Does sex matter in reintroduction of griffon vultures Gyps fulvus

摘要: M. Bose´, P. Le Gouar, C. Arthur, J. Lambourdie`re, J.P. Choisy, S. Henriquet, Lecuyer, Richard,C. Tessier and F. SarrazinAbstract In small populations of monogamous speciessex ratio bias sex-skewed demographic traits couldlead to higher extinction probabilities than in othermating systems. Therefore a knowledge sexratio, mortality movement would be useful todetermine the optimal strategy for sampling foundersprior reintroduction. We used molecular sexing sexwild-hatched cohorts two colonies (one native andone reintroduced) four released groups griffonvultures Gyps fulvus France. wild-hatched cohortsthe sex was not different from equilibrium what-ever year. Similarly no detected sexratio founding stocks. Recoveries, recaptures, move-ments philopatry were skewed according tosex groups. Our studyrevealed that occurred during griffonvulture life cycle (i.e. birth, death movement).Consequently, random may appropriate toconstitute stock reintroduction programmesfor monomorphic vultures.Keywords Founding stock, France, griffon vulture,Gyps fulvus, sexing, mortality, reintroduction,sex ratio.IntroductionThe proportion males females, i.e. ratio, is animportant factor success newly foundedpopulation (Sarrazin & Legendre, 2000). According toFisher’s (1930) Trivers’ (1972) theories on sexualselection, equilibrated at birth expected inmonogamous species (Cockburn et al., 2002) but differ-ential pressures sexes could occur lead toskewed or dispersal (Gowaty, 1993; Bradshawet 2003). Sex among sexually mature individualsis often male biased (Bessa-Gomes 2004). Moreover, species,stochastic fluctuations populationcould probability systems (Legendre 1999) affecteffective population size by increasing reproductivevariance individuals (Anthony Blumstein,2000). Biased sex-ratio also cause an Allee effect,mostly because limited mate finding (Stephens S Engen 2003).Therefore, sexuallymature required maximize reintroductionsuccess with 1:1 thisratio will growth rate (Legendre,2004). For example, re-establishment monoga-mous white tailed sea eagle Haliaeetus albicilla inScotland slow chance differences thenumbers females led significantnumber failing form pairs (Greenet 1996). Unequivocal identification ofindividuals appears essential projects(Griffiths Tiwari, 1995; IUCN, 1998) but, when select-ing founders, uncertain young mostspecies adults species. Insuch cases usually adopted collectindividuals randomly wild populations, hopingfor balanced group. However,this implies indemographic such as isnot skewed.