No abstract

The habitat suitability index, which reflects spatial variability in species occurrence probability, has been shown to exhibit various contrasting relationships with local demographic performances (survival, productivity) in several species. One proposed explanation for these discrepancies is that the link between the habitat suitability index and demography is influenced by density‐dependent, temporally variable processes. Based on the survival rates of more than 3,000 nests monitored over 12 years in the North African Houbara Bustard, we investigated whether the habitat suitability index computed over the species breeding range is related to nest survival throughout the breeding season, accounting for variation in meteorological conditions. We found that the relationship between the habitat suitability index and nest survival progressively changes along the breeding season and that this intra‐annual variation is consistent between years. Our results support the hypothesis that variation in space use occurs intra‐annually and that biotic interactions throughout the breeding season strongly influence the habitat suitability index–demography relationship.

Summary With a decline exceeding 30% over three generations, the once-common European Turtle-dove is now considered globally threatened by IUCN. As a legal game species in 10 European countries, the recent International Single Species Action Plan for this species highlighted the need to carry out an assessment of the sustainability of current levels of hunting. In 2013–2014, the Western European population was estimated at 1.3–2.1 million pairs, and the hunting bag in the same region to be 1.1 million birds. Using the Demographic Invariant Method, we assessed whether current levels of hunting harvest within Europe constitute overexploitation of the western flyway European Turtle-dove population. We calculated the maximum growth rate λmax that a population might achieve in the absence of any additive mortality. Then we estimated the potential maximum harvestable population fraction (P) allowed by excess population growth. We explored a wide range of plausible scenarios relating to assumed demographic rates, geographic scope of the flyway and management objectives. λmax was estimated to lie between 1.551 and 1.869. Current levels of hunting along the western flyway are more than double the sustainable fraction (P) under all suitably conservative scenarios, and only fall below this threshold under the most restrictive assumptions. We conclude that current levels of legal hunting along the western flyway are unlikely to be sustainable. Reducing uncertainty associated with assessments of the sustainability of turtle dove hunting will require improved information on (in order of decreasing importance) current levels of hunting, adult survival, age structure and population size.

The success of translocation programmes is reflected by the ability of translocated individuals to survive and reproduce in their new environment. However, it has previously been reported that translocated individuals have lower demographic performance than their wild-born conspecifics, due to management and individual factors (such as release conditions or age).Here, we study six breeding parameters in free-ranging females of the North African Houbara bustard (Chlamydotis undulata undulata) and compare these parameters between captive-bred released (n=204) and wild-born (n=101) birds, considering the age of individuals and the period of release (autumn versus spring). Our results indicate that (1) captive-bred released females successfully breed in the wild; (2) for three out of the six breeding parameters studied, released females show lower performances than wild-born females; but, (3) Although we observed consistently reduced breeding performances in one year old females relative to older females, 2 we did not uncover any interaction between age and the origin of females, suggesting that the impairment of breeding parameters in released females is long lasting; and, (4) interestingly, this impairment of breeding parameters depends on the period of release, with lower breeding performances for spring releases compared to autumn releases. Overall, our study highlights the capacity of captive-bred females to reproduce in the wild, contributing to the dynamics of the population beyond their individual history. Our results also uncover complex variations of breeding parameters in translocated birds, but suggest that these differences can be minimized through an appropriate translocation strategy.