摘要:

In the deciduous forests of the tropical area of the Mexican Pacific coast, the treeSpondias purpureais fruiting at the end of the dry season. The fruits are consumed by terrestrial vertebrates including the white-tailed deer (Odocoileus virginianus). If no free water sources are available, the deers’ liquid requirements may be met by fruit consumption. By an exclusion experiment we were able to demonstrate that foraging chachalacas (Ortalis poliocephala) increase the rate of fruit fall about 5 times.

ISSN:0165-0521    

DOI:10.1076/snfe.32.1.1.13466

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

The influence of fruit ingestion by the bat, Sturnira lilium, on germination of the seeds of the tree Solanum riparium was studied in a secondary rain forest in northwestern Argentina. Bat frequencies in disturbed areas were analyzed by mist net captures. Germination rates were determined for seeds collected from trees and bat feces. S. lilium was the most abundant fruit bat in the study area. Fruit digestion and the passage of seeds through the intestine did not significantly affect germination in S. riparium. In this case the fruit bats, therefore, probably provide only seed dispersal.

ISSN:0165-0521    

DOI:10.1076/snfe.32.1.4.13464

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

A population of the common opossum, Didelphis marsupialis, inhabiting a highly degraded agricultural area in northern Colombia was studied by live-trapping for over two years. Three transects were established in strips of riparian vegetation within a matrix of agricultural crops. Sampling was performed once in October 1993 and then monthly from August 1994 through December 1995. Four population-level characteristics were estimated: abundance, sex ratio, age structure, and breeding activity. Abundance was very high at the beginning of the study but declined dramatically and then fluctuated at low numbers. The sex ratio did not vary among high-abundance, decline, and low-abundance population phases, but there was a deficiency of females with young at high abundance and of adults during the decline. The impact of these characteristics on the population dynamics of D. marsupialis is discussed with special emphasis on reproductive traits. These characteristics may also contribute to the potential of D. marsupialis as a reservoir for a wide variety of infectious agents.

ISSN:0165-0521    

DOI:10.1076/snfe.32.1.7.13462

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

The diet of the marsupial Philander frenata (Didelphimorphia, Didelphidae) at Restinga de Barra de Maricá, Rio de Janeiro state, Brazil, was analyzed in 180 faecal samples collected in 29 months from 1986 to 1990, and by food preferences in the laboratory. In the faeces remnants mainly of invertebrates, besides fruits and vertebrates were found, and diet comparisons were made between sexes, ages and seasons of different humidity. Laboratory experiments corroborated the field data. No significant difference in diet was found between sexes. Although field data showed that subadults and adults eat more vertebrates than young, in the laboratory all animals irrespective of their age showed the same food preference. Invertebrates were more consumed in humid than in superhumid months. Vertebrates were taken opportunistically. There was an inverse relationship between eating of fruits and available water in the environment. Fruits are probably water complements in dry months, as these marsupials have difficulties in maintaining water balance without access to drinking water.

ISSN:0165-0521    

DOI:10.1076/snfe.32.1.12.13460

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

The foraging mode and vertical distribution of tyrant flycatchers of twelve sympatric species (Tyrannidae) were compared between forest edge and savanna in the Brazilian Amazon. Five species can be regarded as aerial salliers or hawkers, four as gleaners, and three as generalist hunters. Their patterns of foraging behavior were significantly different among the species but not in the two habitats. Perch positions changed significantly according to the time of day. Generally the tallest trees in a given plot were chosen, with the larger bird species perching more often at the top of the trees. Factors that affect the structure and behavior of this flycatcher guild are discussed.

ISSN:0165-0521    

DOI:10.1076/snfe.32.1.17.13459

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

We studied a population of Tropidurus spinulosus, an arboreal lizard species from the dry chaco of Salta, Argentina. This species is reproducing seasonally. Females are reproductively active from November to January, whereas males are October through December. More than a clutch per cycle could be laid. Clutch size was 5.0 and is positively correlated to snout-vent length. Reproductive characteristics are similar to other Tropidurus species. Arboreality and environmental adaptations are proximal interpretations of the species-specific reproductive biology in this lizard.

ISSN:0165-0521    

DOI:10.1076/snfe.32.1.28.13465

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

Eucinostomus argenteus is widely distributed along the Brazilian coast where it enters bays and lagoons. Imboacica and Cabiúnas are small coastal lagoons located in the southeastern coast of Brazil and in both localities E. argenteus is considered as a constant species. The diet of specimens collected between July 1991 through April 1993 was analysed by frequency of occurrence, numeric and volumetric methods. The predominant items ingested differed in each lagoon. In Imboacica lagoon, the stomach content comprised mainly of algae, polychaeta, detritus and sand particles, however in Cabiúnas lagoon calanoid copepods and shrimp larvae. Distinct features of the aquatic communities of the lagoons are discussed as possible causes for the differences observed.

ISSN:0165-0521    

DOI:10.1076/snfe.32.1.33.13463

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

A new augochlorine bee genus, Ischnomelissa gen. n., is described and figured. The genus is based on a new species from the mountains of Colombia, Ischnomelissa zonata. Ischnomelissa superficially resembles species of Caenaugochlora (Ctenaugochlora), but differs in having a rounded preoccipital ridge, an acute marginal cell apex, an elongated propodeum, and a single gonostylus (not divided into ventral and dorsal gonostylar processes). Color variation within I. zonata and the position of the group in augochlorine phylogeny is briefly discussed. Modified couplets are provided for Eickwort’s 1969 key to genera and subgenera in order to correctly identify the genus.

ISSN:0165-0521    

DOI:10.1076/snfe.32.1.41.13461

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

The three larval instars of Hydraena particeps Perkins, 1981 are described, based on material collected in the field and reared in the laboratory. Illustrations of structural features and chaetotaxy are provided. For the first time the three larval instars of one species of the genus Hydraena are described. Several characters are compared to those of Hydraena hernandoi Fresneda and Lagar from Europe and the North American Hydraena circulata Perkins.

ISSN:0165-0521    

DOI:10.1076/snfe.32.1.47.13467

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor