Space use of common genets<Emphasis Type="Italic">Genetta genetta</Emphasis> in a Mediterranean habitat of northeastern Spain: differences between sexes and seasons

The seasonal home range size and spatial relationships of 16 adult genetsGenetta genetta Linnaeus, 1758 (6 males and 10 females) were estimated in a Mediterranean habitat of northeastern Spain. Genets minimum density was estimated as 0.98/km². Mean annual home range was 113.1 ha in males and of 72.0 ha in females. Males had larger home ranges than females in all seasons, but differences were only significant in winter. Home range size changed seasonally and showed a similar pattern in both sexes, with lower values in summer (males — 41.2 ha, females — 29.0 ha) and maximum ones in spring (males — 78.8 ha, females — 56.1 ha). Animals displayed spatial fidelity throughout the year. Core areas (MCP50) represented 27% and 19% of total home range size for males and females, respectively. Resting home ranges (based on locations of inactive animals) were 9 times lower than overall home range size. Individuals of the same sex overlapped less than individuals of different sexes, especially with regard to core areas, which showed almost no overlap. The results obtained suggest that (1) different factors are likely to affect the space use of genets, such as body mass, food abundance and reproductive cycle; (2) genets use space in a heterogeneous way, with areas of greater activity than others within their home range; (3) there was intrasexual segregation with regard to space use.     

Seasonal and sexual variation in diel activity rhythms of pine martenMartes martes in the Białowieża National Park (Poland)

From 1991–1996, the activity rhythms of 14 radio-collared pine martensMartes martes (Linnaeus, 1758) (6 males and 8 females) were studied in the pristine deciduous and mixed forests of the Białowieża National Park. Tracking data (5823 h) indicated that the activity rhythms of pine martens varied between sexes and seasons. In spring, male activity peaked at 20.00–00.00 h, whereas in summer and autumn-winter, activity was bimodal, peaking at 18.00–22.00 h and 02.00–04.00 h. Female activity in spring was more evenly distributed than that of males, but in summer their activity peaked at 20.00–00.00 h, while in autumn-winter females had a bimodal rhythm with peaks at 18.00–20.00 h and 02.00–06.00 h. In breeding females, activity rhythms changed in the course of pregnancy and nursing. On average, martens started their activity 73±209 (SD) min before sunset and finished 87±245 min after sunrise. Females became active earlier than males but both sexes terminated activity at the same time. For both males and females the daily activity rhythm was not related to the diurnal course of temperature.     

Female defense polygyny in the territorial triggerfish <Emphasis Type="Italic">Sufflamen chrysopterum</Emphasis>

The occurrence of polygyny requires specific environmental conditions such as female aggregation or patchy resource distribution. However, it is difficult to determine the factors responsible for polygyny in species in which the territories of both sexes overlap. To overcome this, we performed female removal experiments in the polygynous triggerfish Sufflamen chrysopterum (Balistidae) in the Okinawa coral reef. Both sexes defended their territories exclusively against consexuals of the same species, and female aggregation was absent. Each male territory included 1–3 female territories, and nonterritorial males were significantly smaller than territorial males. Further, the body size of territorial males was positively correlated with that of the largest female in their territories, and larger males tended to mate with more females. The results of the female removal experiments (n = 10 females) indicated that females competed for better territories rather than larger mates. In contrast, males abandoned the territories once the females emigrated. These results strongly suggest that males defend females rather than sites and compete for larger and a greater numbers of females. Thus, in S. chrysopterum, female defense polygyny occurs in the absence of female aggregation.     

Kin-related social organization in a winter population of the voleClethrionomys rufocanus

Kinship amongClethrionomys rufocanus was investigated during the winter of 1992/93 in a 3-ha enclosure using both molecular and catch-mark-release techniques. Forty-six adult voles (22 males and 24 females) having high heterozygosities, which were collected from several natural populations, were released into the enclosure on 29 September 1992. Most fall-born individuals of both sexes stayed in their natal site during the non-breeding period (December–March), although reproductively active females dispersed during the fall breeding season (October–November). These philopatric individuals aggregated and formed an maternal family in the winter. Several females which failed to reproduce were solitary during this season. Some individuals which were derived from several families also aggregated into a mixed lineage group. Survival rate of fall-born voles from earlier litters was higher than that from later ones. Maternal families broke up soon after the onset of spring reproduction. Most females established a territory near the wintering site and made a kincluster, in which close relatives neighbored each other. Maternal families in winter bring about female kin-clusters in spring, which may influence reproductive output in the breeding season.     

Population dynamics of Microtus arvalis in a weed strip

A population of Microtus arvalis Pallas, 1779, living in a weed strip was studied by capture–recapture method over a 2-year period. Weed strips are characterized by their linear shape and high vegetation cover, and are not comparable to the habitats examined in most previous studies on M. arvalis.Abundance of voles was found to be high in the strip with a maximum of 410 voles/ha known to be alive in the first year and 641 voles/ha in the successive year. Abundance was minimal in spring and increased until July. A decrease in population size at the beginning of August was followed by a new increase in both years. One difference between the 2 years was a pronounced peak abundance at the end of June in the second year. The peak may be related to a shift in sex ratio in favour of females in this year (ratio of males:females of 1:8). Also the time of residency of females was significantly longer in the second year than in the year before, and the survival rate of females was greater than in males.The turnover was generally very high and reached maximum values of 80% renewal of population every 2 weeks.     

Long-distance movements of individuals in a free-living bank vole population: an important element of male breeding strategy

The experiment involved two stages: the first one consisted of studying the dynamics of long-distance movements and the characteristics of moving individuals in a free-living population of bank voles and the second one — of an analysis of paternity of young individuals born to females representing specific breeding colonies (basing on an analysis of six microsatellite fragments). The study has shown that both male and female bank voles are capable of covering long distances of up to almost 1 km. Males moved significantly more frequently than females. The proportion of travelling males was the highest in spring and the lowest in autumn. Almost all moving males were adult and they were sexually active. Almost all moving females were adult, however, the majority of them were sexually inactive. This indicates that the character and causes of long-distance movements of females and males differ. Female movements are supposed to be related to the search for living and breeding grounds by young, already adult individuals, driven out from their mothers’ territory. Multiple paternity occurred in 25% of all litters analysed. Young whose fathers were males from outside of their mother’s breeding colonies occurred in litters throughout the whole breeding season. They made up 59% of all young analysed and in the spring (June) all the young animals were born to fathers originating outside of the female’s breeding colony. The results obtained may confirm the hypothesis that long-distance movements of male bank voles constitute a part of their breeding strategy, involving them in searching for breeding partners over an extensive area.     

Life-history traits of Amur sleeper, <Emphasis Type="Italic">Perccottus glenii</Emphasis>, in the invaded Vistula River: early investment in reproduction but reduced growth rate

In recent decades, Amur sleeper is one of the most invasive fish species in Eastern and Central Europe. Generally, it is assumed that success of an invasive species can largely depend on the plasticity of its life-history traits, e.g., indicated by higher investment in reproduction in the initial stage of its invasion. On the other hand, such energy allocation to production of gonads should negatively impact somatic growth rate. The aim of this article was to explore this phenomenon in a non-native population of Amur sleeper inhabiting artificial reservoir on a large lowland river in Central Europe. Through analysis of the population age structure, sex-dependent growth rate and life-history traits we assessed investment in reproduction and its possible relationship with growth pattern as well as compared the results with literature data from native and introduced range. Samples collected monthly from April 2005 to March 2006 were used to estimate sex ratio, GSI, fecundity, eggs diameter frequency over the year, duration of spawning season, and mode of spawning. Age structure was calculated from scales and the same data were also used to back-calculate standard length (SL) at age. The population in the Włocławski Reservoir was represented by eight age groups, and its life span was one of the longest recorded both in its natural range and introduced areas. The weight–length relationship showed that the Amur sleeper grew isometrically and there was no difference between females and males. Although the Amur sleeper growth rate was relatively slow in the Włocławski Reservoir, its increment in the first year of life was comparable to that in other introduced areas and higher than in its natural range. The female age of maturation (1+) found in the reservoir was earlier than observed in its natural range as well as in most introduced areas (2+, 3+). Female length at maturation was similar to that reported elsewhere. The back-calculated standard length (SL) of females and males showed that in the first two age classes (1 and 2) males achieved larger SL than females. Meanwhile, at age 3, 4 and 5, females were larger than males but these differences were insignificant, except for class 5. For both sexes the average annual increment of SL decreased with age but in females the increment was always higher than in males (P < 0.05). The growth rate differences between females and males resulted possibly from their unequal investment in reproduction. Multiple spawning in the Włocławski Reservoir lasted from April to the end of August and was almost 3 months longer than in other regions. Thus, this higher investment in reproduction displayed by, e.g., earlier maturation of females and longer spawning season in the Włocławski Reservoir, may contribute to invasive success of Amur sleeper in newly colonized areas; however, the costs of this strategy result in slower growth in older age classes.     

Sexual differences in natal dispersal and philopatry of the grey-sided vole

The natal dispersal distance of the grey-sided vole,Clethrionomys rufocanus (Sundevall), was measured in a large outdoor enclosure (2.1 ha) in Hokkaido, Japan. Voles in about half of the enclosure (1 ha) were fed. Distance from the natal site to the site of reproduction was significantly greater in males (64.9 m) than in females (35.3 m). In males, 24.8% settled within one home range length of their natal site and 49.6% settled further than two range lengths from their natal site. In femles, the respective percentages were reversed: 51.2% and 22.0%. The timing of large movements (≥50 m) was related to body mass in both sexes. The population density was always higher on the fed grid than on the control grid, which resulted in the frequency of large movements being greater on the fed grid that on the control grid. Thus, the percentage of voles performing a large movement was not different between the grids in both sexes.     

Asymmetric size effect of sexes on reproductive fitness in an aphid parasitoid Aphidius ervi (Hymenoptera: Aphidiidae)

Most studies on size–fitness relationships focus on females and neglect males. Here, we investigated how body size of both sexes of an aphid parasitoid, Aphidius ervi Haliday, affected the reproductive fitness. Reproductive fitness was generally positively correlated with body size for both sexes in this species. Large individuals of both sexes had greater longevity, large males fathered more progeny, and large females had higher fecundity, parasitism, and greater ability in host searching and handling. We demonstrated in this study that size effects of males and females were asymmetric on different reproductive fitness parameters. With increasing body size females gained more than males in longevity and fecundity while males gained more than females in the number of female progeny. Regardless of female size, large males sustained a female-biased population longer than small males. These results suggest that male body size should also be considered in the quality control of mass-rearing programs and the evaluation of parasitoid population growth.     

Population structure ofCtenomys minutus (rodentia, ctenomyidae) on the coastal plain of Rio Grande do Sul, Brazil

Ctenomys minutus Nehring, 1887 inhabits fields and pastures of the coastal plains of Santa Catarina (SC) and Rio Grande do Sul (RS), southern Brazil. This species shows territoriality, low vagility, and sedentary behavior. The sexr atio is unbalanced; there are more females both in the general (1.3∶1) and in the adult population (1.26∶1). The population was sexually dimorphic, with males being significantly larger than females in all measured in dividuals. Analysis indicated allometric form of variation in both sexes.     

The effects of winter severity and population density on body stores in the Iberian wild goat (<Emphasis Type="Italic">Capra pyrenaica</Emphasis>) in a highly seasonal mountain environment

We studied the factors that determined kidney fat stores (KFs) and kidney stores (Ks)—defined as the residuals from the linear regression of kidney mass and kidney fat, respectively, on body weight—in 463 Iberian wild goats (Capra pyrenaica) from the Sierra Nevada (southern Spain). Despite the fact that body stores in both sexes were highest during the warmest months of the year and lowest during the coldest months when food resources are limited, the observed pattern was sex- and age-dependent. The KFs of male goats fell more than those of females in winter, and the yearlings of both sexes needed one season more than young or adults to restore their KFs. Goats of all age classes showed the same seasonal patterns in their Ks, although Ks were lower in females than in males throughout the yearly cycle. In addition, we found strong delayed effects of both snowfalls and population density on body stores, and in years with a lot of snow, goats' KFs reached their lowest levels in the current winter–spring, but the highest in the following summers and autumns. This pattern was less noticeable in the Ks. Population density negatively affected the body stores of wild goats, especially in winter, and the amount of snow fallen in the year of birth (cohort effect) did not seem to influence the body stores in our data set. In addition, we assessed the accuracy of the residuals from the regression between body size and body mass for monitoring body condition of live wild goats and concluded that, although it poorly indicates fat stores, it could be used as a general proxy of body condition. Finally, we discuss the expected effects of climate warming on body stores in this Mediterranean Caprinae species.     

Sex-differentiated migration patterns, protandry and phenology in North European songbird populations

This study aims to investigate causes and mechanisms controlling protandrous migration patterns (the earlier breeding area arrival of males relative to females) and inter-sexual differences in timing of migration in relation to the recent climate-driven changes in phenology. Using standardised ringing data from a single site for eight North European migratory passerines collected throughout 22 years, we analysed sex-differentiated migration patterns, protandry and phenology of the entire populations. Our results show protandrous patterns for the first as well as later arriving individuals for all studied species. Males show more synchronous migration patterns compared to females and, hence, first arriving females followed males more closely than later arriving individuals. However, we found no inter-sexual differences in arrival trends as both sexes advance spring arrival over time with the largest change for the first arriving individuals. These findings seem in support of the “mate opportunity” hypothesis, as the arrival of males and females is strongly coupled and both sexes seem to compete for early arrival. Changes in timing of arrival in males and females as a response to climatic changes may influence subsequent mating decisions, with subsequent feedbacks on population dynamics such as reproductive success and individual fitness. However, during decades of consistent earlier spring arrival in all phases of migration we found no evidence of inter-sexual phenological differences.     

Spatial Segregation of the Sexes and Nutrients affect Reproductive Success in a Dioecious Wind-pollinated Grass

In many dioecious plant species in which spatial distributions of males and females have been examined, the sexes are spatially segregated – usually along an environmental gradient. Unless pollen is uniformly distributed in a population, spatial segregation of the sexes should reduce the average mating success of individuals. In three Californian populations of Distichlis spicata – a wind-pollinated grass species that exhibits spatial segregation of the sexes – I examined patterns of pollen movement and the effects of pollen load and nutrient availability on seed set to determine whether spatial segregation of the sexes actually reduces mating success for both males and females. In two of the populations, pollen dispersal was restricted, and pollen augmentation consistently, significantly increased seed set. However, in the third population – which had the lowest seed set – I found that although there were some indications of pollen limitation, pollen dispersal was not restricted, and seed production was limited primarily by nutrient availability. These results imply that in some populations of D. spicata nutrient limitation on the production of seeds by females may be sufficiently strong that spatial segregation of the sexes causes a fairly low cost to reproductive success compared with a more random distribution of the sexes. However, in other populations, pollen does limit mating success, and the spatial segregation of males and females in these populations is reducing the fecundity of both males and females.     

Adult philopatry and dispersal in the field vol Microtus agrestis

Summary Using mark-recapture data, we related the movements of adult field voles to population density, sex ratio and population growth. Dispersal movements (defined as distances larger than 1 home range diameter) were few in both sexes; 4 out of 197 (2.0%) in males and 8 of 316 (2.5%) in females. The distance moved between sequential trapping periods was similar for males and females; the mean being 10.2 m and 9.0 m respectively. Both males and females moved larger distances during the breeding season than during the nonbreeding period. The distance moved between sequential trapping periods showed a strong negative relation to density, i.e. both sexes moved shorter distances at higher densities, but there were no differences between periods of increasing and declining population densities. These results contradict the dispersal predictions of all major hypotheses proposed to explain population fluctuations in small mammals. The dispersal patterns fit a geometric distribution, suggesting that competition is the primary factor determining the dispersal characteristics of this population.     

CIRCADIAN CHARACTERISTICS OF CORTICOSTERONE SECRETION IN REDBACKED VOLES (CLETHRIONOMYS GAPPERI)

To provide necessary background for study of stress response in redbacked voles (Clethrionomys gapperi), the circadian and ultradian rhythm in corticosterone release was characterized. Animals were maintained under a 16h light, 8h dark cycle. A total of 55 males and 46 females provided 101 independent blood samples over a 6-month span. Samples were obtained at 1h to 2h intervals during the light and at 2h intervals during the dark. Using edited data (5 values beyond the upper 95% limit were removed), a significant time effect was found by analysis of variance (ANOVA) for both sexes at P <. 001. The composite single cosine best describing the circadian waveform for each sex consisted of three components (24h, 12h, and 6h), each significant at P <. 05 (overall model P <. 001). The 24h mean (mesor) was about 60% higher in females than males (646 ng/mL vs. 412 ng/mL, P =. 01), with amplitudes of 429 and 298 ng/mL being proportional (66% vs. 72%) to the respective mesor. The predictable range of change within a 24h span (determined by the double amplitude of a 24h + 12h + 6h cosine model) was large: It was more than 1600 ng/mL for females and more than 900 ng/mL for males. Highest values were found during the dark phase, with the 24h acrophase located at 2h into the dark span for both sexes. With the caveat of fewer samples obtained during dark than during light, the actual peak values for females occurred at 2h and for males at 6h into the 8h dark span. These results provide baseline information about the circadian time structure for serum corticosterone in red-backed voles under normal light-dark, lowstress conditions. (Chronobiology International 18(6) 933–945, 2001)     

Habitat selection and home range size of field voles<Emphasis Type="Italic">Microtus agrestis</Emphasis> in Słowiński National Park,Poland

Habitat preference, home range size and intra-specific overlap were investigated in summer 1998 among field volesMicrotus agrestis (Linnaeus, 1761) in Słowiński National Park (N Poland). Eight individuals (2 females, 6 males) were radio-tracked for one week in August. Field voles were shown to exhibit a marked preference for meadow and the ecotone between grassland and habitats with common reed, while avoiding alder forest and proper reedbeds. No significant differences between night and day in habitat-use of voles were noted. The results suggest that, at the end of the breeding season, it was food resources, rather than the risk of predation, played an important role in the voles’ utilisation of space. The home ranges of males were larger and more diverse than those of females; their sizes being correlated with body mass, such that heavier males had larger home ranges. This further suggests that intra-sexual competition exists between males for females. The low number of females influenced their spatial behaviour, as females had completely exclusive home ranges. Four males (out of six) had overlapping home ranges with other males; three of the overlaps were of less than 20%. Attributes of promiscuity (such as a 3.5:1 operational sex ratio of males to females, intra-sexual competition between males and the territorial exclusivity of females) influenced the social system. However, the period of radio-tracking during this study was too short to define accurately the social system in the field vole population.     

Growth and Development in Wild Owl Monkeys (<Emphasis Type="Italic">Aotus azarai</Emphasis>) of Argentina

Life history predicts that in sexually dimorphic species in which males are the larger sex, males should reach sexual maturity later than females (or vice versa if females are the larger sex). The corresponding prediction that in sexually monomorphic species maturational rates will differ little between the sexes has rarely been tested. We report here sex differences in growth and development to adulthood for 70 female and 69 male wild owl monkeys (Aotus azarai). In addition, using evidence from natal dispersal and first reproduction (mean: 74 mo) for 7 individuals of known age, we assigned ages to categories: infant, 0–6 mo; juvenile, 6.1–24 mo; subadult, 24.1–48 mo; adult >48 mo. We compared von Bertalanffy growth curves and growth rates derived from linear piecewise regressions for juvenile and subadult females and males. Growth rates did not differ between the sexes, although juvenile females were slightly longer than males. Females reached maximum maxillary canine height at ca. 2 yr, about a year earlier than males, and females’ maxillary canines were shorter than males’. Thus apart from canine eruption and possibly crown–rump length, the development of Azara’s owl monkeys conforms to the prediction by life history that in monomorphic species the sexes should develop at similar paces.     

Relation between daytime activities and environmental conditions in Tatra chamois (<Emphasis Type="Italic">Rupicapra rupicapra tatrica</Emphasis>)

The influence of selected ecological variables on the behaviour of the Tatra chamois (Rupicapra rupicapra tatrica) was analysed in the presented study. Both sexes including juvenile individuals were tested. In females, important correlations were found among particular activities and amount of sunshine, aspect and slope of their habitat. Females with juveniles changed sites more often, and they used a wide range of habitats with various attributes. Males had less variable activities which either corresponded to ecological factors or their solitary life strategy. The behavioural activity of males was most influenced by sunshine amount, temperature and slope of their habitat.     

Age variation in a fluctuating population of the common vole

We analysed variation in age in a fluctuating population of the common vole (Microtus arvalis) in southern Moravia, Czech Republic, to test the assumption of the senescence hypothesis that the age of voles increases with increasing population density. Between 1996 and 1998, we monitored the demographic changes by snap-trapping and live-trapping in a field population passing through the increase, peak and decline phase of the population cycle. We used the eye lens mass method to determine the age of snap-trapped animals and those that died in live-traps. The average age of winter males was clearly higher after the peak phase breeding season than before it. No such phase-dependent shift in age, however, was observed in the female component. Male age continued to increase from autumn to spring over the pre-peak winter, and the highest age was in spring of the peak phase year. However, after the peak phase breeding season the highest age was achieved in winter, with the decline phase males during the next spring tending to be younger. The average age of females in spring populations was always lower than in winter populations. The average age of voles from live-traps was always higher than voles from snap-traps, particularly in winter and spring populations, suggesting the presence of senescent animals. Although the density-dependent changes in age are consistent with those observed for other voles, they provide only weak evidence that population cycles in the common vole are accompanied by pronounced shifts in individual age, particularly in female voles.Due to an error in the citation line, this revised PDF (published in December 2003) deviates from the printed version, and is the correct and authoritative version of the paper.