Showing papers in "Journal of Zoology in 2007"

Large‐scale seasonal variation in the prevalence and severity of chytridiomycosis

Abstract: The chytrid fungus Batrachochytrium dendrobatidis has been implicated as the causative agent of mass mortalities, population declines and the extinctions of studies have shown that the prevalence of chytridiomycosis (the disease caused by the fungus) increases in cooler months, the magnitude and timing of these seasonal fluctuations have yet to be accurately quantified. We conducted disease sampling in a single population of stony creek frogs Litoria wilcoxii on 13 occasions over a 21-month period and used quantitative real-time polymerase chain reaction to detect and quantify the number of B. dendrobatidis zoospores present on samples. Disease prevalence varied significantly across sampling sessions, peaking at 58.3% (in early spring) and dropping to as low as 0% on two occasions (late summer and early autumn). There was a significant negative relationship between disease prevalence and mean air temperature in the 30 days prior to sampling. These large-scale seasonal fluctuations in chytridiomycosis levels will strongly influence conservation programs and amphibian disease research.

Anurans as prey: an exploratory analysis and size relationships between predators and their prey

Abstract: The vertebrate predators of post-metamorphic anurans were quantified and the predator–prey relationship was investigated by analysing the relative size of invertebrate predators and anurans. More than 100 vertebrate predators were identified (in more than 200 reports) and classified as opportunistic, convenience, temporary specialized and specialized predators. Invertebrate predators were classified as solitary non-venomous, venomous and social foragers according to 333 reviewed reports. Each of these categories of invertebrate predators was compared with the relative size of the anurans, showing an increase in the relative size of the prey when predators used special predatory tactics. The number of species and the number of families of anurans that were preyed upon did not vary with the size of the predator, suggesting that prey selection was not arbitrary and that energetic constraints must be involved in this choice. The relatively low predation pressure upon brachycephalids was related to the presence of some defensive strategies of its species. This compounding review can be used as the foundation for future advances in vertebrate predator–prey interactions.

Diet and prey profiles of three sympatric large carnivores in Bandipur Tiger Reserve, India

Abstract: We conducted a field study of diets of three sympatric large carnivores, the tiger Panthera tigris, the leopard Panthera pardus and the dhole Cuon alpinus in Bandipur Tiger Reserve, India, based on analyses of 381, 111 and 181 scats, respectively. The frequency of occurrence of prey items in scats was converted to relative biomass and number of prey consumed using regression equations based on earlier feeding trials. The results showed that although these predators kill ?11-15 species of vertebrate prey, relatively abundant ungulate species provide 88-97% of biomass consumed by them. Although the dietary niche overlap among the three species was high (Pianka's index of 0.75-0.93), some specialized predation was observed. The largest ungulates, gaur Bos gaurus and sambar Cervus unicolor, provided 73% of biomass consumed by tigers, whereas medium-sized chital Axis axis and wild pig Sus scrofa formed 65 and 83% of the biomass intake of leopards and dholes, respectively. In terms of the relative numbers of prey animals killed by the three predators, chital, which is the most abundant prey species, dominated their diets (tiger=33%, leopard=39% and dhole=73%). The results of the study, in conjunction with earlier work, support the prediction that abundance of ungulate prey species, as well as their availability in different size classes, are both critical factors that facilitate sympatry among the three predators.

Diets of savanna ungulates from stable carbon isotope composition of faeces

Abstract: Hypotheses to explain diversity among African ungulates focus largely on niche separation along a browser/grazer continuum. However, a number of studies advocate that the browser/grazer distinction insufficiently describes the full extent of dietary variation that occurs within and between taxa. Disparate classification schemes exist because of a lack of uniform and reliable data for many taxa, and failure to incorporate spatio-temporal variations into broader assessments of diet. In this study, we tested predictions for diet and dietary niche separation of African savanna ungulates using stable carbon isotope evidence from faeces for proportions of C3 (browse) to C4 (grass) intake among 19 species from the Kruger National Park, South Africa. Dietary predictions from the literature are confirmed in the case of browsers (black rhinoceros Diceros bicornis, giraffe Giraffa camelopardalis, bushbuck Tragelaphus scriptus, kudu Tragelaphus strepsiceros), mixed-feeders (impala Aepyceros melampus, nyala Tragelaphus angasii), and most grazers (white rhinoceros Ceratotherium simum, Burchell’s zebra Equus burchellii, warthog Phacochoerus africanus, hippopotamus Hippopotamus amphibius, blue wildebeest Connochaetes taurinus, tsessebe Damaliscus lunatus, waterbuck Kobus ellipsiprymnus). In contrast, several species showed results differing from most expectations derived from the available literature, including eland Taurotragus oryx, steenbok Raphicerus campestris, grey duiker Sylvicapra grimmia, buffalo Syncerus caffer, roan antelope Hippotragus equinus and sable antelope Hippotragus niger. Many of these discrepancies can be accounted for by seasonal and/or regional dietary differences. Cluster analysis based on a data matrix that incorporates the extent of spatio-temporal dietary variation among Kruger Park ungulates reveals several distinct categories of feeding preferences that extend beyond a two-edged browser/grazer dichotomy, such as mixed-feeders with a preference for either forage class, and spatial/seasonal shifts between uniform and mixed-feeding styles among variable browsers (e.g. grey duiker) and variable grazers (e.g. buffalo). These results highlight the need for approaches that are sensitive to spatio-temporal variations and the continuity of diet.

Eye shape and activity pattern in birds

Abstract: Many aspects of an animal's ecology are associated with activity pattern, the time of day when that animal is awake and active. There are two major activity patterns: diurnal, active during the day in a light-rich, or photopic, environment, and nocturnal, active after sunset in a light-limited, or scotopic, environment. Birds are also cathemeral, or equally likely to be awake at any time of day, or crepuscular, awake and active at dawn and dusk. Each of these activity patterns is associated with different levels of ambient light. This study examines how the morphology (size and shape) of the eye varies according to these different light environments for birds in a phylogenetic context. Activity pattern has a significant influence on eye shape and size in birds. Birds that are adapted for scotopic vision have eye shapes that are optimized for visual sensitivity, with larger corneal diameters relative to axial lengths. Birds that are adapted for photopic vision have eye shapes that are optimized for visual acuity, with larger axial lengths relative to corneal diameters. Birds adapted for scotopic vision also exhibit absolutely larger corneal diameters and axial lengths than do photopic birds. The results indicate that the light level under which the bird functions has a more significant influence on eye shape than phylogeny.

Echolocation calls in Central American emballonurid bats: signal design and call frequency alternation

Abstract: In southern Central America, 10 species of emballonurid bats occur, which are all aerial insectivores: some hunt flying insects preferably away from vegetation in open space, others hunt in edge space near vegetation and one species forages mainly over water. We present a search call design of each species and link signal structure to foraging habitat. All emballonurid bats use a similar type of echolocation call that consists of a central, narrowband component and one or two short, frequency-modulated sweeps. All calls are multi-harmonic, generally with most energy concentrated in the second harmonic. The design of search calls is closely related to habitat type, in particular to distance of clutter. Emballonurid bats foraging in edge space near vegetation and over water used higher frequencies, shorter call durations and shorter pulse intervals compared with species mostly hunting in open, uncluttered habitats. Peak frequency correlated negatively with body size. Regular frequency alternation between subsequent calls was typical in the search sequences of four out of 10 species. We discuss several hypotheses regarding the possible role of this frequency alternation, including species identification and partitioning of acoustic channels. Furthermore, we propose a model of how frequency alternation could increase the maximum detection distance of obstacles by marking search calls with different frequencies.

Diet of free-ranging cats and dogs in a suburban and rural environment, south-eastern Brazil

Abstract: In spite of the worldwide occurrence of domestic cats and dogs, and their close relationship with humans, the number of published papers on free-ranging cats Felis catus and dogs Canis familiaris, is small. The diet of both species was estimated in a suburban and rural environment in July 2002 and January 2003. Visual observations and scat collection of both species were accomplished along a 10 km transect line in the Campus 'Luiz de Queiroz', University of Sao Paulo, Piracicaba, south-eastern Brazil. The diet of both species was determined by analysis of sterilized, washed, dried and sorted scats. Estimated abundances of free-ranging cats and dogs in the sampled area were 81 ( � 4.32) and 42 ( � 2.96), respectively. Cats and dogs were more abundant in the suburban than in the rural environment (t= 3.78, Po0.001, N = 55; t= 8.38, Po0.001, N = 55, respectively) and cats were more abundant than dogs in the suburban environment (t= 6.76, Po0.001, N = 55), even though there was no significant difference between the abundance of both species in the rural environment (t = 0.82, P= 0.46, N= 55). Invertebrates were the most commonly consumed item by both species, followed by mammals (cats: 63.24 and 20.51%; dogs: 57.05 and 25.15%, respectively). Niche breadth was 0.4892 for cats and 0.4463 for dogs. Niche overlap was almost complete (0.97108). The consumption of mammals was estimated to be between 16.76 and 25.42 kg individual � 1 year � 1 for dogs and between 2.01 and 2.9 kg individual � 1 year � 1 for cats. These data might be useful to establish a management program to minimize the predation pressure of free-ranging cats and dogs on wildlife.

Concordant molecular and phenotypic data delineate new taxonomy and conservation priorities for the endangered mountain yellow-legged frog

Abstract: The mountain yellow-legged frog Rana muscosa sensu lato, once abundant in the Sierra Nevada of California and Nevada, and the disjunct Transverse Ranges of southern California, has declined precipitously throughout its range, even though most of its habitat is protected. The species is now extinct in Nevada and reduced to tiny remnants in southern California, where as a distinct population segment, it is classified as Endangered. Introduced predators (trout), air pollution and an infectious disease (chytridiomycosis) threaten remaining populations. A Bayesian analysis of 1901 base pairs of mitochondrial DNA confirms the presence of two deeply divergent clades that come into near contact in the Sierra Nevada. Morphological studies of museum specimens and analysis of acoustic data show that the two major mtDNA clades are readily differentiated phenotypically. Accordingly, we recognize two species, Rana sierrae, in the northern and central Sierra Nevada, and R. muscosa, in the southern Sierra Nevada and southern California. Existing data indicate no range overlap. These results have important implications for the conservation of these two species as they illuminate a profound mismatch between the current delineation of the distinct population segments (southern California vs. Sierra Nevada) and actual species boundaries. For example, our study finds that remnant populations of R. muscosa exist in both the southern Sierra Nevada and the mountains of southern California, which may broaden options for management. In addition, despite the fact that only the southern California populations are listed as Endangered, surveys conducted since 1995 at 225 historic (1899-1994) localities from museum collections show that 93.3% (n=146) of R. sierrae populations and 95.2% (n=79) of R. muscosa populations are extinct. Evidence presented here underscores the need for revision of protected population status to include both species throughout their ranges.

Niche overlap and resource partitioning between two sympatric fox species in southern Brazil

Abstract: Mechanisms that favour the co-occurrence of morphologically and ecologically similar species in South America are potentially relevant, because two or more species often occur in sympatry. In the present study, we investigated possible mechanisms of resource partitioning between two sympatric species of foxes, the crab-eating fox Cerdocyon thous and the pampas fox Pseudalopex gymnocercus, in the National Park of Aparados da Serra in southern Brazil (29°10′S, 50°05′W). We considered three main niche dimensions – habitat, diet and time – and evaluated the overlap between the two species in these dimensions. We conducted the study from June 2000 to October 2001 in an area composed of open grasslands and Araucaria forests. We studied the foxes by using a combination of scat analysis and direct observation. A comparison of their diet indicated that it was very similar for both species in all seasons (Pianka's indexes ranging from 0.920 to 0.957). The most common food item for both species of foxes was rodents, followed by coleopterans, birds and plant remains (seeds and fruits). As expected by the niche-complementarity hypothesis, we detected differences along other niche axes. Pseudalopex gymnocercus seemed to occur only in open areas, including grasslands and dirt roads, whereas C. thous was more generalist in habitat use, occurring both inside and at the edge of forests. However, both fox species were common in grassland habitats, where they might compete for resources. The differences were more marked for activity time, with the crab-eating fox being significantly more nocturnal (circular mean of time of sighting=23:39 h, se=56 min) than the pampas fox (circular mean=19:56 h, se=64 min; Watson's F=6.06, P=0.02). We suggest that the larger C. thous could be limiting the activity of P. gymnocercus by interference competition.

Radio‐telemetric monitoring of dispersing stag beetles: implications for conservation

Abstract: Migratory movements of the endangered stag beetles Lucanus cervus (18 males, 38 females) were monitored radio-telemetrically for three reproductive periods (2003–2005) The aim of the study was to estimate the migratory range of free-ranging individuals as a measure of connectivity among neighbouring populations for future conservation measures Miniature transmitters of c 350 mg (battery life: 10–15 days) were attached externally to the pronotum Transmitter/beetle mass ratio was 128% on average (71–280%) Male dispersal behaviour consisted of frequent flights directed to sites with reproductive females and rarely of on-ground movement Total displacement distance recorded was up to 2065 m, the maximum distance of a single flight being 1720 m Flights always began at elevated structures such as trees and shrubs and took place in an air temperature range of 11–27°C Within this range, temperature did not influence flight distance Female dispersal behaviour consisted mostly of a single flight, followed by mating and consequent ground movements towards oviposition sites Total displacement distance recorded was up to 7626 m, the maximum distance of a single flight being 701 m Climatic constraints of flights were the same as in males Modelling the dispersal behaviour suggests that about 1% of males are capable of maintaining gene flux among nest sites within a radius of about 3 km However, the colonization of new nest sites depends on the dispersal ability of females and amounts to less than 1 km Thus, isolated populations (distance to the next population greater than 3 km) have an increased probability of local extinction

An ecomorphological analysis of extant small carnivorans

Abstract: An ecomorphological study of extant small carnivorans demonstrates that dietary groups can be distinguished using quantitative morphological characters. Small (<10 kg) modern carnivorans were divided into three dietary classes: carnivores, insectivores and omnivores/hard-object feeders. Statistical analyses revealed differences between these classes including longer carnassial blades in carnivorans, as opposed to larger molar grinding areas, larger post-canine dentitions, and wider fourth premolars in omnivores/hard-object feeders. Insectivores are not consistently distinguished from other dietary types, although they do tend to have weaker dentaries and shorter temporalis muscle moment arms. These trends can be used to help interpret morphologies of taxa of uncertain ecologies, including fossil taxa.

Echinostome infection in green frogs (Rana clamitans) is stage and age dependent

Abstract: The increasing threat of emerging infectious diseases in both wildlife and humans has spurred interest in the causes of disease emergence, including the role of anthropogenic change. A prior field study of infection patterns in amphibians suggests that echinostome infection may be an emerging disease of green frogs Rana clamitans living in urbanized environments. We examined the impact of echinostome infection on green frog tadpoles at a wide range of developmental stages (Gosner stage 25–39). Echinostome infection was associated with green frog mortality rates of up to 40% in an early developmental stage, and none in later developmental stages. Tadpoles exposed to higher echinostome doses exhibited higher edema rates, a potential sign of compromised renal function. Histopathological analysis further supported the hypothesis that echinostome-induced tadpole mortality resulted from compromised renal function. Given that the timing of highest cercarial shedding can coincide with the most vulnerable stages of green frog tadpole development, echinostomes could significantly impact green frog survival in nature.

Evolutionary implications of bite mechanics and feeding ecology in bears

Abstract: Bite forces (BFs) based on a dry skull static model were computed for 122 specimens of all eight species of extant ursids. It was found that the giant panda has high BFs for its body size, and large moment arms about the temporomandibular joint, both muscle inlever moment arms and outlever moment arms to the carnassial and canine. The insectivorous sloth bear and to some extent the omnivorous black bears were the opposite. The small sun bear has very large canines and high BFs, which are not well understood, but could potentially be related to its frequent opening of tropical hardwood trees in pursuit of insects. Force profiles along the lower jaw revealed significant differences among the various species, both related to diet and inferred applied BFs. The panda is the only specialized ursid with respect to craniodental morphology and BFs, but is still unspecialized for herbivory compared with other large, herbivorous mammals, probably owing to a rather short evolutionary history, but possibly its morphology is constrained by genealogy. The low BFs in the sloth bear and its mandibular force profiles are derived for a diet of insects and fruit, requiring only low BFs and largely dorsoventral bite moments. In contrast, the unspecialized morphology and moderate BFs relative to body size of the polar bear and spectacled bear are probably also a result of a short evolutionary history.

Habitat selection and feeding ecology of the cheetah (Acinonyx jubatus) in thicket vegetation: is the cheetah a savanna specialist?

Abstract: Habitat selection and feeding ecology of a reintroduced population of cheetahs Acinonyx jubatus were studied in a 16 000 ha game reserve in the Eastern Cape Province (South Africa). Seventy per cent of the reserve is characterized by very dense thicket vegetation (valley bushveld) and the remainder is open and savanna-like. The results illustrated a strong effect of sex and group size on the behaviour of cheetahs. The coalition (three adult males) killed significantly larger animals (55% of kills weighed more than 65 kg) than single female cheetahs (less than 2% of kills weighed more than 65 kg). Female cheetahs showed temporal and spatial avoidance of lions by hunting at dawn and dusk and positioning their home ranges [95% utilization distribution (UDs)] significantly farther from the pride of lions than did the coalition. The coalition hunted earlier and later than female cheetahs, and 46% of their kills were made in darkness. In addition, their home range overlapped that of the lions and they showed neither temporal nor spatial avoidance of the lions. The rates of kleptoparasitism were lower and the kill retention times were longer than those reported elsewhere in Africa, and it is suggested that this is a consequence of the cover provided by the thicket vegetation and prey size. The home ranges (95% UDs) of female cheetahs incorporated more thicket vegetation than that of the coalition, indicating that the coalition is less susceptible to predation than single females. These data suggest that cheetahs possess greater behavioural flexibility than previously reported, that they can hunt successfully in thicket vegetation, sometimes in darkness, that they are not restricted to killing small to medium-sized prey, and that they may not be savanna specialists.

Peccary movements as determinants of the movements of large cats in Brazilian Amazonia

Abstract: As part of a study on the ecology of a community of middle-sized and larger mammals in a seasonally dry forest in the far north of the Brazilian Amazonia, peccaries (the white-lipped peccary Tayassu pecari and the collared peccary Tayassu tajacu) and large cats (the jaguar Panthera onca and the puma Puma concolor) were regularly surveyed for 1 year. Diurnal and nocturnal surveys were carried out by the line-transect method, in five different forest types along a 10 km transect, and data were collected on their use of the forest types. The peccary herds and the large cats were sighted regularly throughout the study period, but more frequently over the dry season in the high-ground forests in eastern Maraca. Over the dry season, when food was scarce except in the Buritizals, T. pecari, closely followed by a P. onca, monopolized the Buritizal forests, whereas T. tajacu, followed by a P. concolor, exploited the other available high-ground forest types. Fluctuations in food supply regulated the dynamics of the two species of peccaries, which ultimately determined the whereabouts of the large cat predators. This may be a counter-strategy to survive in an extremely seasonal environment where food, more than any other variable, is the key determinant of the survival of both peccaries and large cats.

Activity patterns of Asiatic black bears (Ursus thibetanus) in the Central Mountains of Taiwan

Abstract: Shifts in activity patterns and time budgets in response to environmental variables may yield insights into key factors affecting animal life histories. Activity data on wild Asiatic black bears Ursus thibetanus are limited, and non-existent in tropical portions of their geographic range. During November 1998–November 2000, we monitored the activity (active vs. inactive) of bears within a national park in the tropics of central Taiwan. On the basis of 4630 readings from motion-sensitive transmitters obtained in 24-h monitoring sessions, bears were active 54–57% of the time over the course of the year. However, bears were more active during summer (60 � 15% SD) and fall (60 � 15%) than in spring (47 � 13%). They were active mainly during daylight hours in spring and summer, and also during fall when acorns, a principal fall food, were scarce. However, extensive nocturnal activity occurred in fall when acorns were abundant. Increased nocturnal activity in fall is consistent with studies of the related American black bear Ursus americanus, and suggests that this behavior is not necessarily driven by preparation for winter denning or because of disturbance by hunters (as posited in previous studies), as bears in our study did not den (except parturient females) and were not hunted or otherwise disturbed by people.

Skeletal and dental growth and development in chimpanzees of the Taï National Park, Côte D'Ivoire

Abstract: An extraordinary collection of 22 immature skeletons from Tai National Park, Cote d'Ivoire, has provided a rare opportunity to establish the timing of dental eruption and its correlation with skeletal fusion and morphometrics in wild chimpanzees of known chronological ages. Comparison of the immature Tai chimpanzees Pan troglodytes verus with adults from the same population show that sex differences in skeletal maturation apparently appear during the Juvenile II stage, about age 8. A few skeletons from other chimpanzee field sites conform to the dental and skeletal growth in Tai chimpanzees. The tempo of wild chimpanzee growth contrasts sharply with the rate demonstrated for captive individuals. Captive chimpanzees may mature as much as 3 years earlier. The ability to link physical development with field observations of immature chimpanzees increases our understanding of their life-history stages. These data provide an improved dataset for comparing the rates of growth among chimpanzees, Homo sapiens and fossil hominids.

Using sparse survey data to investigate the declining abundance of British harbour seals

Abstract: This study presents an analysis of changes in the regional abundance of harbour seals Phoca vitulina based on repeated aerial surveys of haulouts, and demonstrates the use of sparse data to deliver advice about population status and management. Generalized linear models with negative binomial errors were used to represent these overdispersed data. The shape parameter of the negative binomial distribution was directly estimated from the data where this was possible. Information from time-series of counts where there were few gaps in the data was used to improve the estimation of this parameter in areas where fewer surveys had been carried out. The results show that the number of harbour seals in eastern England has not increased since the end of the 2002 phocine distemper epidemic. There is also evidence of a general decline in most of the large harbour seal colonies around Britain. The populations in the Inner Hebrides were an exception, with numbers appearing to be stable or increasing. Between 2001 and 2006, the population in Orkney and Shetland declined by 40% (95% confidence interval: 30–50%), indicating harbour seals in these areas experienced substantially increased mortality or very low recruitment over this period. The widespread declines, ranging from Shetland to The Wash, suggest that the causes may have been present over a large part of the North Sea.

Feeding ecology and seed dispersal of sympatric cheirogaleid lemurs (Microcebus murinus, Cheirogaleus medius, Cheirogaleus major) in the littoral rainforest of south-east Madagascar

Abstract: The lemurs of Madagascar are known for their extraordinary species diversity. The mechanisms that allow the coexistence of these species are still poorly known. Here feeding patterns were investigated for three small nocturnal lemur species of Cheirogaleidae (Microcebus murinus, Cheirogaleus medius and Cheirogaleus major) occurring sympatrically in a littoral rainforest in south-east Madagascar. During three rainy seasons, the plant species eaten by these three lemurs were described in relation to morphological and biochemical characteristics. All three species were mainly frugivorous and fed on 68 different plant species with small- and medium-sized fruits. A total of 91% of these forage plant species was visited by all three lemur species. Fruits larger than 25–30 mm were avoided. Seeds of a total of 51 food plant species were swallowed and passed the gut unharmed. Thus, even these smaller lemur species play an important role in seed dispersal. There were no differences in the morphological and biochemical characteristics of fruits eaten between the three species, but the feeding height was significantly different between the species. Thus, competition avoidance and niche separation are presumably not based on different feeding patterns of M. murinus, C. medius and C. major in the littoral rainforest, but on different habitat utilization.

Quantifying the influence of topographic position on cougar (Puma concolor) movement in southern California, USA

Abstract: Large carnivores are frequently used as focal species for landscape-level planning and conservation purposes. Information on cougars Puma concolor, for example, is being used to predict movement corridors and linkage areas in habitats influenced by rapid urbanization. However, animal movement through habitat terrain is a function of multiple factors, including complex topographic features. To assess the use of topographic position during movements by cougars in the Santa Ana Mountain Range of southern California, we analyzed the travel paths of 10–17 radio-tagged individuals monitored during 44 overnight sessions. We examined selection for canyon bottom, gentle slope, steep slope and ridgeline topography at the scale of the movement session and at the scale of the home range. At both scales of selection, our results suggest that traveling or hunting cougars discriminated in their use of topographic position, that canyon bottoms and gentle slopes (<6°) ranked highest in compositional analyses of selection, and that these patterns were not highly confounded by the presence of preferred vegetation types. Ridgelines were used significantly less often than other positions. Our novel method of quantifying availability and use of topographic positions permits the assessment of terrain features, such as canyon bottoms, in facilitating cougar movements. For complex landscapes, models of animal movement should consider the topographic context that motivates patterns of habitat use, and should be developed using data obtained and analyzed at the appropriate spatial and temporal scales.

Dispersal patterns, social structure and mortality of wolves living in agricultural habitats in Spain

Abstract: Wolf Canis lupus dispersal, social structure and mortality have been extensively studied in natural and semi-natural areas of North America and northern Europe but have never been assessed in agricultural areas. From 1997 to 2004, 14 wolves (11 in a wolf-saturated area and three in a low-density area) were radio-collared with long-lasting transmitters in a Spanish agricultural area containing a high-human-population density, a dense network of roads and a shortage of wild ungulates. The wolves mainly feed on an overabundance of livestock carrion. Nine wolves (one of them, three times) dispersed during the study period. The mean age and distance of natal dispersal were 24.8 months and 32 km. The natal dispersal period was much longer in wolves radio-collared in the saturated area (mean >14.6 months) than in the low-density area (<1 month). All three of the dispersers living in the low-density area, and two of the six dispersers in the saturated area settled and bred during the study. The average tenure of six breeders was 4.5 years. The radio-collared wolves spent 72% of the monitoring time living in packs and the rest living in pairs, as dispersers or as peripheral wolves, but the percentage of loners was much higher in the saturated (33.5%) than in the low density (1.6%) areas. The overall annual mortality was 18% (lower than in most populations studied in less modified habitats), but lone wolves had a significantly higher mortality than members of packs and pairs. Nine wolves died during the study, none of them due to natural causes. In general, our results are very similar to those obtained in less modified habitats, except for the dispersal distance, which was much shorter than in other studies. We suggest that barriers and habitat constraints may reduce dispersal distances in our study area.

Bottom or midwater: alternative foraging behaviours in adult female loggerhead sea turtles

Abstract: Intrapopulational polymorphism in habitat use is widely reported in many animal species. The phenomenon has recently also been recognized in adult female loggerhead sea turtles Caretta caretta, with small females tending to inhabit oceanic areas (where water depths are >200 m) while presumably feeding pelagically and large females tending to inhabit neritic areas (where depths are 5 h that was in contrast with bottom dormancy by sea turtles inhabiting other regions. The diving behaviours observed during this study were consistent with their estimated main feeding habits, which demonstrated resource polymorphism in a marine reptile.

Use of native woodlands and traditional olive groves by foraging bats on a Mediterranean island: consequences for conservation

Abstract: We recorded bat activity on Zakynthos island (Greece) to test the hypotheses that (1) olive (Olea europea) groves and native woodlands provide comparable foraging habitat for insectivorous bats, (2) lower foraging activity occurs in olive groves treated with insecticide chemicals. We acoustically sampled bat activity (passes per minute) in four wooded habitats (organic and non-organic olive groves, oak woodland (Quercus ilex and Quercus coccifera) and pine (Pinus halepensis) woodland from June to August 2005. Habitat type did not affect overall bat activity. A single application of insecticide chemicals annually did not affect activity over traditional olive groves. Habitat use on the island differed in several ways from that reported in studies at mainland sites. Most strikingly, pine woodland supported higher bat activity than expected relative to other habitat types, and we recorded unexpectedly high levels of M. capaccinii activity in woodland habitats. We suggest that traditional olive groves buffer some bat species from the effects of deforestation. Conservation plans for Mediterranean bats should consider the biodiversity value of these groves along with the need to conserve small woodland patches. Finally, understanding island-specific patterns of habitat use is essential to bat conservation on small off-shore islands.

Can mite parasitism affect the condition of bat hosts? Implications for the social structure of colonial bats

Abstract: Ectoparasitism may be recognized as one of the main costs of coloniality, but little is known about how it affects the fitness and social structure of bats, the most gregarious of mammals. We studied these issues using the colonial bat Miniopterus schreibersii and its haematophagous parasitic mite Spinturnix psi as a model. Body condition is an important indicator of individual fitness that is potentially affected by ectoparasitism. Thus, we measured host body condition and mite loads in a total of 969 bats throughout the annual cycle. Mites were rare while hosts hibernated, increased in abundance in spring and peaked during nursing season of bats, when they were particularly abundant on lactating females and young bats. This strong seasonal variation in mite loads is related to the reproductive cycle of mites, which in turn appears to be synchronized with the reproductive cycle of their hosts. Mite loads and the condition of bats were negatively correlated, and information available suggests that this may be due to an effect of parasitism, although other possible causes for this trend cannot be excluded. However, a negative correlation was only observed during the bat's nursing season, when mites were most abundant, and heavily parasitized bats lost about 10% of their weight. Mite parasitism did not seem to be a significant disadvantage of coloniality, except in nurseries, where it might impose some costs. However, as females and young usually aggregate in these colonies, we presume that for them such costs are probably offset by advantages of group living. Adult males, however, are usually absent from nurseries, which may be a strategy to minimize mite parasitism. Overall, the results suggest that ectoparasitism may play a role in determining the social structure of M. schreibersii and of many other temperate bats that have similar life cycles and ectoparasitic loads.

Foraging requirements of the endangered long-fingered bat: the influence of micro-habitat structure, water quality and prey type

Abstract: Myotis capaccinii is one of the most endangered Mediterranean bats. We radio tracked 21 adult individuals to assess foraging range and analyse micro-habitat selection around a nursery roost in central Italy. Habitats were characterized by development of riparian vegetation, distance between banks, degree of water clutter and levels of water pollution (expressed by macro-benthic bioindicators). Diet was also analysed to see whether prey rarity might account for species decline. Myotis capaccinii proved highly mobile: the maximum straight line distance between roost location and the farthest foraging fix recorded on one night was c. 21 km, whereas this variable averaged 7.5 km for the entire study. In general, the species preferred calm waters bordered by well-developed riparian vegetation and large (45 m) inter-bank distances. Such factors determined the overall quality of foraging sites. Although diet was dominated by pollution-tolerant insects such as Chironomus midges, bats preferred less polluted waters. Our study also confirmed the occurrence of piscivory in this bat. Of the factors potentially responsible for species endangerment, the most likely are general habitat degradation, that is alteration of riparian vegetation and pollution, and cave roost loss. Given the large ecological niche overlap, increasing Myotis daubentonii may be outcompeting M. capaccinii. The most urgent actions to preserve M. capaccinii are extensive restoration of riparian vegetation and strict roost protection. Our study offers indications about where, and how, restoration of riparian vegetation may translate into best conservation results.

Density of Microhodotermes viator (Hodotermitidae) mounds in southern Africa in relation to rainfall and vegetative productivity gradients

Abstract: Giant earth mounds (heuweltjies) formed by the southern harvester termite Microhodotermes viator occupy a large proportion of the land surface of the Succulent karoo, Nama-karoo and Fynbos biomes. Microhodotermes viator is associated with specific vegetation types and low winter rainfall, prompting the hypothesis that rainfall and vegetative productivity govern the distribution and population densities of M. viator. Using an analysis of aerial photographs, the density of termite mounds at 34 sites in 10 vegetation types was determined across the full range of their distribution. The number of mounds ranged from 143 to 704 km−2 with a mean of 297. When all sites were considered together, mound density was not related to temperature, altitude, rainfall and vegetative productivity [as measured by the normalized difference vegetation index (NDVI)]. However, if the single Fynbos and five Coastal Renosterveld sites (with rainfall >350 mm year−1) were excluded from the analysis, then mound density was significantly related to both rainfall and NDVI values. A separate analysis of the relationship between mound density, rainfall and soil fertility was undertaken. There was a significant relationship between rainfall and mound density for sites occurring on soils of high-fertility status but not for sites occurring on soils of low-fertility status. These results suggest that soil fertility and vegetation composition are parameters that influence the effect of rainfall and vegetative productivity on termite mound distribution and density. Finally, the positive relationship between rainfall and mound density in areas with <350 mm year−1 suggests that M. viator populations are in equilibrium with climatic conditions. This provides further evidence that heuweltjies are constructed by their current occupants, M. viator, and are not the product of an extinct termite species as has been suggested previously.

Mortality parameters of the wolf in Italy: does the wolf keep himself from the door?

Abstract: Information on population parameters is rarely collected from carcasses. This method can be particularly useful – with limitations – when protected species are involved (e.g. the grey wolf Canis lupus in Italy). Local data on population structure, reproduction, survivorship and causes of mortality are necessary to build reliable conservation models to assess the state of a population and to predict its evolution. On the other hand, ‘best guesses’ or data from ecologically different areas have often been used to build population viability analysis and other conservation-oriented models. A sample of 154 wolf carcasses was found, collected and analysed from 1991 to 2001 in central-eastern Italy, the historic core of the wolf distribution range. Collision with a vehicle was the main cause of death in both sexes; however, road kills may be biased with a greater detectability, and we treated our data accordingly. Road kills were concentrated on the younger ( � 4 years old) age classes, whereas fully adult wolves died mainly because of poaching, intraspecific strife and pathologies. Cubs and subadults (� 2 years old) showed a mortality peak in November/December, at the beginning of the dispersal period, whereas adults died mainly in January/February (mating season). The population structure of our sample of wolf carcasses appeared to be well balanced, although perinatal and cub mortality was underestimated. The sex ratio was 1:1 in the younger age classes and 1:0.7 in the older age classes. Only 20.7% of females, 2–6 years old, showed signs of reproduction; placental scar and embryo number varied from one to seven (mean, 4.4) per individual. Survivorship theoretical curves indicated a fair survival of cubs and subadults, but a steep decline as wolves approached maximum life span (9 years old). Our data and other published data on food habits and genetic features of the wolf in central-eastern Italy suggest that, despite ongoing heavy human-induced losses, this predator has fully recovered in the last 30 years from the brink of extinction.

Secret lives of maned wolves (Chrysocyon brachyurus Illiger 1815): as revealed by GPS tracking collars

Abstract: The maned wolf Chrysocyon brachyurus is a nocturnal and shy species, which has proven difficult to study in the field; consequently, data about its behavioural biology are almost absent from the scientific literature. However, recent advances in global positioning system (GPS) technology mean that it is now possible to study the socio-spatial dynamics of this species in the field. In the present study three related maned wolves (an adult pair and their juvenile female offspring) were monitored by GPS tracking collars for a 6-month period, which included the birth of a litter of pups to the adult pair. The three GPS collars were programmed to record the position of the wearer every 2 h (simultaneously for all three individuals). Analyses of the data from the three individuals showed that the female had the largest home range, then the male and finally the juvenile. Furthermore, there was considerable overlap in home-range use by all three individuals. The home ranges of the adult pair also varied in relation to the birth of pups (decreasing dramatically and then showing a slow increase). During the night, which is the normal period of activity for this species, the three individuals avoided contact with each other. However, during the day, the adult pair usually slept together and their juvenile slept within a few hundred metres of their location. The distance travelled at night was greatest for the female, then the male and finally the juvenile. These data suggest that (1) the social bond between the male and female is strong, (2) maned wolves are highly tolerant of their juvenile offspring, even in the case of new pups being born, and (3) that maned wolves do not hunt together and, in fact, avoid each other when hunting.

The trade-off between tooth strength and tooth penetration: Predicting optimal shape of canine teeth

Abstract: We investigate the shape of canine teeth under the assumption that the tooth’s morphology is optimized by the evolutionary trade-off to minimize breakage and maximize ease of the penetration of prey. A series of experiments using artifi cial teeth to puncture the hides of a deer Odocoileus virginianus and pig Sus scrofa domesticus were conducted to establish the relationships between the tooth shape and the force needed to puncture the hide. The shapes of these teeth were also used in a beam theory analysis to calculate the strength of the teeth. Because the relative costs of puncturing and breakage were not known, a complete prediction of tooth shape was not possible. Instead, we used two independent measures of tooth shape: aspect ratio (total tooth length/tooth width at base) and rate of taper along the shank of the tooth. We quantifi ed rate of taper in several species of felids, and by assuming this was the optimal design, we determined the relative costs of breakage and puncturing that would produce such a taper. Then, we used the relative costs to predict the aspect ratio of the optimum tooth. The average predicted value is about 2.5, very close to the average value in extant species of cats.

Killer whale evasive tactics vary with boat number

Abstract: Controlled exposure experiments that measure animal response to vessels can inform relevant wildlife-viewing guidelines and reveal how they make decisions about changes in their environment. Previous experimental studies documented stereotyped avoidance responses by killer whales to boats. Additional observations collected during these studies showed an apparent shift in avoidance behaviour at high traffic levels. Our study tested experimentally whether whales did respond differently to approach by few (1–3) versus many (>3) vessels. Data were collected in summer 2004 in Johnstone Strait, British Columbia, using a theodolite to track the positions of boats and individually identifiable focal whales during control and treatment (few vs. many boats) phases. The responses of 16 adult male killer whales differed significantly between treatment levels (Wilcoxon's test, P=0.0148). Swimming paths became more tortuous when few boats approached whales, but straighter as many boats approached. Pooling treatments would have masked significant responses with high statistical confidence (Wilcoxon's test, P>0.999), falsely suggesting that boat presence had no effect. The division between few and many boats was supported by 140 opportunistic observations on 26 whales from a population of 216. We used generalized additive models to control for the effects of confounding variables, detected a non-linear relationship between number of boats and whales' swimming path directness and confirmed an inflection point at approximately three boats within 1000 m. We urge caution when designing controlled exposure assessments that rely on a simple absence–presence framework, which can mask multivariate or non-linear responses. Experimental design, coupled with analytical techniques incorporating statistical power and appropriateness of treatments and response variables, must be considered when interpreting the biological significance of null findings from impact assessments. Our study provides new information about levels of habitat degradation that this marine apex predator can tolerate.