bluuebunny/crossref_metadata_2025_split huggingface dataset:
Interspecific scaling of the hindlimb skeleton in lizards, crocodilians, felids and canids: does limb bone shape correlate with limb posture?
Authors: Blob Richard W. 
Published: February 2006

AbstractDuring locomotion, lizards and crocodilians generally use a more sprawling limb posture than most mammals and experience substantial axial rotation of the femur. Consequently, the limb bones of most mammals are loaded predominantly in bending, but the limb bones of lizards and crocodilians are loaded primarily in torsion. As body size increases, torsional shear stress in limb bones is expected to increase more than bending stress; therefore, limb bone diameters of lizards and crocodilians might be expected to scale with relatively greater positive allometry than limb bone diameters of mammals that use upright posture. To test this hypothesis, scaling patterns of the femur and tibia in lizards (iguanians and varanids) and crocodilians were compared with patterns in felid and canid mammals, using both non‐phylogenetic statistical methods and phylogenetically independent contrasts. Comparisons with theoretical models indicate that size‐related changes in limb bone geometry do not completely compensate for size‐related increases in limb bone stress in the lizard or crocodilian lineages examined. Unless lizards and crocodilians compensate for size‐related increases in limb bone stress through other mechanisms (e.g. changes in limb kinematics or the mechanical properties of limb bones), limb bone stresses are predicted to be relatively greater among larger species of these lineages. However, limb bone diameters appear to scale with greater positive allometry (relative to body mass) in varanids than in iguanians, suggesting that larger lizard lineages might compensate for increased stress through changes in bone geometry to a greater degree than smaller lineages. Allometric scaling patterns for many limb bone diameters among iguanians are more similar to those of felids and canids than to those of varanids; thus, sprawling locomotor habits do not correlate clearly with a particular pattern of limb bone scaling. This suggests that similarity of interspecific scaling patterns of limb bone lengths and diameters is not sufficient to justify inferences of similar locomotor function.
Female nesting behaviour, pup growth and ontogeny in Brants' whistling rat (Parotomys brantsii)
Authors: Jackson T. P. 
Published: February 2006

AbstractThis study examines aspects of the nesting behaviour of Brants' whistling rat Parotomys brantsii, a medium‐sized rodent indigenous to southern Africa. In the semi‐arid regions in which it occurs P. brantsii breeds opportunistically, modifying its breeding period in relation to rainfall. Within a winter rainfall area, females produced up to four litters of three to four young during the winter–spring period following a gestation period of c. 38 days, with females showing a post‐partum oestrus. The behaviour of females was modified by the birth of their pups, after which they spent extended periods underground, interspersed with bouts of food‐collecting activity. With the emergence of pups above‐ground, females increased their vigilant activity. At 5 weeks pups had developed all the important behavioural characteristics of adults, such as creating their own overnight food stores, collecting nesting material and defending a warren area against conspecifics. This was also the age at which the young dispersed from their natal nest area as well as the time at which females could reach sexual maturity, despite physical immaturity. The high reproductive output of female P. brantsii, as well as the rapid ontogeny of their young, compared to other otomyine rodent species, may represent an adaptation for maximizing reproductive potential in the semi‐arid areas they inhabit.
The highly specialized secretory epithelium in the buccal cavity of the alkalinity adapted Lake Magadi cichlid, Oreochromis alcalicus grahami (Teleostei: Cichlidae): a scanning and transmission electron microscope study
Authors: Maina J. N. 
Published: February 2006

Abstract Oreochromis alcalicus grahami is a small cichlid fish that lives in the hot, highly alkaline, highly saline peripheral lagoons of Lake Magadi, Kenya. The fish faces profound diurnal oscillations of oxygen concentration. During the day, from photosynthetic activity of cyanobacteria (blue‐green algae), the water is supersaturated with oxygen but after sunset when photosynthetic activity stops the water is virtually anoxic as a result of bacterial respiration. During the night and after explosive exercise, O. a. grahami characteristically skims the surface of the water with the mouth agape, suggesting that the buccal cavity is used as a gas‐exchange organ. Contrary to expectation, however, the buccal cavity was found to be conspicuously non‐vascularized: the surface epithelial lining was fundamentally of a mucus secretory type. In addition, certain cells in the deeper layers showed extensive lateral labyrinths similar to the epithelium of the renal tubules. These morphological features respectively indicated roles of secreting a protective film and regulation of ions taken across the epithelial lining of the buccal cavity. The allocation of gas‐exchange to the gills and the air‐bladder, osmoregulation essentially to the gills, and mucus secretion/protection to the buccal cavity displays an adaptive trade‐off process in an elite animal. Effective use of the buccal cavity as a gas‐exchanger would entail air‐gulping followed by brief retention of it in the cavity to allow oxygen uptake. During such interval, both the gills and the air‐bladder would of necessity be rendered temporarily non‐functional. Skimming the top layer of water with the mouth open ensures that the gills are passively ventilated with well aerated water and the air‐bladder is simultaneously used for gas‐exchange, a strategy that should enhance oxygen acquisition, especially at higher ambient temperatures.
Factors affecting the duration of activity by pine martens (Martes martes) in the Białowieża National Park, Poland
Authors: Zalewski Andrzej 
Published: February 2006

AbstractThe duration of activity bouts by pine martens Martes martes was studied in the pristine deciduous forests in Białowieża National Park (north‐eastern Poland). From 1991 to 1996, 14 martens were monitored by radio‐tracking throughout 5823 h. On average, male martens were active for 9 h/day and females for 8.5 h/day. The duration of the martens' diel activity varied greatly among bimonthly periods (from 2.8 h/day in February–March to 12 h/day in June–July). Martens decreased their activity from 13 h/day on warm days to 2.5 h/day on cooler days. In the winter months, when martens curtailed their activity, they often hunted larger prey or scavenged ungulate carcasses. On average, 69% of the martens' active time was during the night. The number of activity bouts per day varied from one to six (mean 2.6) and increased with growing ambient temperature. Activity bouts of males were significantly longer (4 h, on average) than those of females (3 h) and were not related to ambient temperature. The duration of short inactive bouts increased in the cold season and inactivity lasted longer in females than in males.
Food habits and livestock depredation of two Iberian wolf packs (Canis lupus signatus) in the north of Portugal
Authors: Vos J. 
Published: February 2006

AbstractTwo Iberian wolf Canis lupus signatus packs were studied in the north of Portugal during spring and summer 1996. The study areas are located in two mountainous areas close to the Spanish border. Both regions presented a very low density of wild ungulates and intensive livestock production. The food habits and the livestock depredation of the wolves were considered. The study material included 87 dropping samples, interviews with shepherds, carcass investigation and government reports of livestock depredation. Prey preference was measured in both areas. Wolves fed exclusively on livestock, especially goats. Wolf attacks on goats affected mostly large flocks of > 100 heads, but where there were horses, wolves preyed preferentially on horses. In both study areas, sheep was recorded as a regular prey by the government reports but never appeared in the scat analysis results. This apparent contradiction will be discussed. The wolf's dependence on livestock can be explained by the scarcity of wild prey and the high density of livestock. Conservation of wolves in such impoverished areas depends on an efficient livestock depredation management plan and the reintroduction of native prey species.
The influence of body size on dive duration of underyearling southern elephant seals (Mirounga leonina)
Authors: Irvine Lyn G. , Hindell Mark A. , van den Hoff John , Burton Harry R. 
Published: February 2006

AbstractThe dive duration of 16 underyearling (6–12 months old) southern elephant sealsMirounga leoninaduring their second trip to sea was investigated using geolocating time–depth recorders. Underyearling seals had a lesser diving ability, with respect to duration and depth, than adult southern elephant seals. Individual underyearlings dived for average durations of up to 20.3 min and depths up to 416 m compared to durations and depths of 36.9 min and 589 m, respectively for adults. Dive duration was positively related to their body mass at departure, indicating that smaller seals were limited to shorter dive durations, perhaps as a result of their lesser aerobic capacity. All seals often exceeded their theoretical aerobic dive limit (average of 22.1 ± 18.1%). The number of dives exceeding the theoretical aerobic dive limit was not related to mass, suggesting that factors other than mass, such as foraging location or prey availability, may have been responsible for differences in diving effort. Foraging ability, indicated by the ability of the seals to follow vertically moving prey, was positively related to seal mass, indicating that small mass restricted foraging ability. The shorter dive durations of the smaller seals inferred that they had shallower dive depths in which to search for prey, thus restricting foraging ability. Although foraging ability was restricted by size, foraging success was found to be inversely related to mass, the smaller seals gaining a higher proportion of blubber than larger seals during their foraging trips. Thus, despite smaller seals being restricted to shallower depths and shorter durations, their foraging success was not affected.
Growth, survival and behaviour of larval long‐toed salamanders (Ambystoma macrodactylum) exposed to ambient levels of UV‐B radiation
Authors: Belden L. K. , Wildy E. L. , Blaustein A. R. 
Published: February 2006

AbstractMortality is the most extreme effect of ultraviolet‐B radiation (UV‐B; 280–315 nm) on living organisms, but sublethal effects of UV‐B may also be important. Moreover, there may be population differences in response to UV‐B, but this aspect has not been well explored for animal populations. Amphibians have been a model system for studying the detrimental effects of UV‐B. However, previous research on the effects of UV‐B on amphibians has mainly focused on embryos. Few studies have investigated how UV‐B affects larvae. We examined potential sublethal effects of UV‐B on the long‐toed salamander Ambystoma macrodactylum from two different populations. Observational data from field transects indicated that larvae are potentially exposed to UV‐B in their natural habitat. Choice tests indicated that larvae select shaded regions more often than those in the sun, but do not directly distinguish between regions with high and low UV‐B. Laboratory experiments indicated a survivorship difference between individuals from low‐ and high‐elevation sites. When exposed to relatively low levels of UV‐B individuals from low‐elevation sites experienced higher mortality than controls (no UV‐B). There were no differences in mortality between UV‐exposed and non‐exposed larvae from the high‐elevation population. Although mortality of UV‐B exposed larvae was not significantly different from controls in the high‐elevation population, sublethal effects on growth were observed. Individuals from the high‐elevation site grew significantly less when exposed to UV‐B than individuals shielded from UV‐B. Our study demonstrates that larval A. macrodactylum are exposed to UV‐B in nature, that UV‐B exposure can cause mortality as well as having sublethal effects on growth and that there are potential population differences in sensitivity to UV‐B radiation.
Environmental determinants of the composition of desert‐living rodent communities in the north‐east Badia region of Jordan
Authors: Scott Dawn M. , Dunstone Nigel 
Published: February 2006

AbstractThe spatial and temporal compositions of rodent communities in habitats of the Badia region of north‐east Jordan were investigated between 1996 and 1997. Live grid‐trapping and spot‐lighting techniques were employed to estimate rodent densities. Sixteen environmental variables including soil content, vegetation cover and relief were recorded within the study sites. TWINSPAN was used to derive six habitat classes based on the similarity of their rodent communities. These were hammada, harrat, marab, wadi and two types of sand dunes. The derived classifications were similar to the original categorization of habitat types based on ground‐truthed observations of the sites selected from satellite imagery. Multivariate statistical analyses (TWINSPAN and DECORANA) revealed three major rodent groups in relation to local habitat types: (1) petrophiles: Gerbillus dasyurus, Acomys russatus and Meriones tristrami; (2) open hammada‐dwelling species: Jaculus jaculus, Gerbillus henleyi and Meriones crassus; (3) psammophiles: Meriones libycus, Gerbillus nanus and Gerbillus cheesmani. Species richness was highest in marabs and lowest in red sand dunes. Species diversity (Hill's index) was highest in sand dunes and lowest in red sand dunes. Rodent biomass was highest in sand dunes and lowest in wadis. CANOCO showed rodent community composition to be correlated with vegetation parameters and soil content. TWINSPAN grouping and DECORANA ordination of rodent species provides some evidence for habitat preference, size disparity and competition as mechanisms of resource partitioning facilitating coexistence.
Maximum dive depths of common diving petrels (Pelecanoides urinatrix) during the annual cycle at Mayes Island, Kerguelen
Authors: Bocher Pierrick , Labidoire Bruno , Cherel Yves 
Published: February 2006

AbstractMaximum dive depths of common diving petrels Pelecanoides urinatrix were measured monthly over > 1 year, from January 1995 to February 1996, with miniature gauges attached to the birds at Mayes Island, Kerguelen Archipelago. Overall, maximum dive depths of 347 diving petrels averaged 31 ± 6 m (range: 8–64 m), with a mode at 30–35 m. Mean maximum dive depths differed significantly over the study period. The lowest value (22 ± 8 m) was obtained in winter and it was associated with euphausiid crustaceans, suggesting a change in foraging behaviour associated with a shift in the main prey consumed. During the breeding season, birds fed mainly upon the hyperiid amphipod Themisto gaudichaudii (66% of the total number of prey), followed by the large carnivorous copepod Paraeuchaeta antarctica (15%) and zoea larvae of the crab Halicarcinus planatus (13%). Comparison of the diving capabilities of diving petrels (genus Pelecanoides) with those of other diving seabirds suggests that, relative to body mass, diving petrels can dive deeper than penguins and also possibly than alcids, and are thus the most proficient divers among birds.
Variation in home range and use of habitat in the striped skunk (Mephitis mephitis)
Authors: Bixler Andrea , Gittleman John L. 
Published: February 2006

AbstractWe studied home‐range size, home‐range overlap and use of habitat in a population of striped skunksMephitis mephitisin eastern Tennessee. Variables determined to influence home‐range size were season and body weight: skunks had larger ranges in the spring than in winter and heavier females had larger ranges. Habitat, sex and sample sizes of radio‐fixes did not correlate with home‐range size. All home ranges overlapped by 1.4–100% of the range area. There was no pattern of greater intersexual than intrasexual overlap; this differs from many other carnivore studies. Movements of individuals and distribution of den sites indicated that striped skunks, irrespective of sex or size, prefer edge habitat in comparison to forest or field.
Tooth succession in the greater cane rat Thryonomys swinderianus (Temminck, 1827)
Authors: van der Merwe M. 
Published: February 2006

AbstractTooth succession was followed in captive greater cane rats Thryonomys swinderianus of known ages with the aid of regular radiographs. The incisors and single premolar tooth (dP 4/4) in each quadrant are persistent deciduous teeth that are not replaced by permanent teeth. Tooth succession is relatively slow, with eruption of the lower cheek teeth in advance of the upper ones. During the first 5 months of post‐natal development, three cheek teeth per quadrant become functional. Another 5 months elapse before the fourth cheek tooth erupts. The same slow growth can be seen in the increase in mass, which only doubles 5 months after puberty (5 months).
The mechanical properties of down feathers from gentoo penguins (Pygoscelis papua)
Authors: Bonser Richard H. C. , Dawson Colin 
Published: February 2006

AbstractIn a recent paper, Dawson et al. (1999) investigated how the morphology of the contour and downy afterfeathers of gentoo penguins Pygoscelis papua function as thermal insulators. Their model considered how the morphology of individual feather barbs interact to create an efficient insulatory barrier. They noted that, during diving, the feathers must be compressed and return to their original configuration due to stored strain energy. In addition, the downy feathers of penguins have to withstand significant wind loading whilst the birds are on land (Taylor, 1986). Despite the obvious necessity for mechanical competence and resilience of down feathers, we still know little about their mechanical performance.
Genetic tests of the taxonomic status of the ring‐tailed lemur (Lemur catta) from the high mountain zone of the Andringitra Massif, Madagascar
Authors: Yoder Anne D. , Irwin Jodi A. , Goodman Steven M. , Rakotoarisoa Soava V. 
Published: February 2006

AbstractA recent survey of the high‐mountain zone of the Madagascar Parc National (PN) d'Andringitra revealed the presence of an apparently isolated troop of the ring‐tailed lemur Lemur catta. These animals display phenotypic and ecological characteristics that are unusual for the monotypic genus Lemur, thus raising the possibility that they are members of a different undescribed species. We present analyses of two mitochondrial genes to test the hypothesis that L. catta from Andringitra should be considered a distinct species. The results indicate that taxonomic revision is not warranted under the expectations of the phylogenetic, coalescent, or biological species concepts. Rather, the genetic patterns observed among the Andringitra and lowland mitochondrial haplotypes are consistent with those expected for a single species.
Social and population structure of a gleaning bat, Plecotus auritus
Authors: Entwistle A. C. , Racey P. A. , Speakman J. R. 
Published: February 2006

AbstractBrown long‐eared bats Plecotus auritus occupying 30 summer roosts in north‐east Scotland were studied over 15 years. During this time 1365 bats were ringed, and a further 720 recaptures were made. Individual bats showed a high degree of roost fidelity, returning to one main roost site; < 1% of recaptured bats had moved among roost sites, and all recorded movements (n= 5) were < 300 m. Adults of both sexes were loyal to the roost sites at which they were first captured, indicating long‐term use of roosts. At least some juveniles (n= 32) of both sexes returned to the natal roost. Mark–recapture estimates indicated that colonies of this species were substantially larger (c. 30–50 individuals) than assumed in previous studies. Plecotus auritus differs from most other temperate zone, vespertilionid species in that there was no evidence of sexual segregation during summer, with males present in all colonies throughout the period of occupancy. Population structure in summer seems to be consistent with a metapopulation model, with discrete sub‐populations showing minimal interchange. The group size, colony composition and population structure described in this species may be associated with the wing shape (particularly aspect ratio) and foraging behaviour of P. auritus. It is postulated that relative motility, linked to wing structure, may affect the distribution of individuals, and may have implications for the genetic structure of this species. Correlations between aspect ratio and both colony size and migratory behaviour, across British bat species, indicate that wing shape could be an important factor contributing to patterns of social behaviour and genetic structuring in bats.
Adult dispersal in the co‐operatively breeding Damaraland mole‐rat (Cryptomys damarensis): a case study from the Waterberg region of Namibia
Authors: Hazell R. W. A. , Bennett N. C. , Jarvis J. U. M. , Griffin M. 
Published: February 2006

AbstractA total of 104 Damaraland mole‐rats was collected in 1988, 1990, 1991 and 1993 from an open water canal in the Otjiwarongo district of Namibia. The mole‐rats were apparently dispersing above ground when they fell in and drowned; they had travelled at least 20 m in distance from their natal burrow systems. The dispersing mole‐rats of both sexes were significantly larger than 73 animals trapped from a nearby control population. Sequential tooth wear and eruption patterns showed that dispersers were adult animals. There was a bias towards male mole‐rats dispersing. Furthermore, in years with lower rainfall (< 300 mm) it was found that dispersal became even more male biased. Eighty per cent of males and 40% of female dispersers showed signs of reproductive readiness, with more males than females being ready to breed. Thus it appears that, in these otherwise totally subterranean mammals, at least one form of dispersal occurs, above ground, and that adult mole‐rats are the principal dispersers.