Marie-Line Maublanc

Herd Size in Large Herbivores: Encoded in the Individual or Emergent?

In large mammalian herbivores, the increase of group size with habitat openness was first assumed to be an adaptive response, encoded in the individual. However, it could, alternatively, be an emergent property: if groups were nonpermanent units, often fusing and splitting up, then any increase of the distance at which animals perceive one another could increase the rate of group fusion and thus mean group size. Dynamical models and empirical data support this second hypothesis. This is not to say that adaptive modifications of mean herd size cannot occur. However, this changes the way in which we can envisage the history of gregariousness in large herbivores during the Tertiary.

Inter-individual associations and social structure of a mouflon population (Ovis orientalis musimon)

We analysed individual associations between mouflon (Ovis orientalis musimon) observed during one year in order to find ontogenetic patterns underlying the social structure of the population. A correspondence factorial analysis was performed on Simpsons coefficients to compare association profiles. No strong association was found between adults but some of the young adult females maintained a preferential bond with their mother until the age of three. Yearling males were firstly unstable in their social relations and subsequently developed a strong preference for peers (the preferred companion(s) of young adult males were always young adult males). Animals did not prefer to associate with other individuals of their own family (Wilcoxon test: n = 53; z = 0.463; a < 0.01). Localized abundant food sources caused large regroupings during spring. This was the only case where we noted a series of observations where the same unrelated animals were seen together. With the exception of the mother-offspring relationship, individual social preferences were based on the sex and age of the partner rather than on identity. The existence of social behaviour profiles dependent on sex and age is proposed to explain the above results.

Spatial structure and activity in groups of mediterranean mouflon (Ovis gmelini): a comparative study

Abstract The spatial structure of groups of Mediterranean mouflon was compared during spring/summer in a small population living on a sandy terrace in eastern Germany and within part of a large population inhabiting a low mountain in southern France. A similar comparison was also conducted throughout the year in the French population. The aim of the study was to define proximate mechanisms participating in the spatial structure of the groups. We measured the proximities in the group, distances to nearest neighbours and activity of the individuals according to their sex and age. Lambs and females were closer to each other than to the other individuals on average at both sites and throughout the year (closer in 55–57% of the couples). Lambs tended to be central to the groups and females peripheral (19 groups with central lambs vs. eight groups with peripheral lambs in Niederfinow in spring/summer, P = 0.04). Lambs, yearling males and adult males were closer to peers but some variations were found between sites and periods. The distance to the nearest neighbour was not clearly correlated with the frequency of association. The proportion of individuals behaving like their nearest neighbour was higher when the distance between them was short (Niederfinow, spring/summer: N = 8, ϱ = −0.857; Vialais, autumn/winter: N = 8, ϱ = −0.976). This was no longer true when lambs were excluded from the analyses. Nearest neighbours were close when both were engaged in the same activity other than feeding, they kept a medium distance when both were feeding and they were more distant when only one of them was feeding. The differences between the two populations did not affect the spatial behaviour of the individuals in the groups except for a slight tendency of the animals to be closer in the German population. We propose an explanation of the spatial structure of the groups based on the behavioural characteristics of the different sex and age classes and we discuss the concordance of our results with those found in domestic species.

Effects of Age and Sex on Space Occupation by European Roe Deer

The effects of age and sex on annual home-range characteristics of European roe deer ( Capreolus capreolus ) were investigated by means of radiotracking individuals from a high-density population within a deciduous forest. Subadult males often used more diffuse home ranges than did adults and subadult females, whereas old males exhibited the most concentrated pattern of space occupation. Subadult males also showed a higher dispersal than did subadult females. Such results contrast with those obtained at low densities and suggest that population density influences the process of range acquisition in a sex-dependent way, probably because of the retention of territoriality by adult males at high densities.

Philopatry in mouflon rams during the rutting season: Psycho-ethological determinism and functional consequences

Our study of mouflon (Ovis musimon) rams in the Caroux-Espinouse massif (southern France) shows that several forms of philopatry occur. Some of the rams were sedentary, as were the ewes, up to the age of four years. Most of the rams, however, started to enlarge their home range from the age of two years. Rams of intermediate age visited their birth ranges during various periods of the year, whereas the adult males returned only during the rut. As potential mates were present on the home ranges of most of the dispersive males, it is difficult to interpret this process merely in terms of adaptation. We propose, instead, a psycho-ethological explanation, whereby the physiological disturbances intervening during the rut alter the significance of the range, the ram having to update the whole set of its sensory-motor past. This interpretation suggests that the animal has no representation of any pre-defined place, nor of any fixed aim. Rams would be able to reduce the imbalances they experience by creating a type of behaviour driven by a self-referential process, where spatial investment would outweigh any other evaluation, as an adaptative cost related to a possible inbreeding. This approach leads to reconsider the importance of spatial investment in animals cognition and generally speaking the way an animal relates to its environment.

Population subdivision among mouflon sheep (Ovis gmelini) ewes and ranging behaviour of rams during the rut

Population subdivision among mouflon sheep Ovis gmelini ewes and ranging behaviour of rams were investigated in the Caroux-Espinouse massif (southern France). Radio-tracking data from 32 ewes and 41 rams monitored in the course of a 10-year study were used to identify female units and to document the movement patterns of males during the rutting period. Cluster analyses, based on the distance between arithmetic centres and on the degree of overlap of locations, were computed. Ewes were found to be partitioned in three or four main units to which they were faithful. Movement patterns of rams were much more variable: half were faithful to a rutting range, overlapping one or more unit(s), and the others were not. We suggest that a combination of social and spatial attachment could explain this ranging behaviour. Females build up their spatial habits following their mothers and, when adults, they occupy the area where they have been reared. Their spatial attachment is consistent with their social preferences for other females. Males balance between antagonistic spatial attachment and social preferences for other males, and differ in terms of spatial behaviour. The genetic implications are discussed.

Survival and spatial fidelity of moufl on (Ovis gmelini): A Bayesian analysis of an age-dependent capture-recapture model

We study the influence of age and sex on survival and spatial fidelity of moufl on (Ovis gmelini) in the Caroux-Espinouse massif. Survival and movement probabilities are estimated through a Bayesian analysis of an age-dependent capture-recapture model. Prior information is based on external data, namely on radio-tracked animals. Recapture rates differed between age, sexes, and areas. Whatever the area, survival of males and females less than 5 years old was high and decreased for older animals, particularly males. Female spatial fidelity was high; males were as faithful as females to their capture area in their first 2 years of life but gradually used distinct areas in two successive years as they were getting older.

Dispersal patterns of Corsican mouflon ewes: importance of age and proximate influences

Abstract The dispersal patterns of radio-collared Corsican mouflon ( Ovis musimon ) ewes inhabiting a low Mediterranean massif in the south of France were followed. Despite spatial instability being more marked in winter and spring, females ( n = 17) remained on a single home range. The changes in spatial behaviour which appeared in March did not seem to be linked solely to ecological parameters. The use of the spring range was particularly noticeable among the different seasonal ranges since it was characterised by long-distance movements ( n =16, x =740±320 m) and the large overall area used ( x =330±90 ha). The age of individuals had an important influence on space use. With increasing age, spatial patterns became more firmly fixed, which appeared to be linked to a better understanding of the different ecological and social contexts occurring in the population. Some characteristics of spatial behaviour may create certain management difficulties in the introduction or reintroduction of the species. Age and season seem to have a strong effect on the organization of spatial patterns. Managers and hunters should therefore consider the implications of the age of individuals and thus their stage of development, and also of the season, to guide management decisions. For example, disturbance of young individuals must be strictly limited, particularly during the spring and the rut which appear to be important periods in the organization of spatial behaviour patterns.

Short-term browsing by roe deer has little effect on survival and growth of sessile oak seedlings

We studied the effect of roe deer (Capreolus capreolus) browsing on the growth and mortality of sessile oak (Quercus petraea) seedlings. First, we measured the height and basal diameter, and counted the number of shoots of the 849 seedlings of an experimental plantation, 60 of which were individually protected by fencing. We then introduced two tame roe deer females every day for three weeks from late May to mid-June. Measurements and counts were repeated after roe deer removal, then once again the following winter. We found no significant effect of browsing on mortality, total height, or basal diameter of the seedlings. However, the browsed seedlings exhibited a lower number of shoots despite regrowth observed after roe deer removal. We propose to use the tolerance of oak to deer browsing to promote natural and inexpensive methods, to protect oak during regeneration, such as the spatial arrangement of plants or the use of slash or surrounding vegetation in favourable environments.

Experimental evidence of socio-spatial intolerance between female roe deer

Female roe deer tend to live in mixed-sex groups in winter but in solitary manner on reduced home ranges in spring. This tendency is commonly related in the literature to the rearing of hiding fawns. We studied the socio-spatial relationships between six female roe deer, introduced at 1 year of age into a partly wooded 14.2-ha enclosure. Animals were monitored with GPS telemetry collars for a period of 3 years, a male being added at the end of the 2nd year. Females did not share large overlapping home ranges. In the absence of any male and offspring, they spread out in May–June (birthing season) and in July-August (rutting season). During these seasons, the size and overlap of their home ranges were minimal, while the mean distance between the arithmetic centres of their respective locations reached its maximum value and was greater than expected under the hypothesis that the females positioned their ranges independently of one another. Related females were not preferentially associated beyond 2 years of age. Moreover, the introduction of a male affected this spatial organisation only slightly. Overall, the socio-spatial organisation of female roe deer appears to be almost independent of their reproductive status, and very similar to that of males, as is the case in a number of other small-bodied ruminants.