Spatial organization of the arboreal carnivorous marsupial Phascogale tapoatafa

Phascogale tapoatafa is a squirrel-sized carnivorous marsupial (Dasyuridae) found in dry eucalyptus forests of Australia. Radio-tracking and live-trapping studies at three sites in Victoria indicated that population densities were typically low, with females occupying home ranges averaging 41 ha (minimum convex polygon method) that were intrasexually exclusive. Male home ranges (mean 106 ha) overlapped extensively with females and other males, and expanded during the short breeding season to an average length of 2.7 km. When presented with the faeces of unfamiliar conspecifics, both female and male P. tapoatafa investigated the faeces of females significantly longer than those of males, suggesting that the exclusive home ranges of females are reinforced by olfactory communication, and that males are less responsive to the presence of potential rivals than to potential mates. Both sexes foraged throughout their home range, but the core area of intensive use was less than one-third of the total area traversed. The spatial organization of P. tapoatafa differs markedly from that of the closely related species Antechinus stuartii , but is similar to that of the only other extensively studied carnivorous marsupial, Dasyurus geoffroii.     

Woodland fragmentation affects space use of Eurasian red squirrels

When habitats become fragmented, variation in patch size and quality are expected to impose changes on the spacing pattern and social organization of animal populations. General theory predicts different possible responses including shrinking home ranges (fission response), increasing range overlap (fusion) and incorporation of multiple patches in the home range (expansion response) as fragmentation increases. We studied space use and social organization in a metapopulation of red squirrels (Sciurus vulgaris) in 15 woodland fragments differing in size and tree species composition. Home ranges and core areas of males were larger than females, and fragmentation had different and complex effects on the spacing pattern of both sexes. In food-supplemented patches, high densities led to increased intra-sexual overlap. In linear-shaped patches, squirrels used smaller home ranges and core areas and had lower male–male and male–female overlap levels, independent of patch quality or size. Home range and core area size of males increased with patch size, and male core areas overlapped extensively those of other males and females. Hence males seemed to show a fission response only in some patches. In contrast, home range and core area size of females was not related with patch size, but decreased with habitat quality, supporting predictions of a fusion response and intra-sexual defense of food-based core areas. Hence, where patch size and shape strongly affected space use of male red squirrels, social organization of females was only affected in small, food-supplemented patches, suggesting that the basic spatio-social organization of adult females is very resistant to fragmentation.     

Spatial distributions of male and female strawberry poison frogs and their relation to female reproductive resources

In many species with a resource-based mating system, males defend resources to increase their attractiveness to females. In the strawberry poison frog, Dendrobates pumilio, suitable tadpole-rearing sites appear to be a limited resource for females. Territorial males have been suggested to defend tadpole-rearing sites to increase their access to females. In this study we investigate the spatial association between tadpole-rearing sites and the sexes as well as the spatial association of males and females. If strawberry poison frogs have resource defense polygyny, we expect males and females to be associated with tadpole-rearing sites and that females will deposit their offspring in tadpole-rearing sites inside the territories of their mates. To test this hypothesis, home range and core area sizes were calculated for both sexes and the association patterns were compared in two areas that differed in their abundance of tadpole-rearing sites. Home ranges and core areas of females were much larger than male home ranges. Females showed a clumped distribution in the vicinity of tadpole-rearing sites. Males were not clumped and were less associated with tadpole-rearing sites. Females generally did not use tadpole-rearing sites in the territory of their mates and we therefore conclude that males did not defend tadpole-rearing sites for females. Our data are consistent with the general assumption that female distribution is influenced by resource distribution and that male distribution depends on female distribution. Nevertheless, the distribution of D. pumilio females was also influenced by male spacing patterns. Males probably initially establish their core areas where female density is high and then females move among territories to sample males. Males compete vigorously for places with high female density, the defense of which is likely important for enhancing their mating success. In general, the spacing patterns did not differ between populations but the sex ratio was strongly female biased in the habitat with more tadpole-rearing sites, reflecting the direct reliance of females on these resources.     

Sex‐specific food provisioning in a monomorphic seabird,the common guillemot Uria aalge: nest defence,foraging efficiency or parental effort?

Sexual differences in food provisioning rates of monomorphic seabirds are well known but poorly understood. Here, we address three hypotheses that attempt to explain female-biased food provisioning in common guillemots Uria aalge : (1) males spend more time in nest defence, (2) females have greater foraging efficiency, and (3) males allocate a greater proportion of foraging effort to self-maintenance. We found that males spent no more time with chicks than females but made longer trips and travelled further from the colony. There was extensive overlap between sexes in core foraging areas, indicating that females were not excluding males from feeding opportunities close to the colony. However, as a result of their longer trips, the total foraging areas of males were much greater than those of females. There was no difference between sexes in overall dive rate per hour at sea, in behaviour during individual dives or in a number of other measures of foraging efficiency including the frequency, depth and duration of dives and the dive: pause ratio during the final dive bout of each trip, which was presumably used by both sexes to obtain prey for the chick. These data strongly suggest that sexes did not differ in their ability to locate and capture prey. Yet males made almost twice as many dives per trip as females, suggesting that males made more dives than females for their own benefit. These results support the hypothesis that female-biased food provisioning arose from a difference between sexes in the allocation of foraging effort between parents and offspring, in anticipation of a prolonged period of male-only post-fledging care of the chick, and not from differences in foraging efficiency or time spent in nest defence.     

The spatial organization of otters (Lutra lutra) in Shetland

The dispersion of otters Lutra lutra was studied along the coasts of an area of Shetland. The population was relatively stable, with about one adult otter per kilometre of coast. They fished diurnally in a strip of water usually within 100 m of the shore. Females lived in exclusive group ranges, occupied by up to four females, with well-defined boundaries which were respected by successive occupants. For two groups, where relatively complete information was available, range size was 4.7 and 6.4 km, occupied by two and four females, respectively; a third range was about 14 km, with possibly 4–5 females. Within the group ranges individual females moved on their own or with their cubs. Each had a core area, where they were observed > 50% of the time; these core areas were separate from each other, although each individual used the entire group range. Several or all females in each range bred in any one summer. Male ranges were larger than those of females, and overlapped with two or more female group ranges; there were several resident males along each section of coast, but the information on males was incomplete. The habitats of the sexes were different; males spent more time on exposed coasts than did females. There were frequent visits to all coasts from non-resident otters of both sexes.
Behavioural interactions related to territoriality are described; otters showed little overt aggression, except between adult males, but there was some individual avoidance. It is argued that the survival value of this spatial organization can be understood in terms of resource dispersion, but several types of resources have to be considered (including prey and fresh water), and detailed predictions of spatial organization from resource dispersion are unwarranted.     

Range use of the forest chimpanzees of Kibale: Implications for the understanding of chimpanzee social organization

We contrast the range use patterns of male and female chimpanzees (Pan troglodytes) based on repeated sightings over three years of 19 individuals in the Kanyawara community of Kibale Forest Reserve, Uganda. Depending on how home range size was calculated, male chimpanzees used an area that was 1.5 to 2 times greater than that of females. There was no difference between the sexes in whether their home ranges were used in a clumped or uniform fashion. However, males were more likely to be seen in boundary areas than females. These results are discussed in light of previously proposed models of chimpanzee social organization. It is concluded that the scenario in which females have smaller core areas within the defended home range of the males is most strongly supported by the range use patterns observed in Kibale chimpanzees. © 1993 Wiley-Liss, Inc.     

Group Release of Sanctuary Chimpanzees (<Emphasis Type="Italic">Pan troglodytes</Emphasis>) in the Haut Niger National Park,Guinea, West Africa: Ranging Patterns and Lessons So Far

The release of wild or captive-bred mammals within their historical ranges typically aims to reestablish populations in areas where they have become extinct or extirpated, to reinforce natural populations, or to resolve human–wildlife conflicts. Such programs, which also typically in parallel help foster the protection of the release site, concern a wide range of endangered mammalian species, including our closest living relatives: chimpanzees. In June 2008, the Chimpanzee Conservation Center (CCC), which is located in the High Niger National Park (HNNP) in Guinea, released a group of 12 chimpanzees (Pan troglodytes verus) comprised of 6 females and 6 males (8–20 yr old). The selected release site lies 32 km from the sanctuary in the Mafou, a core area of HNNP where wild chimpanzees are also known to occur. The purpose of this release was therefore to reinforce the natural chimpanzee population within the Mafou core area and to promote the protection of the HNNP. Nearly 2 yr postrelease, 9 chimpanzees still remain free-living. Two thirds of the release chimpanzees were equipped with VHF-GPS store-on-board tracking collars. We used data from retrieved collars to explore the release chimpanzees’ habitat use, individual day range, and core area use (50% and 80%) during the first year of the release. Males traveled significantly further than females. Although minimum day range did not differ between the sexes or vary seasonally, some release males were active for longer during the day than the females. Males also ranged over larger areas and used a wider network of core areas than the females. Habitat use was similar to that recorded in wild chimpanzees in the HNNP. As of September 2010, 2 males and 3 females form a group at the release site. Two of these females gave birth to healthy offspring respectively 16 and 20 mo postrelease. Another female successfully immigrated into a wild chimpanzee community. We suggest that the success of this chimpanzee release can be attributed to the CCC’s lengthy rehabilitation process and the savanna-mosaic habitat of the HNNP. This release demonstrates that under special socioecological circumstances, the release of wild-born adult chimpanzees of both sexes is a viable strategy, which can also function as an effective conservation tool.     

Study of h-TSH immunoreactive adenohypophyseal cells following treatment with methymazole

The TSH-producing adenohypohyseal cells of Wistar rats were studied after treatment with orally administered methymazole by the PAP immunocytochemical method. These cells were compared with those of normal animals. The effects of methymazole were different in the females to those observed in males. In both sexes, the numerical density (number of TSH cells per 1000 microns 2) increased after treatment. The cellular and cytoplasmic areas increased in the females while they decreased in the males. The nuclear area and the nuclear area/cytoplasmic area ratio increased in the males and decreased in the females following treatment with methymazole. This treatment caused the appearance of large, intensely stained cells, with an eccentric nucleus and cytoplasmic processes accompanied by weakly stained cells that were situated close to blood vessels.     

Do male roe deer clump together during the rut?

Movement s an d habitat use of 7 male and 7 female roe deerCapreolus capreolus (Linnaeus, 1758) were studied by radioteleme try from March 1999 to February 2001. Annual and bimonthly home ranges of males were small (ca 10 ha, 95% kernel), with large overlap among individuals throughout the year. Exclusive core areas (ca 0.4 ha, 25% kernel) were concentrated in the forest, a limited and sought-after resource in the study area. The difference in overlap between male exclusive core areas and female home ranges in the pre-rut and rut periods suggested that females made excursions to search for territorial males during the rut Our results support the mating strategy hypothesis of territorial behaviour Different space use patterns occurred between the sexes, with females apparently playing an active role in mate choice by visiting males at clumps of core areas in the forest.     

Winter habitat preferences of feral American mink<Emphasis Type="Italic">Mustela vison</Emphasis> in Biscay,Northern Iberian Peninsula

We studied correlates of habitat use of riparian feral American minkMustela vison Schreber, 1777 during winter in Biscay (Northern Iberian Peninsula). We live-trapped and radio-tagged 10 American mink (5 males and 5 females) and successfully radiotracked 7 of them (3 males and 4 females). During resting periods both sexes selected areas with dense scrub and near to deep waters. Both sexes used underground dens as well as resting sites located above the ground, but during cold days females rested in buildings much more often than males. Active females used areas of dense scrub, and males used large scrub patches. The results are interpreted in the light of mink hunting techniques and perceived predation risk: on larger scales, mink select areas primarily by food abundance, while on very small scales they use scrub and similar structures providing safe areas to hunt, forage and rest. The strong preference for banks with dense scrub provides options for management of the species.     

Spatial and temporal interactions of free-ranging pacas (<Emphasis Type="Italic">Cuniculus paca</Emphasis>)

Although the paca is the most frequently hunted game species throughout the Neotropics, its behavioral and ecological requirements remain poorly understood. Here, we describe ranging behavior, spatio-temporal intraspecific interactions, and cavity use within a mosaic landscape in Central Belize, based on radio-tracking of four males and two females. This study is the first to investigate social interactions and spatial structure within a paca population in unprotected marginal habitat. We detected extensive home range overlap between males and between sexes. Male-male overlap was less extensive within core areas, while female core ranges were almost entirely occupied by one or more males. On average, pacas used at least six cavities within their home range. The majority of cavities were in the core areas and we did not detect simultaneous co-habitation of the same location. On average, females occupied cavities that were closer together, and closer to water bodies, than those of males. Overall, our study suggests a general tolerance during nocturnal foraging activities, but exclusive use of core areas and associated cavities. The larger ranges of males than females and the extensive overlap between conspecifics suggest a polygamous or promiscuous mating system in this landscape.     

Resource-defense Polygyny and Male Territory Quality in the New Zealand Fur Seal

The polygynous New Zealand fur seal, Arctocephalus forsteri, breeds in densely-packed colonies with males defending exclusive territories. The distribution of individuals within a colony of these seals was monitored over three consecutive breeding seasons and behavioural thermoregulation was found to be an important factor influencing the site selection of both males and females. Shaded areas and pools of water were used by both sexes for cooling and use of these cooling substrates increased as rock surface temperature increased, resulting in a clumped distribution on hot days. Substrate preferences were tested experimentally by manipulating the availability of cooling substrates during two seasons. The number of females using an area increased significantly after shade or pools of water were added to that area. For males, pool additions resulted in increased use of those areas, while adding shade had no effect. Cooling substrates had a patchy distribution and could therefore be monopolised by territorial males. Using the number of females on a territory as a measure of male mating success, it was found that female numbers were most strongly positively correlated with the area of shaded substrate on a territory. Total territory area was also positively correlated with number of females. It is argued that thermoregulatory constraints are a major factor affecting female site choice, and that this in turn affects male mating success.     

Spatial and temporal habitat use of kob antelopes (Kobus kob kob, Erxleben 1777) in the Comoé National Park, Ivory Coast as revealed by radio tracking

Spatial and temporal habitat use of kob antelopes (Kobus kob kob) have been investigated in the Comoé National Park (Ivory Coast, West Africa) by use of radio telemetry. A total of 23 kob were equipped with radio collars and radio tracked for up to 15 months. Home ranges of males were smaller and those of females larger than expected from theoretical models. Adult males used smaller areas than adult females and did not show seasonal home range shifts. Daily distances travelled did not differ between sexes. Kob walked less during the night than by day and covered shorter distances in the wet season. Whereas an increase in home range overlap between females resulted in higher rates of association among individuals, association of adults of mixed sexes was not correlated with the degree of home range overlap. Territorial behaviour of males and predator avoidance by females are suggested to explain the sex‐specific differences in home range size of adults and the deviation from the predicted sizes. Predator avoidance is presumed as the main reason for the reduced walking distances at night as well as in the wet season. Reproductive behaviour and feeding ecology are assumed to determine the degree of association of conspecifics.     

Space use and temporal partitioning of sympatric Tasmanian devils and spotted‐tailed quolls

Sympatric species can minimise interspecific competition by spatial avoidance or by altering their temporal activity to reduce encounter rates. The Tasmanian devil (Sarcophilus harrisii), the largest carnivorous marsupial, coexists with the smaller spotted‐tailed quoll (Dasyurus maculatus) in Tasmania, Australia. Quolls may be susceptible to interspecific competition from devils, because they utilise similar habitats, consume similar prey species and are displaced by devils at food sources. Such competition might cause quolls to spatially or temporally avoid devils. To investigate whether spatial or temporal avoidance occurred, we deployed GPS collars on sympatric devils and quolls and conducted a camera survey at a site in northwest Tasmania where the devil population was not affected by devil facial tumour disease. GPS tracking coincided with the lactation period when devils and quolls had young in dens and continued until weaning occurred. We found little spatial segregation of home range and core area placement between devils and quolls and among devils. Quolls showed more spatial segregation within the sexes than between them. Devils had larger home ranges than quolls. Male devils had larger home ranges than females, but there was no difference in home range size between the sexes of quolls. Females of both species travelled significantly further per night than did males. There was moderate temporal partitioning between the two species: devil activity peaked after dusk and devils remained active until the early morning, while quoll activity showed distinct peaks around dusk and dawn. In conclusion, quolls did not spatially avoid devils but moderate temporal partitioning occurred. It is plausible that quolls are active at different times of the diel cycle to reduce encountering devils, but further studies are needed to resolve the cause of this temporal partitioning.     

Exclusive core areas in overlapping ranges of the sleepy lizard, Tiliqua rugosa

Where animal home ranges overlap extensively, objectively identifyingexclusive areas within individual ranges has been difficult,particularly in species lacking overt territorial behaviors.By analyzing the overlap between successively smaller core areasamong individuals in a population of the long-lived Australianskink, the sleepy lizard (Tiliqua rugosa), we objectively determinedexclusive areas within animal ranges. Using 4-year radio trackingdata, we found that ranges consisted of relatively large sallyzones (mean 66–80% total range), around home ranges withmultinucleate cores strongly associated with key refuge sites.Total range and home range area varied significantly among years,being smaller in a drought year. Total ranges overlapped extensivelybetween and within sexes, but for both sexes, intrasexual overlapof inner range cores rapidly approached zero, suggesting intrasexualterritoriality. Intersexual inner core overlap reflected thisspecies socially monogamous mating system. But, male overlapof female ranges and inner cores was consistently higher thanfemale-male overlap. Refuges and/or mates may be defended resourceswithin these core areas, although aggressive behavioral interactionswere rarely observed. In the extensively overlapping sally zones,males shared space with females other than their principal partner.In productive years, with larger home ranges and more extensiveoverlap, some lizards associated with extra partners, suggestingthat males opportunistically use sally zones for polygyny. Consequently,we suggest that benefits to females from male association maychange with environmental quality, such that if food resourcesare low, monogamy may be favored if females increase foragingefficiency as a consequence of male vigilance during pairing.     

Home range, association and related aspects of elephants in the eastern Transvaal Lowveld

Home range and association patterns of elephants Loxodonta africana in private nature reserves adjacent to the Kruger National Park, South Africa, were determined over a period of six years by using radio telemetry. The minimum convex polygon (MCP) and harmonic mean (HM) methods were used for data processing. The minimum and maximum range areas required by females were estimated at 115 and 465 km², respectively, whilst those of males varied between 157 and 342 km². Core areas of females comprised on average 10·1% of the range areas as calculated by the MCP method. Range areas between females in the Klaserie and Timbavati Private Nature Reserves differed significantly. A significant difference in range size was also found between the male population (pooled data) and the females of the Klaserie Private Nature Reserve. Range areas increased from the wet to the dry season. Three male elephant categories were established, namely males utilizing the same area during the study period, those who shifted their range areas and individuals with very large range areas which frequented the area on an irregular basis. A loose relationship existed between males. Association between females can be attributed to kinship and not to the overlapping of range areas. Results indicated avoidance behaviour between females in their core areas, which might partially explain the ability of elephants to tolerate high densities. It is concluded that male elephant hunting should be approached with caution.     

Metapopulation structure and habitat quality in modelling dispersal in the butterfly Iolana iolas

Quantifying dispersal is fundamental to understanding the effects of fragmentation on populations. Although it has been shown that patch and matrix quality can affect dispersal patterns, standard metapopulation models are usually based on the two basic variables, patch area and connectivity. In 2004 we studied migration patterns among 18 habitat patches in central Spain for the butterfly Iolana iolas, using mark–release–recapture methods. We applied the virtual migration (VM) model and estimated the parameters of emigration, immigration and mortality separately for males and females. During parameter estimation and model simulations, we used original and modified patch areas accounting for habitat quality with three different indices. Two indices were based on adult and larval resources (flowers and fruits) and the other one on butterfly density. Based on unmodified areas, our results showed that both sexes were markedly different in their movements and mortality rates. Females emigrated more frequently from patches, but males that emigrated were estimated to move longer daily dispersal distances and suffer higher mortality than females during migration. Males were more likely to emigrate from small than from large patches, but patch area had no significant effect on female emigration. The effects of area on immigration rate and the within-patch mortality were similar in both sexes. Based on modified areas, the estimated parameter values and the model simulation results were similar to those estimated using the unmodified patch areas. One possible reason for the failure to significantly improve the parameter estimates of the VM model is the fact that resource quantity and butterfly population sizes were strongly correlated with patch area. Our results suggest that the standard VM modelling approach, based on patch area and connectivity, can provide a realistic picture of the movement patterns of I. iolas .     

Effects of spatial variation in food availability on spacing behaviour and demography of Eurasian red squirrels

In heterogeneous habitats with limited resources, spacing behaviour will affect individual variation in breeding success and density of populations, and is thus of general interest to ecologists. We investigated how red squirrels Sciurus vulgaris adapt their social organisation to tine‐grained heterogeneity in habitat quality, studying spacing behaviour, habitat use and population dynamics in a forest in north Italy, characterised by a mosaic of high‐quality (chestnut‐pine) and poor‐quality patches. We compared the data with those from more homogeneous broadleaf and mixed woodlands with similar overall tree seed abundance (“stable” habitats). Squirrels lived at lower densities (pre‐breeding density 0.39‐0.58 ha^‐1) than in “stable” habitats, although breeding rate was not reduced. Female breeding success was related to being primiparous as yearlings, and increased with body mass and proportion high‐quality habitat in the home range. Persistency rate of females was as in stable habitats, It was higher than male persistency, but immigration and recruitment rates were male biased, resulting in even sex‐ratio. All residents occupied high‐quality patches, and no subadults established a permanent home range in poor‐quality habitat. Home range and core‐area size was typically larger in males than in females and a male's core‐area overlapped those of other males and of females. Female core‐areas were overlapped by males but not. or very little, by other females (intrasexual territoriality). Home ranges, or core‐areas, were not smaller than in “stable” habitats, nor did we find a higher degree of core‐area overlap. We conclude that in patchy habitats dominant, resident red squirrels exclude dispersing animals from preferred, high‐quality habitat, producing a spacing pattern referred to as ideal despotic distribution, and that poor patches were only used temporarily by transient individuals, resulting in a reduction of density in comparison to populations in “stable” habitats.     

Habitat use and behaviour of European hedgehogErinaceus europaeus in a Danish rural area

HedgehogsErinaceus europaeus Linnaeus, 1758 were radio-tagged and monitored during the summer of 2001 in a Danish rural area with the objective of quantifying home ranges, nightly distances travelled, habitat use, activity patterns, day-nesting habits, and body-weight changes of the five males and five females being recorded. Males had larger home-range sizes and travelled longer nightly distances than females. The two most common habitat types within the home ranges of the hedgehogs were deciduous forest and arable land, whereas the two most frequently used habitat types were deciduous forest and grassland. No differences between the sexes were found in the proportions of different habitat types within the home ranges or in habitat use. Non-random habitat use was found; forested areas and edge habitats seemed preferred to open areas. The most frequently used day-nesting habitat was deciduous forest. Foraging was by far the most time-consuming nightly activity for both sexes. Males lost weight during the study period (May–July), whereas females gained weight. A peak in the frequency of sexual behaviour was found from late-June to mid-July. The high level of male ranging activity and the weight loss of males are interpreted as a consequence of the promiscuous mating system of hedgehogs.     

Disturbance-dependent spatial distribution of sexes in a gynodioecious understory shrub

Several ecological conditions and processes occurring naturally in plant populations may lead to spatial aggregation of sexes within populations of sexually polymorphic species. In addition, ecological disturbances such as forest management or fire could also affect the spatial distribution of sexes within populations. Spatial aggregation of sexes can have important consequences for the fitness of the individuals in sex-biased patches through increased pollen limitation and/or variation in the male fitness of hermaphrodites. Therefore, spatial aggregation of sexes could be relevant for the maintenance of the sexual polymorphism in plant species. Here, we used point pattern analysis to study the spatial distribution of female and hermaphrodite individuals within a single population of the gynodioecious understory shrub Daphne laureola, inhabiting a young pine reforestation and the adjacent natural undisturbed area. In the undisturbed area, we found that hermaphrodites were distributed randomly whereas females were spatially aggregated at short distances. Such aggregation could result from narrower ecological amplitude, cyto-nuclear determination of sex and limited dispersal and/or increased cloning in females. In the reforested area, females were slightly more abundant and the two sexes were randomly distributed among all plants. Recolonization processes after certain forest disturbances could thus favour the establishment of females and alter the spatial distribution of sexes in this understory species.