Large-scale population disappearances and cycling in the white-lipped peccary, a tropical forest mammal.

Many vertebrate species undergo population fluctuations that may be random or regularly cyclic in nature. Vertebrate population cycles in northern latitudes are driven by both endogenous and exogenous factors. Suggested causes of mysterious disappearances documented for populations of the Neotropical, herd-forming, white-lipped peccary (Tayassu pecari, henceforth "WLP") include large-scale movements, overhunting, extreme floods, or disease outbreaks. By analyzing 43 disappearance events across the Neotropics and 88 years of commercial and subsistence harvest data for the Amazon, we show that WLP disappearances are widespread and occur regularly and at large spatiotemporal scales throughout the species' range. We present evidence that the disappearances represent 7-12-year troughs in 20-30-year WLP population cycles occurring synchronously at regional and perhaps continent-wide spatial scales as large as 10,000-5 million km2. This may represent the first documented case of natural population cyclicity in a Neotropical mammal. Because WLP populations often increase dramatically prior to a disappearance, we posit that their population cycles result from over-compensatory, density-dependent mortality. Our data also suggest that the increase phase of a WLP cycle is partly dependent on recolonization from proximal, unfragmented and undisturbed forests. This highlights the importance of very large, continuous natural areas that enable source-sink population dynamics and ensure re-colonization and local population persistence in time and space.

Long-term trends in a forest ungulate community: park establishment increases numbers, but poaching is a constant threat.

Deforestation represents one of the greatest threats to tropical forest mammals, and the situation is greatly exacerbated by bushmeat hunting. To construct informed conservation plans, information must be gathered about responses to habitat degradation, regeneration, and hunting over a sufficiently long period to allow demographic responses. We quantified changes in the abundance of three commonly occurring ungulate species (i.e., bushbuck, Tragelaphus scriptus; red duiker, Cephalophus sp.; blue duiker, Cephalophus monticola) at eight sites in Kibale National Park, Uganda (old growth=3; logged=3; regenerating=2) for 23 years. Changes in abundance (363 surveys totaling 1 450 km) were considered in regard to the park's management strategy, regional economic indicators, and estimates of illegal hunting. Bushbuck abundance increased in old-growth and logged forests from 1996 to 2009, and then oscillated around this level or declined. Duiker abundance demonstrated a similar pattern, but abundance in the old-growth forests showed a general increase from 1996 to present day. Duiker abundance in the logged forests exhibited an early increase, but subsequent oscillation. Poaching signs per patrol have remained stable over the last decade, despite increases in the size of the surrounding population, cost of living, and cost of schooling, thus reflecting successful efforts in conservation education and enforcement. Our study highlights the positive impact of park establishment, patrol, and conservation efforts on ungulate populations and shows the adaptability of forest mammal populations to different management schemes.

Correction to: Towards the restoration of the Mesoamerican Biological Corridor for large mammals in Panama: comparing multi-species occupancy to movement models.

[This corrects the article DOI: 10.1186/s40462-019-0186-0.].

Towards the restoration of the Mesoamerican Biological Corridor for large mammals in Panama: comparing multi-species occupancy to movement models.

BACKGROUND: Habitat fragmentation is a primary driver of wildlife loss, and the establishment of biological corridors is a conservation strategy to mitigate this problem. Identifying areas with high potential functional connectivity typically relies on the assessment of landscape resistance to movement. Many modeling approaches exist to estimate resistance surfaces but to date only a handful of studies compared the outputs resulting from different methods. Moreover, as many species are threatened by fragmentation, effective biodiversity conservation requires that corridors simultaneously meet the needs of multiple species. While many corridor planning initiatives focus on single species, we here used a combination of data types and analytical approaches to identify and compare corridors for several large mammal species within the Panama portion of the Mesoamerican Biological Corridor. METHODS: We divided a large mammal assemblage into two groups depending on the species sensitivity to habitat disturbance. We subsequently used cost-distance methods to produce multi-species corridors which were modeled on the basis of (i) occupancy of nine species derived from camera trapping data collected across Panama, and (ii) step selection functions based on GPS telemetry data from white-lipped peccary Tayassu pecari, puma Puma concolor, and ocelot Leopardus pardalis. In addition to different data sources and species groups, we also used different transformation curves to convert occupancy and step-selection results into landscape resistance values. RESULTS: Corridors modeled differed between sensitive and tolerant species, between the data sets, and between the transformation curves. There were more corridors identified for tolerant species than for sensitive species. For tolerant species, several corridors developed with occupancy data overlapped with corridors produced with step selection functions, but this was not the case for sensitive species. CONCLUSION: Our study represents the first comparison of multispecies corridors parametrized with step selection functions versus occupancy models. Given the wide variability in output corridors, our findings underscore the need to consider the ecological requirements of several species. Our results also suggest that occupancy models can be used for estimating connectivity of generalist species. Finally, this effort allowed to identify important corridors within the MBC (i) at a country scale and (ii) for several species simultaneously to accurately inform the local authorities in conservation planning. The approach we present is reproducible in other sites and/or for other species.

Effectiveness of Panama as an intercontinental land bridge for large mammals.

Habitat fragmentation is a primary driver of wildlife loss, and establishment of biological corridors is a common strategy to mitigate this problem. A flagship example is the Mesoamerican Biological Corridor (MBC), which aims to connect protected forest areas between Mexico and Panama to allow dispersal and gene flow of forest organisms. Because forests across Central America have continued to degrade, the functioning of the MBC has been questioned, but reliable estimates of species occurrence were unavailable. Large mammals are suitable indicators of forest functioning, so we assessed their conservation status across the Isthmus of Panama, the narrowest section of the MBC. We used large-scale camera-trap surveys and hierarchical multispecies occupancy models in a Bayesian framework to estimate the occupancy of 9 medium to large mammals and developed an occupancy-weighted connectivity metric to evaluate species-specific functional connectivity. White-lipped peccary (Tayassu pecari), jaguar (Panthera onca), giant anteater (Myrmecophaga tridactyla), white-tailed deer (Odocoileus virginianus), and tapir (Tapirus bairdii) had low expected occupancy along the MBC in Panama. Puma (Puma concolor), red brocket deer (Mazama temama), ocelot (Leopardus pardalis), and collared peccary (Pecari tajacu), which are more adaptable, had higher occupancy, even in areas with low forest cover near infrastructure. However, the majority of species were subject to ≥1 gap that was larger than their known dispersal distances, suggesting poor connectivity along the MBC in Panama. Based on our results, forests in Darien, Donoso-Santa Fe, and La Amistad International Park are critical for survival of large terrestrial mammals in Panama and 2 areas need restoration.

Efectividad de Panamá como un Puente Terrestre Intercontinental para Mamíferos Mayores Resumen La fragmentación del hábitat es un causante primario de la pérdida de biodiversidad, y el establecimiento de corredores biológicos es una estrategia común para mitigar este problema. El Corredor Biológico Mesoamericano (CBM) es un ejemplo notable que pretende conectar áreas boscosas protegidas entre México y Panamá para permitir la dispersión y flujo genético de organismos del bosque. El funcionamiento del CBM se ha cuestionado debido a que la degradación de los bosques en Centroamérica continúa, pero no se dispone de estimaciones confiables de la ocurrencia de especies. Los mamíferos grandes son indicadores adecuados del funcionamiento de los bosques tropicales Por lo tanto evaluamos su estado de conservación en el Istmo de Panamá, la sección más angosta del CBM. Utilizamos muestreos con cámaras trampa y modelos de ocupación para múltiples especies bajo un modelo Bayesiano para estimar la ocupación de 9 especies de mamíferos medianos a grandes, y desarrollamos una métrica de conectividad ponderada por la ocupación para evaluar la conectividad funcional para cada especie. El puerco de monte (Tayassu pecari), jaguar (Panthera onca), hormiguero gigante (Myrmecophaga tridactyla), venado cola blanca (Oidocoileus virginianus), y tapir (Tapirus bairdii) presentaron una ocupación baja en el CBM en Panamá. El puma (Puma concolor), venado corzo (Mazama temama), ocelote (Leopardus pardalis) y el saino (Pecari tajacu), que son más adaptables, presentaron mayor ocupación, aún en áreas con poca cobertura boscosa, cercanas a infraestructura. Sin embargo, la mayoría de las especies estuvo sujeta a ≥ 1 vacío que era mayor que sus distancias de dispersión conocidas, lo que sugiere una conectividad pobre a lo largo del CBM en Panamá. Basados en nuestros resultados, los bosques de Darién, Donoso-Santa Fé y el Parque Internacional La Amistad son críticos para la supervivencia de mamíferos terrestres grandes en Panamá mientras que 2 áreas requieren restauración.

Distribución potencial del cerdo asilvestrado, Sus scrofa (Artiodactyla: Suidae) y el pecarí de collar, Pecari tajacu (Artiodactyla: Tayassuidae) en la región de Laguna de Términos, México

Introducción: La presencia de los cerdos asilvestrados (Sus scrofa) combinado con la fragmentación del hábitat presente en la región de Laguna de Términos, Campeche, puede generar cambios en los patrones de distribución y presencia de pecaríes de collar (Pecari tajacu). Objetivo: Evaluar el traslape o segregación espacial en la distribución de cerdos asilvestrados y pecaríes de collar mediante modelos de distribución potencial de ambas especies en la región de Laguna de Términos, Campeche. Métodos: Se generaron modelos de distribución potencial usando datos de presencia y variables antrópicas y bioclimáticas en Maxent. Resultados: Los modelos mostraron segregación espacial entre ambas especies. Los cerdos asilvestrados fueron positivamente influenciados por la cercanía a cultivos de palma de aceite (Elaeis guineensis) y por la precipitación estacional; la distribución potencial para pecaríes de collar estuvo positivamente correlacionada con la temperatura y la cobertura arbórea. Se confirmó la presencia de cerdos asilvestrados en Escárcega, Carmen, Candelaria y Palizada, en el estado de Campeche y en Balancán y Jonuta en el estado de Tabasco. Nuestros modelos predicen áreas potenciales para los cerdos asilvestrados principalmente en la Reserva de la Biosfera Pantanos de Centla en Tabasco y en áreas cercanas a la frontera con Guatemala. Discusión: Consideramos necesario implementar un plan de control para los cerdos asilvestrados, no solo en la región de Laguna de Términos, sino en áreas aledañas con la finalidad de impedir la expansión de su distribución y el desplazamiento de especies nativas como los pecaríes en otras áreas del sur del país.

Introduction: The presence of feral pigs (Sus scrofa) in addition to habitat fragmentation at Laguna de Términos, Campeche, could cause changes in the distribution patterns and presence of collared peccaries (Pecari tajacu). Objective: Modelling of potential distribution to assess the overlap or spatial segregation of both species at Laguna de Términos, Campeche. Methods: Potential distribution models were generated with presence data, anthropic and bioclimatic variables using the maximum entropy algorithm (Maxent). Results: The potential distribution models showed spatial segregation between both species. The presence of feral pigs was positively influenced by palm oil crops (Elaeis guineensis) proximity and seasonal rainfall; the potential distribution of collared peccaries was positively correlated with temperature and canopy coverage. Evidence of feral pigs presence was confirmed in Escárcega, Carmen, Candelaria and Palizada in Campeche state and in Balancán and Jonuta in Tabasco state. Our models predicted potential areas for feral pigs in Pantanos de Centla Biosphere Reserve in Tabasco and in areas near the Guatemalan border. Conclusions: We believe a control plan for feral pigs is needed, not only in Laguna de Términos region, but also in adjacent areas in order to prevent the range extension and displacement of native species such as peccaries in other areas in Southern Mexico.

Spider Monkey (Ateles geoffroyi) Travel to Resting Trees in a Seasonal Forest of the Yucatan Peninsula, Mexico.

Resting by primates is considered an understudied activity, relative to feeding or moving, despite its importance in physiological and time investment terms. Here we describe spider monkeys' (Ateles geoffroyi) travel from feeding to resting trees in a seasonal tropical forest of the Yucatan Peninsula. We followed adult and subadult individuals for as long as possible, recording their activities and spatial location to construct travel paths. Spider monkeys spent 44% of the total sampling time resting. In 49% of the cases, spider monkeys fed and subsequently rested in the same tree, whereas in the remaining cases they travelled a mean distance of 108.3 m. Spider monkeys showed high linear paths (mean linearity index = 0.77) to resting trees when they travelled longer distances than their visual field, which suggests travel efficiency and reduced travel cost. Resting activity is time consuming and affects the time available to search for food and engage in social interactions.

Emergent group level navigation: an agent-based evaluation of movement patterns in a folivorous primate.

The foraging activity of many organisms reveal strategic movement patterns, showing efficient use of spatially distributed resources. The underlying mechanisms behind these movement patterns, such as the use of spatial memory, are topics of considerable debate. To augment existing evidence of spatial memory use in primates, we generated movement patterns from simulated primate agents with simple sensory and behavioral capabilities. We developed agents representing various hypotheses of memory use, and compared the movement patterns of simulated groups to those of an observed group of red colobus monkeys (Procolobus rufomitratus), testing for: the effects of memory type (Euclidian or landmark based), amount of memory retention, and the effects of social rules in making foraging choices at the scale of the group (independent or leader led). Our results indicate that red colobus movement patterns fit best with simulated groups that have landmark based memory and a follow the leader foraging strategy. Comparisons between simulated agents revealed that social rules had the greatest impact on a group's step length, whereas the type of memory had the highest impact on a group's path tortuosity and cohesion. Using simulation studies as experimental trials to test theories of spatial memory use allows the development of insight into the behavioral mechanisms behind animal movement, developing case-specific results, as well as general results informing how changes to perception and behavior influence movement patterns.

Patch depletion behavior differs between sympatric folivorous primates.

Food competition in group-living animals is commonly accepted as a critical determinant of foraging strategies and social organization. Here we examine food patch depletion behavior in a leaf-eating (folivorous) primate, the guereza (Colobus guereza). Snaith and Chapman (2005) studied the sympatric folivorous red colobus (Procolobus rufomitratus), which shares many food resources with the guereza. They determined that red colobus deplete the patches (feeding trees) they use, while we found contrary evidence for guerezas using the same methods. We found that the time guerezas spent feeding in a patch was affected by neither tree size, an indicator of food abundance, nor the size of the feeding group, an indicator of feeding competition. For their principal food item (young leaves), intake rate remained constant and coincided with a decrease in the distance moved to find food within a patch, implying that guerezas do not deplete patches. This points to a fundamental difference in the use of food by guerezas and red colobus, which may be linked to the large difference in their group sizes and/or to a disparity in their digestive physiologies. However, further analyses revealed that the number of feeders within a patch did not affect patch depletion patterns in either species, leaving the potential for a physiological basis as the most plausible explanation. Our research highlights the need for a more critical examination of folivorous primate feeding ecology and social behavior, as all folivorous primates are typically lumped into a single category in socioecological models, which may account for conflicting evidence in the literature.