Nicolás Caruso

Carnivore occurrence: do interview-based surveys produce unreliable results?

Interviews with local people have been widely used by biologists as a cost-effective approach to studying certain topics in wildlife ecology and conservation. However, doubts still exist about the validity and quality of the information gathered, especially in studies targeting cryptic or elusive species, such as carnivores. We assessed the reliability of interviews (n = 155) in detecting the presence of three species of carnivores with different characteristics, by comparing interview results with data obtained through camera trapping surveys at 52 sites in central Argentina. The degree of concordance between methods was low for Geoffroys cat Leopardus geoffroyi and especially for the puma Puma concolor . However, Geoffroys cats were detected more frequently by camera traps than interviews, whereas the opposite was true for pumas. For the pampas fox Pseudalopex gymnocercus , a less elusive species, we observed a high degree of concordance and a similar probability of occurrence between methods. Our results indicate that data obtained by interviewing local inhabitants should be used with caution because the information about species presence provided by local people may be inaccurate and biased.

Species-Specific Responses of Carnivores to Human-Induced Landscape Changes in Central Argentina

The role that mammalian carnivores play in ecosystems can be deeply altered by human-driven habitat disturbance. While most carnivore species are negatively affected, the impact of habitat changes is expected to depend on their ecological flexibility. We aimed to identify key factors affecting the habitat use by four sympatric carnivore species in landscapes of central Argentina. Camera trapping surveys were carried out at 49 sites from 2011 to 2013. Each site was characterized by 12 habitat attributes, including human disturbance and fragmentation. Four landscape gradients were created from Principal Component Analysis and their influence on species-specific habitat use was studied using Generalized Linear Models. We recorded 74 events of Conepatus chinga, 546 of Pseudalopex gymnocercus, 193 of Leopardus geoffroyi and 45 of Puma concolor. We found that the gradient describing sites away from urban settlements and with low levels of disturbance had the strongest influence. L. geoffroyi was the only species responding significantly to the four gradients and showing a positive response to modified habitats, which could be favored by the low level of persecution by humans. P. concolor made stronger use of most preserved sites with low proportion of cropland, even though the species also used sites with an intermediate level of fragmentation. A more flexible use of space was found for C. chinga and P. gymnocercus. Our results demonstrate that the impact of human activities spans across this guild of carnivores and that species-specific responses appear to be mediated by ecological and behavioral attributes.

Characterization of puma–livestock conflicts in rangelands of central Argentina

Livestock predation is one of the major causes of conflicts between humans and pumas (Puma concolor). Using data from interviews with ranchers and kill-site inspections, we characterized puma–livestock conflicts in Villarino and Patagones counties of central Argentinean rangelands. Depredation was considered the major cause of livestock losses, and puma attacks were reported in 46.6% and 35.4% of ranches in Villarino and Patagones, respectively. The majority of ranches underwent losses smaller than 1000 USD. The proportion of livestock lost to predation (0.1–10.4%) and financial losses (5.3–1560.4 USD) per ranch/year varied across ranches, and small sheep ranches in Villarino were affected the most. Depredation was recorded only at night and preferentially in grassland with shrubs and cropland habitats. Although nocturnal enclosures appeared to decrease sheep losses, puma hunting was considered the most effective form of reducing depredation and was implemented by most ranchers. Mortality rates were 3.7 and 1.1–1.56 individuals/year × 100 km2 for sheep and pumas, respectively. Nocturnal fencing, shepherding and spatial separation from predators may efficiently reduce sheep losses. However, the poor association between the intensity of puma persecution and puma-related livestock losses suggests that conflict mitigation in central Argentina is not only about reducing damage but also about increasing tolerance.

Activity patterns of Molina’s hog-nosed skunk in two areas of the Pampas grassland (Argentina) under different anthropogenic pressure

This study describes and compares the activity patterns of free-ranging Molina’s hog-nosed skunks (Conepatus chinga) in a protected area (PA) and in a cropland area (CA) in the Pampas grassland of Argentina. Sixteen skunks (PA: three males, four females; CA: three males, six females) were captured and monitored using radio-telemetry techniques for 92–395 days each. In both areas, C. chinga was largely nocturnal and the start and cessation of activity was related to sunset and sunrise, respectively. Skunks spent more time active in the PA, where the level of anthropogenic activity was lower, and this difference was due to increased activity during the daylight hours. Finally, activity was greater for females than for males, and in the warm season when compared to the cold season. In the Pampas grasslands of Argentina, activity of Molina’s hog-nosed skunks seems to be influenced by both food availability and predation risk related to human presence.

Summer habitat use and activity patterns of wild boar Sus scrofa in rangelands of central Argentina

Biological invasions are one of the main components of human-caused global change and their negative impact on invaded ecosystems have long been recognized. Invasive mammals, in particular, can threaten native biodiversity and cause economic impacts in the region where they are introduced, often through a wide range of conflicts with humans. Although the wild boar, Sus scrofa, is considered by the IUCN as one of the 100 invasive species most damaging to biodiversity in the world, in Argentina there have only been a few studies focused on its ecology with most of them conducted in protected areas. In this study, we evaluated the effect of several factors related with human disturbance, landscape composition, degree of fragmentation and the presence of a potential competitor and a predator on the habitat use of wild boar using data from camera traps and site-occupancy modeling. Additionally, we described the daily activity pattern of the species and we studied the level of overlap with both a potential competitor and a predator. The sampling effort totaled 7,054 camera trap days. Farm density, proportion of shrubland and proportion of grassland with bushes were the detection variables included in the most supported model whereas proportion of grassland and capture rate of the Pampas fox Lycalopex gymnocercus were the occupancy variables included in the most supported model. However, the proportion of grassland was the only variable that showed statistically significant support in the averaged model, indicating that habitat use of wild boar in this area was significantly negatively affected by the level of grass cover. Wild boars were mostly nocturnal, with more activity between 21:00 and 3:00 and a peak around midnight. Wild boars showed a high level of overlap with the activity pattern of the Pampas fox and a low overlap with the activity pattern of the puma Puma concolor. Despite wild boar being introduced in Argentina a few decades ago, this study is the first landscape-scale research carried out in an agricultural landscape in Argentina and the first one based on camera-trapping data. Our study contributes valuable information that could be used to design strategies to reduce wild boar population or to minimize the damage caused by this invasive species in Argentina.

Updating the distribution and population status of Jaguarundi, Puma yagouaroundi (É. Geoffroy, 1803) (Mammalia: Carnivora: Felidae), in the southernmost part of its distribution range

We report new occurrence records of Puma yagouaroundi (É. Geoffroy, 1803), a widely distributed but little known Neotropical carnivore, obtained over the last 10 years in Buenos Aires province, central Argentina. The records were collected by camera trapping surveys (n = 384 stations) and 195 interviews with local inhabitants. Our results improve our understanding of this species’ geographic range, especially its southernmost limit, and abundance, and confirm the need for more detailed studies to better assess the conservation status of this species in central Argentina and other parts of its range.

First Density Estimation of Two Sympatric Small Cats, Leopardus colocolo and Leopardus geoffroyi, in a Shrubland Area of Central Argentina

Geoffroys and Pampas cats are small felids with large distribution ranges in South America. A camera trap survey was conducted in the Espinal of central Argentina to estimate abundance based on capture—recapture data. For density estimations we used both non-spatial methods and spatially explicit capture—recapture models (SECR). For Geoffroys cat we also obtained density estimates from 8 radio-tracked individuals. Based on the data on 10 Geoffroys cats and 7 Pampas cats, non-spatial methods produced density ranges of 16.21–21.94 indiv./100 km2 and 11.34–17.58 indiv./100 km2, respectively. The density estimated using SECR models was 45 animals/100 km2 for Geoffroys cat, whereas we were unable to produce a reliable estimate for the Pampas cat. The SECR estimate for Geoffroys cat is more similar to that obtained from telemetry data (58.82 cats/100 km2). In agreement with the hypothesis of its greater adaptability, Geoffroys cat was more abundant than the Pampas cat.