Consistency in bird use of tree cover across tropical agricultural landscapes.

In tropical regions where forests have been replaced by agriculture, the future of biodiversity is increasingly dependent on the presence of remnant forest patches and on-farm tree cover within agricultural landscapes. While there is growing evidence of the importance of tree cover within agricultural landscapes, most studies have been conducted in a single landscape, making it difficult to ascertain whether the conservation value of different types of tree cover can be generalized across landscapes. To explore whether use of different forms of tree cover by birds is consistent across landscapes, we compared the number of individuals, species richness, and diversity of birds associated with different forms of tree cover in four agricultural landscapes in Central America, using a standardized methodology and sampling effort. In each landscape, we compared bird assemblages in six tree cover types (secondary forests, riparian forests, forest fallows, live fences, pastures with high tree cover, and pastures with low tree cover). We observed a total of 10 723 birds of 283 species, with 83-196 species per landscape. The specific patterns of bird species richness, number of individuals, and diversity associated with tree cover types varied across the four landscapes, but these variables were consistently higher in the forest forms of tree cover (riparian forests, secondary forests, and forest fallows) than in non-forest habitats. In addition, forest forms of tree cover had distinct species composition from non-forest forms in all landscapes. There was also consistency in the use of different types of tree cover by forest birds across the four landscapes, with higher richness and number of individuals of forest birds in forested than non-forested forms of tree cover, and more forest bird species in pastures with high tree cover than in pastures with low tree cover. Our findings indicate that riparian and secondary forests are consistently of higher value for bird conservation (particularly for forest species) than live fences and pastures with tree cover. Consequently, agricultural and land use policies that promote the retention of secondary and riparian forests and increase tree cover within pastures would greatly benefit bird conservation, regardless of the landscape in which they are applied.

Patterns of animal diversity in different forms of tree cover in agricultural landscapes.

As tropical regions are converted to agriculture, conservation of biodiversity will depend not only on the maintenance of protected forest areas, but also on the scope for conservation within the agricultural matrix in which they are embedded. Tree cover typically retained in agricultural landscapes in the neotropics may provide resources and habitats for animals, but little is known about the extent to which it contributes to conservation of animal species. Here, we explore the animal diversity associated with different forms of tree cover for birds, bats, butterflies, and dung beetles in a pastoral landscape in Nicaragua. We measured species richness and abundance of these four animal taxa in riparian and secondary forest, forest fallows, live fences, and pastures with high and low tree cover. We recorded over 20,000 individuals of 189 species including 14 endangered bird species. Mean abundance and species richness of birds and bats, but not dung beetles or butterflies, were significantly different among forms of tree cover. Species richness of bats and birds was positively correlated with tree species richness. While the greatest numbers of bird species were associated with riparian and secondary forest, forest fallows, and pastures with >15% tree cover, the greatest numbers of bat species were found in live fences and riparian forest. Species assemblages of all animal taxa were different among tree cover types, so that maintaining a diversity of forms of tree cover led to conservation of more animal species in the landscape as a whole. Overall, the findings indicate that retaining tree cover within agricultural landscapes can help conserve animal diversity, but that conservation efforts need to target forms of tree cover that conserve the taxa that are of interest locally. Preventing the degradation of remaining forest fragments is a priority, but encouraging farmers to maintain tree cover in pastures and along boundaries may also make an important contribution to animal conservation.

[Nutritional values in the diet of white-lipped peccary Tayassu pecari (Artiodactyla: Tayassuidae) in Corcovado National Park, Costa Rica]. / Valor nutricional de los alimentos de Tayassu pecari (Artiodactyla: Tayassuidae) en el Parque Nacional Corcovado, Costa Rica.

We determined the potential nutritional levels in 25 species of plants, and in earthworms, that constitute part of the diet of white-lipped peccary (Tayassu pecari) in Corcovado National Park, Costa Rica, from January 1998 to March 1999. The highest content of fat and energy was found in seeds of the Myristicacea family. The highest content of calcium was found in vegetative parts of Dieffenbachia spp. Nutritious contents differed among plant parts (seeds, fruits, stems and leaves). Fat and energy content were larger in seeds and fruits, whereas the largest content of protein was found in fruits and leaves. Mineral content also differed among plant parts. Calcium, potassium and magnesium were higher in leaves whereas copper and zinc were higher in seeds. Differences of diet between white-lipped peccaries in Corcovado and in other tropical regions of Latin America could be partially explained by our results. We found several species with higher fat and energy content than palms, which can explain the low consumption of palm seeds in Corcovado. It is possible that the regular consumption of stems and leaves of some species is related to their high mineral content. Seasonality of reproduction in Corcovado seems to be related not only to fruit availability but also to the nutritional quality of food.

The role of fragmentation and landscape changes in the ecological release of common nest predators in the Neotropics.

Loss of large mammalian carnivores may allow smaller mesopredators to become abundant and threaten other community members. There is considerable debate about mesopredator release and the role that other potential factors such as landscape variables and human alterations to land cover lead to increased mesopredator abundance. We used camera traps to detect four mesopredators (tayra, Eira barbara; white-nosed coati, Nasua narica; northern raccoon, Procyon lotor; and common opossum, Didelphis opossum) in a biological corridor in Costa Rica to estimate habitat covariates that influenced the species' detection and occurrence. We selected these mesopredators because as semi-arboreal species they might be common nest predators, posing a serious threat to resident and migratory songbirds. Pineapple production had a pronounced positive effect on the detectability of tayras, while forest cover had a negative effect on the detection of coatis. This suggests that abundance might be elevated due to the availability of agricultural food resources and foraging activities are concentrated in forest fragments and pineapple edge habitats. Raccoon and opossum models exhibited little influence on detection from habitat covariates. Occurrence models did not suggest any significant factors influencing site use by nest predators, revealing that all four species are habitat generalists adapted to co-existing in human altered landscapes. Furthermore, fragmentation and land cover changes may predispose nesting birds, herpetofauna, and small mammals to heightened predation risk by mesopredators in the Neotropics.

Abundancia, tamaño y estructura poblacional del tiburón punta blanca de arrecife, Triaenodon obesus (Carcharhiniformes: Carcharhinidae), en Bahía Chatham, Parque Nacional Isla del Coco, Costa Rica / Abundance, size and population structure of whitetip reef sharks, Triaenodon obesus (Carcharhiniformes: Carcharhinidae), in Bahía Chatham, Parque Nacional Isla del Coco, Costa Rica

Approximately 12 species of shark inhabit at Coco Island National Park (PNIC); some are migratory, such as the hammerhead shark (Sphyrna lewini) and whale shark (Rincodon typus), and others are resident, like the whitetip shark (Triaenodon obesus). The whitetip shark is a species related to coral reefs, it inhabits coastal environments and is nocturnal and, it is very common in tropical waters, but there are few studies worldwide. In fact, only short researches have been done about their behavior at PNIC. Therefore, this study aimed to give data about the abundance, size and population structure of the whitetip shark at Chatham Bay in Coco Island National Park, providing baseline information for monitoring its population which is also very vulnerable to climate change. In order to accomplish this aim, a mark-recapture method was used, as well as underwater visual counts to determine their relative abundance and visual recaptures at Chatham Bay. The most effective hours for tagging were between 18:00 and 22:00 (sunset), when the whitetip sharks were more active probably related to foraging behavior. In addition, the depth was a relevant factor for tagging, sharks were caught in shallow water (10.9±1.9m). This species prefers to feed in shallow water and this behavior is probably related to the distribution and occurrence of rock and coral reefs in Chatham Bay. Based on the results, whitetip shark do not have a defined spatial ontogenic segregation, since in the same sites both juveniles and adults were found. The study confirmed that whitetip shark use specific residence sites: during the tagging trips, different individuals were recaptured; and during the underwater counts, at least 32.76% of tagged sharks were observed. The average length of the tagged sharks was 101.8±12.1cm (130.0cm maximum and 71.0cm minimum). The relative abundance of the whitetip shark in Chatham Bay observed was estimated on 49.5±10.4 sharks/hour. Furthermore, using the recapture data obtained during the night tagging expeditions, a population of 408 (IC = 181-1050) sharks was estimated.

Doce especies de tiburones habitan las aguas del Parque Nacional Isla del Coco (PNIC) y uno de los más abundantes es el tiburón punta blanca de arrecife, Triaenodon obesus. El presente estudio determinó la abundancia, tallas y estructura de la población de esta especie en la zona de Bahía Chatham, PNIC. Se utilizó el método de marcaje y recaptura y se realizaron conteos subacuáticos visuales, con el fin de determinar su abundancia relativa y contabilizar recapturas visuales. Los tiburones punta blanca de Bahía Chatham no presentan segregación ontogénica espacial definida; pero si una alta fidelidad a los a sitios de residencia dentro de esta bahía. La longitud total promedio de los tiburones marcados fue de 101.8±12.1cm, con una longitud total máxima de 130.0cm y una mínima de 71.0cm. La mediana de las longitudes totales de los tiburones machos (103.5±21.33cm) y hembras (100.1±11.2cm) no difirieron significativamente (H = 1.78; p=0.1818). La abundancia relativa en Bahía Chatham, PNIC fue de 49.5±10.4 tiburones/h. El tamaño estimado de la población usando el método de de captura-recaptura fue de 408 (IC=181-1050).

Valor nutricional de los alimentos de Tayassu pecari (Artiodactyla: Tayassuidae) en el Parque Nacional Corcovado, Costa Rica / Nutritional values in the diet of white-lipped peccary Tayassu pecari (Artiodactyla: Tayassuidae) in Corcovado National Park, Costa Rica

We determined the potential nutritional levels in 25 species of plants, and in earthworms, that constitute part of the diet of white-lipped peccary (Tayassu pecari) in Corcovado National Park, Costa Rica, from January 1998 to March 1999. The highest content of fat and energy was found in seeds of the Myristicacea family. The highest content of calcium was found in vegetative parts of Dieffenbachia spp. Nutritious contents differed among plant parts (seeds, fruits, stems and leaves). Fat and energy content were larger in seeds and fruits, whereas the largest content of protein was found in fruits and leaves. Mineral content also differed among plant parts. Calcium, potassium and magnesium were higher in leaves whereas copper and zinc were higher in seeds. Differences of diet between white-lipped peccaries in Corcovado and in other tropical regions of Latin America could be partially explained by our results. We found several species with higher fat and energy content than palms, which can explain the low consumption of palm seeds in Corcovado. It is possible that the regular consumption of stems and leaves of some species is related to their high mineral content. Seasonality of reproduction in Corcovado seems to be related not only to fruit availability but also to the nutritional quality of food.

Se determinó el valor nutritivo y mineral de 25 especies vegetales y una especie animal (lombriz de tierra) que forman parte de la dieta del chancho cariblanco (Tayassu pecari) en el Parque Nacional Corcovado, Costa Rica, desde enero de 1998 hasta marzo de 1999. Los mayores contenidos de grasa y energía bruta se encontraron en semillas de la familia Myristicaceae. El mayor contenido de calcio se encontró en partes vegetativas de Dieffenbachia spp. Los contenidos nutritivos fueron diferentes entre las diferentes partes vegetativas analizadas (semillas, frutos, tallos y hojas). El contenido de grasa y energía bruta fue mayor en semillas y frutos, mientras que el mayor contenido de proteina cruda se encontró en frutos y hojas. El contenido de minerales tambien fue diferente entre las partes vegetativas analizadas. Los contenidos de calcio, potasio y magnesio fueron mayores en hojas mientras que los de cobre y zinc fueron mayores en semillas. Diferencias en la dieta de los chanchos cariblancos de Corcovado con los de otras regiones tropicales de Latinoamérica pueden ser parcialmente explicadas con los resultados nutritivos de este estudio. Se encontraron varias especies con mayor contenido de grasa y energía bruta que las palmas, lo que puede explicar el bajo consumo de semillas de palmas en Corcovado. Es posible que el consumo regular de partes vegetativas (hojas y tallos) de algunas especies se deba al alto contenido mineral de estas. La estacionalidad de la reproducción parece estar relacionada no solo a la disponibilidad de alimentos sino tambien a la calidad nutritiva de los mismos.

Sex ratio and breeding of white-lipped peccaries Tayassu pecari (Artiodactyla: Tayassuidae) in a Costa Rican rain forest

White-lipped peccaries are non-seasonal breeders in South America, but little is known about their reproduction in Central America. There are few studies about the sex ratio of this species in the field. We studied the reproduction and sex ratio of white-lipped peccaries during 200 hours of field observation of four radiomarked and two unmarked herds, from July 1996 to April 1997, in Corcovado National Park, Costa Rica. Sex ratio data of three additional, radiomarked herds observed in 1998 were also included. We recorded numbers of mountings, presence of newborns and numbers of nursing interactions. The peccaries showed a distinct reproductive seasonality, with one mating peak in February and another in July. The greatest number of newborns and the peak in nursing activity were observed during July and August, when fruit availability for the peccaries was high. The adult sex ratio was significantly female biased (1.4:1-1.8:1), also in contrast with South American populations.

Dieta estacional del Tayassu pecari (Artiodactyla: Tyassuidae) en el Parque Nacional Corcovado, Costa Rica / Seasonal diet of Tayassu pecari (Artiodactyla: Tayassuidae) in Corcovado National Park, Costa Rica

The diet of the white-lipped peccari Tayassu pecari was studied from July 1996 to April 1997 in Corcovado National Park, Costa Rica, through fecal analysis and direct observations. The feces consisted of 61.6 porcent fruits, 37.5 porcent vegetative parts, 0.4 porcent invertebrates and 0.5 porcent unidentified material. These proportions are similar to those reported for white-lipped peccaries diet in South America, but the species consumed were different. In represented family. In contrast, the diet of the Peruvian Amazon peccary primarily consists of plant parts (Arecaceae). Costa Rican peccary diet consisted of vegetative parts from Araceae and Heliconaceae. Direct observation showed that peccaries spent 30 porcent of feeding time rooting. Samples take from rooting sites suggest that peccaries fed on earthworms. Diet differed between months, season and habitats. They are more fruitsin coastal and primary forest and more vegetative parts in secondary forest. In the months Octubrer and November the comsuption of vegetative parts exceeded fruit consumption. Key words: Seasonal diet, fecal analysis, direct observations, Tayassu pecari, white-lipped peccary, rain forest, Costa Rica

White-lipped peccary (Tayassu pecari, Artiodactyla: Tayassuidae) diet and fruit availability in a Costa Rican rain forest

We studied fruit availability, diet and habitat use by white-lipped peccary (Tayassu pecari) in Corcovado National Park, southwest Costa Rica, from July 1996 to April 1997. The results show that the availability of important fruits for the white-lipped peccary differs between habitats and climatic seasons. Fruit availability was highest in the primary forest than secondary and coastal forest. There was a period of shortage of fruits to ends of the wet season, during which the consumption of not seasonal resources like leaves and shafts increased. The important fruits during this period of shortage were Ficus sp and Licania operculipetala. The several types of forest were used according to the fruit availability, and it was a direct relation between the consumption and the fruit availability.