American marten occupancy and activity patterns at the southern extent of their range in the eastern United States

The relatively recent rediscovery of an American marten (Martes americana) population that was reintroduced over 30 years ago in southern Vermont provides an opportunity to investigate the relative importance of other mesocarnivores, and forest stand (e.g., DBH, downed logs, vertical structure) and habitat variables to their presence on the Green Mountain National Forest. Marten are state-listed as an endangered species in Vermont and occur there at the southern extent of their range in the eastern United States. We collected detection data from camera surveys in 5 km2 units between 2019 and 2021 (December-April; n = 40 units, 238 cameras). We examined activity patterns and applied an occupancy modeling framework to the detection data to assess the relative importance of covariates at unit and camera levels and assess interactions of marten with other mesocarnivores. We did not find any unit-level occupancy models with significant covariates that were better supported than the base model in the single-season unit-level analysis. Distance to the nearest release site was the covariate most supported for detectability at both spatial scales, and marten occupancy at the camera level was positively influenced by the amount of canopy cover. Two species interaction models did not indicate any positive or negative association beyond random with other mesocarnivores and activity patterns among mesocarnivores had substantial overlap. Marten recovery since the time of the reintroduction appears slow, and even 30 years later, the marten distribution is limited and suggests that dispersal is restricted at some level. We recommend a further investigation of the possible impact of other mesocarnivores to juvenile survival or other vital demographic rate (e.g., recruitment) in marten that were not explicitly measured in this study.

Syntopy between Endangered San Joaquin Kit Foxes and Potential Competitors in an Urban Environment

The endangered San Joaquin kit fox (Vulpes macrotis mutica; SJKF) occurs in the city of Bakersfield, CA, where several putative competitors also occur, including domestic cats (Felis catus), striped skunks (Mephitis mephitis), raccoons (Procyon lotor), and opossums (Didephis virginiana). We used data from a multi-year (2015-2022) city-wide camera station survey to assess whether the other species were simply sympatric with SJKF or coexisting syntopically (i.e., occurring in the same habitats without apparent competition). Annual detection rates for the other species were not correlated with SJKF rates either within SJKF habitat suitability categories (low, medium, and high) or for all categories combined. Also, detection rates for the other species did not increase in response to a significant decline in SJKF abundance caused by sarcoptic mange. The use of all SJKF habitat suitability categories by the other species and co-detections with SJKF at camera stations indicate high spatial overlap. Interference and exploitative competition between the species are apparently negligible, likely due to similar body sizes and high resource abundance. Thus, SJKF and the other species appear to be coexisting syntopically in the urban environment, resulting in a significant additional SJKF population that facilitates range-wide conservation and recovery of this endangered species.

Habitat modification destabilizes spatial associations and persistence of Neotropical carnivores

Spatial relationships between sympatric species underpin biotic interactions, structure ecological communities, and maintain ecosystem health. However, the resilience of interspecific spatial associations to human habitat modification remains largely unknown, particularly in tropical regions where anthropogenic impacts are often greatest. We applied multi-state multi-species occurrence models to camera trap data across nine tropical landscapes in Colombia to understand how prominent threats to forest ecosystems influence Neotropical carnivore occurrence and interspecific spatial associations, with implications for biotic interactions. We show that carnivore occurrence represents a delicate balance between local environmental conditions and interspecific interactions that can be compromised in areas of extensive habitat modification. The stability of carnivore spatial associations depends on forest cover to mediate antagonistic encounters with apex predators and structurally intact forests to facilitate coexistence between competing mesocarnivores. Notably, we demonstrate that jaguars play an irreplaceable role in spatially structuring mesocarnivore communities, providing novel evidence on their role as keystone species. With increasing global change, conserving both the extent and quality of tropical forests is imperative to support carnivores and preserve the spatial associations that underpin ecosystem stability and resilience.

Spatiotemporal interactions of a novel mesocarnivore community in an urban environment before and during SARS-CoV-2 lockdown

Studying species interactions and niche segregation under human pressure provides important insights into species adaptation, community functioning and ecosystem stability. Due to their high plasticity in behaviour and diet, urban mesocarnivores are ideal species for studying community assembly in novel communities.

We analysed the spatial and temporal species interactions of an urban mesocarnivore community composed of the red fox Vulpes vulpes and the marten Martes sp. as native species, the raccoon Procyon lotor as invasive species, and the cat Felis catus as a domestic species in combination with human disturbance modulated by the SARS‐CoV‐2 lockdown effect that happened while the study was conducted.

We analysed camera trap data and applied a joint species distribution model to understand not only the environmental variables influencing the detection of mesocarnivores and their use intensity of environmental features but also the species’ co‐occurrences while accounting for environmental variables. We then assessed whether they displayed temporal niche partitioning based on activity analyses, and finally analysed at a smaller temporal scale the time of delay after the detection of another focal species.

We found that species were more often detected and displayed a higher use intensity in gardens during the SARS‐CoV‐2 lockdown period, while showing a shorter temporal delay during the same period, meaning a high human‐induced spatiotemporal overlap. All three wild species spatially co‐occurred within the urban area, with a positive response of raccoons to cats in detection and use intensity, whereas foxes showed a negative trend towards cats. When assessing the temporal partitioning, we found that all wild species showed overlapping nocturnal activities. All species displayed temporal segregation based on temporal delay. According to the temporal delay analyses, cats were the species avoided the most by all wild species. To conclude, we found that although the wild species were positively associated in space, the avoidance occurred at a smaller temporal scale, and human pressure in addition led to high spatiotemporal overlap.

Our study sheds light to the complex patterns underlying the interactions in a mesocarnivore community both spatially and temporally, and the exacerbated effect of human pressure on community dynamics.

Parasites of the Reintroduced Iberian Lynx (Lynx pardinus) and Sympatric Mesocarnivores in Extremadura, Spain

The Iberian lynx (Lynx pardinus) is one of the most endangered felid species in the world. Conservation efforts have increased its population size and distribution and reinforced their genetic diversity through captive breeding and reintroduction programmes. Among several threats that the Iberian lynx faces, infectious and parasitic diseases have underlined effects on the health of their newly reintroduced populations, being essential to identify the primary sources of these agents and assess populations health status. To achieve this, 79 fresh faecal samples from Iberian lynx and sympatric mesocarnivores were collected in the reintroduction area of Extremadura, Spain. Samples were submitted to copromicroscopic analyses to assess parasite diversity, prevalence, and mean intensity of parasite burden. Overall, 19 (24.1%, ±15.1–35.0) samples were positive for at least one enteric parasite species. Parasite diversity and prevalence were higher in the Iberian lynx (43.8%) compared with the others mesocarnivores under study (e.g., the red fox Vulpes vulpes and the Egyptian mongoose Herpestes ichneumon). Ancylostomatidae and Toxocara cati were the most prevalent (15.6%) parasites. Obtained results revealed that Iberian lynx role as predator control might have reduced parasite cross-transmission between this felid and mesocarnivores due to their decreasing abundances. Surveillance programs must include regular monitoring of this endangered felid, comprising mesocarnivores, but also domestic/feral and wild cat communities.

Abiotic conditions mediate intraguild interactions between mammalian carnivores

Intraguild (IG) interactions are common among mammalian carnivores, can include intraguild predation (IGP) and interspecific killing (IK), and are often asymmetrical, where a larger more dominant species (IG_predator ) kills a smaller one (IG_prey ). According to ecological theory, the potential for an IG_predator and IG_prey to coexist depends on whether the direct consumptive benefits for the IG_predator are substantial (IGP) or insignificant (IK), the extent to which the IG_prey is the superior exploitative competitor on shared prey resources, and overall ecosystem productivity. We used resource selection models and spatially explicit age and harvest data for two closely related mesopredators that engage in IG interactions, American martens (Martes americana; IG_prey ) and fishers (Pekania pennanti; IG_predator ), to identify drivers of distributions, delineate areas of sympatry and allopatry, and explore the role of an apex predator (coyote; Canis latrans) on these interactions. Model selection revealed that fisher use of this landscape was strongly influenced by late winter abiotic conditions, but other bottom-up (forest composition) and top-down (coyote abundance) factors also influenced their distribution. Overall, fisher probability of use was higher where late winter temperatures were warmer, snowpack was deeper, and measures of productivity were greater. Martens were constrained to areas of the landscape where the probability of fisher use, coyote abundance, and productivity were low and selected for forest conditions that presumably maximized prey availability. Marten age data indicated an increased proportion of juveniles outside of the predicted area of sympatry, suggesting that few animals survived >1.5 years in this area that supported higher densities of fishers and coyotes. Consistent with asymmetrical IG interaction theory, the IG_predator (fishers and, to a lesser degree, coyotes) competitively excluded the IG_prey (martens) from more productive, milder temperature habitats, whereas IG_predators and IG_prey coexisted in low productivity environments, where a combination of abiotic and biotic conditions enabled the IG_prey to be the superior exploitative competitor.