First experimental evidence for female mate choice in a nocturnal primate

Female mate choice can be hypothesised in most nocturnal primates, since females show a higher investment in their offspring than males. The aim of this experimental study was to investigate if female grey mouse lemurs perform mate choice and whether age, relatedness (to the male), or male advertisement call activity systematically influence their decisions. A two-way mate choice design was developed in which females could choose between two males. Mate choice was deduced from the time spent in proximity to the males and from mating behaviour. During oestrus 12 of 17 females participated actively in the experiment and all of them showed either a significant spatial (n=11) or behavioural (n=1) preference for one male. In four cases copulations were observed. The influence of age on female mate choice was not statistically significant. In the cases with copulations, however, females mostly preferred the older male. This might indicate a preference for older age as an indicator of experience, fitness, and/or status. The influence of relatedness on female mate choice could not be definitely clarified. However, results imply a mechanism of kin recognition on the basis of familiarity. In the majority of choices, females preferred the male with higher trill call activity. Since trill call activity correlates with the relative dominance status of males, these results suggest an importance of the male dominance status for female mate choice in grey mouse lemurs. Altogether our findings indicate that females use a complex of different cues to choose their mates.     

Overwinter body temperature patterns in captive jerboas (<Emphasis Type="Italic">Jaculus orientali</Emphasis>s): influence of sex and group

The jerboa (Jaculus orientalis) has been described in the past as a hibernator, but no reliable data exist on the daily and seasonal rhythmicity of body temperature (T _b). In this study, T _b patterns were determined in different groups of jerboas (isolated males and females, castrated males and grouped animals) maintained in captivity during autumn and winter, and submitted to natural variations of light and ambient temperature (T _a). T _b and T _a variations were recorded with surgically implanted iButton temperature loggers at 30-min intervals for two consecutive years. About half (6/13) of isolated female jerboas hibernated with a T _b < 33°C, with hibernation bouts interspersed with short periods of normothermy from November to February. Hibernation bout durations were longer (4–5 days) than those of normothermia phases (1–4 days). During hibernation, the minimum T _b was low (T _bmin ~10.7°C). In contrast, one of the 12 isolated males showed short hibernation bouts of ca. 2 days late in the hibernation season, February–March. The males had T _bmin values of 15.1°C. In contrast to predictions, no castrated males hibernated. When jerboas were grouped, females and males exhibited concomitant torpor bouts. In males, the longest bouts were observed during the late hibernation season. These data suggest complex regulation of hibernation in jerboas.     

Data logging of body temperatures provides precise information on phenology of reproductive events in a free-living arctic hibernator

Precise measures of phenology are critical to understanding how animals organize their annual cycles and how individuals and populations respond to climate-induced changes in physical and ecological stressors. We show that patterns of core body temperature (T _b) can be used to precisely determine the timing of key seasonal events including hibernation, mating and parturition, and immergence and emergence from the hibernacula in free-living arctic ground squirrels (Urocitellus parryii). Using temperature loggers that recorded T _b every 20 min for up to 18 months, we monitored core T _b from three females that subsequently gave birth in captivity and from 66 female and 57 male ground squirrels free-living in the northern foothills of the Brooks Range Alaska. In addition, dates of emergence from hibernation were visually confirmed for four free-living male squirrels. Average T _b in captive females decreased by 0.5–1.0°C during gestation and abruptly increased by 1–1.5°C on the day of parturition. In free-living females, similar shifts in T _b were observed in 78% (n = 9) of yearlings and 94% (n = 31) of adults; females without the shift are assumed not to have given birth. Three of four ground squirrels for which dates of emergence from hibernation were visually confirmed did not exhibit obvious diurnal rhythms in T _b until they first emerged onto the surface when T _b patterns became diurnal. In free-living males undergoing reproductive maturation, this pre-emergence euthermic interval averaged 20.4 days (n = 56). T _b-loggers represent a cost-effective and logistically feasible method to precisely investigate the phenology of reproduction and hibernation in ground squirrels.     

The timing of hibernation in Tasmanian echidnas: why do they do it when they do?

We investigated the patterns of hibernation and arousals in seven free-ranging echidnas Tachyglossus aculeatus setosus (two male, five female) in Tasmania using implanted temperature data loggers. All echidnas showed a ‘classical’ pattern of mammalian hibernation, with bouts of deep torpor interrupted by periodic arousals to euthermia (mean duration 1.04±0.05 (n=146). Torpor bout length increased as body temperature fell during the hibernation season, and became more variable as temperature rose again. Hibernation started in late summer (February 28±5 days, n=6) and males aroused just before the winter solstice (June 15±3 days, n=3), females that subsequently produced young aroused 40 days later (July 25±3, n=4) while females that did not produce young hibernated for a further two months (arousal Sept 27±5, n=7). We suggest that hibernation in Tasmanian echidnas can be divided into two phases, the first phase, marked by declining minimum body temperatures as ambient temperature falls, appears to be obligatory for all animals, while the second phase is ‘optional’ and is utilised to varying amounts by females. We suggest that early arousal and breeding is the favoured option for females in good condition, and that the ability to completely omit breeding in some years, and hibernate through to spring is an adaptation to an uncertain climate.     

The ecology of suburban juvenile European hedgehogs (Erinaceus europaeus) in Denmark

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Dispersal patterns in black howler monkeys (Alouatta pigra): Integrating multiyear demographic and molecular data

Dispersal is a fundamental process in the functioning of animal societies as it regulates the degree to which closely related individuals are spatially concentrated. A species’ dispersal pattern can be complex as it emerges from individuals’ decisions shaped by the cost–benefit tradeoffs associated with either remaining in the natal group or dispersing. Given the potential complexity, combining long-term demographic information with molecular data can provide important insights into dispersal patterns of a species. Based on a 15-year study that integrates multiyear demographic data on six groups with longitudinal and cross-sectional genetic sampling of 20 groups (N = 169 individuals, N = 21 polymorphic microsatellite loci), we describe the various dispersal strategies of male and female black howler monkeys (Alouatta pigra) inhabiting Palenque National Park, Mexico. Genetically confirmed dispersal events (N = 21 of 59 males; N = 6 of 65 females) together with spatial autocorrelation analyses revealed that the dispersal pattern of black howlers is bisexual with strong sex-biases in both dispersal rate (males disperse more often than females) and dispersal distance (females disperse farther than males). Observational and genetic data confirm that both males and females can successfully immigrate into established groups, as well as form new groups with other dispersing individuals. Additionally, both males and females may disperse singly, as well as in pairs, and both may also disperse secondarily. Overall, our findings suggest multiple dispersal trajectories for black howler males and females, and longer multiyear studies are needed to unravel which demographic, ecological and social factors underlie individuals’ decisions about whether to disperse and which dispersal options to take.     

Female in space,or female in space and time? First data on the socio-spatial organization and mating system of the woodland dormouse (Graphiurus murinus)

We studied the socio-spatial organization of the woodland dormouse, Graphiurus murinus, by means of a monthly live-trapping and nest-box monitoring programme. Adult male (N = 5) home ranges were almost twice as large as those of females (N = 8), and both intra and intersexual home-range overlap was significantly larger in males than in females. However, the dispersion pattern of females was rather clumped, even during the breeding period, suggesting that females are not territorial. Sexual receptivity in females was asynchronous. In such circumstances, the Female in Space and Time hypothesis predicts that males will be non-territorial, a scenario which is matched by our data. Therefore, it is likely that the woodland dormouse has a promiscuous mating system.     

Social System of <Emphasis Type="Italic">Microcebus berthae</Emphasis>, the World’s Smallest Primate

Our goal was to provide a first characterization of the social system of pygmy mouse lemurs (Microcebus berthae), the worlds smallest primate species. During a 4-mo field study of 12 females and 27 males, we combined capture-recapture and morphometric data with detailed behavioral observations of individually marked subjects and genetic paternity analyses of a population in Kirindy Forest, western Madagascar. We describe the social organization of Microcebus berthae as a solitary forager living in an individualized neighborhood system characterized by extensive intra- and intersexual home range overlap of adult individuals within a male-biased population. Male and female pygmy mouse lemurs inhabited home ranges (males: 4.9 ha; females: 2.5 ha) that are more than twice as large as those of sympatric Microcebus murinus. On average, pygmy mouse lemurs of both sexes spent about half of the days sleeping alone. Preliminary analysis of genetic population structure suggests female philopatry and male dispersal. Sleeping associations of variable composition that consisted not preferentially of close relatives and proximity during part of the nightly activity contributed together with regular social interactions to the maintenance of a social network. The spatial distribution pattern of adult males and females, the absence of sexual size dimorphism, relatively large male testicular volume and moderate female estrous synchrony suggest a promiscuous mating system with a high potential for scramble competition. In general, there are many similarities between the social system of Microcebus berthae and those of other Microcebus spp. However, striking differences with sympatric gray mouse lemurs (Microcebus murinus) in female home range size, dispersion and sleeping behavior indicate the existence of species-specific socioecological adaptations in closely related species occupying very similar ecological niches.     

Distribution,biology, and ecology of the deep‐water squat lobster Galacantha diomedeae (Crustacea: Decapoda: Galatheoidea: Munidopsidae) in the Mexican Pacific

During deep‐water exploratory surveys in the Mexican Pacific, 134 specimens of Galacantha diomedeae were collected between 1,035 and 2,136 m depth, below the Oxygen Minimum Zone. Greatest densities of G. diomedeae were observed between 1,300 and 1,600 m, with a maximum of 71 organisms per hectare at 1,318 m, and no clear bathymetric pattern of size distribution was detected. A total of 67 males, 43 ovigerous females, and 24 non‐ovigerous females were collected. The global sex ratio was 1:1, with some predominance of females shallower than 1,300 m and the opposite pattern at 1,300–1,600 m. Ovigerous females (carapace width [CW]=15.5?32.3 mm) were significantly larger than other females (CW = 5.1?29.9 mm), and females (including all females) were larger than males (CW = 6.0?29.9 mm). Among males and among all females, the growth coefficient was near 3 (Student's t test, males = 0.0027, all females = 0.0041; for both males and females, p > 0.05), indicating isometric growth. Ovigerous females were present all year, except in January, suggesting continuous reproduction. The observed low numbers of eggs (11–126), large egg sizes (2.07–2.77 mm), and advanced embryos at stage 5 are consistent with extended, lecithotrophic embryonic development with a reduced pelagic phase of the larvae. The relationship between ovigerous female size (N = 43) and number of eggs per female was marginally significant (y = 8.0474x–98.297; R² = 0.373), and there was no significant relationship between egg size and carapace size. There was no clear increase in egg size with embryonic development (phases 1–5). Individuals of G. diomedeae were found in a narrow range of environmental conditions, and mainly occupied oxic water (DO ≥0.5 ml/L) and sediments with intermediate to low organic carbon content.     

Hibernation by a free-ranging subtropical bat (Nyctophilus bifax)

Knowledge about torpor in free-ranging subtropical bats is scarce and it is widely believed that low and stable ambient temperatures are necessary for prolonged torpor. We present temperature-telemetry data from free-ranging male (n = 4) and female (n = 4) subtropical vespertilionid bats, Nyctophilus bifax (~10 g), exposed to pronounced daily fluctuations of ambient temperature. All bats used torpor on every day in winter and both males and females exhibited multi-day torpor bouts of up to 5.4 days. Although females were larger than males, patterns of torpor were similar in both sexes. Torpor use was correlated with prevailing weather conditions and, on days when bats remained torpid, maximum ambient temperature was significantly lower than on days when bats aroused. Moreover, the duration of interbout normothermic periods at night increased with increasing average nightly ambient temperature. Skin temperature of torpid bats varied by 10.2 ± 3.6°C day⁻¹ (n = 8, N = 47) and daily minimum skin temperature was positively correlated with the daily minimum ambient temperature. Our study shows that prolonged torpor is an important component of the winter ecology of a subtropical bat and that torpor and activity patterns of N. bifax predominantly reflect prevailing weather conditions.     

Daily Torpor in Free-Ranging Gray Mouse Lemurs (Microcebus murinus) in Madagascar

I aimed to determine when and under which seasonal environmental conditions gray mouse lemurs (Microcebus murinus), a small nocturnal primate species endemic to Madagascar, utilize daily torpor. Using temperature-sensitive radio collars, I measured skin temperature (T _sk ) of free-ranging mouse lemurs under natural conditions. My results showed that male and female mouse lemurs in the wild enter torpor spontaneously over a wide range of ambient temperatures (T _a ) during the dry season, but not during the rainy season. Mouse lemurs that remained normothermic had significantly lower body masses (mean: 59.7 g) than individuals that used torpor (mean: 80.2 g). Skin temperatures dropped to 20.9°C and the mean torpor bout duration is 10.3 h. The use of torpor on a given night varied among individuals, whereas the propensity for torpor did not differ significantly between males and females. I found no evidence that T _a can be used to predict whether mouse lemurs will remain normothermic or enter torpor. It appears that the most reliable indicator for the occurrence of torpor in free-ranging Microcebus murinus is time of the year, i.e., photoperiod.     

Some observations of two kinds of lemuridae (Varecia variegata variegata andLemur fulvus albifrons) in the reserve of Nosy Mangabe

A total of nine groups of ruffed lemurs (Varecia variegata variegata), as well as one solitary individual, were observed on Nosy Mangabe, an island located off the eastern coast of Madagascar, for a total 536 min between November 30 and December 8, 1983. The average group size was 2.8 animals (N=5), and the population density was 175 animals/km², as estimated from direct observation and location of vocalization. During the same period, nine groups of brown lemurs (Lemur fulvus albifrons) and one solitary individual were observed for a total 320 min. One group of brown lemurs was composed of eight animals (two adult males and females, one male juvenile, two infants, and one individual of undetermined age and sex). Feeding competition occurred between the two species, with whichVarecia variegata variegata dominating.     

Different Population Dynamics of Microcebus murinus in Primary and Secondary Deciduous Dry Forests of Madagascar

The goal of this study was to identify causes for lower population densities of mouse lemurs (Microcebus murinus) in secondary than in primary dry deciduous forests of western Madagascar. Variations in the abundance of Microcebus murinus are linked to the capacity to enter energy-saving torpor during the dry season. Under natural conditions in primary forest, Microcebus murinus can maintain daily torpor (and possibly hibernation) as long as body temperatures remain below 28°C. Females are more likely to hibernate than males, resulting in skewed sex ratios of captured Microcebus murinus in the primary forest. In the secondary forest the sex ratio of subjects captured during the dry season is more balanced than in primary forest, indicating that fewer females go into torpor in secondary than in primary forest. Secondary forests have fewer large standing or fallen trees that might provide holes as shelter for Microcebus murinus. Ambient temperatures are higher in secondary than in primary forests and higher outside than inside tree holes. These high ambient temperatures might hinder the ability of Microcebus murinus to maintain torpor for prolonged periods in secondary forests. Mouse lemurs from secondary forest have lower body mass than in primary forest. The year-to-year recapture rate is zero in secondary forest and thus significantly lower than in primary forest. This indicates that survival rates are lower in secondary than in primary forests. Thus, secondary forests may be of limited value as buffer zones or even corridors for mouse lemurs.     

The inbreeding strategy of a solitary primate,Microcebus murinus

Inbreeding depression may be common in nature, reflecting either the failure of inbreeding avoidance strategies or inbreeding tolerance when avoidance is costly. The combined assessment of inbreeding risk, avoidance and depression is therefore fundamental to evaluate the inbreeding strategy of a population, that is how individuals respond to the risk of inbreeding. Here, we use the demographic and genetic monitoring of 10 generations of wild grey mouse lemurs (Microcebus murinus), small primates from Madagascar with overlapping generations, to examine their inbreeding strategy. Grey mouse lemurs have retained ancestral mammalian traits, including solitary lifestyle, polygynandry and male‐biased dispersal, and may therefore offer a representative example of the inbreeding strategy of solitary mammals. The occurrence of close kin among candidate mates was frequent in young females (~37%, most often the father) and uncommon in young males (~6%) due to male‐biased dispersal. However, close kin consistently represented a tiny fraction of candidate mates (< 1%) across age and sex categories. Mating biases favouring partners with intermediate relatedness were detectable in yearling females and adult males, possibly partly caused by avoidance of daughter–father matings. Finally, inbreeding depression, assessed as the effect of heterozygosity on survival, was undetectable using a capture–mark–recapture study. Overall, these results indicate that sex‐biased dispersal is a primary inbreeding avoidance mechanism at the population level, and mating biases represent an additional strategy that may mitigate residual inbreeding costs at the individual level. Combined, these mechanisms explain the rarity of inbreeding and the lack of detectable inbreeding depression in this large, genetically diverse population.     

Evidence of prolonged torpor in Goodman’s mouse lemurs at Ankafobe forest,central Madagascar

The small-bodied mouse lemurs of Madagascar (Microcebus) are capable of heterothermy (i.e., torpor or hibernation). The expression of these energy-saving strategies has been physiologically demonstrated in three species: M. berthae, the pygmy mouse lemur (daily torpor), M. murinus, the gray mouse lemur (daily torpor and hibernation), and M. griseorufus, the reddish-gray mouse lemur (daily, prolonged torpor and hibernation). Additional evidence, based on radiotracking and seasonal body mass changes, indicated that mouse lemur capabilities for heterothermy extended to M. lehilahytsara, the Goodman’s mouse lemur. In this study, we confirm the use of hibernation in Goodman’s mouse lemurs at a new location, a high-plateau forest fragment in Ankafobe, central Madagascar. Our evidence is based on sleeping site monitoring of radiocollared individuals and the retrieval of three mouse lemurs from inside a tree hole, all of which displayed a lethargic state. Though our data are preliminary and scant, we show that hibernation occurs in high-plateau mouse lemurs, and suggest that a buffered environment (i.e., tree holes instead of nests) may be crucial to avoiding potentially extreme ambient temperatures.     

Age,growth and reproduction of the white seabream Diplodus sargus sargus (Linneaus, 1758) off the eastern coast of Algeria

The objective of this study was to determine the basic population‐specific parameters necessary for fish stock assessment in the area and to compare these with data from other Mediterranean regions. White seabream Diplodus sargus sargus (n = 449) were caught along the Algerian coast between December 2005 and December 2006. Total length ranged from 12.2 to 34.6 cm, representing age classes between 0 and 10 years. Validity of the otolith readings for estimating age and growth was supported using the back‐calculation method. The von Bertalanffy growth parameters for all fish were calculated as: TL = 36.3 cm, k = 0.154 year⁻¹, t₀ = −0.488 year. The growth performance index (φ) showed a relatively slow growth of the local population. The length‐weight relationship showed an isometric growth (b = 2.98; r = 0.98). Subspecies Diplodus sargus sargus was characterized as being a proterandric hermaphrodite. Overall ratio of males to females was 1 : 1.4, with males predominant in the smaller size intervals and females in the larger ones. The reproductive season extended from January to May, with a March–April peak in spawning activity. Fifty per cent maturity of the tested cohort was reached at a total length of 20.2 cm for males and 20.0 cm for females.     

Daily energy expenditure of the grey mouse lemur (Microcebus murinus): a small primate that uses torpor

We aimed to investigate the pattern of utilisation of torpor and its impact on energy budgets in free-living grey mouse lemurs (Microcebus murinus), a small nocturnal primate endemic to Madagascar. We measured daily energy expenditure (DEE) and water turnover using doubly labelled water, and we used temperature-sensitive radio collars to measure skin temperature (T _sk) and home range. Our results showed that male and female mouse lemurs in the wild enter torpor spontaneously over a wide range of ambient temperatures (T _a) during the dry season, but not during the rainy season. Mouse lemurs remained torpid between 1.7–8.9 h with a daily mean of 3.4 h, and their T _sk s fell to a minimum of 18.8 °C. Mean home ranges of mouse lemurs which remained normothermic were similar in the rainy and dry season. During the dry season, the mean home range of mouse lemurs showing daily torpor was significantly smaller than that of animals remaining normothermic. The DEE of M. murinus remaining normothermic in the rainy season (122 ± 65.4 kJ day⁻¹) was about the same of that of normothermic mouse lemurs in the dry season (115.5 ± 27.3 kJ day⁻¹). During the dry season, the mean DEE of M. murinus that utilised daily torpor was 103.4 ± 32.7 kJ day⁻¹ which is not significantly different from the mean DEE of animals remaining normothermic. We found that the DEE of mouse lemurs using daily torpor was significantly correlated with the mean temperature difference between T _sk and T _a (r ²=0.37) and with torpor bout length (r ² =0.46), while none of these factors explained significant amounts of variation in the DEE of the mouse lemurs remaining normothermic. The mean water flux rate of mouse lemurs using daily torpor (13.0 ± 4.1 ml day⁻¹) was significantly lower than that of mouse lemurs remaining normothermic (19.4 ± 3.8 ml day⁻¹), suggesting the lemurs conserve water by entering torpor. Thus, this first study on the energy budget of free-ranging M. murinus demonstrates that torpor may not only reflect its impact on the daily energy demands, but involve wider adaptive implications such as water requirements. Accepted: 29 August 2000     

Isolation of new microsatellite markers and application in four species of mouse lemurs (Microcebus sp.)

We report the development of 13 new microsatellite markers for mouse lemurs (Microcebus sp.). Two markers were isolated from the fat tailed dwarf lemur (Cheirogaleus medius) and 11 from the grey mouse lemur (Microcebus murinus). A total of 561 individuals from four different species of mouse lemurs was genotyped with the newly developed markers. All markers showed Mendelian inheritance in 21 families of mouse lemurs. All markers show polymorphism in several species of mouse lemurs and seven amplified in C. medius. Among these new markers are the first 10 published for M. berthae and the first 11 for M. griseorufus.     

Integrating video and genetic data to estimate annual age-structured apparent survival of American black bears

Camera or genetic data are increasingly used to estimate wildlife abundance and density. We integrated video camera data with genetic data over 7 years to estimate annual age-structured apparent survival of American black bears (Ursus americanus). We identified 70 individuals through meticulous scrutiny of 7531 video captures, cross-referenced with 721 genetic captures from hair samples concurrently collected from stations in view of cameras. We used the Cormack–Jolly–Seber model in Program Mark to estimate annual age-structured apparent survival for yearling males, yearling females, 2+ year-old males, and 2+ year-old females. We manually calculated cub survival. We compared parameter estimates based on combined video and genetic data with those based on only genetic data. Combining video and genetic data provided a means to test video-based identification accuracy, which was highest for females (97%–100%). Annual apparent survival was highest for yearling females (φ = 0.92, SE = 0.07), followed by 2+ year-old females (φ = 0.88, SE = 0.05), 2+ year-old males (φ = 0.84, SE = 0.06), and yearling males (φ = 0.80, SE = 0.14). Annual cub survival (φ = 0.86, SE = 0.07) was likely biased because we could not account for mortality that occurred in-den through early spring. Annual apparent survival and recapture probabilities derived from only genetic data were lower than those derived from combined video and genetic data. Our finding that noninvasive data can be used to estimate annual age-structured apparent survival of a species with relatively indistinct traits is broadly relevant to wildlife research and conservation.     

Reproductive biology of Prochilodus argenteus Agassiz, 1829 (Pisces: Prochilodontidae) in São Francisco River,Brazil

Knowledge of the main reproductive parameters of a species is fundamental for comprehension of the reproductive behavior of a species within its habitat. To evaluate the reproductive biology of curimbatá, Prochilodus argenteus, an important species for commercial fisheries of the São Francisco River basin, Brazil, 153 females and 174 males were captured during 1999–2000 in the São Francisco River. The females (maximum total length 71.2 cm and maximum weight 7.8 kg) were larger than the males (65.0 cm and 4.3 kg). The weight–length ratio indicated isometric growth for females (b = 3.15) and for males (b = 3.04). Prochilodus argenteus presented total spawning from October to January. Increase in rainfall was the main triggering factor for reproduction, showing a positive correlation with the gonadosomatic index (r = 0.84 females; r = 0.95 males). Size at gonadal maturation of females and males was 31.0 and 25.5 cm, respectively. This study provides information to aid in future implementation of captive breeding and management practices that intend to reduce the ongoing depletion of natural stocks.