摘要:

Dorylaimus parasiticussp. nov.(Nematoda: Dorylaimidae) si described from the digestive tract and general body cavity ofSalamandra salamandra, Rana perezi, andBufo bufo, amphibians of the Iberian Peninsula (Spain). This is the first record of a member of the Order Dorylaimida size, a thick transversely striated body cuticle with 20 to 26 longitudinal ridges.

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1995.tb02756.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

The diet of ottersLurra lutrnliving in a sea loch on the Isle of Mull was described by means of spraint analysis. Seasonal and spatial differences in the spraint composition were explored in the context of fluctuations in prey availability, as revealed by trapping. ButterfishPholis gunnellusand the cottidsMyoxocephalus scorpiusandTaurulus bubaliswere the most commonly occurring prey in spraints. In the winter, the proportion of rocklings (Ciliataspp. andGaidropsarusspp.) and non‐rockling gadoids (Gadidae) in the diet increased. Their relatively large size makes these latter species an important constituent of the winter diet. Seasonal and spatial variation in fish consumption largely reflected fluctuations in availability. The mean size of principal prey fishes in spraints was similar to that observed in the traps. These observations suggest that otters were not strongly selective with regard to fish species and size. Shore crabs, in contrast, were not taken in proportion to availability. The findings are discussed in the light of other studies of the diet of coastal otters. It is suggested that the lack of selectivity demonstrated in this study, compared with previous studies, may be explained by area‐related variations in prey availabil

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1995.tb02757.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

The mole rat (Spalax ehrenbergi) is a blind, solitary, highly aggressive subterranean rodent well adapted to underground life, and in Israel involves four chromosomal species (Nevo, 1991). Little is known to date about its reproductive biology and all attempts to breed mole rats in captivity have failed. The present study investigated the effects of three different light regimes on vaginal smear and annual cycle of body weight, age at sexual maturity, and various parameters of reproductive behaviour of female mole rats. Daily vaginal smears throughout the year revealed that the mole rat does not have a regular oestrous cycle, but exhibits an annual rhythm with a seasonally cornified smear. Regardless of the photoperiods the females were exposed to in the laboratory, relatively high proportions of cornified smears were found during the winter breeding season. A second, albeit small, peak of cornified cells was found during the summer season. Photoperiod had no effect on annual body mass cycle either, and mole rats kept under the different lighting regimes reached their maximum weight just prior to the beginning of the breeding season. In young females, vaginal opening occurs at the age of four weeks and first cornified smear at the age of 4–7 months. The presence of a cornified smear was found to be an insufficient criterion for receptivity, but providing the opportunity for a female to choose her mate enhances the chances of copulations occurring during encounters. We conclude that the mole rat is a seasonal breeder which reproduces during the winter, but has the potential of summer breeding too. Our findings also suggest that females probably have the potential to breed in their first winter. The seasonally constant vaginal smear periods, and the post copulation vaginal smear data are the first evidence suggesting that the mole rat is a reflex ovulator, but the ovulatory failure we observed after single copulations raises the possibility that multiple copulations are necessary to induce ovulatio

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1995.tb02758.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

The sleeping habits of moustached tamarins,Saguinus mystax, and saddle‐back tamarins,Saguinus fuscicollis, were studied in northeastern Peru. Five types of sleeping sites were distinguished: 1) Jessenia bataua palms; 2) tree hollows; 3) dense tangles of vegetation; 4) crotches; 5) open horizontal branches. Both tamarin species used Jesseniu‐palms most frequently. Tree hollows ranked second in the saddle‐back tamarins, but were never used by moustached tamarins. Sleeping sites of moustached tamarins were located significantly higher than those of saddle‐back tamarins.Jessenia‐palms used by moustached tamarins were significantly higher than palms from a random transect sample, but this was not the case forJessenia‐palms used by saddle‐back tamarins. For both species, concealment seems to be more important than height above ground. The maximum number of subsequent nights spent in the same sleeping site was two in moustached tamarins and six in saddle‐back tamarins. The two tamarin species did not compete for sleeping sites. While the general pattern of sleeping site selection conforms to hypotheses predicting safety from predators as a major factor, differences between the two tamarin species reflect general niche differences between them. Most sleeping sites are located in exclusively used parts of the home range. Moustached tamarins generally use sleeping sites that are close to the last feeding site of the afternoon. The distance between simultaneously used sleeping sites of moustached and saddle‐back tamarins are generally close together, which helps to minimize time spent out of interspe

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1995.tb02759.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

In comparison with other carnivores, European badgers,Meles melesL., show an unusually high degree of natal philopatry. In this paper, we present data on temporary and permanent movements between groups, in both male and female badgers, in a moderately high density population. A relatively small proportion of males dispersed, alone, to neighbouring territories. Dispersing males were larger than those remaining in their natal groups, and following dispersal they had higher testosterone titres and maintained testicular activity for a greater part of the year. Circumstantial evidence suggests that immigrants were the principal breeding males in their new territories. Dispersal was slightly more common in females, which dispersed away from large groups, where their chances of breeding were relatively low. Females dispersed in coalitions of 2–3, over longer distances, to territories occupied by single females. Resident females disappeared following the arrival of the immigrants, suggesting that territory ‘takeovers’ may have occurred. Members of both sexes also made temporary ‘visits’ to neighbouring territories, probably to obtain extra‐group matings. Comparison with other badger populations suggests that the frequency of male dispersal declines at high population densities. In contrast, there is no effect of density on female dispersal, which occurs only rarely in some other populations. We suggest that the pattern of female/female competition is too complex to be explained solely in terms of variation in populat

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1995.tb02760.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

Two species of land nemertines have been reported from Rodrigues. The first,Geonemertes rodericana, was discovered by Gulliver in 1874 at which time extensive searches revealed no other species on the island; in 1993 two of the present authors visited Rodrigues and could find onlyG. pelaensis, a species which is widespread on other Indopacific islands including Rkunion, a new locality reported in the present paper. Histological re‐examination ofG. rodericanashows that, while the two species are closely related, both being correctly placed in the genusGeonernertes(Prosorhochmidae), they differ not only in colour but also in internal features; for example,G. pelaensisis hermaphroditic whileG. rodericanais dioecious. A full description ofG. rodericanais given here for the first time.Geonemertes rodericanahas only been recorded from the island of Rodrigues and is now feared to be extinc

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1995.tb02761.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

We present a comparative test of Charnov's recent theoretical model of mammalian life‐history evolution. Phylogenetic analysis of life‐table data from 64 species, ranging across nine orders. supports all of Charnov's assumptions and most of his predictions. The allometries of time from independence to maturity (a), annual fecundity, and adult and juvenile mortality rates are in agreement with previous work and with the theory, as are the signs of the relationships among these traits when body size is controlled for. As predicted, the non‐dimensional products of a and each of the other three traits are independent of adult body size, as is survivorship to maturity. However, we find that the ratio of weaning weight to adult weight (δ) is correlated with adult weight, in contradiction with the theory, and we do not find the predicted relationships between δ and the three non‐dimensional products. The discrepancies could be because we have equated independence with weaning, or because the model assumes determinate growth: they could arise if large mammals have relatively longer periods of post‐weaning care, or continue to grow after starting to reproduce. There is some evidence that δ is influenced by the nature of mortality around independence (density‐dependent or density‐independent), and we suggest this as a possible area for further work. In general, the areas of agreement between Charnov's theory and the data are more impressive than the differences, indicating that it could be a major breakthrough in understanding the evolution of life histories in p

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1995.tb02762.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

We studied causes and consequences of egg‐size variation among clutches of American kestrels (Falco sparverius). Egg. from 275 clutches were measured 1990 to 1992. To test the hypothesis that the size of eggs was contrained by food availability in the pre‐laying period, we censused small mammal populations in the three years and performed a food supplementation experiment in 1990 and 1991. Kestrels did not advance the date they laid their first egg but did lay significantly larger eggs in response to extra food. The size of eggs was correlated with small mammal abundance on the territoty, and females in good body condition tended to lay large eggs. Body size did not affect egg size, and there were no relationship between agg size and laying date except in 1900, the poorest food year. Clutches with a large mean egg volume had better hatching success than clutches containing small eggs. We argue that there is a phonetypic component to egg size in kestrels, and that kestrels use egg size to fine‐tune reproductive investiment to available reso

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1995.tb02763.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

The noctuleNyctulus noctula(Schreber, 1774) is a relatively large (c. 25 g) insectivorous bat which catches insects on the wing (by aerial hawking). Emergence at a maternity roost was earliest relative to sunset when females were lactating, and bats may then have risked predation by flying at higher light levels during a period of high energy demand. Flight performance was quantified by using stereophotogrammetry. At feeding sites bats flew at 6.0 ± 2.1 m/s. This was faster than predicted minimum power speed (Vmp), and either between Vmpand maximum range speed (Vmr), or close to their predicted Vmr, depending on which aerodynamic model of flight power requirements was used. The echolocation behaviour of noctules is flexible. Long duration, low frequency calls (c. 20 kHz) with little frequency modulation were emitted while cruising, but at foraging sites the calls became more frequency‐modulated. As the noctule is traditionally thought of as using low frequency echolocation, it was expected to receive weak echoes from small targets and therefore to specialize in eating large insect prey. Although the bats ate mainly beetles, large numbers of small dipterans were also eaten. The noctule is probably able to detect such small items because, when foraging, its calls become broadband and sweep from high frequencies. Higher harmonics are also present, and these may assist in the detection of small prey. In noctules, as in many bats, there appears to be a 1:1 link between wingbeat and call production during the search phase of foragi

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1995.tb02764.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

The advertisement calls of 23 Bolivian anuran species in the family Leptodactylidae are described including information on calling behaviour. For each species, a characteristic audiospectrogram and oscillogram are presented. Numerical information about the spectral and temporal features of the calls is provided and, when available, the results are compared with any previous description of the calls. A phenogram based on holistic comparisons of the mating calls (audiospectrogram correlation) is presented for the generaEleutheroduciylus, Leptoducrylus. andPlzysalaemus. The intrageneric variability of four basic call parameters is compared. The results suggest that fundamental and dominant frequency (and possibly duration for the genus Physalaemus) are the most likely variables to play a role in isolation of congeneric species.

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1995.tb02765.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY