La dieta del jaguar (Panthera onca), el puma (Felis concolor) y el manigordo (Felis pardalis) (Carnivora: Felidae) en el Parque Nacional Corcovado, Costa Rica

Mediante análisis de excretas se estudio la dieta del jaguar (Panthera onca), el puma (Felis concolor) y el manigordo (Felis pardalis) en el Parque Nacional Corcovado, Costa Rica, entre agosto de 1993 y junio de 1994. Los mamíferos fueron las presas principales, mientras que los reptiles y las aves resultaron menos importantes de acuerdo a la frecuencia relativa de aparición y biomasa estimada relativa. Las presas del jaguar y el puma resultaron ser especies de más de 2500 g de masa corporal, mientras que las del manigordo, cuya presa principal fue la rata espinosa Proechimys semispinosus, fueron especies de menos de 2500 g de masa corporal. No se observaron cambios importantes en la alimentación durante el período de estudio, no obstante la diversidad trófica del jaguar y del manigordo se incrementaron en la estación seca.The diets of the jaguar (Panthera onca), the puma (Felis concolor) and the ocelot (Felis pardalis) were studiedin a tropical rainforest in Corcovado National Parle, South Pacific belt of Costa Rica, from August 1993 to June 1994. A total of 50 Km of trails were examined month1y for fecal material. Analysis of relative frequency of ocUrrence and telative estimation bionlass in the fecal samples showed that mammals were the main preys of the three feüds, while reptiles and birds were less important. The preys of jaguar and puma have body weights aboye 2500g, and the preys of ocelot, whose main prey was the spiny rat, Proechimys semispinosus, less than 2500g. Thete wéteno important changes in foad habits during the stu'dy, although trophic diversity of jaguar and ocelot increase during the dry seasons

Seed predation by mammals in forest fragments in Monteverde, Costa Rica

Few studies have evaluated seed predation in fragmented landscapes, in which lower species diversity is expected to modifying ecological interactions. The rates of seed removal by mammals were investigated in a continuous forest and two fragmented patches of Premontane Tropical Moist Forest, in Monteverde, Costa Rica. The composition of mammalian seed-predators in each site was recorded during 16 months. The removal of four native tree species of experimental seeds: Ocotea valeriana and Ocotea whitei (Lauraceae), Panopsis costaricensis (Proteaceae) and Billia colombiana (Hippocastanaceae) in forest understories was followed during two annual fruiting seasons for each species. Results indicated similar species composition of seed-predators between continuous forest, the largest fragment (350 ha). However the smaller fragment (20 ha), had fewer seed predators. In this fragment, the specialized seed predator Heteromys desmarestianus (Rodentia) was more abundant. Unexpectedly, seed-predation in the two forest fragments and the continuous forest did not differ statistically for any of the seed species. Apparently, the higher abundance of small seed-predators in the fragments was compensated by the absence of medium and large seed-predators, like Agouti paca, Dasyprocta punctata (both Rodentia) and Pecari tajacu (Artiodactyla) recorded in continuous forest. Removal of experimentally-placed seeds was higher when the number of naturally occurring seeds in the sites was lower. This result could best be attributed to differential satiation of seed predators rather than differences in richness or abundance of seed predators. Rev. Biol. Trop. 57 (3): 865-877. Epub 2009 September 30.<br>Pocos estudios han evaluado la depredación de semillas en ambientes fragmentados, en éstos la menor diversidad de especies debe estar modificando las interacciones ecológicas. Se investigó la remoción de semillas por mamíferos en un bosque continuo y dos fragmentos en Monteverde, Costa Rica. Se registró la composición de mamíferos en cada sitio durante 16 meses y se observó la remoción de semillas experimentales del suelo del bosque. Se utilizó semillas de cuatro especies de árboles: Ocotea valeriana, Ocotea whitei, Panopsis costaricensis y Billia colombiana, durante dos periodos anuales de fructificación cada una. Los resultados indican una composición de depredadores de semillas similar entre el bosque continuo y el fragmento de 350 ha, más diversos que el fragmento de 20 ha, en el cual el especialista en semillas Heteromys desmarestianus fue más abundante. La depredación de semillas entre el bosque continuo y los fragmentos no fue estadísticamente diferente al considerar todas las especies de semillas, debido a la mayor abundancia de depredadores pequeños, que pudo compensar la ausencia de depredadores de talla mediana y grande que sí están presentes en el bosque continuo. La depredación sobre semillas fue mayor cuando la oferta de semillas no experimentales fue menor, indicando que la saciedad de los depredadores puede estar determinando la remoción de semillas en fragmentos, más que la riqueza o abundancia de especies depredadoras

Seed predation by mammals in forest fragments in Monteverde, Costa Rica

Few studies have evaluated seed predation in fragmented landscapes, in which lower species diversity is expected to modifying ecological interactions. The rates of seed removal by mammals were investigated in a continuous forest and two fragmented patches of Premontane Tropical Moist Forest, in Monteverde, Costa Rica. The composition of mammalian seed-predators in each site was recorded during 16 months. The removal of four native tree species of experimental seeds: Ocotea valeriana and Ocotea whitei (Lauraceae), Panopsis costaricensis (Proteaceae) and Billia colombiana (Hippocastanaceae) in forest understories was followed during two annual fruiting seasons for each species. Results indicated similar species composition of seed-predators between continuous forest, the largest fragment (350 ha). However the smaller fragment (20 ha), had fewer seed predators. In this fragment, the specialized seed predator Heteromys desmarestianus (Rodentia) was more abundant. Unexpectedly, seed-predation in the two forest fragments and the continuous forest did not differ statistically for any of the seed species. Apparently, the higher abundance of small seed-predators in the fragments was compensated by the absence of medium and large seed-predators, like Agouti paca, Dasyprocta punctata (both Rodentia) and Pecari tajacu (Artiodactyla) recorded in continuous forest. Removal of experimentally-placed seeds was higher when the number of naturally occurring seeds in the sites was lower. This result could best be attributed to differential satiation of seed predators rather than differences in richness or abundance of seed predators

Lista de mamíferos de Costa Rica

Una actualización de la lista de mamíferos de Costa Rica de 1983 incluye 223 especies terrestres, veinte de ellas nuevas para el país (principalmente Chiroptera). Un total de 122 nuevos registros de localidad se informan en siete localidades diferentes. Los nuevos registros fueron obtenidos de la literatura (53%), la Colección de Mamíferos del Museo de Zoología, Universidad de Costa Rica (33%) y c.omunicaciones personales (11 %) principalmente; 46% de los nuevos registros son anteriores a 1983.An update of the 1983 checklist of Costa Rican mammals ineludes 223 terrestrial species, twenty of them new to the country (mainly Chiroptera). A total of 122 new locality records are reported in seven different 10caUties. The new records were taken from literature (53%); the Collection of Mammals ofthe Museo de Zoología, Universidad de Costa Rica (33%) and personal communications (11 %) mainly; 46% of the new records are previous to 1983

The ‘truck-driver’ effect in leaf-cutting ants: how individual load influences the walking speed of nest-mates

The foraging behaviour of social insects is highly flexible because it depends on the interplay between individual and collective decisions. In ants that use foraging trails, high ant flow may entail traffic problems if different workers vary widely in their walking speed. Slow ants carrying extra‐large loads in the leaf‐cutting ant Atta cephalotes L. (Hymenoptera: Formicidae) are characterized as ‘highly‐laden’ ants, and their effect on delaying other laden ants is analyzed. Highly‐laden ants carry loads that are 100% larger and show a 50% greater load‐carrying capacity (i.e. load size/body size) than ‘ordinary‐laden’ ants. Field manipulations reveal that these slow ants carrying extra‐large loads can reduce the walking speed of the laden ants behind them by up to 50%. Moreover, the percentage of highly‐laden ants decreases at high ant flow. Because the delaying effect of highly‐laden ants on nest‐mates is enhanced at high traffic levels, these results suggest that load size might be adjusted to reduce the negative effect on the rate of foraging input to the colony. Several causes have been proposed to explain why leaf‐cutting ants cut and carry leaf fragments of sizes below their individual capacities. The avoidance of delay in laden nest‐mates is suggested as another novel factor related to traffic flow that also might affect load size selection The results of the presennt study illustrate how leaf‐cutting ants are able to reduce their individual carrying performance to maximize the overall colony performance.Fil: Farji Brener, Alejandro Gustavo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigaciones en Biodiversidad y Medioambiente. Universidad Nacional del Comahue. Centro Regional Universidad Bariloche. Instituto de Investigaciones en Biodiversidad y Medioambiente; Argentina. Universidad Nacional del Comahue. Centro Regional Universitario Bariloche. Laboratorio de Ecotono; ArgentinaFil: Chinchilla, Federico A.. Universidad de Costa Rica. Estación Biológica Palo Verde; Costa RicaFil: Seth, Rifkin. Universidad de Puerto Rico; Puerto RicoFil: Sanchez Cuervo, Ana Maria. Universidad de Puerto Rico; Puerto RicoFil: Triana, Emilia. Universidad de Costa Rica. Escuela de Biología; Costa RicaFil: Quiroga, Verónica Andrea. Universidad Nacional de Salta; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste. Instituto de Biología Subtropical. Universidad Nacional de Misiones. Instituto de Biología Subtropical; ArgentinaFil: Giraldo, Paola. Universidad Nacional de Caldas; Colombi