bluuebunny/crossref_metadata_2025_split huggingface dataset:
Selection of nest trees by southern flying squirrels (Sciuridae: Glaucomys volans) in Arkansas
Authors: Taulman James F. 
Published: February 2006

AbstractNatural nest‐site selection was investigated in 50 radiocollared southern flying squirrels Glaucomys volans during spring and summer, 1994–1996, in the Ouachita National Forest of Arkansas. Squirrels nested in 226 trees in a variety of habitats at five study areas. Contrary to previous reports describing southern flying squirrels as habitat generalists, in this study squirrels showed selection in both the habitat and tree type in which nests were placed. Where it was available, mature pine–hardwood forest was selected for nesting. Young (< 15 years old) and immature (15–40 years old) pine plantations and harvested areas were avoided as nesting habitats. At harvested study areas, squirrels nested in protected riparian mature forest strips (greenbelt) along, and 10–20 m either side of, intermittent creeks and in adjacent mature forests. Squirrels constructed only outside nests in pine trees. In mature pine–hardwood forest, pines were used for outside nests more frequently than hardwoods; in greenbelt habitat, pines and hardwoods were chosen equally for outside nests. Both outside and cavity nests were found in hardwoods; standing dead trees (snags) contained only cavity nests. Snags were selected over hardwoods for cavity nesting in both mature pine–hardwood forest and greenbelt habitat. All hardwood species and all decay classes of snags were used for diurnal nesting in greater frequency than expected. Considering both cavity and outside nest‐site selection, pines were used less than expected. Results suggest that mature forests are optimal flying squirrel nesting habitats and should be retained adjacent to harvested areas to provide resources to squirrels abandoning stands after disturbance. Within harvested areas, nesting habitat can be substantially improved through the retention of overstory hardwoods and snags, as well as protection of mature forest strips along drainages.
Variation of adult body size of the tortoise Testudo hermanni in Greece: proximate and ultimate causes
Authors: Willemsen R. E. , Hailey A. 
Published: February 2006

AbstractSeventeen populations of T. hermanni in Greece differed substantially in mean adult body size, over a range of about one and a half times in length and three times in mass. Females were the larger sex in all populations; the degree of sexual size dimorphism did not vary with mean body size. The proximate cause of the variation of body size among populations was differences in the duration of growth, rather than egg or hatchling size or the growth rates of juveniles. The age at maturity (α) increased with body size in the 17 populations, while the Bertalanffy growth constant (k) decreased with body size. The quantities αM and M/k (where M is the instantaneous mortality rate) were invariant with body size, suggesting that differences between populations were adaptive rather than the result of short‐term disturbance. Body size was greater in cooler areas, and increased with both latitude and altitude. This pattern is opposite to that found in most ectotherms (the reverse Bergmann's rule), and to that which occurs between tortoise species. Several hypotheses about the possible ultimate causes of variation of body size were rejected, including adaptation to long‐term habitat disturbance (land use), character displacement, social factors, energetics, thermoregulation, r‐K selection, the length of the season available for incubation, or differences in juvenile mortality. The most likely ultimate cause of size variation between sites is differences in adult mortality, the correlation with environmental temperature being through the frequency of fires.
Winter activity of a population of greater horseshoe bats (Rhinolophus ferrumequinum)
Authors: Park Kirsty J. , Jones Gareth , Ransome Roger D. 
Published: February 2006

AbstractActivity patterns of greater horseshoe bats Rhinolophus ferrumequinum were investigated at caves in Cheddar (south‐west England) during the hibernation season. An ultrasound detector and datalogger were used to monitor and record the number of echolocation calls in a single cave. Activity of R. ferrumequinum remained largely nocturnal throughout winter, and the mean time of activity over 24 h was 88 to 369 min after sunset. There was an increase in diurnal activity from late May to early June, probably because bats remained active after foraging at dawn towards the end of the hibernation season. Visits to the cave did not increase bat activity. Cave air temperature reflected external climatic temperature, although there was variation in cave temperature and its range within and among caves. Individual R. ferrumequinum are usually dispersed in caves in regions where temperature fluctuations correlate with climatic variations in temperature. There was a positive correlation between the number of daily bat passes monitored by the bat detector and datalogger (= daily activity) and cave temperature. Nocturnal activity may be sometimes associated with winter feeding. Neither date nor barometric pressure had a significant effect on daily activity. Activity patterns largely reflected the findings from individual R. ferrumequinum studied by telemetry (Park, 1998), in that bat activity increased with cave and climatic temperatures, and the temporal pattern of activity remained consistently nocturnal throughout winter, starting at dusk.
Habitat selection by barbastelle bats (Barbastella barbastellus) in the Swiss Alps (Valais)
Authors: Sierro A. 
Published: February 2006

AbstractRecent faecal analyses have shown that barbastelle bats Barbastella barbastellus are highly specialized moth predators. The predominance of moths (> 99% by volume) in their diet both in wooded areas of the Swiss Alps and in denuded steppe areas of Central Asia further suggests that this narrow diet does not stem from a highly specialized habitat selection, but merely from peculiar species‐specific foraging constraints. Non‐opportunistic predators relying on a few prey types must find areas providing their basic prey in abundance. Using radiotracking, habitat selection was investigated in a population of barbastelle bats inhabiting xeric forests in the Swiss Alps. In particular, I tested the prediction that the biologically most productive areas within the forest are exploited in priority. Eleven individuals were radiotracked from June through to October 1992, and in June 1993. The home range (59 ha) of the overall radiotracked population was divided in 236 cell units of 0.25 ha each. Within each cell, habitat and vegetation structure was described using 19 environmental variables. Habitat selection by the bats was investigated through stepwise regression analysis, which retained 11 variables showing a significant positive relationship with habitat use. The four variables accounting for 31% of the overall variance were: litter thickness, percentage of shrub layer cover, percentage of pine tree cover, and circumference of oak trunks. The results showed a clear preference by barbastelles bats for richly structured forests, and an avoidance of open woodland on stony outcrops and rocky slopes. This confirms that the biologically most productive parts of the forest were exploited in priority.
The food supply of Arabian oryx (Oryx leucoryx) in the desert of Oman
Authors: Spalton J. A. 
Published: February 2006

AbstractThe crude protein content, water content and in vitro digestibility of grasses in the diet of the Arabian oryx Oryx leucoryx were investigated. In the main food species, Stipagrostis spp., levels of crude protein, water content and digestibility were generally highest in the flower component while in other species, leaf was the best quality food. Crude protein content, water content and digestibility were highly correlated and all declined exponentially following rainfall. Levels remained comparatively high, even during extended drought, largely because fog and dew‐fall enabled some plants to continue to produce green leaf material. The crude protein content of rumen material from oryx that died during drought was negatively correlated with time since rainfall. Estimates of dietary crude protein derived from the protein content of rumen material were comparable to those predicted for available grass forage. The results are discussed in the context of the food and water requirements of oryx. It is suggested that during drought some grasses continue to be a source of adequate crude protein and water and of sufficient digestibility but that levels are close to minimum maintenance requirements. This and the decreasing biomass of available forage of sufficient quality lead to condition loss and death, particularly of the most vulnerable animals. Crude protein may become limiting sooner than does water.
Age‐related participation in allosuckling by nursing warthogs (Phacochoerus africanus)
Authors: Plesner Jensen S. , Siefert L. , Okori J. J. L. , Clutton‐Brock T. H. 
Published: February 2006

AbstractThis paper examines the distribution of non‐offspring nursing or ‘allosuckling’ in warthogs Phacochoerus africanus. Of the 16 breeding groups studied, 11 contained two or more nursing females. Allosuckling occurred in six of these groups (55%). The number of juveniles per nursing female was lower for groups with allosuckling, although juvenile mortality was not measurably affected by either allosuckling, group size or the number of females in a group. Time spent drinking was longer for juveniles in smaller litters but was not influenced by allosuckling or juvenile age. Longer intervals between the females' nursing bouts resulted in longer drinking bouts for the juveniles, but there was no correlation with inter‐meal intervals. The proportion of successful sucking bouts increased with juvenile age. This success rate was greater in groups without allosuckling, suggesting a better co‐ordination between mother and offspring. Females appeared able to distinguish between juveniles and to nurse selectively. Four‐ to 5‐year‐old females nursed fewer juveniles than did older or younger females in their groups and were thus less likely to be donors.
Diet of tawny owls (Strix aluco) in relation to field vole (Microtus agrestis) abundance in a conifer forest in northern England
Authors: Petty S. J. 
Published: February 2006

AbstractThe diet of tawny owls Strix aluco was determined from pellets and prey items in owl nests in Kielder Forest, a planted spruce forest in northern England. Field voles Microtus agrestis were their most important food, and formed the highest proportion of tawny owl diet in winter and early spring. Common shrews Sorex araneus, common frogs Rana temporaria and birds were taken more frequently in late spring and summer. Clear cuts, areas from which timber had been felled at the end of the rotation, provided the main field vole habitat in the forest and remained suitable for voles for 10–15 years after re‐planting. Field vole abundance was measured three times a year on numerous clear cuts throughout the study area using a vole sign index based on fresh grass clippings in runways. Tawny owls responded functionally to the 3 to 4‐year cycles of field vole abundance. In years when voles were scarce, adult owls took more common shrews and common frogs, as determined from pellet analysis. In contrast, more bird prey was fed to nestlings when field voles were scarce, as determined from prey items in nests. The proportions of the main prey in nests changed over a 19‐year period. More bank voles Clethrionomys glareolus and wood mice Apodemus sylvaticus occurred in every year after 1992 than in any year before this. Numbers of wood mice in owl nests increased significantly throughout the study period, whereas bank vole numbers exhibited non‐cyclic, multi‐annual fluctuations that were unrelated to field vole cycles. It is argued that fluctuations in rodent prey reflected changes in rodent guilds in the study area; reasons for this are discussed. This is the first study of tawny owl diet in spruce forests in Britain and highlights the value of such large‐scale dynamic habitats for rodent populations and their predators.
Morphology and phylogenetic implications of oesophageal modifications in the Limnodriloidinae (Oligochaeta, Tubificidae)
Authors: Gustavsson Lena M. , Erséus Christer 
Published: February 2006

AbstractTwo features have been considered apomorphic for the subfamily Limnodriloidinae (Tubificidae): the lobed prostate glands, which are broadly attached to prostatic pads inside the atrial ampullae, and the ‘modified oesophagus’ in segment IX. The homology of the modified oesophagus may be questioned, as it is not of the same kind in all taxa. In Limnodriloides, Smithsonidrilus, and Tectidrilus, there is a pair of diverticula, whereas in Thalassodrilides, Parakaketio, and Doliodrilus, the oesophagus is dilated to form a barrel‐shaped portion. In a few species of Limnodriloides lacking diverticula, a short part of the corresponding oesophagus is swollen. A scrutiny of these features shows that they are morphologically different in several aspects: the thickness and the structure of the epithelium, the granulation, the shape of the cells and the length of the modifications. Moreover, a regular, semi‐embedded blood plexus always occurs around the barrel‐shaped portion but rarely around the diverticula (if present, plexus irregular), and never around the swollen part of the oesophagus. These different types of modifications fail the similarity test and thus should be regarded as independently evolved structures and coded as different characters in a parsimony analysis. Species from other subfamilies within the Tubificidae were also morphologically investigated, and modifications of the alimentary canal were found in a few of them: Ainudrilus lutulentus, Heronidrilus bihamis, H. fastigatus (all Rhyacodrilinae) and Clitellio arenarius (Tubificinae). The modification in segment VIII of Heronidrilus spp. resembles the barrel‐shaped portion in, for example, Thalassodrilides, and should primarily be coded as the same character in a congruence test of homology.
Food habits of the long‐nosed snake (Rhinocheilus lecontei), a ‘specialist’ predator?
Authors: Rodríguez‐Robles Javier A. , Greene Harry W. 
Published: February 2006

AbstractWe explored predator specialization by examining dietary variation in the widespread North American long‐nosed snake, Rhinocheilus lecontei. We examined the stomach contents of more than 800 museum specimens, and supplemented our findings with published dietary records. Sixty‐six percent of 135 prey eaten by R. lecontei were lizards, 26% were mammals, and 7% were squamate eggs; teiid lizards of the genus Cnemidophorus comprised 72% (64 of 89) of all lizard prey. Ninety‐four percent of specimens with food contained a single item, and all 79 prey for which we determined direction of ingestion were swallowed head‐first. Among those specimens containing food, long‐nosed snakes from Mexico were significantly larger, and ate a higher percentage of mammals, than specimens from the United States. Larger R. lecontei sometimes fed on larger prey, and perhaps excluded smaller prey from their diet. To assess relative trophic niche breadth for R. lecontei, we compared the percentage of lizards and of Cnemidophorus in the diet of long‐nosed snakes with the percentage with which other terrestrial snakes consumed lizards as their modal prey, and with which these same snakes ate members of their preferred lizard prey genus. Although we uncovered no statistical basis for labelling R. lecontei a specialist, its diet may often be restricted to lizards and even to Cnemidophorus, and therefore recognizing long‐nosed snakes as specialist predators remains a subjective decision. Our study also demonstrates that quantitative natural history can place related species in a resource use continuum, and thereby can help to elucidate the evolutionary basis for specialization.
A second primitive marine snake: Pachyophis woodwardi from the Cretaceous of Bosnia‐Herzegovina
Authors: Lee M. S. Y. , Caldwell M. W. , Scanlon J. D. 
Published: February 2006

AbstractThe fossil of a second primitive snake from Cretaceous marine sediments is identified and redescribed: Pachyophis woodwardi Nopcsa. This snake was similar to Pachyrhachis in having pachyostotic vertebrae, a slender neck and a small head. However, Pachyophis differed from Pachyrhachis in being even more aquatically adapted: the mid‐dorsal vertebrae and ribs are more swollen (pachyostotic), the body was more laterally compressed, and the dentary contains more teeth. The hindlimb (well developed in Pachyrhachis) cannot be confirmed as present or absent in Pachyophis. A cladistic analysis demonstrates that Pachyophis and Pachyrhachis form a clade. This grouping, here termed the Pachyophiidae, forms the most basal group of snakes so far known and is the sister group to all other well‐known snakes.
Body size, and interactions between European and American mink (Mustela lutreola and M. vison) in Eastern Europe
Authors: Sidorovich V. , Kruuk H. , Macdonald D. W. 
Published: February 2006

AbstractBody sizes of European mink (Mustela lutreola L.), polecat (M. putorius L.) and American mink (M. vison Schreber) were studied over a 10‐year period in an area of north‐eastern Belarus, before and after the invasion by American mink, and data are presented on interspecific interactions. On arrival in the study area American mink males were larger than males of European mink and polecat, and American mink females were larger than females of the other species. After arrival of the American mink its mean body size decreased, whilst the resident male and female European mink and female polecat increased as measured in absolute mass, length and relative mass. The observations suggest a strong character convergence most plausibly explained as a response to the invading exotic by the residents as well as in the invading species itself, whilst a divergence had been expected. There was no evidence to show whether these differences were genetically based. The body size data are consistent with the hypothesis that European mink, and to a lesser extent polecat, are responding to direct aggression from American mink (rather than merely competing for resources), with the smaller individual European mink being more likely to disappear first. We provide direct evidence for the aggressive nature of inter‐specific relations from observations using radio‐tracking: all observed inter‐specific interactions were aggressive, significantly more so than intraspecific encounters, causing the European mink to flee, and several left the study area altogether. Implications for niche theory and for conservation management are discussed.
Postnatal growth and age estimation in the Indian false vampire bat (Megaderma lyra)
Authors: Rajan K. Emmanuvel , Marimuthu G. 
Published: February 2006

AbstractThe Indian false vampire bat Megaderma lyra produces a single young under captive conditions, which is altricial at birth. Empirical growth curves were derived by measuring length of forearm, body mass and length of the total gap of the fourth metacarpal–phalangeal joint. Length of forearm and body mass followed a linear pattern of growth until day 28 and subsequently reached stability. The length of the total gap of the metacarpal–phalangeal joint initially showed a linear increase up to 4 days, followed by a linear decrease until 34 days when it closed. A quantitative method of estimation of age was derived from values of length of forearm and length of the total gap of the fourth metacarpal–phalangeal joint during the preflight (first 28 days) and postflight stages, respectively. Width of the 95% confidence level was ± 1.2 days at a mean length of forearm of 51.6 mm, and ± 0.07 days at a mean length of the total gap of the fourth metacarpal–phalangeal joint of 1.89 mm. Initiation of flight occurred 24 days after birth. At 28 days of age, young were able to forage on their own. There was no significant difference in the growth pattern of young held in captivity compared to that of young grown under natural conditions.
Use of the nutrients in bamboo by the red panda (Ailurus fulgens)
Authors: Wei Fuwen , Feng Zuojian , Wang Zuwang , Zhou Ang , Hu Jinchu 
Published: February 2006

AbstractNutrient use by the red panda Ailurus fulgens was measured in animals fed only on their natural bamboo Bashania spanostachya diet. The project was carried out at the field observation station of Yele Natural Reserve in Sichuan, China. Two‐week long trials were conducted at monthly intervals from May to November 1995. Results showed that dry matter digestibility differed significantly among seasons and between diets. Digestibilities of dry matter and key nutrients were high in summer–autumn, intermediate in spring and low in winter. Shoots were more easily digested than leaves and exhibited the highest digestibility. These variations were positively correlated with nutrient contents in bamboo. The results also indicated that the red panda poorly processed its bamboo food. This was demonstrated by the lower digestion coefficients of dry matter and nutrients, especially that of cell wall constituents. This implied that microbial digestion only played a minor role in its digestive strategy, similar to the giant panda Ailuropoda melanoleuca, another herbivorous carnivore. In addition, the transit of bamboo through the red panda gut was very rapid (2–4 h). In order to survive on this poor‐quality diet, it seems that the red panda has to select high‐quality items of bamboo such as tender leaves and shoots. These are ingested in large quantities (over 1.5 kg of fresh leaves and 4 kg of fresh shoots daily) that pass through the digestive tract fairly rapidly so as to maximize nutrient intake.
Diet choice and capture success of wild dog (Lycaon pictus) in Hluhluwe‐Umfolozi Park, South Africa
Authors: Krüger Sonja C. , Lawes Michael J. , Maddock Anthony H. 
Published: February 2006

AbstractThe small population of wild dog Lycaon pictus (n= 3 to 30) in Hluhluwe‐Umfolozi Park (HUP) has declined since 1992. The survival of dogs in HUP is dependent on the reintroduction of more dogs; however, wild dog reintroduction programmes are fraught with problems and many have failed. In this paper the diet and capture success of the wild dog pack in the Hluhluwe Section, and the influence of dietary considerations on the success of the future reintroduction of wild dogs in this reserve, are investigated. Diet choice was determined from scat analysis, personal observation and field staff records. Eight ungulate prey species were identified from scat analysis: nyala Tragelaphus angasi and impala Aepyceros melampus were the most abundant ungulate species in HUP and accounted for 77% of the diet. On the whole, wild dogs included prey types in the diet consistent with a rate‐maximizing foraging approach, although some prey were clearly taken opportunistically. The dogs preyed mostly on small‐ (> 25 kg) to medium‐sized (40–90 kg) prey, while the young of large (< 90 kg) prey species or scavenged carcasses supplemented the diet during the dry season. Adult nyala were taken more frequently than other age classes, but wild dog preyed on juvenile impala more than expected. Female prey were taken more frequently than males but selection did not differ from prey population sex ratios. Prey capture success was similar to that of previous studies from both open and densely wooded habitats and the wild dogs successfully caught 48% of all prey species pursued. Results suggest that wild dogs are quite capable of adapting both their diet choice and foraging technique to the dense vegetation in HUP. We conclude that prey type, prey availability and habitat constraints on prey capture success, will not affect the reintroduction of more wild dogs into HUP.