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Título: Consumption rate, food preferences and transit time of captive giant otter, Pteronura brasiliensis: Implications for the study of wild populations.
Autor(es): Sarah Kathleen Carter
Fernando César Weber Rosas
Andrew Cooper
Ana Cristina Cordeiro Duarte
Assunto: Pteronura brasiliensis
ISSN: 0167-5427
Revista: Aquatic Mammals
Volume: 25
Resumo: Food consumption, food preferences and transit time of digesta were determined in captive giant otters, Pteronura brasiliensis, at the National Institute of Amazon Research (INPA), Manaus, Brazil. Food consumption of an adult female was 0.0997 kg #1 day #1. Giant otters showed sig-nificant and varied preferences for the single Siluriformes (catfish) and various Characiformes species offered. The adult female preferred Anostomidae and Hypophthalmus (catfish), fol-lowed by Triportheus. Myleinae (pacu) were the least preferred, and other species of Characiformes offered were intermediate between Triportheus and Myleinae but not different from one another. The subadult male preferred Psectrogaster, Potamorhina and Semaprochilodus, followed by Hypophthalmus and finally Hemiodontidae. Within species, larger fish are chosen significantly more often than smaller fish (78.7% of trials, P= 0.002). Species, size and individual otter significantly affected the percentage of times fish offered were consumed completely (P<0.016). Overall, most fish were consumed com-pletely beginning with the anterior end. Characoids were consumed completely more often than sil-uroids (77.8% vs. 38.6% of trials, P<0.0001), but the percentage of times different characoids were consumed completely varied (range 0–100%). Small fish (5–15 cm) are more likely to be consumed completely than medium (15–25 cm) fish (84.9% vs. 80.2% of trials, P<0.02). Transit time of particulate markers averaged 3.13 h. Captive preferences arecompared to diets of wild otters in the region (central Amazônia), and implications of study results for determination of food habits in wild otters using scat analysis are discussed. Introduction The giant otter, Pteronura brasiliensis, is endemic to South America, inhabiting remote areas of the Amazon, Orinoco and La Plata river basins from Venezuela south to southern Brazil (Carter & Rosas, 1997). Giant otters are classified as vulner-able by the World Conservation Union (IUCN), and are subject to increasing threats to the quantity and quality of their habitat from development, deforestation and exploitation of natural resources such as gold and oil in the Amazon and other regions of South America (Carter & Rosas, 1997). Giant otters are primarily piscivores, fishing in the margins of rivers and lakes (reviewed in Carter & Rosas, 1997). Food habits studies of giant otters are most often based on identification and quanti-fication of hard parts of prey species found in the feces (e.g. Laidler, 1984; Rosaset al., in press). Occasionally direct observation is possible (e.g. Duplaix, 1980; Brecht-Munn & Munn, 1988), but this method is logistically difficult, costly and time consuming. Studies which utilize scats for diet determination are less intrusive and less costly. Uncertainty is introduced into results from such studies because hard parts found in scats depend on the consumption method of the prey, the rate at which parts pass through the animal’s digestive system, the rate at which prey remains decay and other factors (Pierce & Boyle, 1991). Few giant otters are maintained in captivity worldwide, and even fewer in regions within their #1999 EAAM current natural range (Carter & Rosas, 1997). Thus opportunities to study dietary selectivity in this species are limited. Two giant otters are maintained in captivity at the National Institute of Amazon Research (INPA) in Manaus, Amazonas, Brazil. Studies conducted in such controlled situations may help identify potential sources of bias in determin-ing diet from feces samples (Cottrell et al., 1996) and determine factors influencing prey choice of wild giant otters (Hughes, 1980). We examined feeding rates, food preferences, method of prey consumption and transit time of captive giant otters. Results based on two individuals will neces-sarily be limited in scope and should be interpreted with caution, but our findings provide insight into potential factors influencing observed diets of giantotters in the wild.
ISSN: 0167-5427
Local de publicação: Estados Unidos
Aparece nas coleções:Coordenação de Biodiversidade (CBIO)

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