Mathieu Garel

Age, Size, and Spatiotemporal Variation in Ovulation Patterns of a Seasonal Breeder, the Norwegian Moose (Alces alces)

In seasonal environments, timing of reproduction is an important fitness component. However, in ungulates, our understanding of this biological process is limited. Here we analyze how age and body mass affect spatiotemporal variation in timing of ovulation of 6,178 Norwegian moose. We introduced a parametric statistical model to obtain inferences about the seasonal timing of ovulation peak, the degree of synchrony among individuals, and the proportion of individuals that ovulate. These components showed much more spatiotemporal variation than previously reported. Young (primiparous) and old (≥11.5 years of age) females ovulated later than prime‐aged (2.5–10.5 years of age) females. In all age classes, ovulation was delayed with decreasing body mass. Ovulation rates were lower and more variable among primiparous females than among older females. Young females required higher body mass than older females did to ovulate. The body‐mass‐to‐ovulation relationship varied with age, showed large regional variation, and differed among years within region. These results suggest that (1) environmental and population characteristics contribute to shape seasonal variation in the breeding pattern and (2) large regional variation exists in the size‐dependent age at maturity in moose. Hence, the life‐history trade‐off between reproduction and body growth should differ regionally in moose.

Sex-specific Growth in Alpine Chamois

Abstract Studying between-sex differences in body growth has strong implications for understanding life-history tactics of animals. We used age and carcass mass data from 2,312 female and 2,622 male alpine chamois (Rupicapra rupicapra) harvested in the French Alps to model the sex-specific body growth patterns of this species. Males were heavier (asymptotic body mass: 29.6 kg) than females (22.3 kg), with an adult sexual size dimorphism of 32.4%. Sexual size dimorphism originated from both differences in body growth after 1.5 years of age and differences in length of the growth period. Females reached asymptotic body mass almost 3 years earlier (3.5 years) than males (6.2 years). We also found that females 1st reproduced before achieving asymptotic growth, at 78% of their asymptotic body mass. Between-sex differences in growth patterns in this species are most likely due to stronger selection pressure for larger size in males than in females due to intrasexual competition.

Population abundance and early spring conditions determine variation in body mass of juvenile chamois

Abstract For species living in seasonal environments the understanding of demographic processes requires identifying the environmental factors during spring and summer that shape phenotypic variation. We assessed the effects of plant phenology and population abundance during spring–summer on variation in autumn body mass among cohorts (1995–2006) of juvenile alpine chamois (Rupicapra rupicapra). We computed several metrics based on the normalized difference vegetation index (NDVI) to assess interannual variation in plant phenology and productivity. Body mass of both sexes decreased similarly during years with late springs (−20%) and with increasing population abundance (−15%), with no interactive effect. Our results also suggested that forage quality more than forage quantity influenced body mass of juveniles. Variation in body mass of juveniles thus can be used as an indicator of the relationship between chamois populations and their environment. This study also demonstrates the utility of satellite-based data in increasing our understanding of the consequences of spring–summer conditions on life-history traits.

Are abundance indices derived from spotlight counts reliable to monitor red deer Cervus elaphus populations

Abstract Management of large herbivores could be improved by investing less effort in estimating absolute abundance and more effort tracking variation over time of indicators of ecological change (IEC) describing animal performance, herbivore impact on habitat, and relative animal abundance. To describe relative changes in animal abundance, monitoring trends in numbers through indices may constitute a useful and low cost method, especially at large spatial scales. Reliability of indices to detect trends should be evaluated before they are used in wildlife management. We compared population trends estimated from spotlight counts, a standard census method for deer populations, with population size estimates of a red deer Cervus elaphus population monitored using Capture-Mark-Recapture (CMR) methodology. We found a strong negative effect of conditions of observation (e.g. rainfall) on both the number of animals (-24.4%) and the number of groups (-31.6%) seen per kilometre. After controlling for observation conditions, we found that these two abundance indices were linearly correlated with CMR estimates, with the group-based index being better correlated (r = 0.75) than the individual-based index (r = 0.68). These consistent trends between indices and CMR estimates provide support in using standardised spotlight counts as an IEC describing relative changes in abundance for the monitoring and management of red deer populations.

Human Disturbances, Habitat Characteristics and Social Environment Generate Sex-Specific Responses in Vigilance of Mediterranean Mouflon

In prey species, vigilance is an important part of the decision making process related to predation risk effects. Therefore, understanding the mechanisms shaping vigilance behavior provides relevant insights on factors influencing individual fitness. We investigated the role of extrinsic and intrinsic factors on vigilance behavior in Mediterranean mouflon (Ovis gmelini musimon×Ovis sp.) in a study site spatially and temporally contrasted in human pressures. Both sexes were less vigilant in the wildlife reserve compared to surrounding unprotected areas, except for males during the hunting period. During this period, males tended to be less strictly restricted to the reserve than females what might lead to a pervasive effect of hunting within the protected area, resulting in an increase in male vigilance. It might also be a rutting effect that did not occur in unprotected areas because males vigilance was already maximal in response to human disturbances. In both sexes, yearlings were less vigilant than adults, probably because they traded off vigilance for learning and energy acquisition and/or because they relied on adult experience present in the group. Similarly, non-reproductive females benefited of the vigilance effort provided by reproductive females when belonging to the same group. However, in the absence of reproductive females, non-reproductive females were as vigilant as reproductive females. Increasing group size was only found to reduce vigilance in females (up to 17.5%), not in males. We also showed sex-specific responses to habitat characteristics. Females increased their vigilance when habitat visibility decreased (up to 13.8%) whereas males increased their vigilance when feeding on low quality sites, i.e., when concomitant increase in chewing time can be devoted to vigilance with limited costs. Our global approach was able to disentangle the sex-specific sources of variation in mouflon vigilance and stressed the importance of reserves in managing and conserving wild sheep populations.

What determines global positioning system fix success when monitoring free-ranging mouflon?

We have assessed behavioural and environmental factors influencing the success of global positioning system (GPS) fixes recorded from 15 collared free-ranging female Mediterranean mouflon (Ovis gmelini musimon x Ovis sp.). We have demonstrated that fix success was 8% lower in resting animals (0.81, 95% CI = 0.79–0.84) than in active animals (0.89, 95% CI = 0.86–0.91) at an average temperature (13.8°C), but was similar and relatively constant at lower temperatures. When temperatures increased above the average temperature, fix success strongly decreased in resting animals (0.44, 95% CI = 0.36–0.52 at 30°C) as compared to active animals (0.76, 95% CI = 0.65–0.85). These results probably involved behavioural changes in habitat use of mouflon, as temperature and activity strongly influence the use of cover in ungulates. We also found that the success of GPS fixes was influenced by habitat types, increasing from 0.76 to 0.93 (under average sky openness of 33%) along a continuum going from forested to open areas. After controlling for differences in vegetation, sky openness had a positive effect on fix success (from 0.76 to 0.97 in evergreen oak forest). Our approach based on free-ranging animals and using a robust interpolation procedure should provide biologists with a more reliable method to account for bias in GPS studies.

Ageing of ungulate pellets in semi-arid landscapes: how the shade of colour can refine pellet-group counts

Pellet-group counts can be useful in monitoring ungulate population trends, particularly in elusive species. In semi-arid areas, ambient conditions conserve the pellets during the dry season. Thus, dating of accumulated pellet groups should be helpful in approximating the numbers of ungulates present during any chosen part of the dry season. The aims of this study were to confirm that the decay rate of pellet groups was low during the dry season, to identify the major causes of decay and to test the usefulness of criteria, easily measurable in the field, in dating pellets. Every month during the dry season pellet groups of five African savanna ungulates were collected fresh and deposited on bare ground at an experimental site. The levels of hardness, cracking, scattering, attack by insects and shade of colour of the pellets were monitored until the rainy season started. As expected, only a few pellet groups decayed completely during the dry season. The pellets’ shade of colour was the best criterion to date them. We discuss pellet colour as an original tool for monitoring the trends in ungulate use of target areas in semi-arid environments.

Responses of Heather Moorland and Mediterranean Mouflon Foraging to Prescribed-Burning and Cutting

ABSTRACT We assessed the effects of prescribed burning and cutting on mouflon (Ovis gmelini musimon × Ovis sp.) spring habitat using an experimental design (17.28 ha) of 2 burned, 2 cut, and 2 untreated plots within a homogeneous stand dominated by heather (Erica cinerea and Calluna vulgaris). Overall, we found a shift in treated plots from ligneous species to herbaceous species with high digestive and energetic values for mouflon. We also found a consistently higher number of mouflon feeding on these treated habitats compared to untreated plots. Such effects were still apparent 4 years after habitat modifications. Our approaches could be used by managers to improve and maintain the range of mouflon populations experiencing habitat loss (e.g., woody plant encroachment) and for which the condition of an animal has often a high economical value through trophy hunting.

Errors in Age Determination of Mouflon in the Field

Abstract In mouflon (Ovis gmelini musimon × Ovis sp.) populations, most age-related ecological studies have used morphological characteristics to determine age categories in the field although the validity of this approach remains largely untested. We estimated error rates in age determination from observations of known-age mouflon in southern France. Based on repeated observations of 163 animals, we estimated the sex-, age- and time-variations in error rates. We showed that the age-related pattern of error was the same for both sexes and was not time dependent. Male (7.4% [6.7; 11.1] CI95%) and female (6.7% [3.2; 12.9] CI95%) lambs had a low and similar probability (P = 0.61) of error, whereas older mouflon, and more females (53.2% [43.2; 62.5] CI95%) than males (27.1% [19.2; 34.5] CI95%, P ≤ 0.001), had a high probability to be misclassified. Over and above the skill of the observers, the morphological criteria used to discriminate age categories probably account for these high and sex-specific error rates. To correct these errors, we recommend that: 1) criteria used in the field be tested on a sample of known-age animals from the studied population; or 2) field aging be restricted to well-defined age categories such as lambs, ewes, and rams.

Roaring counts are not suitable for the monitoring of red deer Cervus elaphus population abundance

The successful management of large herbivores requires the monitoring of a set of indicators of ecological change (IEC) describing animal performance, herbivore impact on habitat and relative animal abundance. Roaring counts during the rut have often been used to assess the abundance of red deer Cervus elaphus populations, but a formal evaluation of this method is still lacking. In this paper, we examined the usefulness of the number of red deer recorded during roaring counts for managing red deer populations. Using standardised spotlight counts applied for the monitoring of red deer at La Petite Pierre, France, as a reference method, we found that roaring counts did not correlate with spotlight counts. Moreover, we did not find any evidence that roaring counts decreased with increasing number of male and female red deer harvested in the reserve during the previous hunting season. We thus conclude that managers should not rely on roaring counts for managing red deer populations.