摘要:

Between July 1980 and February 1984, six jaguars (two males, four females) were fitted with radio‐collars and monitored for a cumulative total of 105 months, in the Pantanal region of southwestern Brazil. Mean home range size (minimum convex polygon) for five of them (one male, four females) was 142‐ 1 km2. Mean home range size during the dry season was 54·3 km2, whereas in the wet season it was significantly smaller, 12·8 km2. Mean home range overlap of the four females was 42%. Use of gallery forest and forest patches exceeded the availability of these habitat types in the animals' home ranges, whereas open forest and grassland were used less than expected on the basis of their availability. Mean distance moved between locations on consecutive days was 2·4 km (0.2‐10·4 km). The mean one‐day movement of the male jaguar was significantly (P<0·001) larger than that of the females. Mean distance travelled by all animals during one‐day intervals in the dry season was significantly greater (P<0·001) than that travelled in other months. Jaguars were more active during daytime than night‐time (P<0·001). Overall level of activity for the wet season did not differ from that of the dry season. With their larger body size, jaguars in the Pantanal may require more food than jaguars in other areas of the species' range. This, in addition to differences in prey availability and the annual availability of dry land, appear to influence the difference in home range size between

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1991.tb04770.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

The mating behaviour and male mating success ofHyla ebraccatawere examined over three study periods. Mated males were larger than unmated males on a significant number of nights and for one of the three study periods. In field observations of pair formation, female behaviour was consistent with choice of large males: females moved freely through the chorus, remaining within 10 cm of males larger than the nightly mean, before the male initiated amplexus. In 27% (n = 3) of these observations, males chased and fought over the female. However, the females removed two of these three males from amplexus, suggesting that females can also exercise choice after amplexus. There was a significant negative correlation between male size and dominant frequency of the primary note, indicating that the male's advertisement call contained size‐related information. Comparisons of the size of mated and unmated males suggest that two factors may have affected the degree to which female choice influenced male mating success. First, the distance between calling males may have limited the opportunity for females to express a mating preference. Secondly, an increase in mean and a decrease in the variance of male size in one of the three study periods also may have limited the ability of females to express a preference for large male

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1991.tb04771.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

A comparative account of the morphology of chilopod coxal organs is given with special reference to their possible function.Allometric relationships which exist between the size of the centipede and the number of coxal pores and organs are discussed in the context of size‐dependent physiological constraints which may affect the function of the coxal organ

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1991.tb04772.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

Oxystele variegata (Anton, 1838) is one of the commonest intertidal topshells on the coast of South Africa. In this study we show that the so‐calledO. variegataactually consists of two sympatric species, which differ in shell colour patterns, in the proportions of the central tooth of the radula, and in the electrophoretic mobilities of some enzymes:O. impervia(Menke, 1843) (which tends to occur higher up the shore), andO. variegata(Anton, 1838) (occurring further down the shore).The shell of O. impervia has a pattern of dark red, orange, yellow or brown maculations, on a ground colour that is red, orange, yellow or brown, respectively; that ofO. variegatahas a pattern of red maculations or lines on a ground colour that is either off‐white, or greenish‐grey. BothO. imperviaandO. variegataexhibit an immense variety of shell colours and pattern and in both, shell colour variation is an interplay between two factors: ground colour and maculated spiral bands. By expanding the maculated spiral bands in breadth, at the expense of the ground colour, an original shell pattern of spiral bands may be transformed into one of axial or diagonal stripes.The radula of both species resemble the typical trochid pattern. They are, however, consistently different: the central tooth of the radula ofO. imperialusually has a shallow base and a cusp that is slightly indented, whereas that of O. variegata usually has a deep base, and a well indented cusp.Further differences between the species were revealed by electrophoretic studies. Of six loci examined, two were found to be taxonomically diagnostic. Another two had at least one species‐specific allele at a frequency of 0·1 or greater, and significant heterogeneity in allelic frequency between the two species was found in the four non‐diagnostic loci.The differences in shell colour patterns, radular tooth structure and enzyme mobilities support the conclusion that O. impervia and O. variegata are separate but closely related species, with similar geographic distributions and an overlappin

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1991.tb04773.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

Penaeus latisulcatuswere collected monthly over three years from the large Peel‐Harvey Estuary and nearby shallow and deeper marine waters in south‐western Australia. The relationships between catch rates obtained by seine net, and various environmental variables and sampling locations in the estuary, strongly indicate that salinity and distance from estuary mouth exert a marked influence over the distribution and abundance of prawns within the estuary. Since commercial catches of prawns in the Peel‐Harvey were very low during the 1970s, when the macroalgaCladophora montagneanacoated much of the substratum of the estuary, the extent of the preferred sandy substratum ofP. latisulcatusis also assumed to affect abundance. The modal carapace lengths (CL) of males and females caught by beam tide nets during their migration out of the estuary were sharply defined and in each year remained similar during the migratory period (typically February to July), when freshwater discharge, salinity and temperature were changing markedly. Although this provides strong evidence that the time when king prawns leave the estuary is at least partly related to factors associated with the attainment of a certain body size, it is also relevant that the decline in catch rate was greatest in the year when salinity fell most rapidly. Migration reached a maximum between March and May and in each month peaked just after the full moon. Comparisons between length‐frequency data for emigrating prawns and prawns caught commercially by trawling in marine waters indicate that, after leaving the estuary, manyP. latisulcatusmigrate a few kilometres northwards and remain there for a few months. The months when the incidence of mature ovaries is relatively high in the larger of the trawled female prawns (CL>30 mm) is consistent with the time of immigration of new recruits (2‐3 mm CL) into the estuary (December‐April).Penaeus latisulcatusstart migrating into the Peel‐Harvey Estuary later than into inshore marine waters (November or December vs. September) and subsequently emigrate from this alternative nursery area at a larger size (carapace length>20 mm

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1991.tb04774.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

The behavioural interactions between caterpillars ofMaculinea rebeliHir. and theirMyrmicaant hosts were studied, both in the wild at the time of adoption, and inside captive nests of sixMyrmicaspecies.In the wild, freshly moulted, final instar caterpillars left their food‐plants at a time of day that coincided with the peak foraging activity ofMyrmica(18:00‐20:00 h). Once on the ground, caterpillars made no attempt to search forMyrmicabut settled and waited for foraging ants to find them, which took up to 1.5 h. There was no adoption ritual: foragers of anyMyrmicaspecies picked up the caterpillars within 1–4 sec of discovery, and carried them directly to their nests.Caterpillars grew from<2 mg to 110 mg in laboratory ant‐nests. About 60 mg was gained in autumn but 40% of this was lost during the winter, while the temperature was<14 °C. Although caterpillars survived best with their normal host,Myrmica schencki, they could also survive in the nests of otherMyrmicaspecies. The presence of queen ants had no effect upon survival. The behaviour of the caterpillars was described and illustrated: this included the production of secretions that were drunk by the ants, begging for food and direct feeding by ants. The preferred solid food was ant eggs.The results are discussed in terms of the social biology ofMyrmicaants. It is hypothesized thatMaculinea rebelicaterpillars mimic the touch pheromones of ant worker‐larvae. This would explain the inability of ants to recognize caterpillars before touching them, their immediate adoption by anyMyrmicaspecies after discovery, host specificity inside wild ant‐nests, the absence of queen‐effect and the intimate attention o

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1991.tb04775.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

The water and energy metabolism of free‐living male common seals (Phoca vitulina) during the mating season was investigated using labelled water methods. All three seals, which were captured on two occasions, were in negative energy balance during the study. The daily energy expenditure of one animal, estimated using doubly‐labelled water was 52·5 MJ. This is equivalent to six times the basal metabolic rate predicted from Kleiber's (1975) allometric equation. Rates of water turnover were slightly lower than predicted from the allometric equation of Richmond, Langham&Trujillo (1962). The observed rates of water turnover and energy expenditure are considerably higher than those of seals which fast during the mating season, and are consistent with the observed differences in behaviour between males of the common seal and other pinniped males during ma

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1991.tb04776.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

The effects of 6‐methoxybenzoxazolinone (6‐MBOA) and supplemental food on the reproductive activity ofTatera leucogasterwere examined using a field experiment. The experiment was carried out during the dry season when no pregnancies were observed. Animals provided with 6‐MBOA‐treated millet seeds for 10 days were not significantly different from animals provided with sham‐treated seeds. Supplemental food appeared to have no effect on female reproductive activity, but increased the body mass of both sexes and also the mass of the testes and seminal vesicles. These results provide no evidence for an effect of 6‐MBOA on reproductive activity of this equatorial rodent, but supplemental food may promote the maturation and recrudescence of reproductive orga

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1991.tb04777.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

We used measurements of morphological parameters of common nighthawks (Chordeiles minor) and big brown bats (Eptesicus fuscus)to derive predictions about foraging behaviour based on the animals foraging at the same site. We tested the predictions using data from direct observation, radio telemetry and diet analysis and found a high degree of convergence in behaviour by these two species.

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1991.tb04778.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

Our aim is to investigate whether the stiffness of tendons, when measured at room temperature, can be safely used in considering the function of the tendons at the higher temperatures encountered in life. We have examined stress‐strain plots given by tendons subjected to longitudinal tension. Under cyclic loading the plot becomes a hysteresis loop because of energy losses. Tail tendons were chosen because they are conveniently long, thin and uniform. The results show a small, but statistically significant, variation with temperature in the energy loss of hysteresis. The slope of the stress‐strain plot (i.e. the tangent modulus) shows no significant variation. We conclude that changes with temperature, in the range 20 to 41 °C, are not functionally impor

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1991.tb04779.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY