Condition‐dependent natal dispersal in a large herbivore: heavier animals show a greater propensity to disperse and travel further

Abstract

Recherche 5558, Universite´de Lyon, Universite´de Claude Bernard Lyon 1, 43 boulevard du 11 novembre 1918, FR 69622, Villeurbanne Cedex, France Summary 1. Natal dispersal is defined as the movement between the natal range and the site of first breeding and is one of the most important processes in population dynamics. The choice an individual makes between dispersal and philopatry may be condition dependent, influenced by either phenotypic attributes and/or environmental factors. 2. Interindividual variability in dispersal tactics has profound consequences for population dynamics, particularly with respect to metapopulation maintenance. A better understanding of the mechanisms underlying this variability is thus of primary interest. 3. We investigated the ranging behaviour of 60 juvenile European roe deer, Capreolus capreolus, monitored with GPS collars for 1 year prior to their first reproduction, from 2003 to 2010 in South-West France. Dispersal occurs across a spatial continuum so that dividing individuals into two categories (dispersers vs. philopatric) may lead to information loss. Therefore, to investigate condition-dependent dispersal more accurately, we developed an individual-based measure of dispersal distance, which took into account interindividual variation in ranging behaviour. We assessed the influence of body mass, the degree of habitat heterogeneity and sex on dispersal initiation date, dispersal propensity and distance. 4. The overall population dispersal rate was 0Á34, with a mean ± SD linear distance between natal and post-dispersal home ranges of 12Á3 ± 10Á5 km. Dispersal distances followed a classical leptokurtic distribution. We found no sex bias in either dispersal rate or distance. Forest animals dispersed less than those living in more heterogeneous habitats. Heavier individuals dispersed with a higher probability, earlier and further than lighter individuals. Our individual-based standardised dispersal distance increased linearly with body mass, with some suggestion of a body mass threshold of 14 kg under which no individual dispersed. 5. Natal dispersal in roe deer was thus dependent on both phenotypic attributes and environmental context. Our results suggest that population connectivity can be altered by a change in average body condition and is likely higher in the rich and heterogeneous habitats typical of modern day agricultural landscapes.

The role of seasonality and non‐lethal carry‐over effects on density‐dependent dispersal

“…Given that dispersal can be energetically costly (Bonte et al 2011), delayed effects of density on dispersal caused by temporal variation in resources could be a widespread, but underappreciated, phenomenon (Morris and Diffendorfer 2004, Debeffe et al 2012, Bitume et al 2014. This is particularly important because humans are creating an increasingly disturbed and fragmented landscape, and it is widely recognized that the persistence of a species relies on the ability to explore and move through the landscape (Parmesan 2006, Swift and Hannon 2010, Post 2013.…”

The link between behavioural type and natal dispersal propensity reveals a dispersal syndrome in a large herbivore

“…Roe deer are medium-sized, slightly dimorphic and weakly polygynous mammalian herbivores that are widely spread across Europe [25]. Natal dispersal is not sex-biased in this species [26 -28], but heavier fawns disperse more frequently, earlier and further than lighter fawns, while fawns in pure forest disperse less than those in more heterogeneous habitats [27]. We controlled for this condition-and habitat-dependence while exploring the link between dispersal propensity and a suite of four behavioural traits (exploration, mobility, activity and stress response), encompassing three of the five major components of personality that are commonly recognized [29] (i.e.…”

Effects of rearing conditions on natal dispersal processes in a long‐lived predator bird

“…Natal dispersal is a key driver of the functioning, dynamics, and evolution of populations and metapopulations (Clobert, Baguette, Benton, & Bullock, 2012; Debeffe et al., 2012; Dobson, 2012; Greenwood & Harvey, 1982). The natal dispersal process involves a complex sequence of behaviors including departure from the natal site, transience, and settlement or recruitment, although it is commonly summarized as the movement of an individual from site of birth to site of first reproduction (Clobert et al., 2012).…”

“…Thus, postfledging survival may be influenced by nestling mass because heavier individuals are fitter and so are better equipped to cope with short periods of food shortage (Green & Cockburn, 2001; Hsu, Dijkstra, & Groothuis, 2017), for example. As well, larger and heavier individuals may be dominant over smaller lighter ones and thus will have an advantage when attempting to disperse and/or recruit successfully (Cam & Aubry, 2011; Debeffe et al., 2012; Green & Cockburn, 2001; Hsu et al., 2017). …”

“…Individuals raised under good conditions are more likely to stay in their natal environment due to a combination of low dispersal propensity and high competitive ability (Bowler & Benton, 2005; Clobert et al., 2012; Muriel, Morandini, Ferrer, Balbontín, & Morlanes, 2016). On the other hand, high‐quality individuals may also be better competitors and/or be better able to bear the costs of dispersal, in which case the quality of the rearing environment might in fact have a positive rather than negative effect on dispersal (Bonte et al., 2012; Bowler & Benton, 2005; Clobert et al., 2012; Debeffe et al., 2012). So, as long‐distance dispersal is energetically expensive and may involve a high mortality risk, the acquisition of a good body condition prior to dispersal plays a critical role in determining the extent to which animals disperse (Barbraud, Johnson, & Bertault, 2003).…”