bluuebunny/crossref_metadata_2025_split huggingface dataset:
Eye morphology reflects habitat demands in three closely related ground beetle species (Coleoptera: Carabidae)
Authors: Bauer Thomas , Desender Konjev , Morwinsky Thomas , Betz Oliver 
Published: February 2006

Abstract Asaphidion flavipes, A. curtum, and A. stierlini, which are similar in shape and size, were compared for morphological measurements of the head and eyes. The species not only differ in body size but also in the relative length of their antenna, the surface area of their compound eyes, the number and density of their ommatidia, and the structure of their visual space. These differences can be interpreted functionally and correlate well with features of the various habitats in which the species are found.
Applicability of external measurements to sexing of the Cape petrel Daption capense at within‐pair, within‐population and between‐population scales
Authors: Weidinger Karel , van Franeker Jan Andries 
Published: February 2006

AbstractSexual size dimorphism in the Cape petrel Daption capense was analysed to improve methods for sexing live birds in field studies. Samples originated from two geographically distant study populations in the Antarctic: Nelson Island, South Shetland Islands (sample N: 83 M, 89 F), and Ardery and O'Connor Islands, Windmill Islands (sample A: 36 M, 27 F). Using single characters with cut points calculated from sexed individuals, about 59–76% (N; best separator tarsus length) and 61–86% (A; best separator tube length) of birds could be assigned to the correct sex. Combination of characters improved performance of sample‐specific discriminant functions to a maximum of 84% in the N‐sample (five characters) and 95% in the A‐sample (four characters). The most useful character sets as well as ranking of individual characters (their weights) differed between samples. At the same time, cross‐testing revealed asymmetry in the applicability of sample‐specific functions to the other sample. Hence, the method of a generalized discriminant (Auk110: 492–502, 1993) was implemented and tested to develop a species‐specific discriminant for the Cape petrel. For all examined character sets, results of their cross‐application to the other sample were improved by using character weights estimated from combined samples instead of weights derived only from the original sample. The generalized function (tube length + 1.05*bill depth at tube + 0.72*culmen length + 0.07*wing length) combined with a cut point calculated from a distribution of discriminant scores (assumed mixture of two normal distributions with possibly unequal variances) is suggested as currently the best compromise for sexing Cape petrels in populations for which specific functions are not yet available: comparison with our best sample‐specific functions shows a decrease in accuracy by only 1% to 3%. However, examination of other promising characters (head length, bill depth at gonys, mid‐toe length) is recommended to improve further a generalized discriminant. In all cases a larger percentage (N: 87–89%, 38 pairs; A: 100%, 27 pairs) of individuals was correctly sexed by within‐pair comparison of discriminant scores than according to the sample‐specific cut point. No clear evidence for assortative mating with respect to body size has been found in this study. Available biometric data show little evidence for geographical variation in the Cape petrel, which suggests good applicability of generalized sex‐discriminants in other populations.
Respiratory stratagems, mechanisms, and morphology of the ‘lung’ of a tropical swamp worm, Alma emini Mich. (Oligochaeta: Glossoscolecidae): a transmission and scanning electron microscope study, with field and laboratory observations
Authors: Maina J. N. , Maloiy G. M. O. , Wood C. M. 
Published: February 2006

AbstractThe swamp worm Alma emini subsists in the highly productive waterlogged swamps around the East African Lake Victoria. The soil consists of putrefying plant matter from which gases like methane, carbon dioxide, and hydrogen sulphide are formed and profusely discharged. The interstitial spaces in the soil are generally anoxic and the soil is highly reducing. To survive in such an inimical habitat, Alma has evolved a remarkably unique respiratory strategy. The posterodorsal part of the body, which is well supplied with blood, is regularly converted into a ‘lung’ across which gases are exchanged at the surface or under water. Air and/or water may be entrapped in the ‘lung’ and carried for use (as a source of oxygen and/or a depository of carbon dioxide) during the ensuing underground sojourn. By evolving a unique respiratory potential, Alma emini has been able to flourish in a highly dynamic and virtually anoxic habitat while essentially having a capacity for aerobic biochemistry. Putative indications of cellular adaptations against hydrogen sulphide toxicity were observed, especially in the cells that line the ‘lung’. A. emini presents a good example of nature's tenacious and innovative designs for surviving in severe environments.
Activity budgets and ranging patterns of the Atlantic forest maned sloth Bradypus torquatus (Xenarthra: Bradypodidae)
Authors: Chiarello Adriano G. 
Published: February 2006

AbstractThree maned sloths were observed for a total of 680 h throughout 14 months in an Atlantic forest reserve of south‐eastern Brazil. The study animals were located in the forest, monthly by radio‐telemetry, and data on daily activity budgets were collected recording the actual time they spent in major activities. Individual home ranges were very small (0.5–6 ha, depending on the method used) and the sloths travelled an average of only 24 m during the 24 h period. A comparison between day‐ and night‐range lengths suggests that maned sloths ranged more during daytime (17 m) than at night (5 m), indicating a predominantly diurnal period of activity. They rested, on average, for 74% of daytime, but a substantial variation was found between individuals (range 60–80%). Although a lack of synchrony was observed in activity pattern between study animals monitored simultaneously, all three sloths tended to start feeding and moving at the same time of the day (07:00–08:00), and the time that elapsed between the start of these activities on consecutive days was about 24 h, indicating a circadian rhythm of activity for the species. This finding contradicts previous studies on congeneric sloths, in which suggestions that Bradypus does not show cyclic patterns of activity were based on qualitative rather than quantitative data. Given the species' highly folivorous diet and the characteristic low basal rate of metabolism in this genus, the rather high levels of activity and the predominantly diurnal period of activity observed for maned sloths are probably related to the lower ambient temperatures found in the Atlantic forest when compared to other more equatorial localities of the Neotropics. Further studies with additional sloths are necessary, however, to ascertain the validity of this conclusion.
Stabilimentum variation and foraging success in Argiope aurantia and Argiope trifasciata (Araneae: Araneidae)
Authors: Blackledge Todd A. 
Published: February 2006

AbstractMany spiders include conspicuous designs of white silk called stabilimenta in the centre of their orb webs. Stabilimenta are highly variable in their form and frequency and are hypothesized to function in either defence against predators or attraction of prey. These hypotheses generate different predictions about the effect of foraging success on variation in the form and frequency of stabilimenta. If stabilimenta serve as prey attractants, then starved spiders should invest more in them than well‐fed spiders, while the opposite pattern is expected if stabilimenta function as a predator defence mechanism. This study examines the effect of variation in foraging success of the yellow garden argiope Argiope aurantia and the banded argiope Argiope trifasciata on variation of their stabilimenta and orb webs. Both species built smaller stabilimenta when fed less, even though a stabilimentum accounts for only 10% of the dry weight of an orb web. Poorly fed A. trifasciata also included stabilimenta in their webs less often than did well‐fed A. trifasciata. Differences in stabilimenta were independent of differences between treatments in the orb webs themselves. These results argue against the prey attraction hypothesis, but not the predator defence hypothesis, since well‐fed spiders invested more in stabilimenta.
Estimating numbers of the water vole Arvicola terrestris: a correction to the published method
Authors: Morris P. A. , Morris M. J. , MacPherson D. , Jefferies D. J. , Strachan R. , Woodroffe G. L. 
Published: February 2006

AbstractIn Britain, the water vole (Arvicola terrestris) has declined in numbers and distribution (Jefferies, Morris & Mulleneux, 1989; Strachan & Jefferies, 1993). This species now enjoys a higher profile than hitherto and many local surveys have been initiated, following published methods. To monitor the status of the population or the effectiveness of habitat restoration projects, a method for estimating numbers of water voles is often needed, preferably based on latrines (a characteristic field sign of this species). Unfortunately, the published literature includes two potentially misleading components. In view of the significance of population size in a declining species, and the heightened interest in this animal, we felt it would be helpful to publish clarification and corrections in the hope of forestalling erroneous reports and conclusions in future investigations.
Foraging behaviour and diet of lactating female southern sea lions (Otaria flavescens) in the Falkland Islands
Authors: Thompson D. , Duck C. D. , McConnell B. J. , Garrett J. 
Published: February 2006

AbstractThis study investigated the foraging behaviour, diving behaviour, movements and diet of lactating southern sea lions in the Falkland Islands. They appeared to be primarily nocturnal, benthic foragers hunting at depths ranging from the surf line down to 250 m, and from just off their breeding sites out to 45 km offshore. Occasional longer trips may extend foraging ranges to over 150 km from breeding sites. Attendance patterns suggest that Falklands' sea lions do not haulout simply to feed their pups. Other factors such as predation and thermoregulation may cause them to come ashore. When at sea they travelled at approximately 1 m s−1, slower than previous studies of otariids indicated. Absence from the breeding site did not imply continuous foraging; all study animals used remote haulout sites away from their pups. Repeated use of the same areas and the short duration of foraging trips suggest that they were able to catch enough food within a fairly small foraging range. Data on diet support the suggestion that lactating sea lions are mainly benthic foragers. They take a wide range of prey species. The most common cephalopods were Loligo gahi, similar in size to those taken by the fishery. There is therefore potential for competition between the sea lion population and the Loligo trawl fishery. There was considerable overlap between the diet of sea lions and those of Gentoo and Magellanic penguins, which suggests that sea lions may compete with both species.
Use of European hare (Lepus europaeus) carcasses by an avian scavenging assemblage in Patagonia
Authors: Travaini Alejandro , Donázar José Antonio , Rodríguez Alejandro , Ceballos Olga , Funes Martín , Delibes Miguel , Hiraldo Fernando 
Published: February 2006

AbstractWe studied the use of European hare (Lepus europaeus) carcasses by avian scavengers in Argentinean Patagonia. A total of 16 hare carcasses were placed in locations that could be observed without disturbing birds feeding on them. Six avian species fed on these carcasses: chimango caracara (Milvago chimango), crested caracara (Polyborus plancus), black vulture (Coragyps atratus), grey eagle‐buzzard (Geranoaetus melanoleucus), red‐backed hawk (Buteo polyosoma) and cinereous harrier (Circus cinereus). Turkey vultures (Cathartes aura), although abundant, never fed on the hare carcasses. The Andean condor also did not feed on the carcasses. Mammals visited hare carcasses on only two occasions. Of the hare carcasses, 69% were fully consumed during the first day of exposure and 25% in two days. There was no difference in the time elapsed from the placement of the carcass and its detection by crested and chimango caracaras. There were similar time periods from detection to first arrival, and time elapsed from first arrival to the start of feeding at the carcass by crested and chimango caracaras. Hare body parts were consumed in different proportions by crested and chimango caracaras whereas black vultures consumed the whole carcass. Interspecific hierarchies at the carcass in a decreasing sequence of dominance were crested caracara > black vulture > chimango caracara, coinciding with that expected from a body mass perspective. The scavenging species that consume hare carcasses did not show a clear pattern denoting they were a highly interdependent assemblage in the way described for scavengers in Africa.
How high ambient temperature affects the daily activity and foraging time of a subtropical ungulate, the greater kudu (Tragelaphus strepsiceros)
Authors: Owen‐Smith Norman 
Published: February 2006

AbstractThe influence of ambient temperature on daily activity level was assessed for greater kudus observed in two study areas in South Africa. Active time proportion for adult females and subadults of both sexes was significantly negatively correlated with maximum daily temperature, but uninfluenced directly by cloud cover. However, maximum temperature differences between days accounted for only a quarter of the variability in active time. On most days the overall activity level and hence daily foraging time allocation were somewhat lower than the maximum levels observed for the prevailing temperature conditions. The upper limit to the distribution of active time was lower during the mild dry season than over the hot wet season, probably due to a seasonal change in pelage by kudus. Temperature influences were strongest during the early growing season, when food availability was low and conditions frequently hot. The active and foraging times of kudus during daylight hours appeared to be restricted below the target level only when maximum daily temperature exceeded 36 °C in the wet season, and 30 °C in the dry season. Only 15% of days exceeded these levels during the respective mid‐seasonal periods, suggesting that foraging activity was effectively constrained by thermal tolerance on only about one day in seven. Optimal foraging models that assume thermal stress to be a consistent daily constraint on foraging time may be misleading.
The behaviour and captive maintenance of the terrestrial nemertine (Geonemertes pelaensis)
Authors: Gerlach J. 
Published: February 2006

AbstractThe first successful captive maintenance of living terrestrial Geonemertes nemertines is reported. Behavioural observations are described, including the first data on diet in this genus. The species G. pelaensis is found to be a predator of small molluscs. In 1907 the Seychelles population was described as a distinct species, G. arboricola, largely on the basis of its arboreal habit. Recent field data from the Seychelles islands of Mahé and Silhouette confirm the tendency towards arboreal behaviour.
Diet of feralXenopus laevis(Daudin) in South Wales, U.K.
Authors: Measey G. J. 
Published: February 2006

AbstractAfrican clawed frogs (Xenopus laevis) in a South Wales pond ate a wide variety and size range of prey. Zoobenthos and zooplankton made the greatest contribution to diets, both numerically and by weight. Terrestrial invertebrates made up a small proportion of the diet numerically but a large proportion of the diet mass during the spring and summer. Nektonic prey were present throughout the year but made up a very small proportion of diet. Cannibalism was important when eggs and larvae were present in the pond. Electivity values were consistently positive for chironomids (larvae and pupae) and daphnids but were consistently negative for tubificids. In addition, electivity increased for larger sizes and pupae ofChironomus plumosus, but was low for the largest size class (> 12 mm). Electivity of other taxa showed an increase when densities of chironomids and daphnids were reduced. Mean sizes of daphnids and cyclopods were consistently larger in frog stomach contents than in the water column, indicating that predation on zooplankton byXenopus laevisis size‐selective.
Microhabitat and spatial dispersion of the grassland mouse (Mus spretus Lataste)
Authors: Gray Samantha J. , Hurst Jane L. , Stidworthy Richard , Smith John , Preston Rowan , MacDougall Robert 
Published: February 2006

AbstractMany small mammals inhabiting vegetation habitats where food resources are scattered have large home ranges with limited overlap. One way that they may effectively defend large territories is to establish dominance over the limited number of sites that provide good protection from predators, since displacement from these sites could have a very high cost to intruders. To examine this hypothesis we studied the fine‐scale use of habitat and spatial dispersion of all adult male Mus spretus inhabiting a 1.1 ha grassland study site near Lisbon, Portugal, by radio telemetry, at the start of the breeding season. The location of each of the 10 males was mapped every hour, 24 h/day for up to seven days. Microhabitat characteristics were compared between a random sample of points in the study site and those where mice were found. Individual ranges did not overlap, despite the close proximity of their borders and the occupation of almost all suitable habitat, suggesting that individual dispersion was strongly influenced by the presence of neighbours; mean range size was 343 ± 95 m2. Residents covered less than one‐third of their total range over 24 h, though neighbours did not intrude despite the apparent opportunities. Each male territory overlapped the territory of at least two females. Mice were neither nocturnal nor crepuscular, moving around mostly during the morning and evening. They avoided open woodland or pathways, preferring grassland sites with tall vegetation and sites where shrubs, bramble, or dead wood provided additional cover. Most fixes per male (70%) were located in one to four core areas, which represented only a tiny proportion of each range (6.9 ± 0.9%). Although exclusive defence of large complex ranges is likely to be impracticable, defence of core areas seems much more feasible. Our results thus support our hypothesis that mice may be able to maintain large exclusive ranges due to a combination of high predation pressure and a limited number of sites with sufficient ground and overhead cover. This will result in a very high risk to mice entering areas where competitors have priority of access to protected sites.
Neotricula aperta (Gastropoda: Pomatiopsidae), the intermediate host of Schistosoma mekongi: allozyme variation and relationships between Khmer, Lao, and Thai populations
Authors: Attwood S. W. , Kitikoon V. , Southgate V. R. 
Published: February 2006

AbstractVariation was studied at 13 electrophoretically detected allozyme loci for samples of six populations of the polytypic snail Neotricula aperta; this was the first time that topotypic material from southern Laos and material from Kampuchea had been so examined. In addition, samples of all three strains of N. aperta from North East Thailand were examined and the findings compared with those of Staub et al. (1990). The samples were taken from the Mekong and Mul rivers of the Lower Mekong Basin. A small sample was also included from a γ‐strain population in the Xé‐Bang‐Fai (XBF) river of central Laos. The γ‐strain population of southern Laos and of Kampuchea has been shown to act as an intermediate host for Schistosoma mekongi.In contrast to the work of Staub et al. (1990) significant multilocus genetic differences (Nei's D, DN= 0.6–1.2) were detected between the three strains from Thailand and no cryptic taxon, that included both α‐ and γ‐strains could be demonstrated. However, there was agreement with the 1990 report in that the β‐strain was divisible into two new taxa, with a reduction in heterozygote deficiency, although the genetic distance was not marked (DN= 0.12). Significant genetic distances were found between γ‐strain snails from the type locality and β‐ and γ‐strain samples from North East Thailand (DN= 2.0 and 1.5, respectively). On the basis of genetic distance measures, the Β‐strain is probably a sibling species of N. aperta and the γ‐strain of North East Thailand may also be a separate species. The population at XBF appears to be N. aperta s.s. The public health implications of the findings are discussed, particularly in the context of Mekong river water resource development.
Long‐term study of litter size in relation to population density in rabbits (Oryctolagus cuniculus) in Lincolnshire, England
Authors: Trout R. C. , Smith G. C. 
Published: February 2006

AbstractAfter the introduction of myxomatosis to the U.K. in 1953, the rabbit Oryctolagus cuniculus population crashed to less than 1% of its original size (Lloyd, 1970). Since that time the population has been slowly recovering, and reached about 20% of pre‐myxomatosis levels by 1980 (Lloyd, 1981; Trout, Tapper & Harradine, 1986). Between 1980 and 1986 an index of rabbit abundance was produced from field surveys, which resulted in an estimated population growth rate of just under 1% per year but there has been no objective assessment of the changes nationally since 1986.
The influence of female size on the extent and intensity of mate guarding by males in Chamaeleo chamaeleon
Authors: Cuadrado Mariano 
Published: February 2006

AbstractIn ectotherms, the size of the female correlates with fecundity and thus, males prefer large more fecund females as potential mates in some species. The idea that the extent and intensity of mate guarding are also size‐related was tested in the common chameleon Chamaeleo chamaeleon. Mate guarding was studied in 43 radio‐tagged females during 3 years in a population in southern Spain. The extent and intensity of male guarding of their mates varied greatly. On average, the guarding started on 20 August and ended on 2 September (mean duration = 12.6 days, range 2–44 days, n= 35; six females were not guarded). Guarding continued for some days after mating (range = 0‐13 days, n= 16). Guarding intensity (mean = 65.8% of net observation time with a guarding mate, range = 23–90, n= 27) and number of guarding males (mean = 1.8, range = 1–7) also varied greatly. The extent and intensity of mate guarding was strongly influenced by female size and the guarding period after mating: large females were guarded early in the season, for longer periods, and more intensively than small ones. Large females were also guarded for longer periods after mating. The overall variation in the guarding period was due to the duration of guarding before mating which was longer for large females. To my knowledge, this is the first time that prolonged mate guarding of larger females has been reported.