摘要:

A characteristic feature of onychophorans is the presence of crural glands in males. These exocrine glands open on the ventral surface at the base of the legs. Their restriction to males suggests a sexual function. Histochemical staining of the glands indicates that their secretion has both a lipid and a protein component. Behavioural bioassays show that the secretion acts as a pheromone attractive to conspecific females. The production of a sex pheromone in onychophorans is discussed in relation to their ecology and phylogeny.

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1993.tb05348.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

The durations of more than 4000 dives and recovery periods on the surface of 31 shags.Phalacrocorax aristotelis, were recorded using radio‐telemetry, during three breeding seasons. Data were also collected on the depth of water where the birds were diving and the size of lesser sandeels.Ammodytes marinus, fed to young each year. On average, shags foraged in water 30 m deep; mean dive and recovery times were 62·0 ± 1·92 sec and 84·4 ± 5·02 sec. respectively. These times were much longer than those recorded in previous studies and also longer than those predicted from allometric relationships for dive and recovery times derived for cormorants. A large proportion (>50%)) of dives appeared to involve anaerobic metabolism.Dive and recovery times were examined in relation to water depth, time of day and position within the diving sequence (dive number). In each year. dive time was positively correlated with water depth: in 1987 dive number also had a negative effect. The relationship between recovery time and dive time was positively accelerated, suggesting that birds were diving anaerobically on longer dives. The percentage of the dive cycle spent underwater therefore decreased significantly as dive time and water depth increased. Average vertical rates of ascent and descent of shags were calculated to be between 1·46 1·87 m sec−1. Estimated prey capture rates were significantly higher in 1989 (average 6±8 fish dive−1) when adults were feeding their young on small, low energy value sandeels than the two previous years (averages 1·4 and 1·9 fish dive−1, respectively) when birds were feeding on larger, higher quality fish. We calculated that, on average, birds spent 8 10 sec (36 48%) longer on the bottom at any given depth in 1989, which suggested that the higher prey capture ratcs were associated with an increase in duration of the bottom

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1993.tb05349.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

The taxonomic status of the Azorean bat (Nyctalus azoreumThomas 1901) was assessed, by a principal components analysis of measurements of the external morphology of the bat, together with specimens of the closest relatedNyctalusspecies from mainland Europe (Nyctalus leisleri). This analysis confirms the recent suggestion, based on a similar analysis of skull morphology, that the Azorean bat represents a good species, distinguished fromN. leisleriby its smaller size—forearm lengths forN. azoreumin range 35·7–42·0 mm (n= 14). compared with 42·0−45·8 mm (n= 8) forN. leisleri.The status and distribution of the Azorean bat was assessed by a survey conducted in the islands in September and October 1988. We assessed the presence or absence of bats, in 62(1′ latitude × 1′ longitude) plots at the west end of the island of Sao Miguel. The study area covered 6% of the total land area of the archipelago and contained representative areas of all the major island habitat types. A less intensive survey throughout four other islands, literature review and information from other sources revealed that the bat is probably distributed throughout the entire archipelago, with the possible exception of Flores and Corvo. Bats were active both in the day and at night. At night, bats were mostly active in coastal villages where they were closely associated with street lighting. During the day, most hats were active in the inland areas near to Caldeira lakes. The maximum number of bats observed simultaneously active in the day was six whilst at dusk swarms of up to 55 (± 5) bats were observed together. At night, bats were also active over approximately 1·5 × the area they occupied in the day. By assuming the bat is found throughout the archipelago, and that our study area was representative, we estimated the maximum population to be between 1750 (from daylight activity) and 23,650 (from nocturnal activity). This latter estimate implies a population density throughout the archipelago of around 0·

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1993.tb05350.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

Two populations of roe deer from Spain, approximately 300 km apart from each other and currently recognized as separate subspecies. were studied to analyse the nature of the morphological differences between these populations and to assess the validity of its taxonomic division. Sixty‐one skulls of roc deer from the Occidental Cantabric Mountains (OCM) and 17 from the Northern lberic Mountains (NIM) were used. No significant sexual dimorphism allowed pooling of male and female samples, on which a large set of 53 measurements was taken. Skulls from the OCM population are, on average, 1·9% larger than those from the NIM population. Twenty‐five out of the 53 characters showed some degree of significant differences between means of both populations, though only four showed highly significant differences. Mandible characters were the most variable traits, showing also significant differences between populations. Eight principal factors were extracted. explaining a total of 84·7% of the sample variance. An ANOVA of factor scores from each population revealed significant differences in PF 1 and PF 3. Interpretation of these two factors suggests that morphological differences between both populations can be summarized as specimens from OCM having larger mandibles and broader neurocranium than specimens from NIM. Mandible differences might reflect morphological adaptations to favour the consumption of ligneous plants, which are more frequently eaten by the OCM roe deer population, whereas a broader neurocranium might be related to antler size. It is concluded that biometric differences observed in skulls from these two populations only reflect minor morphological adaptations to different habitats, thus. there is a lack of morphological data to support the taxonomic distinction of the OCM population as a separate subsp

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1993.tb05351.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

Golden spiny mice (Acomys russatus) and common spiny mice (Acomys cahirinus) are omnivorous rodents that are sympatric in many rocky areas in Israeli deserts. They are similar in body size and diet habits. They differ in thatA. cahirinusare nocturnal whereasA. russatusare diurnal andA. russatusinhabit extremely arid areas whereA. cahirinusare absent. These differences led us to hypothesix thatA. russatusare more conservative in their water needs and thererore are ahle to consumc a drier diet thanA. chairinus.To test this hypothesis we oikrcd both species a dry ration and different numbers of snails and measured their energy and water intakes and their body mass changes.Acomys russatuswere capable of maintaining body mass on a much drier diet thanA. cahirinusand therefore our hypothesis was supported. In order to maintain body massA. cahirinusrequired about 2·1 ml/day (or about 4·7% body mass) preformed water, about twice the volume required byA. russatus.They also required a diet that had a water content of 48·3%, of the fresh matter, which was about 20% higher than that ofA. russatus.The main reason whyA. russatusneeded less water was that they losl less by evaporation thanA. cahirinusdid. We suggest that the lower preformed water needs ofA. russatusand their ability to consume a drier diet allom them to tolerate higher air temperatures and to inhabit extreme deserts whereA. cahirinusare abse

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1993.tb05352.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

We examined the hypothesis that pseudosexual behaviour facilitates reproduction in the unisexual gecko,Lepidodactylus luguhris.Thirty‐eight hatchlings were housed in isolated or social conditions. Age at initial egg development, days between egg development and laying for the geckos’first three clutches of eggs, inter‐clutch intervals and dominance behaviours were recorded.Lepidodactylus lugubrisdeveloped their first clutch of eggs at about 9·5 months of age after their endolymphatic sacs became externally visible. The geckos laid their eggs about 28–30 days later with smaller geckos requiring more time between egg development and laying than larger geckos. Grouped geckos formed dominance hierarchies. In the triad and quadrad groups, the subordinate geckos’growth rates were slowed and their fecundity was suppressed. Pseudosexual behaviour was not observed in the geckos and was unrelated to fecundity because isolated geckos developed and laid three clutches of eggs at the same rate as grouped geckos. Dominance behaviour, not pseudosexual behaviour, was related to fecundity inL. lugubris.Dominance behaviour may facilitate dispersal in this colonizing species because subordinate geckos could increase their fecundity by moving to less popul

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1993.tb05353.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

Analysis of prey remains in scats, particularly hairs, is widely used to study diet of mammalian predators, but identification of hair is often difficult because hair structures vary considerably both within and between species. Use of photographic reference of diagnostically important hair structures from mammals occurring in a predator's habitat has been found to he convenient for routine identification. A photographic reference key was developed for the identification of hairs of the mammals known to occur in a snow leopard (Panthera uncia) habit at in the Annapurna Conservation Area, Nepal. The key included a photographic reference of the diagnostic hair structures of nine species of wild and five species of domestic mammals. The cross‐sectional appearance, shape and arrangement of medulla, the ratio of cortex to medulla. and the form and distribution of pigment in medulla and cortex were important diagnostic aids in the identification of hair

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1993.tb05354.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

Home ranges, relationships between individuals and dispersal among raccoon dogs (Nyctereutes procyonoides) were studied in southern Finland in 1989‐91. The average maximum home range, calculated by the harmonic mean method. was 9·5 km2and the core area (85% utilization) 3·4 km2. There were no statistically significant annual. seasonal or sexual differences in the size of the average core area of adults, but the home ranges of juveniles in autumn were larger than those of adults. However. the maximum home ranges of adults were larger in autumn than in summer, especially those of males, which were conspicuously small in summer and large in autumn. The core areas of adjacent pairs did not usually overlap in the pup‐rearing season. but in autumn some home ranges shifted and there was much more overlap. The home ranges of the male and female of a pair overlapped almost totally, and a male and a female sharing the same home range also travelled together or close to each other, thus supporting the idea that the raccoon dog is monogamous in Finland. None of the adults left the study area, but 38% of the juveniles were recovered further than 10 km from the marking place during the first a

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1993.tb05355.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

The growth of bottlenose dolphins is described from observations made during a capture release programme that has operated in coastal waters of the eastern Gulf of Mexico from 1970 to the present. Measurements of standard length, girth and body mass were recorded from 47 female and 49 male dolphins, some captured as many as nine times. Ages were known from approximate birth dates or estimated from counts of dentinal growth layers. In all three measurements. females grew at a faster initial rate than males, but reached asymptotic size at an earlier age. This extended period of growth in males resulted in significant sexual dimorphism in length, girth and mass at physical maturity. The growth of both sexes was well described by three‐parameter Gompertz models using either cross‐sectional data or a mixture of longitudinal and cross‐sectional data. There was considerable variation in size‐at‐age for both sexes in all year classes. Residuals of size measurements were used to derive measures of relative size for individual dolphins; most dolphins demonstrated little ontogenetic change in relative size. Body mass was adequately predicted by multiple regression equations that incorporated both length and girth as independent

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1993.tb05356.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

The food and energy requirements of breeding gentoo penguins (Pygoscelis papua) were studied at Heard and Macquaric Islands by means of isotope turnover techniques.The food consumption rates of chicks were measured at various stages of growth, providing estimates of the total food provided by adults to rear a chick to fledging.The energy expenditures of attending adults were also measured at different stages of chick‐rearing, allowing the total energy costs associated with breeding to be established for a pair of adults and at the population level on both islands. We estimate the total annual energy budget of a 6·2 kg breeding gentoo penguin to be 1517 MJ which is equivalent to the consumption of 292 kg pr

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1993.tb05357.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY