摘要:

Goniosoma spelaeum(Mello‐Leitão) is a widespread trogloxene harvestman in caves of the Ribeira Valley in São Paulo State. It inhabits walls and ceilings near cave entrances. Populations inhabiting six selected caves of the region were analysed during this study. Mark‐recapture techniques were used to estimate population sizes. Populations vary from tens to hundreds of individuals in each cave, and vary throughout the year. Barra Bonita cave had the largest population and was used to identify other ecological features of the species. These harvestmen show a high degree of philopartry, and recapture rate was high. They remain motionless inside the caves during the day, leaving them after dark to forage, and return just after dawn. They always feed outside the caves and do not carry food into the caves. Soft‐bodied insects were the main food observed in the field. In the laboratory, they accepted plant and animal items and industrial foods. Their main predators are the spiderCtenus fasciatus, the heteropteranZelurus travassosi, and the marsupialPhilander opossum, and their main parasites are dipteran larvae (probably Ph

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1996.tb05933.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

Increase in body mass is an overall measure of growth which hides the dynamics of changes in body components. A study of the allocation of resources to growth versus reproduction is particularly interesting in guinea pigs (Cavia porcellus) where females mature early in the growth phase and produce highly precocial young while still growing rapidly.In order to get information on energy allocation in guinea pigs, fat‐free mass (FFM) of young (1‐30 days) and adult females (reproducing vs. non‐reproducing) was determined by measuringTOtal Body Electrical Conductivity (TOBEC; indexed by TOBEC#) which was calibrated by Soxhlet extraction.FFM was predictable from body length alone, but was best predicted as a function of (TOBEC#*length)0.5. Prediction was further improved by separating the data into two sets, for animals of 23 cm and of>23 cm body length. Fat and total body water (TBW) can also be determined from TOBEC#, but the reliability of fat determinations is low unless samples of 5‐10 equally treated animals can be averaged. The formula developed by Pace&Rathbun (1945) for the estimation of TBW has frequently been used for all kinds of mammals, but is shown consistently to underestimate TBW even in guinea pigs.Using our calibrations, we studied the development of FFM and body fat in young guinea pigs from birth to 30 days, and the development of FFM and fat stores in reproducing, primiparous, and non‐reproducing females of equal age.Young were born with about 11% fat. Young in large litters (3‐5) had relatively and absolutely less fat reserves than young in small litters. In eight young measured on days 1, 3, and 5, fat declined until day 3 and returned to the mass at birth on day 5. Fat mass increased slowly during the lactation period, until day 20, and faster thereafter in weaned young. Relative to body mass, fat decreased from 11.2% at birth to 9.3% on day 30, with a minimum of 6.6% on day 20. Mass of fat on day 30 was independent of litter size. FFM began to grow linearly from day 5 onwards. Body water in FFM varied with age in an inverted U‐shaped pattern.Reproducing females grew in FFM at equal rates to non‐reproducing females, but deposited less than half as much fat until day 210, by which time they had had two litters. Underad libitumfood conditions and a mild thermal regime, reproducing females allocated as much of the available resources to growth in FFM as non‐reproducing females, but reduced storage of fat, instead producing biomass o

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1996.tb05934.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

The food habits of strap‐toothed whales (Mesoplodon layardii) were examined in detail using stomach contents from 14 stranded whales found on South African and New Zealand coasts. Although a few unidentified fish otoliths and crustacean remains were found in two of these stomachs, 24 species of oceanic squids (some of which occur at a great depth) accounted for 94.8% of counted prey items (n= 232).Histioteuthissp. andTaonius pavowere the predominant prey species (25.0 and 17.2% by number, 21.4 and 19.9% by mass, respectively). The presence of sub‐Antarctic squid species suggested a northward migration to South African waters in late summer/autumn. Prey sizes were compared between males with fully grown strap‐teeth and females/immature males without erupted teeth, using dorsal mantle lengths (DML) and weights of squids estimated from beak measurements. Although females/immature males ate longer squids than males, there was no significant difference in the estimated weights of squids eaten by the two groups. The presence of fully‐erupted teeth in adult males, therefore, did not seem to influence the size of prey ingested, even though an adult male could only open its jaws about half as wide as a female. In general, the sizes of cephalopods eaten by strap‐toothed whales were not significantly different from those eaten by smaller odontocetes, such as spotted dolphins and dwarf sperm whales, but were significantly smaller than those eaten by larger odontocetes, such as false killer, long‐finned pilot, Cuvier's beaked, and southern bottle

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1996.tb05935.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

The reproductive pattern in male Angolan free‐tailed batsTadarida (Mops) condylurawas studied at two localities in the Eastern Transvaal during the period 1989‐1991. Males displayed a nine‐month breeding season extending from June to February. Following testicular recrudescence in early June, spermatogenic activity displayed two periods of peak activity in August/early September and November/early December. Although testes became involuted in March, baseline spermatogenic activity was maintained and tests never regressed to prepubertal conditions. Leydig cell morphology closely followed spermatogenic activity, with the diameter of Leydig cell nuclei displaying a concomitant seasonal pa

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1996.tb05936.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

Feathers are subject to large aerodynamic forces during flight and must therefore be stiff and strong, yet also light. Published estimates of Young's modulus of the feather keratin composite vary widely in the literature, and it is suggested that this is predominantly due to test methodology rather than true interspecific differences. The factors influencing the Young's modulus of keratin are discussed, together with their functional implications. Damage resistance must also be good; feathers that are lost or broken can only be replaced infrequently, but regularly, at moult. Feather shafts appear to be very strong for their weight. The possible role of the medullary foam in preventing buckling failure is still unclear; medulla removal only appears to have a minimal effect on both the stiffness and strength of whole sections of the rachis. Melanic keratin has properties that make it more competent at resisting abrasive wear than nonmelanic keratin.

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1996.tb05937.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

Plankton samples were collected from the Chukai‐Kemaman estuary in Malaysia in order to determine the distribution of testate rhizopods in relation to salinity. Two nearby freshwater ponds were sampled for comparison.In the ponds, 35 species of testate rhizopods were found, 13 of which were not found in the estuary. From the estuary 53 species were found, of which 31 were not found in the ponds. Some species appeared to have been lifted into the plankton by the rising tide. At a generic level, theArcellaspecies were very similar in both ponds and estuary (Sorensen Index 80), theDifflugiaspecies were moderately similar (Sorensen Index 47), whileNebelaandQuadrullelawere present in the estuarine samples, but absent from the pond samples.The salinity gradient ranged from sea water down to a conductivity of 27 μS. All the estuarine stations were tidal. The first freshwater testate rhizopods were found in a region where the conductivity was between 3000 and 4000 μS at high tide. Where the conductivity was below 1000 μS at high tide the number of species rapidly increased, and reached a maximum of 25 in the samples from the lowest conductivities. The flowering tree,Hibiscus tiliaceus, appears to be an indicator of the region where the first freshwater testate rhizopods might be encountered upstream from the

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1996.tb05938.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

The intestinal parasite fauna of the mountain gorillas of Bwindi—Impenetrable Forest, Uganda was studied by means of faecal examination and a single post‐mortem. The fauna was remarkably uniform between social groups and individuals, showing only slight differences between age groups; there is no evidence of any interaction between the parasites observed. The only protozoa were entodiniomorph ciliates; amoebae and flagellates were absent. Helminths included a single host‐specific cestode species and at least five nematodes, three of which are hostspecific. The closest relatives of the host‐specific parasites are found in ungulates and paenungulates, not in hosts phylogenetically related to the gorilla.This unique and specialized parasite fauna deserves to be monitored so that any effects of the habituation of the gorillas for tourism can be a

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1996.tb05939.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

The pouched mouse,Saccostomus campestris(Cricetidae), is an African rodent, known to lead a solitary life, where the female is overtly aggressive towards all conspecifics, except during the very short time of sexual receptivity, when she will tolerate the presence of a male and mate with him. In the present study, males were introduced to sexually receptive females to study their behaviour after mating and correlate that to the endocrine status of the female at that time.The present paper demonstrates thatc.12 hours after mating (and ovulation), the behaviour of female pouched mice reflects whether conception has occurred or not; conceived females became aggressive towards the male at that time, while non‐conceived females continued to be amicable towards the male during the subsequent phases of that and the following cycle(s), until conception occurred.Aggressive behaviour was not associated with measurable plasma levels of testosterone, and owing to large intra‐ and inter‐individual differences, no relationship was confirmed between plasma levels of oestradiol‐17β and levels of aggression during the oestrous cycle.Approximately 12 hours after mating, plasma concentration of progesterone was significantly higher in females that had conceived than in those that had not. This could not be correlated with the occurrence of aggression in these females, however, as there were no differences in progesterone levels between single, cycling females and mated non‐pregnant females at any stage during the cycle.The presence of a male, vaginal stimulation, and prolactin are not presumed to be involved in suppression of aggression in female po

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1996.tb05940.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

The bush dog,Speothos venaticus, is a rare forest‐dwelling South American canid. Social behaviour of a captive pack of three adult males and three adult females was observed over four years in a large enclosure. The dogs appeared to be compulsively sociable, sleeping in close physical contact, travelling together in single file, and feeding communally with minimal aggression. An alpha pair was dominant, but there was no clear hierarchy within the pack as a whole. There were, however, separate male and female hierarchies. The pack engaged in various communal behaviours, including greeting ceremonies in which individuals mutually submitted to one another. All dogs urine marked frequently, both sexes adopting postures to direct urine upwards and to soak their fur in odour. Only the alpha female bred successfully, and all other group members carried and guarded the young. These observations are discussed in the contexts of canid social behaviour and the breeding in captivity of this endangered specie

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1996.tb05941.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

The faunal composition of two Holocene fossil deposits of small vertebrates provided new information on the diet and biology ofSceloglaux albifacies, a strigid owl endemic to New Zealand. The taxonomic composition and several measures of diversity of the prey accumulation are given. Most taxa in the deposit had a mass of 50‐150g, but species up to 400g were also present. The owl was a generalist feeder, but the prey biomass distribution showed that a few taxa provided most of its energy requirements. Changes in the diet appeared to coincide with the appearance ofRattus exulans, the Polynesian rat, and the consequent decline or extinction of several prey. The ecologies of extant taxa represented in the deposit suggest that the owl was primarily a nocturnal forest species. Many prey taxa were terrestrial. Species richness was higher for both diurnal (by 50%) and nocturnal (by 63%) vertebrates in the deposit than in the present fauna around the site. Analysis of possible guilds in the pre‐human and present faunas of Takaka Hill suggests that ground‐frequenting taxa were most severely affected by extinctions; three guilds vanished ent

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1996.tb05942.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY