Density and habitat use of one of the last jaguar populations of the Brazilian Atlantic Forest: Is there still hope?

The jaguar (Panthera onca) plays an important role in maintaining biodiversity and ecological processes. We evaluated the status of a jaguar population in one of the last stronghold habitats for its conservation in the Atlantic Forest, the Rio Doce State Park (RDSP). We used a random survey design from 2016/17 to estimate jaguar abundance and density as well as its occupancy and detection probabilities in the entire Park's area. To monitor for temporal fluctuations in density and abundance, we used a systematic survey design in the southern portion of the Park where jaguars were more recorded when using the random approach. We then conducted two surveys in 2017/18 and 2020. Our 2016/17 random survey revealed that jaguar density (0.11 ± SE 0.28 individuals/100 km2) was the lowest obtained for the species across the Atlantic Forest. We noticed that jaguar density increased three times from 2017/18 (0.55 ± SE 0.45 individuals/100 km2) to 2020 (1.61 ± SE 0.6 individuals/100 km2). Jaguar occupancy and detection probability were 0.40 and 0.08, respectively. The low jaguar occupancy probability was positively associated with smaller distances from lakes and records of potential prey. The detection probability was positively associated with prey detection, the rainy season, and smaller distances from lakes. Our work contributes to a growing awareness of the potential conservation value of a protected area in a human-dominated landscape as one of the last strongholds for jaguars across the Atlantic Forest.

Assessing carnivore spatial co-occurrence and temporal overlap in the face of human interference in a semiarid forest.

Apex predators drive top-down effects in ecosystems and the loss of such species can trigger mesopredator release. This ecological process has been well documented in human-modified small areas, but for management and conservation of ecological communities, it is important to know which human factors affect apex predator occurrence and which mediate mesopredators release at large scales. We hypothesized that mesopredators would avoid spatial and temporal overlap with the apex predator, the puma; but that human perturbations (i.e., cattle raising and trophy hunting) would dampen top-down effects and mediate habitat use. We installed 16 camera traps in each of 45, 10 × 10 km grid cells in the Caldén forest region of central Argentina resulting in 706 total stations covering 61,611 km2 . We used single-season occupancy and two-species co-occurrence models and calculated the species interaction factor (SIF) to explore the contributions of habitat, biotic, and anthropic variables in explaining co-occurrence between carnivore pairs. We also used kernel density estimation techniques to analyze temporal overlap in activity patterns of the carnivore guild. We found that puma habitat use increased with abundance of large prey and with proximity to protected areas. Geoffroy's cats and skunks spatially avoided pumas and this effect was strong and mediated by distance to protected areas and game reserves, but pumas did not influence pampas fox and pampas cat space use. At medium and low levels of puma occupancy, we found evidence of spatial avoidance between three pairs of mesocarnivores. All predators were mostly nocturnal and crepuscular across seasons and mesopredators showed little consistent evidence of changing activity patterns with varying levels of puma occupancy or human interference. We found potential for mesopredator release at large scale, especially on the spatial niche axis. Our results suggest that a combination of interacting factors, in conjunction with habitat features and intervening human activities, may make mesopredator release unlikely or difficult to discern at broad scales. Overall, we believe that promoting the creation of new protected areas linked by small forest patches would likely lead to increased predator and prey abundances, as well as the interactions among carnivores inside and outside of protected areas.

First record of a potential neonate tiger shark (Galeocerdo cuvier) at a remote oceanic island in the Eastern Tropical Pacific.

Tiger sharks (Galeocerdo cuvier) play an important ecological role as top predators, yet knowledge of their reproductive ecology is scarce. Here, the authors report the first observation of a potential neonate G. cuvier at Cocos Island, a predator-dominated oceanic island in the Eastern Tropical Pacific (ETP). The individual was detected using baited remote underwater video stations (BRUVS). The cameras also detected female individuals potentially pregnant, suggesting that parturition may take place at or near the island. Nonetheless, it is still unclear if the presence of a single neonate is an isolated event or evidence that the species is using the island for reproduction.

Consumptive effects and mismatch in predator-prey turnover rates cause inversion of biomass pyramids.

The mismatch between the turnover rates of predators and prey is one of the oldest explanations for the existence of inverted trophic pyramids. To date, the hypotheses regarding trophic pyramids have all been based on consumptive trophic links between predators and prey, and the relative contribution of non-consumptive effects is still unknown. In this study, we investigated if the inversion of pyramids in bromeliad ecosystems is driven by (i) a rapid colonization of organisms having short cohort interval production (CPI), and (ii) the prevalence of consumptive or non-consumptive effects of top predators. We used a manipulative experiment to investigate the patterns of prey colonization and to partition the net effects of the dominant predator (damselfly larvae) on biomass pyramids into consumptive (uncaged damselfly larvae) and non-consumptive effects (caged damselfly larvae). Consumptive effects of damselflies strengthened the inversion of trophic pyramids. Non-consumptive effects, however, did not affect the shape of biomass pyramids. Instead, the rapid colonization of organisms with predominantly short CPI sustained the large biomass of top predators found in natural bromeliad ecosystems. Prey colonized bromeliads rapidly, but this high production was never visible as standing stock because damselflies reduce prey densities by more than a magnitude through direct consumption. Our study adds to the growing evidence that there are a variety of possible ways that biomass can be trophically structured. Moreover, we suggest that the strength of biomass pyramids inversion may change with the time of ecological succession as prey communities become more equitable.

Distribución y estado poblacional del lobo de río (Pteronura brasiliensis) en la cuenca del río Madre de Dios, sureste del Perú

Se presenta información del estado poblacional y distribución geográfica del lobo de río (Pteronura brasiliensis) en la región Madre de Dios durante los años 2014 y 2015. La población registrada fue de 128 individuos para ambos años, agrupados en 22 grupos familiares en el año 2014 y 20 grupos en el año 2015. Los sectores con mayores abundancias fueron el Parque Nacional del Manu con 2.2 ind/10 km, seguido del Parque Nacional Bahuaja Sonene con 1.43 ind/10 km. La mayor población de lobo de río fuera de las áreas naturales protegidas (ANP) fue registrada en la cuenca del río Las Piedras con una abundancia de 0.5 ind/10 km, seguido de la cuenca de Los Amigos con 0.43 ind/10 km. Las poblaciones dentro de ANP se muestran estables y protegidas (17 grupos familiares en ambos años), mientras que fuera de ANP se registraron solamente 5 grupos en el año 2014 y 2 grupos en el 2015. Actualmente, las mayores amenazadas para las poblaciones de lobo de río en Madre de Dios y la causa de la degradación de sus hábitats la minería aluvial, agricultura y ganadería cerca de los cauces de ríos. Esta situación sugiere la urgente necesidad del establecimiento de iniciativas de conservación en toda la cuenca del río Madre de Dios, en especial fuera de ANP

Population status and geographic distribution of the giant otter (Pteronura brasiliensis) from Madre de Dios Region (south-eastern Peru) of 2014 and 2015 periods are presented. Population census for each period were 128 individuals, grouped in 22 and 20 resident groups during 2014 and 2015 periods respectively. The Manu National Park (2.2 ind/10 km) and Bahuaja Sonene National Park (1.43 ind/10 km.) were the sectors with the greatest abundance of giant otters inside the natural protected areas (ANP), while, Las Piedras and Los Amigos rivers were the sectors, outside the ANP, with highest value of abundance: 0.5 and 0.43 ind/10 km respectively. The populations inside ANP show more stable and protected (17 resident groups), while outside ANP are more vulnerable, where we registered only five (2014) and two (2015) giant otter groups. Currently, the main threats for giant other populations from Madre de Dios and the cause of the environmental degradation of its habitats are the gold mining, agriculture and logging. This situation suggests the urgent need to establish a conservation program throughout the region, especially outside ANP