Determinants and costs of natal dispersal in a lekking species

Abstract

Avoidance of competition and inbreeding have been invoked as the major ultimate causes of natal dispersal, but proximate factors such as sex, body condition or birth date can also be important. Natal dispersal is expected to be of particular importance to understanding the ecological and evolutionary implications of dispersal strategies, since 1) numerous evidences suggest that individual differences in dispersal strategies are expressed early in life (i.e. at the onset of dispersal movement), 2) ultimate and proximate factors are more likely to act during this stage and 3) this stage is associated with the highest mortality rates in most vertebrates. We analysed the natal dispersal (hereafter, dispersal) behaviour in 100 marked individuals of a lekking species, the North African houbara bustards Chlamydotis undulata undulata, during four years. We investigated the effects of proximate factors on dispersal pattern and distance, as well as the mortality cost associated with movement using multievent models, allowing uncertainty in sex assignment and mixture of live recaptures and dead recoveries. Overall, males exhibited longer dispersal distances than females, contrary to the common pattern in birds. Moreover, males in poorer body condition moved further than those in better condition, whereas distance was independent of body condition in females. Finally, survival rates during dispersal were lower for females than for males and were negatively correlated with the distances covered with a similar distance‐survival slope in the two sexes. Collectively, our results suggest that 1) there is substantial dispersal cost in both sexes, 2) dispersal is strongly male‐biased, 3) this bias is unlikely to be explained by differential movement costs of each sex, and 4) dispersal differences found across different categories of individuals are in broad agreement with both the inbreeding avoidance and intraspecific competition mechanisms for dispersal.

Sex-specific dispersal responses to inbreeding and kinship

“…Sixty-five birds were recaptured in the wild before the end of their transmitters' life span (1e3 years) and fitted with a new transmitter (20 g model RI-2D-M). Two trapping methods were used: snares at a male display site around a stuffed dummy female houbara from the ECWP captive breeding for trapping males or snares around a nest or wild-caught chicks for trapping females (Hardouin et al, 2012;Hingrat et al, 2004;Seddon, Launay, Van Heezik, & Al Bowardi, 1999). In the latter method, all of the chicks in the nest were captured (to avoid abandonment by the female) by hand and restrained in a fabric bag large enough to contain all of the chicks, and this bag was placed under a bush surrounded by snares.…”

“…Finally, when harnesses were retrieved without the bird in the field, we considered the bird to be dead (feathers and/or blood found close to the harness). The radiocollars appeared to have no effect on houbara survival once the birds were released (for details on wild and released houbara survival probabilities, refer to Hardouin et al, 2012Hardouin et al, , 2014Hardouin et al, , 2015. Sixty-five birds were recaptured in the wild before the end of their transmitters' life span (1e3 years) and fitted with a new transmitter (20 g model RI-2D-M).…”

“…Le Gouar, Mihoub, & Sarrazin, 2012), the evolutionary mechanisms that drive dispersal may persist in captive-bred generations (e.g. the repeatability and heritability of exploratory behaviour: Dingemanse, Both, Drent, van Oers, & van Noordwijk, 2002; the consistency of individual personality across captive and wild environments: Herborn et al, 2010; sex-biased dispersal in wild-born and captive-bred houbaras: Hardouin et al, 2012Hardouin et al, , 2014. Captive-bred individuals provide a quasiexperimental opportunity to investigate the effects of environmental (e.g.…”

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

“…In the case of young females (3 year old and younger), the NDD had a clear positive relationship with body condition, a pattern not observed in older females. In fact, if dispersal is fueled by stored energy, a disperser with large energy stores (good body condition) might be able to encounter, visit, and sample a larger number of potential habitats before running out of energy than a disperser with low energy resources (Hardouin et al., 2012; Stamps, 2006; Tilgar et al., 2010). This has been reported in ground squirrels Spermophilus beldingi (Holekamp & Sherman, 1989), eagle owls Bubo bubo (del Mar Delgado et al., 2010), greater flamingos Phoenicopterus ruber roseus (Barbraud et al., 2003), and Spanish Imperial eagles Aquila adalberti (Soutullo et al., 2013).…”

“…(2009) suggest that the probability of surviving to independence is closely related to a nestling’s own quality or body condition. In fact, the onset of dispersal is generally associated with high mortality rates due to predation, stress, energy depletion, and the lack of familiarity with novel environments (Hardouin 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.…”