Patrones de actividad circadiana y lunar del jaguar y el puma en relación con sus presas y competidoras (Carnivora: Felidae)

Introduction: Temporal niche changes can shape predator-prey interactions by allowing prey to evade predators, improve feeding efficiency, and reduce competition among predators. In addition to circadian activity patterns, the monthly lunar cycle can influence the nocturnal activity of mammals. Objective: Through camera trap surveys at sites on the Pacific slope and the Talamanca Cordillera, we investigated the patterns of circadian (day and night) and nocturnal activity during the moon phases of the jaguar (Panthera onca) and puma (Puma concolor). Methods: We investigated the overlap and temporal segregation between pairs of each predator and its primary prey, and between its competitors using overlap analysis, circular statistics, and relative abundance, taking into account differences in habitat, seasons, and human impact between sites. Results: Our results supported the existence of a temporal niche separation between the two predator species, although both were classified as cathemeral - the jaguar was mainly diurnal, while the puma was mainly nocturnal. We found that the jaguar and puma practice different patterns of nocturnal activity during the phases of the moon, with the jaguar exhibiting a dramatic increase in activity during the full moon and the puma maintaining a more consistent level of activity throughout the moon phases. However, during the full moon, both species were more active at night and less active during the day, suggesting that they practice a temporary niche change to take advantage of hunting activities during the brightest lunar illumination of each month. We discuss predicted primary prey and competing species. Conclusion: We conclude that jaguar and puma exhibit significant niche separation in circadian and lunar activity patterns. Through these differences in temporal activity, jaguar and puma can exploit a slightly different prey base despite their similar large size.Introducción: Los cambios temporales de nicho pueden amoldar las interacciones predador-presa al permitir a la presa evadir los predadores, mejorar la eficacia de la alimentación y reducir la competición entre predadores. Además de los patrones de actividad circadianos, el ciclo lunar mensual puede influye en los patrones de actividad nocturna de los mamíferos. Objetivo: Mediante muestreos con cámaras trampa en sitios de la pendiente del Pacífico y la Cordillera de Talamanca, investigamos los patrones de actividad circadiana (día y noche) y nocturna durante las fases de la luna del jaguar (Panthera onca) y puma (Puma concolor). Métodos: Investigamos la superposición y segregación temporal entre pares de cada predador y sus presas primarias, y entre sus competidores utilizando análisis de superposición, estadísticas circulares y abundancia relativa, teniendo en cuenta diferencias de hábitat, estaciones, y de impacto humano entre los sitios. Resultados: Nuestros resultados respaldaron la existencia de una separación temporal de nicho entre las dos especies de predadores, aunque ambos fueron clasificados como catemerales, el jaguar era principalmente diurno, mientras que el puma era principalmente nocturno. Descubrimos que el jaguar y el puma practican distintos patrones de actividad nocturna durante las fases de la luna, con el jaguar exhibiendo un aumento dramático en la actividad durante la luna llena y el puma manteniendo un nivel de actividad más consistente a través de las fases lunares. Sin embargo, durante la luna llena, ambas especies fueron más activas durante la noche y menos activas durante el día, lo que sugiere que practican un cambio de nicho temporal para aprovechar las actividades de caza durante la iluminación lunar más brillante de cada mes. Discutimos las presas primarias predichas y las especies competidoras.  Conclusión: Concluimos que el jaguar y el puma exhiben una separación de nicho significativa en actividad circadiana y lunar. A través de estos distintos patrones de actividad temporal, el jaguar y el puma pueden explotar una base de presas ligeramente diferente a pesar de su tamaño similar

Selección natural del melanismo en jaguar y tigrillo (Carnivora: Felidae)

Introduction: The persistence of coat color polymorphisms, such as the coexistence of the melanistic coat color (black) and "wild type" (spotted), is an evolutionary enigma. Objective: The predictions of Gloger's Rule and the Temporal Segregation hypothesis were tested, which propose that melanistic individuals (a) will occur more frequently in dense tropical forest than in open habitat due to the advantages of camouflage and thermoregulation, and (b) will be most active during the brightest times of the circadian and lunar cycle because black pigmentation is cryptic under bright light. Methods: Based on 10 years of jaguar and oncilla camera trap records from dense tropical forest in Costa Rica, the activity patterns and relative abundance of non-melanistic (rosetted or spotted) versus melanistic morphs was compared. Results: Twenty-five percent of jaguar records in dense forests were melanistic compared to the global average of 10% in open and closed habitats; 32% of oncilla records were melanistic compared to 18% overall in Brazil. Overlap analysis indicated that melanistic jaguars were more active during daylight hours compared to non-melanistic jaguars, which were more nocturnal and crepuscular. Likewise, melanistic oncilla were more diurnal than non-melanistic oncilla; melanistic oncilla were also more active during the full moon, while the non-melanistic oncilla were less active. Conclusion: These results imply that melanistic jaguar and oncilla enjoy the adaptive benefits of superior camouflage when inhabiting dense forest and accumulate a fitness advantage when hunting in brighter light conditions. If true, natural selection would ensure that melanistic individuals persist when dense forest is retained but may be threatened by deforestation and accelerating human presence.Introducción: La persistencia de los polimorfismos del color del pelaje, como la coexistencia del color del pelaje melánico (negro) y el "tipo salvaje" (manchado), es un enigma evolutivo. Objetivo: Probamos las predicciones de la Regla de Gloger y la hipótesis de la Segregación Temporal que proponen que los individuos melánicos (a) ocurrirán con mayor frecuencia en el bosque tropical cerrado que en el hábitat abierto debido a las ventajas del camuflaje y la termorregulación, y (b) serán más activos durante las épocas más brillantes del ciclo circadiano y lunar porque la pigmentación negra es críptica bajo una iluminación brillante. Métodos: Con base en 10 años de registros de cámaras trampas de jaguar y tigrillo de un denso bosque tropical en Costa Rica, comparamos la actividad y la abundancia relativa de formas no melánicas (rosetones o manchados) versus formas melánicas. Resultados: El 25% de los registros de jaguares en bosques densos fueron melánicos en comparación con el promedio global del 10% en hábitats abiertos y cerrados; el 32% de los registros de tigrillo fueron melánicos en comparación con el 18% en general en Brasil. El análisis de superposición indicó que los jaguares melánicos eran más activos durante las horas del día en comparación con los jaguares no melánicos, que eran más nocturnos y crepusculares. Asimismo, el tigrillo melánico era más diurno que el tigrillo no melánico. El tigrillo melánico también fue más activo durante la luna llena, mientras que el tigrillo no melánico fue menos activo. Conclusión: Estos resultados implican que los jaguares y tigrillos melánicos disfrutan de los beneficios adaptativos de un camuflaje superior cuando habitan en un bosque denso y acumulan una ventaja de aptitud cuando cazan en condiciones de iluminación más brillante. Si es cierto, la selección natural aseguraría que los individuos melánicos persistan cuando se retiene el bosque denso, pero pueden verse amenazados por la deforestación y la presencia humana acelerada

Do Wildlife Crossings Mitigate the Roadkill Mortality of Tropical Mammals? A Case Study from Costa Rica

Although Central America is one of the most biologically diverse regions in the world, booming road construction is driving roadkill mortality that threatens to alter the demography, genetic diversity, and viability of wild mammalian populations. Costa Rica has the highest road density in Central America, but the effectiveness of wildlife crossings in mitigating roadkill mortality has not been assessed with controlled experimental studies. Hacienda Baru National Wildlife Refuge is located along a critical biological corridor bisected by one of the busiest highways in the country. The first wildlife underpasses in Costa Rica were built here in 2010 as part of the expansion of Route 34 and subsequently documented by camera-trap and roadkill surveys. Using a control-impact design, we demonstrate a considerable reduction in wildlife mortality in the presence of the crossing structures compared with controls, with the underpasses and overpasses eventually used by 21 mammalian species. Some species made use of the structures right away, while others took over a year to learn to use them. This is the first controlled study in Central America to document the effectiveness of wildlife crossings and provides evidence that well-designed mitigation structures can contribute to wildlife-friendly roadways

Trade-offs between fighting and breeding: a social network analysis of bison male interactions

In most polygynous species, males compete for access to females using agonistic interactions to establish dominance hierarchies. Typically, larger and stronger males become more dominant and thus gain higher mating and reproductive success over subordinate males. However, there is an inherent trade-off between time and energy invested in dominance interactions versus courtship and mating activities. Individuals may overcome this trade-off by selectively engaging in more effective mating tactics. North American bison (Bison bison) are a species of conservation concern that exhibit female-defense polygyny with two predominant mating tactics: (1) tending individual females; or (2) challenging tending males as a satellite and then mating opportunistically. Here, we use social network analysis to examine the relationship between position in the agonistic interaction network of bison males and their mating, reproductive success, and reproductive tactics and effort. To assess the potential for social network analysis to generate new insights, we compare male (node) centrality in the interaction network with traditional David's score and Elo-rating dominance rankings. Local and global node centrality and dominance rankings were positively associated with prime-aged, heavy males with the most mating success and offspring sired. These males invested more effort in the "tending" tactic versus the "satellite" tactic, and they tended more females for longer periods during peak rut, when most females were receptive. By engaging in the most effective mating tactic, dominant males may mitigate the trade-off between allocating time and energy to agonistic interactions that establish dominance, versus courtship and mating. While less dominant males participated more in the alternative mating tactic, network analysis demonstrated that they were still important to the interaction network on both a local and global scale

Do Wildlife Crossings Mitigate the Roadkill Mortality of Tropical Mammals? A Case Study from Costa Rica

Although Central America is one of the most biologically diverse regions in the world, booming road construction is driving roadkill mortality that threatens to alter the demography, genetic diversity, and viability of wild mammalian populations. Costa Rica has the highest road density in Central America, but the effectiveness of wildlife crossings in mitigating roadkill mortality has not been assessed with controlled experimental studies. Hacienda Baru National Wildlife Refuge is located along a critical biological corridor bisected by one of the busiest highways in the country. The first wildlife underpasses in Costa Rica were built here in 2010 as part of the expansion of Route 34 and subsequently documented by camera-trap and roadkill surveys. Using a control-impact design, we demonstrate a considerable reduction in wildlife mortality in the presence of the crossing structures compared with controls, with the underpasses and overpasses eventually used by 21 mammalian species. Some species made use of the structures right away, while others took over a year to learn to use them. This is the first controlled study in Central America to document the effectiveness of wildlife crossings and provides evidence that well-designed mitigation structures can contribute to wildlife-friendly roadways

Diversidad y patrones de actividad de mamíferos silvestres medianos y grandes en la Cordillera de Talamanca, Costa Rica.

Introduction: The Talamanca Range in the southeast of Costa Rica is a priority region for conservation, but its ecosystems and species are little known. The study of wild mammals can contribute to our understanding of the trophic structure and conservation needs of tropical forests, which are some of the most diverse ecosystems on the planet. Objective: To evaluate the species richness, relative abundance and activity patterns of medium and large mammals in La Amistad National Park and the Quetzal Tres Colinas Biological Corridor. Methods: Continuous monitoring was carried out from July 12, 2018 to April 18, 2021 using 18 photo-trapping stations, each consisting of a camera trap and a scent station. Results: Based on a sampling effort of 15 335 camera trap days, we obtained 36 667 records in which we detected 27 species of medium and large wild mammals, all of which are in one of the risk categories at the national or international level. The species with the widest distribution and the greatest relative abundance were Sciurus granatensis, Tapirus bairdii, Sylvilagus dicei and Mazama temama. The least abundant species, with the most restricted distribution, were Ateles geoffroyi, Cebus imitator and Microsciurus alfari. Five species were diurnal, six were nocturnal and crepuscular, and 14 species were cathemeral. The greatest species richness was found in the Premontane and Lower Montane zones, while the endemic species were in both of these zones and the Subalpine zone. Eight species had lunarphobia, six lunarphilia and six had no pattern. Conclusion: These areas protect important Premontane to Subalpine populations of medium-size and large terrestrial mammals, many cathemeral or with lunarphobia, and should continue to be monitored.Introducción: La Cordillera de Talamanca en el sureste de Costa Rica, es una región prioritaria para la conservación, posee ecosistemas y especies poco conocidas. El estudio de mamíferos silvestres permite comprender la estructura y estado de conservación de los bosques tropicales: uno de los ecosistemas más diversos del planeta. Objetivo: Evaluar la riqueza, abundancia relativa y patrones de actividad de los mamíferos terrestres medianos y grandes en el Parque Internacional de La Amistad y el Corredor Biológico el Quetzal Tres Colinas. Métodos: Entre el 12 de julio del 2018 al 18 de abril del 2021, instalamos 18 estaciones de fototrampeo, cada una conformada por una cámara trampa y un atrayente olfativo. Resultados: Con un esfuerzo de muestreo de 15 335 días cámara trampa, obtuvimos 36 667 registros en los cuales detectamos 27 especies de mamíferos silvestres medianos y grandes; todas están en alguna categoría de riesgo nacional o internacional. Sciurus granatensis, Tapirus bairdii, Sylvilagus dicei y Mazama temama mostraron la distribución más amplia y la mayor abundancia relativa. Ateles geoffroyi, Cebus imitator y Microsciurus alfari tuvieron la menor abundancia y la distribución más restringida. Registramos cinco especies diurnas, seis nocturnas-crepusculares y 14 catemerales. Las especies únicas las detectamos en los pisos altitudinales Subalpino, Premontano y Montano bajo, los dos últimos registraron la mayor riqueza. Ocho especies mostraron fobia lunar, seis mostraron filia lunar y seis no mostraron afinidad al brillo lunar. Conclusión: Estas áreas protegen importantes poblaciones premontanas a subalpinas de mamíferos terrestres medianos y grandes, muchos catemerales o con fobia a la luna, y deben seguir siendo monitoreadas

ADAPTATIONS OF WINTER TICKS (DERMACENTOR ALBIPICTUS) TO INVADE MOOSE AND MOOSE TO EVADE TICKS

Most North American moose (Alces alces) outside Newfoundland and south of 60° N latitude are infested annually with winter ticks, Dermacentor albipictus. Moose commonly are host to many thousand winter ticks, and tick-associated die-offs of moose are reported often. Larval winter ticks display such behavior as aggregating in clumps on the leeward side of vegetation at heights of preferred ungulate hosts, apparently aiding in their survival and in contacting vertebrate hosts. Moose, in turn, avoid or reduce infestation by ticks by evading tick larvae on vegetations, tolerating tick-foraging by magpies, and grooming to remove ticks. Recent evidence that grooming by African antelope and North American bison and wapiti is regulated by a centrally controlled mechanism that acts to evoke a preventative grooming before ticks can attach and feed, ahs not been supported for moose. This paper reviews host-finding adaptations of winter ticks, pathenogenic characteristics of winter ticks for moose, the relationship between magpies and moose, and the biological basis of grooming in moose

Bush Dogs in Central America: Recent Range Expansion, Cryptic Distribution, or Both?

Bush dogs (Speothos venaticus) are a small, wide-ranging neotropical pack-hunting canid whose ecology is relatively poorly known. Here, we document new, repeated observations of bush dog groups in east-central (Barbilla National Park) and south-eastern (La Amistad International Park) Costa Rica that suggest either that their recent or historic range has been underestimated, or that their potential range in Central America may have recently expanded and could now include not only borderlands with Panama but perhaps a substantial portion of the Talamanca Mountains up to 120 km to the northnorthwest and at elevations up to 2,119 m. In light of their inherently low density, documenting the current and future distribution of bush dogs in Central America will be challengingLos perros de monte (Speothos venaticus) son un pequeño cánido neotropical cazador en manada cuya ecología es relativamente poco conocida. Aquí, documentamos observaciones nuevas y repetidas de grupos de perros de monte en el centro-este (Parque Nacional Barbilla) y el sureste (Parque Internacional La Amistad) de Costa Rica que sugieren que su área de distribución reciente o histórica ha sido subestimada, o que su potencial El rango de distribución en América Central puede haberse expandido recientemente y ahora podría incluir no solo las tierras fronterizas con Panamá, sino quizás una parte sustancial de las montañas de Talamanca hasta 120 km al noroeste y en elevaciones de hasta 2.119 m. A la luz de su densidad inherentemente baja, documentar la distribución actual y futura de los perros de monte en Centroamérica será un desafío.Universidad Nacional, Costa RicaUniversidad de Massachusetts, Estados UnidosPoint Loma Nazarene University, Estados UnidosCentro de Educación e Investigación del Quetzal, Costa RicaSistema Nacional de Aéreas de Conservación, Costa RicaInstituto Internacional en Conservación y Manejo de Vida Silvestr