Does it exist a link between mother’s behavior and fawn’s survival?

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Systematic and distribution

The European roe deer (Capreolus capreolus) belongs to the Artiodactyla order and to the Cervidae family. The genus Capreolus includes two species: the Siberian deer (Capreolus pygargus, Pallas 1771) and the European roe deer (Capreolus capreolus, Linnaeus 1758). The European roe deer species is itself divided into several sub-species such as Capreolus capreolus Italicus inhabiting the Italian peninsula or Capreolus capreolus Garganta inhabiting the South of Spain (Fig. 1). The deer is a small-sized cervid (adults weigh about 20-30 kg, with a body length of 95-135 cm, Fig. 2) with low male-biased sexual size dimorphism (males are less than 10% heavier than females, Andersen et al. 1998) and strong territoriality of adult males (see Liberg et al. 1998). Most of the year, males carry antlers (25-30 cm) allowing us to distinguish them from females. These antlers grow from December to March and only fall the following fall (Danilkin and Hewison 1996).
During the last glaciation period, roe deer like numerous other species took shelter in the Mediterranean regions but with the warming episode, deer have largely increased their distribution. Hence, roe deer are present across all the European continent (except Ireland) with a high abundance in very different habitats (J. D. C. Linnell et al. 1998). Since the mid-XXth century, roe deer have colonized novel environments thanks to their high ecological and behavioral plasticity, the countryside desertion by humans and the decrease of its natural predators. Since then, roe deer is the most widely distributed and abundant large herbivore in Europe (around 15 million in Europe and more than 1.5 million in France; annual harvest x 6.1 over the last 30 years in France and since 2000 around 500 000 deer are killed every year; data ONCFS; see Fig. 3a,b) which ranks it as a species of ‘least concern’ by the IUCN (source: Red List of Threatened Species IUCN Version 2012.1). In France, it occupies woodland areas, but also highly fragmented environments where woodland habitat is fragmented (Hewison et al. 2001) as well as large agricultural plains without woodland patches (Cibien et al. 1989). Therefore, roe deer has been described as a successful species (R. Andersen et al. 1998).

Personality and demographic performance

Figure 1. The present distribution of European roe deer in western Europe. Source: IUCN 5international Union for Conservation of Nature) 2008.
Figure 2. Morphological differences between male and female roe deer.
Figure. 3. Variation of the number of roe deer shot in France until 2014.
a. Number of roe deer shot by region, b. Variation of the number of roe deer allowed to be shot (in light) and actually shot (in dark) in France from 1990 to 2014 (excluding enclosures). Source: Réseau Ongulés Sauvages ONCFS/FNC/FDC.

Biology and reproduction

Roe deer is a generalist herbivore which feeds on a large number of plant species such as grasses, crop plants, conifers, deciduous trees and shrubs, mosses, ferns, fungi or lichens (R. Andersen et al. 1998). This species is weakly gregarious, living alone or in small groups in most environments (Hewison et al. 1998).
Through various aspects of its breeding behavior, roe deer is unique among ungulates. Females in roe deer are commonly considered as non-territorial. Females seem to range independently of males, so that female ranges often overlap several male territories (e.g. Bramley 1970). During summer, they live solitarily (alone or only with their fawns) in overlapping home ranges (Bramley 1970; Strandgaard 1972). During winter, they form small matriarchal groups consisting of one or a few adults, their dependent offspring and yearling daughters. These groups are often accompanied by one or two males (Kurt 1968; Hewison et al. 1998). The reproductive cycle of female roe deer, with embryonic implantation delayed by five months (Lambert 2002) and only one short ovulation each year, is unique among ungulates (Fig. 4). Despite being monestrous, up to 98% of females in a population are fertilized (Gaillard et al. 1992; Hewison 1996). Females are polytocous: they give birth to 1-4 neonates in May-June, with twins being most common and four being extremely rare. Fawn body mass at birth is about 1.6 kg on average, but highly variable (Gaillard et al. 1993). They grow rapidly the first year to reach 70% of adult body mass at eight months old (onset of first winter, Hewison et al. 2011). Fawns adopt a hider strategy in the first three to four weeks of life (Linnell 1994). Indeed, in ungulates, the mother-young behaviors are represented by the ‘hiding-to-following’ spectrum (Geist 1971; Lent 1974). The species of these groups are basically classified as ‘hiders’ or ‘followers’ depending on whether the newborn lie concealed for their first few days or actively follow their mothers (Lent 1974; Ralls et al. 1986). When the pair has a ‘follower’ strategy, mothers remain in constant proximity with their offspring. ‘Hider’ offspring (Lent 1974), as roe deer fawns, lie hidden secluded from the mother for most of the time up to the age of 6-8 weeks (Espmark 1969; Linnell 1994). The mother visits the fawns three to seven times a day for care and changing of the bed site (Espmark 1969). Consequently, while ‘following’ has been viewed as a strategy for avoiding predators in open habitats and generally for group-living species, ‘hiding’ is thought to reduce predation risk in closed habitats or habitat with a protective cover for more sedentary species (Lent 1974; Estes and Estes 1979). ‘Hider’ offspring have a short detection radius making the searching systematically of predators uneconomical (Byers and Byers 1983) but, the distance between the mother and her newborn is important for not giving cues about the fawn’s location to predators. The mothers should maintain a minimum distance to the hidden offspring and should not look more in the direction of the newborn than in any other direction (Byers and Byers 1983; Fitzgibbon 1993). However, they should not stay too far away and thereby miss the chance to detect predators approaching the hiding place (Lent 1974; Litvaitis and Bartush 1980; Fitzgibbon 1993; Schwede et al. 1994). After weaning, they usually stay with their mother over their first winter before becoming independent when they reach approximately one year of age when most dispersal takes place (Wahlström and Liberg 1995; Debeffe et al. 2012). Both sexes disperse, females as one-year olds and males either as one-year olds or as two-year-olds. Females normally attain sexual maturity at 1.5 years of age, giving birth at 2 years old, but under favorable conditions they may become pregnant already as fawns (Hewison 1996) whereas under poor conditions first reproduction is often delayed one year until the age of 3 years old (Gaillard et al. 1992; Hewison 1996).
Figure 4. Reproductive cycle of male (not in italic) and female (in italic) roe deer.

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Personality and demographic performance

Adult males in roe deer are considered strongly territorial (Bramley 1970; Strandgaard 1972). Territorial males are aggressive and intolerant towards intruder males (adults and sub-adults). Aggressive behaviors can take the form of threat, advertisement and fighting. It is often ritualized in displays (e.g. parallel walk, rubbing, scraping, barking), chases and retreats, more rarely actual combat (Bramley 1970; Danilkin and Hewison 1996). Dominance appears mainly site-specific with reciprocity of dominance among neighboring territory holders: territorial males are dominant within their own territory, but subordinate when exploring a neighboring territory (Danilkin and Hewison 1996). Male territoriality is seasonal (Fig. 4). Territories are established in early spring (March-April) and maintained until late August – early September (e.g. Bramley 1970; Strandgaard 1972). Rut occurs from mid-July to mid-August.

Life cycle and demographic rates

The demographic rates of roe deer are largely influenced by the age structure of the population (Fig. 5). Roe deer survival follows the typical pattern of survival of many populations of vertebrates (Caughley 1966). There are three specific stages. A juvenile stage characterized by a low survival from birth to one year of age, a prime-aged stage with a high and constant survival during prime-aged stage (from one to seven years old) and a senescent stage with a decreasing survival from 8 years of age to death. In large herbivores such as roe deer, adult survival is stable among populations (except under very harsh climatic conditions) and among years, whereas fawn survival may fluctuate highly among years (Gaillard et al. 1998a). Fawn survival is a major driver of roe deer population dynamics (Gaillard et al. 1998a). For instance, in two French populations, fawn survival accounted for about 50-75 % of the variability observed in growth rate of populations, while adult survival accounted for less than 20 %. When focusing on fawn survival, two different components can be defined: one from birth to the onset of winter, the summer survival, and one from the onset of winter to spring, the winter survival (Gaillard et al. 1998a). Summer mortality is mostly dependent on maternal care. Thus, the availability of quality resources is crucial to offset the costs of late gestation and early lactation where the energetic needs dramatically increase (Clutton-Brock et al. 1989). Thus, the availability of quality resources is a key component of fawn summer survival and predation is another major cause of mortality in early-life (Linnell et al. 1995). Once the onset of winter is reached, most variation in fawn winter survival is care independent and depends on winter severity and density-dependent effects (Gaillard et al. 2000).

Table of contents :

Chapter I Introduction
I. Individual heterogeneity and consequences for population dynamics and demography
I.1. Population dynamics: from the population leve
II. Sources of individual heterogeneity: state of the art
II.1. Fixed heterogeneity
II.2. Non-fixed heterogeneity Box 1. Capital vs. Income breeders
II.3. Conclusion
III. Sources of individual heterogeneity: on the importance of personality
III.1. Definitions and history Box 2. Personality and co
III.2. Personality: who and where?
III.3. Personality and life-history traits
III.4. How and why personality exists?
III.4.1. Theoretical and evolutionary explanations: architecture of behavior
III.4.2. Adaptive explanations
III.5. Fitness consequences of personality
IV. Aim of the PhD
Chapter II Material and Methods
I. The roe deer as a study model
I.1.Systematic and distribution
I.2. Biology and reproduction
I.3. Life cycle and demographic rates
I.4. Roe deer as an important socio-economical species
II. The study
II.1. Study sites
II.1.1. Aurignac
II.1.2. Gardouch
II.2. Study populations
II.2.1. Aurignac
II.2.2. Gardouch
III. Data collection
III.1. Capture and behavioral data
III.2. Fawn capture
III.3. Spatial data
III.4. Cartography
III.5. Statistical analyses
Chapter III Into the wild…personality
Chapter IV Personality in captivity and its link with personality in the wild Synthesis
Part 1
Part 2
Chapter V Behavioral trade-off between two dimensions of a behavioral syndrome
Chapter VI Does it exist a link between mother’s behavior and fawn’s survival?
Synthesis
Part 1
Part 2
Chapter VII Discussion
Chapter VIII References

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