Linear strips of natural or semi-natural vegetation are a characteristic feature of rural landscapes throughout the world. Their value for the conservation of fauna in heavily modified landscapes depends on the response of species to the linear shape of the habitat, and the pressures this imposes on population processes and spatial organization. In south-eastern Australia, woodland habitats occupied by the squirrel glider Petaurus norfolcensis, a threatened species of arboreal marsupial, have been preferentially cleared for agriculture leaving only remnants within cleared farmland. In this study, the home range of P. norfolcensis was investigated by radio-tracking 40 gliders within a highly modified landscape where the majority (83%) of remaining wooded habitat occurs as a network of linear strips along roadsides and streams. Individuals were tracked for one to four seasons, resulting in the collection of 4213 independent locational ‘fixes’. All fixes of animals were from remnant woodland. Home ranges were elongated and linear, primarily determined by the shape and arrangement of woodland habitat. Seasonal home ranges were small (mean of 1.4–2.8 ha) and ranged between 320 and 840 m long. Small patches of trees in farmland adjacent to the linear habitats were also extensively used. Despite the highly modified landscape structure, home ranges of P. norfolcensis in the linear network were smaller than those estimated from other studies of this species in continuous habitat. The apparent high quality of the linear habitats is attributed to the density of large old trees, which provide foraging and breeding resources, and the productivity of the environment. Linear landscape elements may have a valuable conservation function where they provide resident habitat or enhance landscape connectivity, but their long-term viability is vulnerable to disturbance.

Chick growth and food provisioning of northern fulmars Fulmarus glacialis were studied at Fair Isle, Shetland, in 2 years of contrasting environmental conditions. Low sandeel Ammodytes marinus availability resulted in very low breeding success in many seabirds in Shetland in 1998, whereas breeding success in 1997 indicated a normal season. Fulmars at Fair Isle experienced lower chick survival in 1998 than in 1997. There were also significant differences in diet and food provisioning in the 2 years; sandeels were the most abundant prey items in 1997, but were completely absent from the diet in 1998. High nestling mortality occurred shortly after hatching in 1998. Those chicks that survived this episode had previously been heavier for their age, and remained heavy throughout development in comparison to chicks in 1997, despite a continued absence of sandeels from the diet. Surviving chicks in 1998 were subsequently fed comparatively small meals at frequent intervals, but with no overall difference in the amount of food delivered. We discuss the implications of differential mortality and resulting growth patterns for the use of seabird breeding parameters to monitor marine environments.

Over one million pairs of seabirds breed annually on the Houtman Abrolhos island group, off the mid-western coast of Australia, the largest seabird breeding station in the eastern Indian Ocean. Eight of the 13 species that breed annually on Pelsaert Island are terns. Dietary samples (regurgitates) were collected from the five most numerous tern species from 1993 to 1999. The prey items identified were related to observations of foraging seabirds around the island. The largest species studied, the crested tern Sterna bergii, foraged mainly for reef fish over shallow reef flats near the breeding islands, as well as for schooling clupeid fish over coastal shelf waters. The smallest species, the roseate tern S. dougallii, also foraged within sight of its colonies, but over deeper waters than crested terns. Three larval fish species characteristic of continental shelf waters (a gonorhynchid, a goatfish and a bellowfish) figured prominently in the diets of roseate terns and three other tern species studied. Of these, only the sooty tern S. fuscata also ate squid and lanternfishes, foraging farthest (480–600 km) from its breeding island, off the shelf edge. The lesser noddy Anous tenuirostris and brown noddy A. stolidus took very similar taxa of prey and also overlapped considerably in their foraging ranges, about 180 km from their colonies, between the islands and the continental shelf edge. However, the lesser noddy took smaller fish than did the larger brown noddy. Although these five abundant tropical tern species, that bred sympatrically, showed some segregation in their diets and, more clearly, in their foraging ranges, considerable overlap of both aspects remained.

We are pleased to announce that from January 2003 the Journal of Zoology will have an Editorial Office based in Virginia, U.S.A. Authors from North America should submit their papers to Professor John L. Gittleman, Department of Biology, Gilmer Hall, University of Virginia, Charlottesville, VA 22904-4328, U.S.A. Email: JLGittleman@virginia.edu

The stature of forest elephants Loxodonta africana cyclotis was determined at the Petit Loango Reserve over 14 months from January to December 1998 and May to June 1999 using three measures: shoulder height, hind footprint length and boli diameter. The shoulder height of 53 identified elephants was measured using photogrammetric methods. The minimum estimated shoulder height was 69 cm from a young calf, and the tallest animal was 216 cm. Hind footprint length and boli diameter data were collected from unidentified individuals. The minimum footprint size was 12.5 cm and the largest 35.3 cm. Boli diameter ranged from 4.0 to 16.0 cm. A comparison of the size categories with those of savanna elephants in Amboseli National Park, Kenya, suggested a similar distribution of size, age and population structure, despite a marked difference in overall stature. These are the first data for measures of African forest elephant size compared to African savanna elephant size. Such data may add morphological evidence supporting recent genetic work suggesting that African forest elephants be re-classified as a distinct species from the African savanna elephant.

Results from a large-scale, capture—recapture study of humpback whales Megaptera novaeangliae in the North Atlantic show that migration timing is influenced by feeding ground origin. No significant differences were observed in the number of individuals from any feeding area that were re-sighted in the common breeding area in the West Indies. However, there was a relationship between the proportion (logit transformed) of West Indies sightings and longitude (r2=0.97, F1,3=98.27, P=0.0022) suggesting that individuals feeding farther to the east are less likely to winter in the West Indies. A relationship was also detected between sighting date in the West Indies and feeding area. Mean sighting dates in the West Indies for individuals identified in the Gulf of Maine and eastern Canada were significantly earlier than those for animals identified in Greenland, Iceland and Norway (9.97 days, t179=3.53, P=0.00054). There was also evidence for sexual segregation in migration; males were seen earlier on the breeding ground than were females (6.63 days, t105=1.98, P=0.050). This pattern was consistently observed for animals from all feeding areas; a combined model showed a significant effect for both sex (F1=5.942, P=0.017) and feeding area (F3=4.756, P=0.0038). The temporal difference in occupancy of the West Indies between individuals from different feeding areas, coupled with sexual differences in migratory patterns, presents the possibility that there are reduced mating opportunities between individuals from different high latitude areas.

In most co-operative breeding species, some individuals contribute much more to helping behaviour than others. The most well-established explanation of such variation is based on kin selection and suggests that, in the absence of detectable differences in relatedness, individuals who suffer lower costs for a given level of help should contribute more. Differences in helping effort between dominance/sex categories were investigated in co-operatively breeding banded mongooses Mungos mungo in Uganda. The most conspicuous form of help in this species is provided by individuals who babysit offspring at the den while the rest of the pack goes off to forage. Across eight groups, the survival rate of pups increased with the average number of babysitters guarding them, consistent with the hypothesis that helpers benefit the brood that they guard. There was no difference between dominant males, subordinate males and breeding females in total contributions to babysitting. Subordinate males, however, contributed more to babysitting in the mornings, which were the longest and presumably the most energetically expensive sessions of the day. In six litters in one well-studied pack, dominant males and breeding females reduced their contribution to babysitting for the period that females were in oestrus. By contrast, subordinate males increased their contribution to become the main babysitters during this time. These results are consistent with the hypothesis that, where helping conflicts with breeding, individuals with little chance of direct reproduction can help at a lower fitness cost than those with a high probability of successful reproduction.

The largest remaining black-tailed prairie dog Cynomys ludovicianus towns in North America are in Mexico, where they coexist with the kit fox Vulpes macrotis, providing a unique opportunity to study the relationship between these threatened species. We hypothesized that the presence of prairie dogs would positively affect the kit fox population in our study area in north-western Mexico, and that these influences would be manifest in home-range size, density and habitat selection. We estimated fox densities fluctuating from 0.32/km2 to 0.8/km2, and radio-telemetry revealed minimum convex polygon home ranges averaging 11 km2. These values are within the bounds of estimates from study sites elsewhere. Foxes used mesquite scrub less than expected, but grassland more than expected in relation to availability. Other habitats, including prairie dog towns, were used at random. Most (65.1% of 43) fox dens were in grassland, and were enlarged kangaroo rat Dipodomys spp. (34.9%) or prairie dog (34.9%) burrows. That kit foxes seemed to select grasslands rather than prairie dog towns was unexpected, particularly as prairie dogs are known to be a major component of kit fox diet. Foxes may reduce the amount of time they spend in prairie dog towns to avoid coyotes, which can be responsible for significant swift fox mortality. In our study area, coyotes were more active in prairie dog towns than in the grassland, where they were regularly shot. However, grassland used by kit foxes is a short-lived product of prairie dog poisoning, which is quickly invaded by scrub, a habitat favoured by coyotes. We conclude that kit fox conservation initiatives in north-western Mexico should be closely linked to conservation of the prairie dog ecosystem.

Zootoca vivipara is a small lizard that shows sexual dimorphism in head size. Males have larger heads than females of the same body size. By observing matings and aggressive interactions between males in the laboratory, we investigated whether this sexual dimorphism could be the result of intra- and/or intersexual selection. Winners of male–male interactions had larger heads than losers. During mating attempts, males with larger heads succeeded in grasping a female faster than males with smaller heads. It follows that head size in Z. vivipara may affect male reproductive success both through intrasexual competition (fighting ability) and through intersexual selection (grasping ability). This suggests that sexual selection may be the cause for the sexual dimorphism in head size in this species.

Some organisms rely on stored energy to fuel reproductive expenditure (capital breeders) whereas others use energy gained during the reproductive bout itself (income breeders). Most species occupy intermediate positions on this continuum, but few experimental data are available on the timescale over which food intake can affect fecundity. Mark–recapture studies of free-ranging female aspic vipers Vipera aspis have suggested that reproductive output relies not only on the energy in fat bodies accumulated in previous years, but also on food intake immediately before ovulation. A simple experiment was conducted to test this hypothesis, maintaining female snakes in captivity throughout the vitellogenic period and controlling their food intake. The energy input of a female strongly influenced the amount of mass that she gained and the number of ova that she ovulated. Multiple regression showed that litter size in these snakes was affected both by maternal body condition in early spring (an indicator of foraging success over previous years) and by food intake in the spring before ovulation. Our experimental data thus reinforce the results of descriptive studies on free-ranging snakes, and emphasize the flexibility of energy allocation patterns among vipers. Reproducing female vipers may combine energy from ‘capital’ and ‘income’ to maximize their litter sizes in the face of fluctuating levels of prey abundance.

The relationship between the population dynamics of ricefield rats Rattus argentiventer and their food supply, rice plants, was investigated in an enclosure in Jatisari, West Java. The density of the rat population fluctuated greatly throughout the year depending on the growth stages of the rice plants. A model illustrating the responses of the rat population to the growth stages of the rice plants is described. The population increased following periods when high-quality rice plants were available, and decreased following periods when only low-quality rice plants were available. The highest rate of increase (r) over a 2-week period was observed during the dry season of 1989 (r=1.77). The lowest rate of increase over 2 weeks was observed during the rainy season of 1989–90 (r=−0.59). The maximum rate of increase for the ricefield rat in the numerical response function was 1.183 month−1, and the best estimate for the numerical response function was robs=−3.890+5.043(1−e−0.026V).

A new species of spitting cobra Naja nubiae sp. nov. is described from north-eastern Africa. The distinctiveness of the new species is confirmed by multivariate analysis of pattern and scalation data. Phylogenetic analysis of mitochondrial DNA sequences reveals the new species to be the sister taxon of N. pallida, but with considerable levels of sequence divergence relative to that species. The populations concerned had previously been assigned to N. pallida. The new species differs from N. pallida principally in having more than one dark band across the neck and under the throat, as well as a pair of spots under the throat. It occupies a disjunct range across Egypt, the Sudan, Chad, Niger and Eritrea, where it seems to occupy primarily relatively mesic habitats. Naja mossambica is more closely related to N. nigricollis than to N. pallida and the new species. A key to the African species of Naja is presented.

Frogs (Amphibia: Anura) have contributed greatly to our understanding of the functions and evolution of sexual behaviour patterns, but few studies have been conducted on ‘primitive’ taxa. Here we describe laboratory observations that characterize aspects of the courtship and mating of the tailed frog Ascaphus truei, one of the most basal of living frogs. Fertilization is internal (a rare and probably apomorphic state for anurans) and sperm transfer is via an erectile intrommitent organ, or ‘tail.’ This structure seems to be an autapomorphy. Inguinal amplexus accomplishes mating (probably a plesiomorphic state), but the combination of amplexus and copulation, previously termed copulexus, is unique (autapomorphic). Mate location is not mediated acoustically (sexual vocalizations probably are apomorphic), but may involve visual or chemical cues. In a competitive context, heavier males do not seem to enjoy an advantage in being the first to initiate mating, and rivals rarely displace males already engaged in copulexus by wrestling. The courtship and mating of the tailed frog consists of a mosaic of traits that are ancestral, derived and unique within the clade Anura. Efficient location and then (with internal fertilization) stimulation of females during copulexus may influence male reproductive success more than wrestling.

Life-history patterns in lions Panthera leo living in savanna woodlands of the Kruger National Park, South Africa, were investigated and compared with those of the Tanzanian ‘plains-like’ ecosystems (e.g. Serengeti Plains and Ngorongoro Crater). First, lower levels of mortality in the juvenile age classes were found in Kruger lions, which in turn, extend the inter-birth period. A further difference was a prolonged period of association of sub-adult males with their natal pride, either directly or in a land tenure system that has not been described previously. Most (80%) of young male coalitions rather than becoming nomadic, remained close to their natal territory after leaving the pride, either as non-territorial sub-adults or adults and even as territorial adults. Only 20% of coalitions did not stay close to their natal range, one of which acquired a territory 20 km away from its natal pride. The pattern of territory acquisition, in fact, was one in which the majority of holders acquired territories close to their natal ranges. These behaviour patterns contrast markedly with those from ‘plains-like’ ecosystems where dispersing males usually move far away from their natal pride's range (>200) km and often remain nomadic for extended periods of time. Dense bush and access to sufficient prey resources in the form of resident buffalo Syncerus caffer herds may be important factors allowing extended residence near the natal pride's territory. Buffalo were more available in our study area habitat than in neighbouring habitats, and comprised the majority of male lion kills. Extended male residence contrasts markedly with current theory on dispersal in polygynous mammals, which holds that only one sex (females for lions) gain an advantage by staying close to the territory of their natal pride. In Kruger it seems that both sexes gain an advantage by not dispersing far, and use currently undocumented mechanisms to avoid inbreeding.

The renal sacs of a diversity of cephalopod molluscs were examined to study the morphology of dicyemid mesozoans. Most of the dicyemid species studied were found to be host specific. Typically, two or more species of dicyemids were present in each host species or each host individual. When dicyemid species co-occurred, their calotte shapes were distinctly different. The following variations in calotte shapes were usually detected within a given host individual: (1) when two species of dicyemids were present, two distinct calotte shapes, conical and discoidal, were observed; (2) when three species of dicyemids were present, three types of calotte configurations were observed, conical (two grades) and discoidal; (3) when more than four species of dicyemids were present, at least one species was characterized by its rare irregularly shaped calotte. As a rule, when more than two dicyemid species were present in a single host individual, calotte shapes were dissimilar. Calotte shapes in dicyemid species from different host species more closely resemble each other than those of dicyemids observed within the same host species. Dicyemids with conical or dome-shaped calottes are found within the convolutions or folds of the renal appendages, whereas those with flat, discoidal calottes attach to the surface of the renal appendages. In the dicyemids, calotte morphology seems to result from adaptation to the structure of host renal tissues and helps to facilitate niche separation of coexisting species.

The external orofacial morphology, perioral bristle distribution and feeding behaviour of Dugong dugon, Trichechus inunguis, T. senegalensis and T. manatus are described. Despite their differing orofacial morphology, dugongs and trichechids possess six similar regions: the oral disk, orofacial ridge, supradisk, chin and upper and lower bristle (modified vibrissae) pads. All living sirenians possess six discrete fields of bristles: four on the upper lip (U1, U2, U3, and U4) and two on the lower lip (L1 and L2). The distribution of these fields is similar among all living sirenians with the exception of the U1 bristle fields in dugongs. Perioral bristle field boundaries are distinguished by distinct changes in their length-to-diameter ratios. Both dugongs and trichechids possess bristle-like hairs covering the oral disk, which possess length-to-diameter ratios intermediate between perioral bristles and postcranial hairs. Sirenians use elaborated facial musculature in conjunction with perioral bristles to acquire, manipulate and ingest aquatic vegetation. The U2 and L1 fields are the primary bristles used to ingest vegetation. The use of the L1 bristle fields is similar among all living sirenians. However, dugongs and trichechids are divergent in their use of the U1 and U2 bristle fields. Dugongs use the U2 bristles fields in a medial-to-lateral motion, while all trichechids use the U2 bristles in a prehensile, lateral-to-medial, grasping motion. These divergent behaviours presumably allow dugongs to exploit benthic foraging (i.e. consumption of rhizomes) to a greater degree than trichechids. Functional hypotheses of rhizome excavation are presented for both dugongs and trichechids.

Niche separation (along habitat use, activity and dietary axes) between two sympatric jackal species, Canis adustus and Canis mesomelas, was investigated in north-west Zimbabwe. Diet of the two jackal species was flexible and opportunistic and dietary overlap between the jackal species was high. However, C. mesomelas ate more springhares Pedetes capensis, and C. adustus ate more safari camp refuse. To a large extent, differences in diet reflect availability within home ranges. Although interspecific home ranges overlapped by up to an average of 26%, the two species did not intensively use the same areas, and favoured different habitats. Canis mesomelas defended territories in the grassland habitat, which was also the favoured habitat of springhares, the predominant vertebrate prey species in the area. Canis adustus centred their home ranges on centres of human activity, benefiting from the regular, but low quality, anthropogenic food resources. In this study, C. adustus, with the more generalist dentition, had a broader niche than C. mesomelas (dietary diversity C. adustus=4.14; C. mesomelas=3.45). Within sympatric areas, differing activity times may further operate to decrease competition, allowing these canids to co-exist. The activity times of the two species differed, with C. adustus being almost entirely nocturnal. Canis mesomelas, while mostly nocturnal, was also active during the morning and in the late afternoon. The jackals in this study did not have clear-cut niches and it is probable that the extreme flexibility of canids in both diet and behaviour allows these species to co-exist sympatrically over part of their range.

The distribution of fossorial water voles Arvicola terrestris on 15 small islands in the Sound of Jura, Argyll, Scotland, was established and populations were characterized in terms of size, structure and genetic composition (12 microsatellites). The results are compared with similar data from four metapopulations of riparian water voles in mainland Scotland. Water voles occurred on six islands, one of which was occupied in 1994, but not on two islands occupied during the 1960s. Probability of occupancy was significantly associated with proximity to the nearest occupied island. Unlike voles on the mainland, which occupy fragmented patches of exclusively riparian habitat, voles on islands were fossorial and occupied large areas of continuous habitat. Spring population sizes were c. 10 times higher on the islands than colonies of mainland metapopulations. Individuals from three islands were genotyped and these populations had 50% lower levels of microsatellite polymorphism than the mainland metapopulations. Rates of inferred contemporary dispersal among islands separated by 1 km or more of sea were very low, according to large differences among islands in genetic composition, proportions of coat colour types and incidence of skin infection. None the less, the long-term persistence of the island populations is likely to depend on such dispersal. Comparisons between island populations and mainland metapopulations indicate that in both fragmented systems the level of dispersal is the primary factor influencing genetic structure. The low genetic variability in the island populations may reflect either past historical events (founder effect and genetic drift) or present ecology (lack of immigration in closed and temporally fluctuating populations).

The red patch located on the propodus of Cherax quadricarinatus males is a sexually dimorphic structure. This patch presents an enigma because it is soft and uncalcified, consisting of a thin red to whitish-orange membrane. It presents an impairment of the fighting capability of the males, which, like many other clawed crustaceans, use these appendages in intra- and interspecific aggressive interactions. Present knowledge on patch structure and colour, development and their endocrine control by the androgenic gland is reviewed. The function of the red patch as a possible sensory organ or social signal is discussed. The red patch may transmit information concerning the gender, size and quality of its owner. Several hypotheses concerning the signal function of the patch are suggested and evaluated in the light of our present knowledge of the social behaviour of C. quadicarinatus.

Amphibious animals may be subject to strong but conflicting selective pressures to enhance locomotor performance both on land and in the water. Biomechanical models suggest that in snakes, adaptations to swimming (e.g. reduction of ventral plates, flattening of tail) will reduce their ability to move on land. The locomotor speeds of six taxa of amphibious (laticaudid) sea-snakes, plus one entirely marine (hydrophiid) species were measured. Because the relative dependence on aquatic vs terrestrial habitats varies with a laticaudid's species, sex and body size, a previous study predicted that these factors should generate significant variation in locomotor speeds within laticaudids. Measurements of swimming and crawling speeds supported this prediction. Some species were faster than others and, within each species, males were faster than conspecific females. The degree of locomotor superiority of males was greater for terrestrial (>40%) than for aquatic (20%) locomotion. Smaller snakes were faster than larger animals in relative speed (body lengths/s) but slower in absolute terms (m/s). The hydrophiid Emydocephalus annulatus was slow in water as well as on land, perhaps because it eats immobile prey and thus, does not depend on speed for foraging. The diversity of locomotor abilities within laticaudid sea-snakes provides a remarkable opportunity to identify factors that influence evolutionary trade-offs between conflicting evolutionary optima.