Changes in diversity and species composition in the assemblage of live and dead bats at wind farms in a highly diverse region.

Besides direct mortality, wind farms also affect aerial fauna by modifying their communities, reducing species diversity and richness through disturbance. During three consecutive years, we used mist nets and acoustic recorders, and conducted carcass searches, to characterize the assemblage of bat species and to estimate bat mortality at two nearby wind farms sited <5 km apart in a highly biodiverse region. We asked whether the diversity, richness and evenness of the assemblages varied yearly, predicting it would decrease through time. Richness and evenness did not change, but the diversity of species recorded acoustically, 96% being aerial insectivores, was significantly lower the third year. We estimate 4 - 15.7 fatalities/MW/year by wind farm, with 63% of species found as carcasses being aerial insectivores. We found >40% of dissimilarity in the species composition of bat assemblages between wind farms despite the short distance between them, with species turnover accounting for more than half of the dissimilarity every year. Similarly, species turnover accounted for >15% of the dissimilarity in the composition of the assemblage of live bats (captured and recorded acoustically) and the assemblage obtained through carcass searches. Our findings suggest that nearby wind farms impact bat communities differentially and aerial insectivores disproportionally. Long term, multi-method surveys are needed to characterize bat communities in highly diverse regions and to evaluate the post-construction effects that wind farms have on them.

Invasive Plant Species Driving the Biotic Homogenization of Plant-Frugivore Interactions in the Atlantic Forest Biodiversity Hotspot.

Although biological invasions are a common and intensively studied phenomenon, most studies often ignore the biotic interactions that invasive species play in the environment. Here, we evaluated how and why invasive plant species are interconnected within the overall frugivory network of the Brazilian Atlantic Forest, an important global biodiversity hotspot. To do this, we used the recently published Atlantic Frugivory Dataset to build a meta-network (i.e., a general network made of several local networks) that included interactions between 703 native and invasive plant species and 331 frugivore species. Using tools derived from complex network theory and a bootstrap simulation approach, we found that the general structure of the Atlantic Forest frugivory network (i.e., nestedness and modularity) is robust against the entry of invasive plant species. However, we observed that invasive plant species are highly integrated within the frugivory networks, since both native and invasive plant species play similar structural roles (i.e., plant status is not strong enough to explain the interactive roles of plant species). Moreover, we found that plants with smaller fruits and with greater lipid content play a greater interactive role, regardless of their native or invasive status. Our findings highlight the biotic homogenization involving plant-frugivore interactions in the Atlantic Forest and that the impacts and consequences of invasive plant species on native fauna can be anticipated based on the characteristics of their fruits.

Diversity and conservation of terrestrial vertebrates (birds, mammals, and reptiles) of Sierra Cucapá, Mexicali, Baja California, Mexico.

Knowledge about the biodiversity of Baja California has been obtained mainly from natural protected areas (NPAs), while some unprotected natural areas have been poorly studied. The Sierra Cucapá in the northeast of the peninsula is one example. The objectives of this study are 1) to integrate existing knowledge of bird, mammal, and reptile diversity in Cucapá from public databases, citizen science platforms, and information generated from fieldwork, 2) to identify the spatial distribution of records in the study area, 3) to compare the composition of vertebrate species of Cucapá with that of NPAs of northern part of the peninsula, and 4) to assess the biological conservation value of Cucapá. We obtained records of 150 species of native vertebrates (102 birds, 34 mammals, and 14 reptiles) of which 10 species of birds, four mammals, and seven reptiles are included in a risk extinction category. The different sources of information contributed in a complementary way to the species inventories. Large areas in western and northern Cucapá lack records. The total difference in species composition between Cucapá and nearby NPAs ranged between 58 and 69% for birds, 61 and 79% for mammals, and 69 and 87% for reptiles. The species richness of Cucapá, its particular species composition, the presence of species in risk extinction categories, and the number and size of unexplored areas indicate that this area represents an opportunity for biological conservation in the northern part of the Peninsula. This work provides compelling data for the protection of Cucapá.

Biologic interactions determining geographic range size: a one species response to phylogenetic community structure.

Range size variation in closely related species suggests different responses to biotic and abiotic heterogeneity across large geographic regions. Species turnover generates a wide spectrum of species assemblages, resulting in different competition intensities among taxa, creating restrictions as important as environmental constraints. We chose to adopt the widely used phylogenetic relatedness (NRI) measurement to define a metric that depicts competition strength (via phylogenetic similarity), which one focal species confronts in its environment. This new approach (NRIfocal) measures the potential of the community structure effect over performance of a single species. We chose two ecologically similar Peucaea sparrows, which co-occur and have highly dissimilar range size to test whether the population response to competition intensity is different between species. We analyzed the correlation between both Peucaea species population sizes and NRIfocal using data from point counts. Results indicated that the widespread species population size was not associated with NRIfocal, whereas the population of restricted-sized species exhibited a negative relationship with competition intensity. Consequently, a species' sensitivity to competition might be a limiting factor to range expansion, which provides new insights into geographic range analysis and community ecology.

Soaring migratory birds avoid wind farm in the Isthmus of Tehuantepec, southern Mexico.

The number of wind farms operating in the Isthmus of Tehuantepec, southern Mexico, has rapidly increased in recent years; yet, this region serves as a major migration route for various soaring birds, including Turkey Vultures (Cathartes aura) and Swainson's Hawks (Buteo swainsoni). We analyzed the flight trajectories of soaring migrant birds passing the La Venta II wind farm during the two migratory seasons of 2011, to determine whether an avoidance pattern existed or not. We recorded three polar coordinates for the flight path of migrating soaring birds that were detected using marine radar, plotted the flight trajectories and estimated the number of trajectories that intersected the polygon defined by the wind turbines of La Venta II. Finally, we estimated the actual number of intersections per kilometer and compared this value with the null distributions obtained by running 10,000 simulations of our datasets. The observed number of intersections per kilometer fell within or beyond the lower end of the null distributions in the five models proposed for the fall season and in three of the four models proposed for the spring season. Flight trajectories had a non-random distribution around La Venta II, suggesting a strong avoidance pattern during fall and a possible avoidance pattern during spring. We suggest that a nearby ridgeline plays an important role in this pattern, an issue that may be incorporated into strategies to minimize the potential negative impacts of future wind farms on soaring birds. Studies evaluating these issues in the Isthmus of Tehuantepec have not been previously published; hence this work contributes important baseline information about the movement patterns of soaring birds and its relationship to wind farms in the region.