bluuebunny/crossref_metadata_2025_split huggingface dataset:
Use of a seaweed habitat by red deer (Cervus elaphus L.)
Authors: Conradt L. 
Published: February 2006

AbstractThe use of a seaweed habitat by red deer Cervus elaphus L. on the Isle of Rum, Scotland, was examined in detail. New information is provided on diet selection, timing of seaweed use relative to tides, inter‐individual differences in seaweed use, and sex differences in site use within the seaweed habitat (‘site segregation’). Interestingly, seaweed use by adult males and females was closely correlated to that of their mothers. This implies that deer ‘learn’ early in life to include seaweed into their diet. Formerly, it has been suggested that male inferiority in indirect competitive ability relative to females causes site segregation in dimorphic ungulates (‘indirect competition hypothesis’). The observed pattern of site segregation within the seaweed habitat was used to test the hypothesis, which predicts that males should be found at sites where they can achieve higher intake rates, but where forage quality is lower than at female sites. With respect to seaweed use, the hypothesis further predicts that segregation should be lower within the seaweed habitat than within terrestrial vegetation communities, and that males should time seaweed use earlier (relative to the tide) than females. This is because seaweed availability is more subject to tidal rhythm than to indirect competition in comparison to terrestrial habitats. Males and females used different bays, and within bays they used different fractions of seaweed. However, male‐preferred sites did not yield higher intake rates and were not of lower forage quality than sites preferred by females. Moreover, segregation was not lower within the seaweed habitat than within terrestrial vegetation communities, and males did not time their seaweed use earlier relative to the tide than did females. The indirect competition hypothesis could not explain the observed pattern of site segregation. Other factors, such as sex differences in sheltering or anti‐predator behaviour, or social harassment, could be responsible instead.
Testes size, body size and male–male competition in acanthocephalan parasites
Authors: Poulin Robert , Morand Serge 
Published: February 2006

AbstractIn most invertebrate taxa, males are smaller than females and large male sizes are only favoured when male–male competition for access to females is intense. In addition, in species where sperm competition is important, relatively large investments in testis growth and ejaculate size will also be selected. The use of copulatory plugs by males of some taxa, however, can prevent sperm competition. We hypothesized that, across related species in which males use plugs, relative testis size would decrease with increases in the severity of male–male competition. We tested this prediction across 112 species of acanthocephalan parasites, worms that use copulatory plugs and in which male–male competition occurs. As a measure of the intensity of male–male competition in a given species, we used sexual size dimorphism. Male and female body volume covaried allometrically, suggesting that sexual size dimorphism in acanthocephalans is the product of sexual selection. Our main finding is that relative testis volume, corrected for male body volume, decreases significantly as male body volume relative to female volume increases, i.e. as the sexual size dimorphism becomes less female‐biased. All our results remained unchanged after we controlled for potential phylogenetic effects. The relationship indicates that investment in testis growth beyond the minimum size required for efficient fertilization becomes increasingly less important in species where males appear to compete intensely for mating opportunities.
Mother–pup vocal recognition in the grey seal (Halichoerus grypus) of Sable Island, Nova Scotia, Canada
Authors: McCulloch S. , Boness D. J. 
Published: February 2006

AbstractParental recognition of offspring would be expected to evolve among densely populated species in which parental investment is large, and separations of the mother–pup pair are frequent. Although otariids present a well‐developed system of mutual vocal recognition, evidence in phocids is weak. Furthermore, allo‐suckling is prevalent in some species and may reflect confusion over the identity of pups. The vocalizations of grey seal Halichoerus grypus pups have been found to be stereotyped and individually distinctive on the Isle of May, Scotland. However, playback experiments showed that mothers fail to discriminate between the vocalizations of their pup and a non‐filial pup. Moreover, widespread allo‐suckling was observed. In contrast, grey seals on Sable Island, Nova Scotia, a population reproductively isolated from that of the Isle of May, show very little allo‐suckling. This may reflect the presence of a recognition system that does not seem to be present on the Isle of May. During the 1999 breeding season on Sable Island, vocalizations of grey seal pups were recorded and playback experiments carried out to determine whether female grey seals respond differently to the playback of vocalizations of their own pup, a familiar pup and an unfamiliar pup. Grey seal mothers were found to make significantly more head turns and body movements towards the loudspeaker during the playback of their own pup call than during the playback of a familiar or unfamiliar pup call. In addition, there was no evidence of an effect of pup age. This suggests that female grey seals can discriminate between pup calls using the stereotyped and individually distinctive vocalizations of their pup, and that different selective pressures may be in operation between the Sable Island and Isle of May colonies.
Nesting phenology of magpie geese (Anseranas semipalmata) in monsoonal northern Australia: responses to antecedent rainfall
Authors: Whitehead Peter J. , Saalfeld Keith 
Published: February 2006

AbstractThe density of nests of the magpie goose Anseranas semipalmata on the Mary River floodplain fluctuated markedly during 1988–93, failing almost completely in unfavourable (El Niño) years. Nest density and timing of nesting were strongly correlated with variations in the time of onset of the wet season, but were much less sensitive to rainfall quanta in the mid‐ to late wet season. Nest densities were higher and nesting was initiated earlier in breeding seasons preceded by sustained rainfalls during the transition from dry to wet seasons. Clutch sizes were slightly larger in years of early wet‐season onset. Within seasons, later clutches contained fewer eggs and the eggs were smaller, probably as a consequence of later nesting by younger birds. Second clutches from a small sample of marked re‐nesting birds and a pulse of nesting after flooding losses, contained similar numbers of eggs to first clutches, but the eggs were larger. Dependence of nesting on events occurring months before clutch initiation, when birds are using habitats distant from nesting colonies, illustrates the importance of integrated management of floodplain systems to meet year‐round habitat needs, and the risks posed by homogenization of wetlands by improvement of pasture for grazing.
Pristina silvicola and Pristina terrena spp. nov., two new soil‐dwelling species of Naididae (Oligochaeta, Annelida) from the tropical rain forest near Manaus, Brazil, with comments on the genus Pristinella
Authors: Collado Rut , Schmelz Rüdiger M. 
Published: February 2006

Abstract Pristina silvicola and P. terrena spp. nov. are described from soil samples of the primary rain forest at the Brazilian Agroforestry Research Facility near Manaus, Brazil. Living and preserved specimens were studied. The species are among the smallest oligochaetes known (1–1.5 mm long) but they are conspicuous by their brilliant, highly refractile coelomocytes. Pristina silvicola is also described from sexually mature specimens. Its character combination invalidates Pristinella as a genus separate from Pristina. Both genera are reunited as Pristina. Pristina silvicola and P. terrena, species which lack a proboscis, share a character combination that is unique in the genus: stomach absent, first nephridia in segment VII, ventral chaetae uniform with upper tooth not longer than lower. They differ from one another in the shape of the brain and in other details of the chaetae.
Geographic and temporal variation in the condition of pups of the New Zealand fur seal (Arctocephalus forsteri): evidence for density dependence and differences in the marine environment
Authors: Bradshaw Corey J. A. , Davis Lloyd S. , Lalas Chris , Harcourt Robert G. 
Published: February 2006

AbstractWe report on the geographic and temporal variation in pup condition in 20 colonies of New Zealand fur seals Arctocephalus forsteri around South Island, New Zealand during three consecutive breeding seasons, 1996–98 (n= 6856 pups) and provide hypotheses to explain the observed patterns. Three alternative data combinations are presented to calculate pup condition from body measurements and identify which combination seems to be best suited for analysing geographic patterns. A morphometric index of pup condition was best estimated by comparing all pups in all years using least‐squares linear regression of the loge‐transformed measurements of length vs mass. Condition varied significantly among years and colonies, but not between sexes. We also estimated seasonal changes in pup densities at colonies and investigated the relationship between pup density and condition. Mean pup densities among colonies ranged from 4.94 to 7.46 pups/100 m2 (summer) and from 4.99 to 7.04 pups/100 m2 (winter) from 1996–98, and differences between summer and winter densities varied with year. Pup density explained a significant proportion of the variation in pup condition in 1996 and 1998, suggesting that condition is partly density‐dependent. After accounting for the effect of density, we found geographic differences in pup condition, and we offer alternative hypotheses to explain these differences. We also show that the 1998 El Niño coincided with a reduction in pup condition. A morphometric index of pup condition seems to be useful as an indicator of spatial and temporal variation in the marine environment.
The influence of risk and vulnerability on predator mobbing by terns (Sterna spp.) and gulls (Larus spp.)
Authors: Clode Danielle , Birks Johnny D. S. , Macdonald David W. 
Published: February 2006

AbstractThe extent to which anti‐predator mobbing can be modified in response to new predators was investigated by examining the response of terns (Sterna hirundo and S. paradisaea) and gulls (Larus fuscus, L. argentatus and L. canus) to introduced mink Mustela vison, native otter Lutra lutra and rabbit Oryctolagus cuniculus models in areas inhabited by mink and areas uninhabited by mink. Gulls and terns typically flock over predators of adult birds (a fleeing response), whilst diving at predators of chicks and eggs (an attacking response). Terns in mink‐inhabited areas flocked over a model of a mink, but did not dive at it as much as they dived at otter and rabbit models. A stronger fleeing rather than attacking response suggests that adult terns perceive mink as a threat to themselves as well as to their chicks and eggs. Gulls, in comparison, dived at the mink model, indicating that mink are not perceived as a threat to the adults of these considerably larger species. Both gulls and terns showed a much lower level of response to mink in mink‐free areas, suggesting that the type and extent of mobbing is altered through experience with predators and the level of risk associated with mobbing the predator.
The mechanics and muscular control of constriction in gopher snakes (Pituophis melanoleucus) and a king snake (Lampropeltis getula)
Authors: Moon Brad R. 
Published: February 2006

AbstractConstriction of prey by gopher snakes Pituophis melanoleucus and king snakes Lampropeltis getula is highly variable in posture, muscular activity and force exertion. These snakes typically use lateral bends of the anterior trunk to wind the body into a vertical coil around the prey. Three common constriction postures are fully encircling loops that form a coil, partially encircling loops, and non‐encircling loops that pinion the prey. Initial tightening of a coil occurs by winding or pressing the loops tighter to reduce the diameter of the coil. The epaxial muscles are highly active during striking and coil formation and intermittently active during sustained constriction. These results refute the hypothesis of a mechanical constraint on constriction in snakes with elongate epaxial muscles. Constricting gopher and king snakes can detect muscular, ventilatory and circulatory movements in rodent prey. In response to simulated heartbeats or ventilation in mice, the snakes twitch visibly, recruit epaxial muscle activity, and increase constriction pressure temporarily, but then quickly relax. Muscular activity and constriction pressure are increased most and sustained longest in response to muscular struggling in prey. Although muscle activity and pressure exertion are intermittent, the constriction posture is maintained until the prey has been completely still for several seconds; thus, a snake can reapply pressure in response to any circulatory, ventilatory or muscular movement by the prey. The pressures of 6.1–30.9 kPa (46–232 mm Hg) exerted on small mammal prey by constricting snakes range from about half to over twice a mouse's systolic blood pressure, and are probably 10 times larger than the venous pressure. These high pressures probably kill mammalian prey by inducing immediate circulatory and cardiac arrest, rather than by suffocation alone.
Sympatry and hybridization between the clawed frogs Xenopus laevis laevis and Xenopus muelleri (Pipidae)
Authors: Fischer W. J. , Koch W. A. , Elepfandt A. 
Published: February 2006

AbstractThough most Xenopus species are polyploid and can be hybridized in the laboratory, natural hybridization seems to be restricted to hybrids of X. laevis laevis×X. gilli. A parapatric distribution pattern between X. l. laevis and X. muelleri seems to prevent interbreeding. We found X. l. laevis and X. muelleri living sympatrically in water bodies in the Republic of South Africa west of Kruger Park and report a natural hybrid of X. l. laevis×X. muelleri. Natural occurrence of such a hybrid has not been reported previously. The hybrid character was confirmed by analysis of its advertisement calls, which were intermediate between those of the parental species, by analysis of its serum albumin pattern, and by determination of the nuclear DNA content of its erythrocytes. The results indicate that this specimen is an F1 hybrid between X. l. laevis and X. muelleri. Backcrossing with both parental species indicated that the hybrid is sterile. It is discussed why sympatry between X. l. laevis and X. muelleri though possible might be rare.
Habitat selection, ranging behaviour and diet of the stone curlew (Burhinus oedicnemus) in southern England
Authors: Green R. E. , Tyler G. A. , Bowden C. G. R. 
Published: February 2006

AbstractDistribution, habitat use and selection, ranging behaviour, diet and food supply of the stone curlew Burhinus oedicnemus were studied in a small, fragmented population at the north‐western edge of its world range. Stone curlews bred on short semi‐natural grassland and spring‐sown arable farmland in areas with sandy soils with stones or rubble. They were most active at night and travelled up to about 3 km from the nest to forage. Individuals used a fragmented home range comprising an average of 30 ha of short semi‐natural grassland, short improved pasture and spring‐sown crops for foraging. Earthworms, soil‐surface arthropods and molluscs were the main prey; the proportion of earthworms being lowest when the soil was dry. Breeding densities were highest on short semi‐natural grassland. Stone curlews were most likely to breed on a spring‐sown arable field if the crop was of a type that became tall and dense relatively late in the summer and if the field was close to short semi‐natural grassland or sheep pasture and distant (> 3 km) from the nearest major road. Sparse vegetation and bare ground were the most obvious characteristics of habitats preferred for nesting and foraging.
The effects of forest fragmentation and isolation on insectivorous small mammals (Lipotyphla) on the Central High Plateau of Madagascar
Authors: Goodman Steven M. , Rakotondravony Daniel 
Published: February 2006

AbstractA small mammal survey of the Lipotyphla (Tenrecidae and Soricidae) was conducted in the montane forest of the Réserve Spéciale d'Ambohitantely, Central High Plateau, Madagascar. Species richness of this group was assessed using standardized pit‐fall trap techniques in a control site of 1250 ha and four smaller forest fragments (136, 30, 12 and 0.64 ha). The forests of this reserve are highly fragmented, isolated for many decades and about 90 km from the nearest large forest block. On the basis of pit‐fall captures, lipotyphlan diversity was highest in the control site with nine species, including eight endemic taxa. The number of species declined progressively with diminishing forest size. The species richness found in the control site, the largest remaining block within the reserve, is comparable to other much more extensive forest blocks at parallel elevations and with similar botanical communities. Thus, it seems that the lipotyphlan community within the control site has not experienced notable local extinctions. The introduced Soricidae, Suncus murinus, has colonized the Ambohitantely forests. However, there is no evidence of competition between this species and members of the family Tenrecidae, particularly Microgale, as has been postulated in the literature.
Does Nathusius' pipistrelle Pipistrellus nathusii (Keyserling & Blasius, 1839) breed in northern Italy?
Authors: Martinoli Adriano , Preatoni Damiano G. , Tosi Guido 
Published: February 2006

AbstractThis paper reports the capture of seven adult Pipistrellus nathusii including a lactating female mist‐netted in July 1997 in Varese province (northern Italy). This record represents the first identification of a breeding female Nathusius' pipistrelle in the south part of the Alps. Other data on the reproduction of this species in Europe are discussed in order to reconsider its distribution and breeding sites.
Intra‐ and inter‐litter variation in life‐history traits in a population of fire salamanders (Salamandra salamandra terrestris)
Authors: Kopp Maja , Baur Bruno 
Published: February 2006

AbstractWe examined intra‐ and inter‐litter variation in larval life‐history traits in relation to maternal weight and date of larval deposition in a population of fire salamanders Salamandra salamandra terrestris in north‐western Switzerland. We also examined whether the timing of larval deposition by female fire salamanders is an adaptive strategy to the changing conditions of a temporary brook. Litters differed in mean weight at birth, weight at metamorphosis, and duration of the larval period. Mean weight at birth tended to be larger in litters deposited later in the season than in those deposited earlier. Large neonates reached metamorphosis more rapidly than small ones. A short larval period resulted in a small size at metamorphosis, indicating a fitness trade‐off between duration of the larval period and size at metamorphosis. Within litters, successively‐born larvae tend to decrease in body size, especially in litters with a relatively large variation in weight at birth. The results suggest that environmental factors such as floods or drying out of the brook may influence the timing of larval deposition.
Variation of male‐biased maternal investment in fallow deer (Dama dama)
Authors: Braza F. , San José C. , Aragón S. 
Published: February 2006

AbstractIn this study 529 fallow deer fawns were captured and weighed at Doñana National Park, Spain. An annual index of male‐biased maternal investment (MBMI) was calculated, and this index was found to vary in relation to environmental factors. Thus, the level of MBMI was sensitive to fluctuations of autumn rainfall and the male‐biased maternal investment carried out by mothers in the previous year (MBMIP). Our results reveal that those factors related to the female's body condition at the beginning of gestation have a high contribution to the variation of differential pre‐natal maternal investment. It has been hypothesized by other authors that male‐biased maternal investment is limited by the level of total maternal expenditure and these authors classified the fallow deer as a species near to its maximum reproductive effort, in which no sex‐biased maternal investment exists. Our study reveals that male‐biased maternal investment in fallow deer does exist and supports the hypothesis that sensitivity of maternal investment to environmental conditions could be expected to occur in species with high reproductive effort and sex‐biased maternal investment.
Behavioural correlates of predation by tiger (Panthera tigris), leopard (Panthera pardus) and dhole (Cuon alpinus) in Nagarahole, India
Authors: Karanth K. Ullas , Sunquist Melvin E. 
Published: February 2006

AbstractBehavioural factors that are likely to contribute to the coexistence of tigerPanthera tigris, leopardP. pardusand dholeCuon alpinus, were investigated in the tropical forests of Nagarahole, southern India, during 1986–1992. Examination of predator scats and kills were combined with radiotracking of four tigers, three leopards, and visual observations of a pack of dhole. The three predators selectively killed different prey types in terms of species, size and age‐sex classes, facilitating their coexistence through ecological separation. There was no temporal separation of predatory activities between tigers and leopards. Hunting activities of dholes were temporally separated from those of the two felids to some extent. Rate of movement per unit time was higher for leopards compared to tigers during day and night. In general, the activity patterns of predators appeared to be largely related to the activities of their principal prey, rather than to mutual avoidance. The three predator species used the same areas and hunted in similar habitats, although tigers attacked their prey in slightly denser cover than leopards. Both cats attacked their prey close to habitat features that attracted ungulates. There was no evidence for inter‐specific spatial exclusion among predators, resulting either from habitat specificity or social dominance behaviours. Our results suggest that ecological factors, such as adequate availability of appropriate‐sized prey, dense cover and high tree densities may be the primary factors in structuring the predator communities of tropical forests. Behavioural factors such as differential habitat selection or inter‐specific social dominance, which are of crucial importance in savanna habitats, might play a relatively minor role in shaping the predator communities of tropical forests.