bluuebunny/crossref_metadata_2025_split huggingface dataset:
Partial seasonality of breeding in red‐necked wallabies (Macropus rufogriseus banksianus
Authors: Higginbottom Karen , Johnson Christopher N. 
Published: February 2006

AbstractReproductive data on individually known free‐ranging red‐necked wallabies Macropus rufogriseus banksianus were obtained over a 6 year period. Although this subspecies is essentially a non‐seasonal continuous breeder, more young wallabies emerged permanently from the pouch in spring than in any other season. This partial seasonality of breeding was the combined result of seasonal variation in duration of pouch lives, a tendency for the first young of females to emerge permanently in spring, and seasonal variation in the incidence of reproductive interruptions. It is proposed that the adaptive significance of this partial seasonality is that it maximizes juvenile survival while maintaining a high reproductive rate.
The oral anatomy of Arctic ruminants: coping with seasonal changes
Authors: Mathiesen S. D. , Sørmo W. , Haga Ø. E. , Norberg H. J. , Utsi T. H. A. , Tyler N. J. C. 
Published: February 2006

AbstractWe studied the feeding apparatus of three species of northern ruminants representative of three feeding types: muskoxen Ovibos moschatus, Norwegian reindeer Rangifer tarandus tarandus and high Arctic Svalbard reindeer Rangifer tarandus platyhrynchus and Siberian musk deer Moschus moschiferus. The shape of the muzzle, the incisor arcade, the incisiform and the molariform teeth indicate that these species are selective feeders, irrespective of their body size or their position on the gazer‐concentrate selector continuum of feeding types. Narrow muzzles seem well adapted for selective feeding on the diminutive but highly nutritious plants, or parts of plants, on tundra swards and Arctic‐alpine meadows and enable the animals to maximize nutrient intake during the short summer. However, their small mouths presumably also restrict reindeer and muskoxen to taking small bites, thereby achieving low rates of dry matter intake when feeding on the very short swards in winter. This is partially obviated by two general strategies; a reduction of energy requirements in winter and, in Norwegian reindeer, migration inland to where foraging conditions are generally more favourable. In Svalbard reindeer, which have little access to lichens or other easy digestible plants in winter, rumen fill increases through the accumulation of slowly fermenting fibrous foods. Despite their narrow muzzles, reindeer and muskoxen are unable to avoid ingesting a certain amount of poor quality forage in winter and cope with this by appropriate modification of digestive function.
Diet composition, rumen papillation and maintenance of carcass mass in female Norwegian reindeer (Rangifer tarandus tarandus) in winter
Authors: Mathiesen S. D. , Haga Ø. E. , Kaino T. , Tyler N. J. C. 
Published: February 2006

AbstractThe uptake of volatile fatty acids (VFAs) from bacterial fermentation of forage in the rumen is enhanced by the presence of papillae which greatly increase the surface area of the mucosa of the rumen. The degree of papillation, expressed as the surface enlargement factor (SEF), seems to be closely related to the level of microbial activity and the rate of production of VFAs in the rumen. In several species of wild ruminants the SEF decreases markedly in winter, apparently in response to a decrease in the quality and availability of forage and also, presumably, in the level of ruminal microbial activity. Contrary to expectation, however, no reduction in the rate of production of VFAs in winter has been detected in semi‐domesticated reindeer at natural pasture in northern Norway. We investigated the body mass, the composition and quality of the diet and the morphology of rumen papillae in adult female reindeer free‐living at natural pasture. Animals were slaughtered in matched aged groups of nine on four occasions: in autumn (September) and winter (November, February and March). The composition and quality of the diet was determined by morphological and chemical analysis of plant fragments recovered from the rumen. The carcass mass of the animals did not differ significantly between collections. The animals ate vascular plants and lichens from 37 different genera. The composition of the diet varied little between months except for the inclusion of a substantial proportion (25.8% of fragments) of lichens in March. The mean density of rumen papillae increased from 55.6 papillae/cm2 in September to 75.7 papillae/cm2 in March (P < 0.001). All other parameters, including the length and perimeter of the papillae and the SEF of the rumen, were lower in March compared with September. However, the mean SEF increased from 8.8 in February to 10.6 in March (P < 0.05), indicating increased ruminal fermentation in late winter. We propose that the increase in the SEF in March might be associated with the increase in the proportion of lichens in the diet. Lichens are highly digestible in reindeer but do not score highly in conventional analyses of diet quality owing to the unusual chemical structure of the structural carbohydrates of which they are composed.
The arctic fox (Alopex lagopus): an opportunistic specialist
Authors: Elmhagen Bodil , Tannerfeldt Magnus , Verucci Paolo , Angerbjörn Anders 
Published: February 2006

AbstractReliable and abundant resources are likely to favour specialization, while unpredictable environmental variation should favour a generalist strategy. The rodent population cycles of northern latitudes can be seen as both predictable and unpredictable, depending on the scale in time and space. The arctic foxAlopex lagopusis an opportunistic carnivore, but paradoxically, it seems to function as a specialist on fluctuating rodent Arvicolinae populations in most inland areas. We have studied the dietary response of arctic foxes in Sweden during 5 years of varying abundance of Norwegian lemmingLemmus lemmus, and how these changes influenced the reproductive success of the foxes. The arctic fox population on mainland Fennoscandia is threatened by extinction and the situation has deteriorated during the 1980s and 1990s because of an absence of lemming peaks. Our results showed that in all years, lemming was the main prey for arctic foxes, with 85% frequency of occurrence in summer faeces (scats). Bird remains (mainly Passeriformes) were present in 34% of the scats, reindeerRangifer tarandusin 21%, voles and shrews in 4% and haresLepus timidusin 2% of the scats. The occurrences of lemming, bird and larger mammal (reindeer and hare) remains in the scats varied significantly between years. Temporal variations within summer seasons and dietary differences between sub‐areas, indicated that arctic foxes fed opportunistically on the alternative prey types. Den occupancy rates were positively correlated with lemming population densities during the previous winter, indicating a strong numerical response. We conclude that from a functional aspect, the arctic fox in Sweden is a lemming specialist, since lemming is the main prey and their abundance is the best predictor of arctic fox reproductive success. Other prey are used opportunistically in relation to their availability.
Social structure of a polygynous tent‐making bat,Cynopterus sphinx(Megachiroptera)
Authors: Storz Jay F. , Bhat Hari R. , Kunz Thomas H. 
Published: February 2006

AbstractThe social structure of an Old World tent‐making batCynopterus sphinx(Megachiroptera), was investigated in western India. A combination of census and mark–recapture data over 2 years (1996–98) was used to infer the form of the mating system, compositional stability of social groups and mode of new social group formation. The breeding population ofC. sphinxwas subdivided into diurnal roosting colonies, each of which contained one to five discrete roosting groups and often one or more solitary bats in adjacent roosts. Bats most frequently roosted in stem tents constructed in the flower/fruit clusters of the kitul palmCaryota urens. Temporal variation in social structure was assessed using visual census data for a subset of the study population over 3 years (1995–98) spanning six consecutive reproductive periods. The sex and age composition of diurnal roosting groups indicated a polygynous harem‐forming mode of social organization, as groups invariably contained a single adult male, 1–37 reproductive females and their dependent young (n= 33 harems). Harem size averaged 6.1 adults in the wet season (n= 19,sd= 3.5) and 13.6 adults in the dry season (n= 14,sd= 8.5). The same harem social configuration was maintained year‐round, despite a high degree of synchrony and seasonality in the timing of reproduction. Juveniles of both sexes dispersed after weaning and sexually immature bats were never present in harems at the time of parturition. Adult females often remained associated as roostmates from one parturition period to the next, and group cohesion was unaffected by turnover of harem males. Adult females frequently transferred among roosts within the same colony, and harems underwent periodic fissions and fusions. The founding of new harems most often resulted from the fissioning of previously cohesive harems within the same colony. However, some harems contained disproportionate numbers of yearling females, indicating that new groups are also founded by nulliparous females of the same age cohort. A significant degree of heterogeneity in age composition among harems was revealed in the 1998 dry season, but was unrelated to age‐stratification of tent roosts. Although formation of new harems may be non‐random with respect to age composition of the founders, founding events are not restricted to newly created tents and often involve recolonization of previously occupied roosts.
Effects of temporal and spatial variations in food supply on the space and habitat use of red squirrels (Sciurus vulgaris L.)
Authors: Lurz Peter W. W. , Garson P. J. , Wauters Luc A. 
Published: February 2006

AbstractIn non‐native conifer plantations characterized by strong spatial and temporal variations in the availability of tree seeds in Spadeadam Forest, northern England, the home range and habitat use of red squirrels Sciurus vulgaris was very flexible. Males tended to have much larger home ranges than females and core‐areas of most breeding females seemed mutually exclusive. Adult female red squirrels were found to increase their home range and core‐area size in forest patches where food was less abundant. Home‐range size was significantly related to home‐range quality and the extent of overlap by other females. In contrast with high‐quality continuous conifer forests: (1) a considerable proportion of adult males and females at Spadeadam shifted home range, (2) both sexes had much larger home ranges than reported from other habitats in Britain or Belgium. Many ranges were multinuclear, particularly from January onwards, when supplies of seeds become depleted through consumption and seed shed. Squirrels tracked the availability of conifer seeds (lodgepole pine cones throughout the study, Norway spruce cones in spring 1992 and Sitka spruce cones in autumn 1993) and intensively used several non‐adjacent activity centres in temporally food‐rich patches. Consequently, habitat preference changed markedly with time. The squirrels seemed to maximize nitrogen intake and to avoid the smaller seeds when possible. This resulted in an overall preference for a mixed diet of lodgepole pine and spruce seeds and avoidance of Sitka spruce seeds when Norway spruce seeds were available. These results lend support to the hypothesis of Ostfeld (1985) that when food is sparse and patchily distributed, females should develop intrasexual territoriality, concentrating their activity in food‐rich patches, while males should be non‐territorial and adapt their space use to the distribution of females.
Are calcitic layers an effective adaptation against shell dissolution in the Bivalvia?
Authors: Harper E. M. 
Published: February 2006

AbstractConventional wisdom, based on properties of reagent‐grade salts, states that organisms which construct their exoskeletons from calcite rather than aragonite have a greater ability to resist dissolution. However, experiments on individual bivalve microstructures show that other factors such as crystal size and the proportion of organic matrix outweigh constituent mineralogy in determining the rate of shell loss in cold waters. Moreover, the loss of shell material was minimal, corresponding to an annual loss in shell thickness of 3–40 μm depending on microstructure. These findings must cast doubt on the commonly held supposition that calcitic layers added to the outside of shells are an adaptation against dissolution in Holocene ‘Aragonite’ seawater.
Abundance, demographics and body condition of a translocated population of St Lucia whiptail lizards (Cnemidophorus vanzoi)
Authors: Dickinson H. C. , Fa J.E. 
Published: February 2006

AbstractThe whiptail lizard Cnemidophorus vanzoi is a large‐bodied teiid found only on two islands (Maria Major and Maria Minor), off St Lucia, West Indies. In May 1995, 42 lizards from Maria Major were introduced to the smaller uninhabited Praslin Island on the same coastline. Three years post‐release, we studied abundance, demography and morphometrics of the translocated lizard population, during a 6‐month period covering wet and dry seasons. Age, sex, snout–vent length (SVL), body mass (BM), tail length, tail regeneration, and overall condition (moulting, reproductive condition, cuts, external parasites) of 107 animals caught during the study are analysed in the present paper. Comparisons are also made with the source population. A body condition index (CI (BM/SVL)), sex ratio (adult males : adult females), age ratio (adults : juveniles), and sexual size dimorphism ratio (SVL adult male : SVL adult females) were calculated for the study population. Distance sampling and mark–re‐sight surveys were used to estimate population size and lizard density. A total of 155 ± 26 individuals were estimated. The lizard population was found to have a high growth rate (r= 0.97–3.95). There were significant seasonal changes in lizard abundance. Seasonal differences in lizard numbers, BM and CI suggest either severe resource limitation during the dry season, or selective aestivation. A high frequency of tail autotomy may point to intense intraspecific competition as the island is relatively free from main predators such as the black rat Rattus rattus. Sex ratio, sexual size dimorphism and sexual dichromatism all indicate a territorial species in a generally non‐territorial family (Teiidae). Some adult males seem to maintain juvenile colours. It is suggested that the introduced population has successfully colonized its new environment and that no significant change in the animals condition or size has occurred during the 3 years since translocation.
Range extension and microhabitat of Lightiella incisa (Cephalocarida)
Authors: De Troch Marleen , Fiers Frank , Vincx Magda 
Published: February 2006

AbstractDuring an intensive meiofauna sampling campaign in intertidal seagrass beds along the Caribbean coast of the Yucatán Peninsula (Mexico), 131 specimens of Lightiella incisa (Cephalocarida, Crustacea) were recovered from the sediment. Two‐thirds of the specimens were adults, one‐third were pre‐adults. This collection is the first record of this minute primitive crustacean in the western part of the Caribbean Sea, and extends the known range 3000 km from the type locality of Hastings Bay, Barbados. A detailed sampling protocol and environmental data made it possible to study the microhabitat preferences of this species, and perhaps for cephalocarids in general for the first time. The vertical distribution of L. incisa in the sediment showed a maximum density in deeper layers, i.e. 3–4 and 4–5 cm depth. Nitrate and nitrite concentrations seem to be most closely related to the distribution of L. incisa. It was clear that L. incisa followed polychaetes to deeper sediment layers. In this study we state that L. incisa is an endobenthic species occupying anoxic sediments oxygenated by bioturbation (e.g. Polychaeta) rather than being an animal living in the oxygenated top layers.
Climate, vegetation, and predictable gradients in mammal species richness in southern Africa
Authors: Andrews Peter , O'Brien Eileen M. 
Published: February 2006

AbstractMany hypotheses have been proposed to account for geographic variations in species diversity. In general these relate to some aspect of climate, particularly climatic variables measuring available or potential energy, but while these relate directly to plant diversity they may only indirectly affect mammal species richness. We have examined these relationships by mapping and correlating mammal species richness in southern Africa (n= 285 species) with 15 climatic variables, two topographic variables, and woody plant species richness (n= 1359 species). The effect of area on richness was held a constant by using an equal‐area grid cell matrix superimposed on species range maps, with each grid cell equal to 25 000 km2. We found that variability in the plant species richness alone accounts for 75% of the variability in mammal species richness. Of the climatic variables, only thermal seasonality approaches this figure, accounting for 69% of the variability, while annual measures of temperature, precipitation or energy account for only 14–35% of variability. Differences from North American mammal diversity studies, where annual temperature, and hence annual potential evapotranspiration (PET), have been found to be more important, are attributed in part to southern Africa's climate and vegetation being largely temperate to tropical, as opposed to temperate to polar in North America. By distinguishing different types of mammal based on size, spatial and dietary guilds, other differences emerge. Strong correlations with annual temperature exist only for large mammals, accounting for 60–67% of the variability in species richness of large mammals compared with <20% for small mammals. Small mammals are strongly correlated with other climatic or vegetation parameters, especially plant richness and thermal seasonality; frugivorous and insectivorous mammal richness is correlated with thermal seasonality and minimum monthly PET; and arboreal and aerial species richness is correlated with plant richness, thermal seasonality and minimum monthly PET. Up to 77% of the variability in richness of arboreal, frugivorous and insectivorous species can be explained by woody plant richness, compared with only 38–48% of the variability in terrestrial herbivores. It is clear from this that different kinds of mammals are differentially affected by climatic and environmental factors, and this explains some of the discrepancies found in earlier studies where no distinction was made between different sizes or guilds of mammal. This result has implications both for the conservation of mammalian communities at the present time and for understanding the evolution and structure of mammalian communities in the past.
Carnivory in the greater noctule bat (Nyctalus lasiopterus) in Italy
Authors: Dondini G. , Vergari S. 
Published: February 2006

AbstractAn analysis of 59 droppings of the greater noctule Nyctalus lasiopterus, collected either during direct handling of the bat or from the bat‐boxes used as shelters in the Pian di Novello Natural Reserve (Tuscany, Italy), has shown that it is a partial carnivore. The content of the samples, collected in October and November of 1995 and in September and October of 1996 and 1997, consisted mainly of bird feathers identified as those of the robin Erithacus rubecula and the blue tit Parus caeruleus. The presence of feathers during the 3 consecutive years of the study period confirms that the diet of the greater noctule in this area is not based exclusively on arthropods as was previously suggested.
Fox (Vulpes vulpes) management in three contrasting regions of Britain, in relation to agricultural and sporting interests
Authors: Heydon Matthew J. , Reynolds Jonathan C. 
Published: February 2006

AbstractFox culling practices in three contrasting rural regions (1280–2320 km2) of Britain were investigated by questionnaire surveys of landowners and tenant farmers. Between 50 and 52% of all farmers identified in each region contributed to the survey (total number of replies = 1123). Fox culling was widespread in all regions, with 70–95% of farmers involved either directly or indirectly as hosts. Motivation for culling foxes and the methods employed reflected regional variation in agricultural and game‐shooting interests. Social factors associated with fox‐hunting for sport also played an important role in one region. The contribution to the total fox cull made by communally organized groups operating over large tracts of farmland, and the efforts of individual farmers at a local scale, also varied regionally. The numbers of foxes culled were close to published estimates of annual productivity in British fox populations. Deliberate culling was therefore likely to be the chief cause of fox mortality in these regions. The marked differences in culling practices between these regions provide a strong case that the impact of culling on fox population dynamics must be assessed for regions of this size, as well as at a more local scale. Studies at a national scale (e.g. the whole of Britain) are probably of little biological or sociological significance. The success of different interest groups in achieving their aims, and the consequences of any change in culling practices must also be considered at a similar geographical scale.
Reduced access to olfactory cues and home‐range maintenance in the sleepy lizard (Tiliqua rugosa)
Authors: Zuri I. , Bull C. M. 
Published: February 2006

AbstractSleepy lizards Tiliqua rugosa are large, long‐lived, Australian skinks that live in stable home ranges. Previous studies showed that the lizards have a good sense of orientation and navigation towards home. However, since they are active only 4 months in every year, there is a question about which environmental cues enable them to locate their home boundaries. In the present study we determined whether surrounding olfactory and chemical cues are important for the sleepy lizards for home‐range maintenance. In the first part of the study we showed in the laboratory that zinc sulphate (ZnSO4) is a chemical that induces anosmia and prevents detection of chemical cues in sleepy lizards for up to 30 days, with no evident long‐term harm to the animals. We then monitored the location of 50 radio‐tagged sleepy lizards. After determining their home ranges they were divided into three groups: an untreated control, a saline‐treated (sham‐operated) group and a ZnSO4‐treated group. Starting 2 days after the treatment, the home ranges of all lizards were re‐determined within the period that ZnSO4 blocked olfaction. Three variables were calculated comparing home ranges before and after treatments: the change in home‐range size, the distance between the centre of activities of the lizards, and the overlap between the individual home ranges before and after treatments. Lizard home ranges varied from 1.9 ± 0.6 ha to 4.6 ± 1.4 ha before treatment, and 1.3 ± 0.3 ha to 3.1 ± 0.7 ha after treatment. There was no significant effect of treatments or of sex on the home‐range size or on the distances between the centre of activities, or on the overlap between the individual home ranges. Our data indicate that olfaction and vomerolfaction are not a major cue for home‐range maintenance in the sleepy lizards.