintain and recover landscape connectivity in the face of global change.
Fruits reaching the floor of tropical forests constitute an attractive resource for a variety of mammals. Study of the characteristics of the frugivory interaction can help to advance in the understanding of the mechanisms favoring animal's coexistence. However, there are few studies focused on analyzing patterns of activity of mammals feeding on fruits in the forest floor. Camera traps were used to record consumption of Licania platypus and Pouteria sapota fruits by Cuniculus paca, Dasyprocta punctata, Nasua narica, Dycotiles crassus and Tapirella bairdii. Patterns of mammal activity were characterized based on the day, time and tree in which they were recorded. Overlap in daily (delta coefficient) and spatial occurrence (same tree and day, Jaccard, Ochiai indices and V ratio) was assessed. High segregation in the activity of frugivores occurred during the day (mean delta = 0.291 and 0.191 for L. platypus and P. sapota, respectively) and among trees/days (max. Jaccard = 0.14 and 0.19 for L. platypus and P. sapota, respectively). Our results suggest that activity overlap among mammalian frugivores feeding in the forest floor is lower than expected. This likely relates to the fact we conducted our analysis at a finer detail than previous studies (for example those focusing exclusively on dietary overlap). Thus, our study increases our understanding of the possible factor that can favor coexistence of tropical frugivorous mammals. Los frutos depositados en el piso del bosque tropical son un recurso sumamente atractivo para una amplia variedad de mamíferos. El estudio de las características de esta interacción puede permitir avanzar en el entendimiento de los mecanismos que favorecen la coexistencia entre especies de mamíferos. Se usaron cámaras trampa para registrar el consumo de frutos de Licania platypus y Pouteria sapota por Cuniculus paca, Dasyprocta punctata, Nasua narica, Dycotiles crassus y Tapirella bairdii. Con base en la información del día, la hora y el árbol donde se registró la fauna, se caracterizó el nivel de traslape en actividad a lo largo del día (coeficiente de traslape, delta) y espacialmente (visitas a los mismos árboles en los mismos días, índices de asociación de Jaccard, Ochiai y cociente V). Se encontró una alta segregación en la actividad diaria (delta promedio = 0.291 y 0.191 en L. platypus y P. sapota, respectivamente) y entre árboles/días (máx. Jaccard = 0.14 y 0.19 en L. platypus y P. sapota, respectivamente). Nuestros resultados indican que el grado de traslape en la actividad de mamíferos alimentándose de frutos en el piso de la selva es en general bajo. Esto puede deberse al hecho de que nuestro estudio analiza los patrones de actividad de la fauna con un mayor nivel de detalle que estudios previos que, por ejemplo, se han concentrado exclusivamente en la dieta de la fauna. Nuestro estudio permite avanzar en el entendimiento de los mecanismos que permiten la coexistencia entre distintas especies de mamíferos frugívoros.
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