Individual Home Range Size Research Articles

Differential Movement Patterns of Juvenile Tengmalms Owls (Aegolius funereus) during the Post-Fledging Dependence Period in Two Years with Contrasting Prey Abundance

Fledgling behaviour and movement patterns throughout the post-fledging dependence period (PFDP), especially in relation to changing environmental conditions, have been rarely studied, despite the fact that this period is recognized as of crucial significance in terms of high mortality of juveniles. The PFDP can extend over quite a protracted period, particularly in birds of prey, and a knowledge of the movement patterns of individuals is fundamental for understanding mechanisms underlying survival, habitat use and dispersion. We radiotracked 39 fledglings of the Tengmalm’s owl (Aegolius funereus) in two years with different availability of prey: 2010 (n = 29) and 2011 (n = 10) and obtained 1455 daily locations. Fledglings reached independence on average in 45 days after fledging in 2010 (n = 22) and 57 days in 2011 (n = 6). Within years, the most important measures influencing the distance moved from the nest box were age of fledglings and number of surviving siblings present. Individual home range size and duration of PFDP in particular were dependent on maximal number of siblings seen outside the nest box. In the season with low prey availability fledglings were observed at greater distances from the nest box than in the year with higher prey availability (mean distance: 350 m in 2010 and 650 m in 2011) and occupied larger home ranges (mean: 30.3 ha in 2010 and 57.7 ha in 2011). The main factor causing these differences between years was probably the different availability of prey in these two years, affecting breeding success and post-fledging survivorship of the Tengmalm’s owls.

Habitat partitioning and fine scale population structure among insular bottlenose dolphins (Tursiops aduncus) in a tropical lagoon

Among marine organisms, little is known on patterns of intra-species habitat partitioning, whereas many studies have examined niche segregation at the multi-species community level. In this study, we investigated the fine-scale population structure and patterns of within-species habitat use of Indo-Pacific bottlenose dolphins (Tursiops aduncus) in a tropical lagoon of the Indian Ocean (Mayotte, 45°10′E/12°50′S). First, we assessed genetic population structure using mtDNA and 14 microsatellite markers to determine if bottlenose dolphins around Mayotte belong to one or several panmictic groups. The analyses revealed no mitochondrial polymorphism and the presence of a single population at Hardy–Weinberg equilibrium. Second, we assessed whether a community structure exists within the bottlenose population. A community is an assemblage of individuals using a common home range. Photo-identification data were used to assess individual home range size and habitat preferences. Home range analysis revealed the presence of at least two communities of bottlenose dolphins around Mayotte: one occurring in the shallower waters inside the lagoon and a second in the vicinity of a deeper reef bank, situated further offshore in the northern part of the island. Stable isotope analyses of δ13C and δ15N were performed to detect intra-species segregation of habitat and resource use. However, no significant structure across the population was detected. Nevertheless, this study highlights that, even at small spatial scales, individual and between community variations of habitat preferences occur in bottlenose dolphin populations. Intra-species niche partitioning may explain habitat segregation in these insular delphinids.

Toward an Identification of Resources Influencing Habitat Use in a Multi-Specific Context

Interactions between animal behaviour and the environment are both shaping observed habitat use. Despite the importance of inter-specific interactions on the habitat use performed by individuals, most previous analyses have focused on case studies of single species. By focusing on two sympatric populations of large herbivores with contrasting body size, we went one step beyond by studying variation in home range size and identifying the factors involved in such variation, to define how habitat features such as resource heterogeneity, resource quality, and openness created by hurricane or forest managers, and constraints may influence habitat use at the individual level. We found a large variability among individual's home range size in both species, particularly in summer. Season appeared as the most important factor accounting for observed variation in home range size. Regarding habitat features, we found that (i) the proportion of area damaged by the hurricane was the only habitat component that inversely influenced roe deer home range size, (ii) this habitat type also influenced both diurnal and nocturnal red deer home range sizes, (iii) home range size of red deer during the day was inversely influenced by the biomass of their preferred plants, as were both diurnal and nocturnal core areas of the red deer home range, and (iv) we do not find any effect of resource heterogeneity on home range size in any case. Our results suggest that a particular habitat type (i.e. areas damaged by hurricane) can be used by individuals of sympatric species because it brings both protected and dietary resources. Thus, it is necessary to maintain the openness of these areas and to keep animal density quite low as observed in these hunted populations to limit competition between these sympatric populations of herbivores.

Passive acoustic telemetry reveals highly variable home range and movement patterns among unicornfish within a marine reserve

Marine reserves are the primary management tool for Guam’s reef fish fishery. While a build-up of fish biomass has occurred inside reserve boundaries, it is unknown whether reserve size matches the scale of movement of target species. Using passive acoustic telemetry, we quantified movement patterns and home range size of two heavily exploited unicornfish Naso unicornis and Naso lituratus. Fifteen fish (N. unicornis: n = 7; N. lituratus: n = 4 male, n = 4 female) were fitted with internal acoustic tags and tracked continuously over four months within a remote acoustic receiver array located in a decade-old marine reserve. This approach provided robust estimates of unicornfish movement patterns and home range size. The mean home range of 3.2 ha for N. unicornis was almost ten times larger than that previously recorded from a three-week tracking study of the species in Hawaii. While N. lituratus were smaller in body size, their mean home range (6.8 ha) was over twice that of N. unicornis. Both species displayed strong site fidelity, particularly during nocturnal and crepuscular periods. Although there was some overlap, individual movement patterns and home range size were highly variable within species and between sexes. N. unicornis home range increased with body size, and only the three largest fish home ranges extended into the deeper outer reef slope beyond the shallow reef flat. Both Naso species favoured habitat dominated by corals. Some individuals made predictable daily crepuscular migrations between different locations or habitat types. There was no evidence of significant spillover from the marine reserve into adjacent fished areas. Strong site fidelity coupled with negligible spillover suggests that small-scale reserves, with natural habitat boundaries to emigration, are effective in protecting localized unicornfish populations.

Home range behaviour in male and female poison frogs in Amazonian Peru (Dendrobatidae: Ranitomeya reticulata)

The poison frog Ranitomeya reticulata was studied for 3 months while mark–recapture surveys were performed. Ranitomeya species deposit terrestrial clutches and carry tadpoles to phytotelmata with few taxa performing biparental brood care including larval feeding. Home range size and spatial affinity to phytotelmata in the genus are linked to mating systems. In R. reticulata, individual home range size and overlap were similar in both sexes, indicating equal levels of site fidelity. Although territory defence was never observed, strong intrasexual intolerance within individuals' core areas was found. The large intersexual home range overlap for breeding pairs indicated that mate fidelity occurs. Individuals' home ranges were not overlapping, suggesting that R. reticulata lacks pair-bonding or strongly cooperative behaviour in parental duties. The number of ground bromeliads containing phytotelmata and home range size of males were positively correlated. Our findings suggest that females do not perform egg-feeding and male-only parental care is likely.

Multiscale Influences of Landscape Composition and Configuration on the Spatial Ecology of Eastern Diamond-backed Rattlesnakes (Crotalus adamanteus)

Landscape composition and configuration affect ecological processes at the population and community levels, but few studies have demonstrated the effects of landscape pattern on individuals. Because heterogeneity influences abundance and distribution of critical resources, it is hypothesized that it indirectly affects home range size of individuals. To examine the spatial ecology of the declining Eastern Diamond-backed Rattlesnake (Crotalus adamanteus; EDB), we conducted a two-year study in southwestern Georgia. We obtained home range estimates via radio-telemetry, employed Euclidean distance analysis to examine habitat associations at two spatial scales, and used the software program FRAGSTATS to analyze landscape heterogeneity and examine its effect on home range size. Although no significant habitat associations were detected, there were trends for a positive association with pine habitat at the landscape scale and a negative association with agriculture within the home range. Home range size was negatively correlated with several landscape metrics representing heterogeneity in patch configuration, such that individuals in heterogeneous landscapes had small home ranges. This relationship was strongest at three spatial scales: the first was similar to mean home range size of EDBs; and the others were three and four times as large as the largest home range recorded. Together, these results suggest that management regimes to enhance population densities of EDBs emphasize the preservation of pine uplands, while maintaining a mosaic of other habitat types, and limit the conversion of forest to agriculture. Also, our results underscore the importance of using robust analytical tools and multiscale approaches in studies of spatial ecology.

Spatial segregation of two vole species (Arvicola sapidus and Microtus cabrerae) within habitat patches in a highly fragmented farmland landscape

Spatial segregation is one of the common mechanisms allowing the co-existence of similar interacting species in heterogeneous environments. Analysing spatial segregation requires information on individual home-range sizes and their degree of spatial overlap. In this study, we used radio-tracking to report for the first time the home-range and core-area sizes of sympatric Cabrera and water voles and to analyse intra- and inter-specific space sharing within habitat patches in a highly fragmented landscape. Results indicated that both species exhibited strong fine-scale site fidelity and reduced variation in range size across sexes and seasons. Monogamous mating system seemed to prevail for both species, although water voles may also exhibit polygynous breeding strategies. Mean home-range and core-area sizes of water voles (946.3 and 156.6 m2) were about twice that of Cabrera voles (418.2 and 55.1 m2). Within habitat patches, individuals of both species often overlapped their home ranges, particularly during the dry season (May–September), though intra-specific home-range overlap was generally higher than inter-specific overlap. Inter-specific space sharing was restricted to areas outside the centre of activity of animals, as no core-area overlap was ever recorded between Cabrera and water voles. Taken together, results support the view that co-existence of Cabrera and water voles in Mediterranean patchy habitats may in part result from spatial segregation among individuals, which may reflect competitive displacement or small-scale habitat partitioning. Results highlight the need to account for species interactions when designing conservation management strategies for sympatric Cabrera and water voles in fragmented landscapes.

Roe deer Capreolus capreolus home-range sizes estimated from VHF and GPS data

In this study, we compared kernel estimates of home-range size between VHF and GPS monitoring. We used three types of data to assess the monthly estimates of individual home-range size (VHF data based on 17 locations, subsampled GPS data based on 17 locations (with 1,000 replicates) and GPS data based on 720 locations) using three estimation methods for the smoothing parameter, h (reference, leastsquares cross-validation (LSCV) and fix). For all the three smoothing parameters, individual home ranges estimated from VHF and GPS data using 17 locations had very similar size. On the other hand, the use of reference or LSCV h values led home-range sizes from VHF or GPS data using 17 locations to be larger than the estimate obtained from the whole set of GPS data (720 locations). Such results emphasise the influence of using too few locations per month. On the contrary, using h fixed at 60 led to a home-range size close to that obtained from the whole set of GPS locations. The centroid of locations for a given individual in a given month only changed a little according to the data set used (the difference being < 100m), suggesting a high accuracy for our locations. VHF and GPS areas can therefore be pooled within the same analysis of habitat use, provided that the smoothing parameter and the number of locations are standardised.

Modeling the flocking propensity of passerine birds in two Neotropical habitats

We examined the importance of mixed-species flock abundance, individual bird home range size, foraging height, and foraging patch characteristics in predicting the propensity for five Neotropical passerine bird species (Slaty Antwren, Myrmotherula schisticolor; Golden-crowned Warbler, Basileuterus culicivorus; Slate-throated Redstart, Myioborus miniatus; Wilson's Warbler, Wilsonia pusilla; and Black-and-white Warbler, Mniotilta varia) to forage within flocks, rather than solitarily. We used study plots in primary mid-elevation forest and in shade coffee fields in western Panama. We expected that all species would spend as much time as possible flocking, but that the social and environmental factors listed above would limit compatibility between flock movements and individual bird movements, explaining variability in flocking propensity both within and among species. Flocking propensity was well predicted by home range size and flock abundance together, for four of the five species. While flock abundance was uniform across plots, home range sizes varied among species and plots, so that home range size appeared to be the principle factor limiting flocking propensity. Estimates of flock abundance were still required, however, for calculating flocking propensity values. Foraging height and patch characteristics slightly improved predictive ability for the remaining species, M. miniatus. In general, individual birds tended to join flocks whenever one was available inside their home range, regardless of a flock's specific location within the home range. Flocking propensities of individual species were lower in shade coffee fields than in forests, and probably vary across landscapes with variations in habitat. This variability affects the stability and species composition of flocks, and may affect survival rates of individual species.

Vulture restaurants and their role in reducing diclofenac exposure in Asian vultures

The provision of supplementary food at vulture restaurants is a well-established tool in the conservation of vulture species. Among their many applications, vulture restaurants are used to provide a safe food source in areas where carcasses are commonly baited with poisons. Rapid and extensive declines of vultures in the Indian subcontinent have been attributed to the toxic effects of diclofenac, a pharmaceutical used in the treatment of livestock, to which vultures are exposed while feeding on the carcasses of treated animals. A vulture restaurant was established at the Oriental White-backed Vulture Gyps bengalensis colony at Toawala, in Punjab province Pakistan, to test the effectiveness of the technique in modifying ranging behaviour and mortality at the colony. Six male vultures were fitted with satellite transmitters to describe variation in movement and home-range during periods when safe food was alternately available and withheld at the vulture restaurant. There was considerable variation in individual home-range size (minimum convex polygons, MCP, of 1,824 km2 to 68,930 km2), with birds occupying smaller home-ranges centred closer to the restaurant being more successful in locating the reliable source of food. Fixes showed that 3 of the tagged vultures fed at the vulture restaurant and the home-range of each bird declined following their initial visit, with a 23–59% reduction in MCP. Mean daily mortality during provisioning was 0.072 birds per day (8 birds in 111 days), compared with 0.387 birds per day (41 birds in 106 days) during non-provisioning control periods. Vultures tended to occupy greater home-ranges, cover greater distances each day and spend proportionately more time in the air during the late brooding and post-breeding seasons. Attendance at the vulture restaurant also declined during this period with fewer birds visiting less often and no tagged vultures visiting the vulture restaurant at all. These findings indicate that vulture restaurants can reduce, but not eliminate, vulture mortality through diclofenac exposure and represent a valuable interim measure in slowing vulture population decline locally until diclofenac can be withdrawn from veterinary use.

Cover, food, competitorsandindividual densities within bushbuckTragelaphus scriptus female clan home ranges

We examined factors predicting female densities within the common home ranges of related females (“clans”) in bushbuckTragelaphus scriptus Pallas, 1776. In this species, each female forms an individual home range, but the home ranges of matrilineal clan members strongly overlap. We found female densities to increase in areas with high canopy cover. Moreover, individual home range sizes tended to decrease with increasing cover. Food plant availability and intruder pressure by two heterospecific competitors did not significantly affect female densities. Apparently, canopy cover is the major limited resource in this species. A possible explanation is that both adult bushbuck and — even more markedly — fawns hide from predators in dense vegetation, in particular in thicket clumps and coalescences. The study shows an effect of habitat properties (eg sufficient canopy cover) on a within-population level in bushbuck, where female densities differ even among proximate clan areas.

농촌 지역의 너구리 Nyctereutes procyonoides 행동권

본 연구의 목적은 농촌지역의 너구리 행동권과 핵심지역의 면적을 분석하는 것으로서, 이를 위해 22개체를 포획하여 원격 무선추적을 실시하였다. 이 중 3개월 이상 무선 추적이 실시된 9개체의 행동권을 분석한 결과 평균 <TEX>$0.80km^2$</TEX> (100% MCP)를 나타내었다. 성별 행동권은 수컷이 평균 <TEX>$0.98km^2$</TEX> (100% MCP)를 나타내었고, 암컷은 평균 <TEX>$0.58km^2$</TEX> (100% MCP)를 나타내어 수컷의 행동권이 넓었다. 그러나 95% MCP (Minimum Convex Polygon)를 적용했을 경우 수컷이 평균 <TEX>$0.63km^2$</TEX>, 암컷이 <TEX>$0.42km^2$</TEX>로서 차이가 많이 줄었다. 또한 암수 쌍이 함께 무선 추적된 두 쌍의 행동권은 95% MCP를 적용했을 경우 암수가 각각 <TEX>$0.26km^2$</TEX>와 <TEX>$0.28km^2$</TEX>로서 차이가 매우 적거나, <TEX>$0.36km^2$</TEX>와 <TEX>$0.36km^2$</TEX>로 통일했으며, 4 계절 모두 짝을 지어 함께 지냈다. 따라서 짝이 없거나 영역이 정해지지 않은 등의 경우를 제외하고 정상적으로 암수가 한 쌍이 되어 지내는 일상의 경우에는 암수의 행동권이 같다고 판단되어진다. 원격 무선 추적된 너구리 중 4 개체는 암수 쌍을 이루고 있었으며, 이들 두 쌍 모두 일부 일처제를 이루고 함께 이동하며 생활하였다. The objectives of this paper are to estimate home range and core habitat area of raccoon dog living in the rural area of Korea. A radio-telemetry study was carried out on 22 raccoon dog individuals. Among these individuals, 4 raccoon dogs made 2 pairs and they were monogamous and moved together all the year round. Mean home-range size of 9 individuals which were radio-tracked more than 3 months was <TEX>$0.80km^2$</TEX> (100% MCP). The mean home range size of male individuals was <TEX>$0.98km^2$</TEX> (N=5, 100% MCP) and that of female individuals was <TEX>$0.58km^2$</TEX> (N=4, 100% MCP). On the other hand, in case 95% MCP(Mininlum Convex Polygon) was applied, the gap of home-range size between sex distinction was closed to <TEX>$0.63km^2$</TEX> (male) and <TEX>$0.42km^2$</TEX> (female). The home range size of two pairs of which the male and the female were radio-tracked at the same time showed little difference. In case of one pair, the home range size(95% MCP) was <TEX>$0.28km^2$</TEX> (male) and <TEX>$0.26km^2$</TEX> (female) and in case of the other pair, it was <TEX>$0.36km^2$</TEX> each (male and female). Consequently there seems no significant difference in the home-range size between a male and a female racoon dog except the unusual cases such as unpaired individuals or the ones with no fixed territory.

Does seasonality explain the evolution and maintenance of delayed implantation in the family Mustelidae (Mammalia: Carnivora)?

Understanding the evolutionary pressures that may have led to the development and retention of delayed implantation in mammals remains an enigmatic puzzle for evolutionary ecologists. Recent studies suggest a strong role of environmental conditions but other attributes of species, notably body size and life history traits, may obscure primary mechanisms. Following the recommendation of Lindenfors et al., we examined environmental correlates related to the evolution of delayed implantation and its subsequent maintenance or loss in the family Mustelidae (Mammalia: Carnivora). We focused on the Mustelidae because evolution and subsequent loss of delayed implantation occurred most commonly within this group. Data on 34 species of mustelids from around the world suggest that delayed implantation may have evolved when optimal times for mating and birthing are separated by more than a gestation period, characteristic of environments with long winters that reduce the opportunities to find mates. Environmental characteristics (seasonality, temperature, snow, latitude, and primary productivity) were highly intercorrelated but seasonality was the best predictor of the evolution or loss of delayed implantation via population traits. Here, structural equations on phylogenetic independent contrasts revealed that high seasonality was correlated with low population density and large individual home range size, which in turn was correlated with presence/absence of delayed implantation. We argue that the evolution of delayed implantation provides the reproductive means to mate during the season (summer) with the greatest prospects for females to ‘choose’ mates when living in high‐latitude seasonal environments that generally reduce these opportunities (i.e. low population density and large ranges). Body mass of female mustelids did not differ between species with and without delayed implantation, refuting the hypothesis that loss of delayed implantation is an evolutionary by‐product of evolving to smaller size. We conclude that understanding the environmental selection pressures responsible for the evolution of life history traits related to density and spacing behaviour allows for a more complete picture of the evolution and subsequent loss of delayed implantation.

Bisexually bonded ranging in chimpanzees (Pan troglodytes verus)

While male mammals seek to maximize access to potential mates, females maximize feeding efficiency. Ranging patterns are therefore often sex specific. Sex-specific ranging patterns have also been reported for East African chimpanzees and a recent study on female ranging patterns concludes that social organization is best described by a male-bonded community model, where females occupy individual home ranges that are distributed within the boundaries of the male-defended range. In West African chimpanzees, however, such sex-specific ranging patterns have not been consistently observed and a bisexually bonded community model, where both sexes use the entire home range equally, has been suggested to best describe social organization. In this study we analyze 5 years of data on individual ranging patterns of chimpanzees in the Tai National Park (Cote d’Ivoire) to test specific predictions of the different models of chimpanzee social organization. We found that although males in Tai had slightly larger home ranges than females, all individual home ranges and core areas overlapped highly. Small individual home range size differences were entirely due to the use of peripheral areas and were correlated with female social dominance. These findings strongly support the bisexually bonded community model for Tai chimpanzees. Thus, we conclude that there are fundamental differences in the space-use patterns of East and West African chimpanzees and discuss possible factors leading to such differences.

Effect of sex and female reproductive status on seasonal home range size and stability in rural red foxes (Vulpes vulpes)

:Intra-population variations in home range size can be considerable among carnivores, especially in the red fox (Vulpes vulpes). In this species, variations are not necessarily sex or age dependent. Our aim was to test whether differences in home range size and stability could be related to red fox female reproductive status, considering that red fox populations exhibit variable proportions of barren vixens. We examined differences in size and stability of seasonal home ranges of 16 foxes (three males and 13 females) radio-tracked from June 2001 to June 2003, in the Ardennes, France. Mean individual home range sizes varied widely, from 31 to 311 ha, with an average of 109 ha. The smaller a home range was, the more stable it was. Home range size was not sex dependent, but female home ranges were more stable than male ones. Reproductive females, mostly 2 y old at least, had smaller home ranges (mean: 50 ha) than non-reproductive females (mean: 174 ha), all 1 y of age. However, there was no difference in female home range stability. We hypothesized that reproductive females monopolize the richest food patches at the expense of non-reproductive females, which are younger and assumed to be subordinate and/or less experienced. Therefore, home range size correlated to food richness may be an important factor for female reproductive success. Competition for food and space could thus explain female reproductive suppression.

Does availability of resources influence grazing strategies in female Svalbard reindeer?

Foraging strategies and range use in wild female Svalbard reindeer (Rangifer tarandus platyrhynchus) were studied in two areas where the historical grazing pressure differed. We mapped vegetation where the reindeer were seen grazing, and related forage availability to characteristics such as home range size, activity budgets and reproductive status. There were significant differences in quantity of forage available between the two areas and the utilization of vegetation types differed between the sites. However, we found no difference in home range size between the two sites, and individual home range sizes were not related to forage quantity, possibly a result of a skewed and small sample size. Even though significant differences in availability of plant species and groups were found, no variation in home range size was found between reproductive and non-reproductive females on Br&amp;oslash;ggerhalv&amp;oslash;ya. Neither did we find any differences between areas or between reproductive groups within or between areas in how female reindeer allocated use of time, or in number of steps taken. However, a significant three way interaction indicated that some variance existed between reproductive groups within or between areas, but we do not conclude that this indicate different grazing strategies. Thus, even though variation in the duration of previous grazing has evidently resulted in rather different foraging conditions in our two areas, we detected no differences in present-day foraging behaviour. Thus, our analyses suggest no relationship or feedback between past grazing and current foraging behaviour in these reindeer.

Home range size and use of space by Bermuda chub Kyphosus sectatrix (L.) in two marine reserves in the Soufrière Marine Management Area, St Lucia, West Indies

Marine reserves (MRs) are expected to conserve fish biodiversity and enhance fisheries production of surrounding areas through export of adult fish biomass. However, the extent to which these benefits occur is dependent on movement patterns of fish, for which there is a paucity of data, particularly for coral reef species. Eleven adult Kyphosus sectatrix were tracked [five in the Grand Caille marine reserve (MR) and six in the Petit Piton MR within the Soufrière Marine Management Area, St Lucia] from February to April 1999, using acoustic telemetry. Average number of days over which fish were tracked was 21.5 (range 5–51). Home range size of individuals, temporal use of space within the home range, and permeability of MR and habitat boundaries to fish movement were examined. Average minimum home range area of K. sectatrix was not significantly different between Grand Caille (30 514 m2) and Petit Piton (39 114 m2). However, the shape of home ranges was conspicuously different between the sites and reflected available reef shape. Individual home ranges overlapped strongly with those of other individuals at the same site, and use of space within the home range was generally restricted to a small number of preferred sites. Preferred sites were often shared among individuals and tended to be occupied at a specific time of day, with some sites were preferred in the morning and or afternoon, whilst others preferred during the middle of the day. Fidelity to a single sleeping‐shelter site was high at night. MR boundaries over contiguous reef at Grand Caille were frequently crossed with individuals spending, on average, 63% of their time (range 37–94) outside the MR. This demonstrates the need for the MR boundary at this site to be implemented farther offshore to encompass the reef, if the MR is to better protect K. sectatrix. At Petit Piton, where MR boundaries effectively encompass available reef, K. sectatrix spent, on average, only 11% of their time (range 0–40) outside the protected area. At Grand Caille boundaries were crossed more readily (individuals spent an average of 18% of their time off reef) than at Petit Piton where individuals spent an average of 0.7% of their time off reef.

Activity, movement, and home range of Virginia opossums (Didelphis virginiana) in Florida

The activity and spatial organization of the Virginia opossum (Didelphis virginiana), a solitary didelphid marsupial, were studied in north-central Florida. Opossums were strictly nocturnal, and the activity level peaked between 2000 h and 0200 h. Activity was influenced by temperature. Below 8°C, duration of nightly activity decreased strongly with decreasing temperature. Above 8°C, activity tended to decrease with increasing temperature. Average nightly activity did not differ among months from August to December or between males and females. Opossums lived in well defined and at least seasonally stable home ranges with moderate to extensive home range overlap. Females tended to more exclusive space use and greater stability of home ranges than mates. Males often shifted home ranges at the end of mating seasons. Three different measures of home range size were presented. Average values for males and females were 141.6 ha and 64.4 ha, respectively (corrected minimum convex polygon). Individual home range sizes of males were influenced by habitat being larger in presumably poorer habitats, and by body size. Average distances moved per hour were 234 m in males and 178 m in females. Nightly movements of males and females averaged 1835 m and 1465 m, respectively (maximums 4665 m and 3973 m). Distances traveled were associated with temperature, home range size or body size. Very limited data from other regions suggest greater space use by opossums in the studied population.

Productivity, Survival, and Movements of Female Moose in a Low-density Population, Northwest Territories, Canada

Moose ( Alces alces andersoni ) occur at low density (140-160 moose/1000 sq km) and are the most important game animal in much of the Mackenzie Valley, western Northwest Territories. Productivity and survival of 30 female moose (>=1.5 yr.) were studied from November 1985 through November 1988. Twenty-nine of these moose were radio-tracked for a total of 1039 relocations. Pregnancy rates were 96% for adult and 40% for yearling females. Most females returned to the same restricted area to calve each year. Mean newborn calf:female ratio and twinning rates were 1.2:1 and 31%, respectively. Mean annual female survival rate was 85%. Annual calf survival was high and stable (44±0.02%). Individual total home range size varied from 40 sq km to 942 sq km. Mean home range size for 29 moose was 174±31 sq km and 202±59 sq km for the 14 moose radio-tracked the entire three years of study. Fall home ranges were twice the size of winter and summer home ranges; seasonal ranges overlapped widely, indicating that these moose were non-migratory. Key words: moose, low density, productivity, movements, Mackenzie Valley, Northwest Territories

Ranging behaviour and activity of red foxes (Vulpes vulpes: Mammalia) in relation to environmental variables, in a Mediterranean mixed pinewood

The relationships between the main abiotic environmental variables, food availability, dict, activity and home range size of the fox in a Mediterranean mixed pinewood were assessed. Food habits were determined by faecal analysis on a weekly basis. Food availability was measured by weekly censuses. Radio‐tracking allowed the detection of fox movements and activity. Individual differences shown by a sample of four radio‐tagged foxes were analysed. Juniper berries (Juniperus oxycedrus) were the staple of the diet during the year, except in summer. Insects, mainly nocturnal Orthoptera and cicada larvae (Cicada orni), were the main prey in the warm season. Large vertebrates, mostly wild boars (Sus scrofa), were scavenged in winter. In the warm season foxes' activity depended largely on the pattern of activity of prey. Food habits tended to depend on food availability, which, in turn was mainly influenced by temperature. In spite of habitat similarity, individual differences in food habits were detected within the same season. Home ranges were larger in pinewood than in neighbouring heterogeneous habitats. Individual home range sizes were: (i) directly correlated to Orthoptera abundance and distribution; (ii) inversely correlated to the abundance of cicada larvae in diet. Resident males may exist in fox society, exploiting other males' territories when good clumped food resources are available.