Density dependence of reproductive success in grey partridge Perdix perdix populations in France: management implications

Abstract

The understanding of the demographic and ecological mechanisms of population regulation is central in applied ecology, in particular when it comes to managing harvested populations. We document the density dependence of the reproductive success in French grey partridge Perdix perdix populations. We used long‐term data collected by the national network monitoring populations with a mere surveillance objective. We investigated a time series spanning 7–14 years for 85 replicate populations by a combined procedure of a regression of reproductive success against density for each population and a metaanalysis of the 85 regression slopes. We avoided two common statistical pitfalls by taking the autocorrelation in time series data into account and by using independent estimates of reproductive success and spring density. The relationship is statistically significant for 10% of the populations, and the meta‐analysis of the 85 replicates displays a highly significant pattern (82.3% of the regression slopes being negative). Thus our results both support the existence of a density dependent reproductive success in the grey partridge and moderate the ubiquity of the phenomenon, despite a general trend. We tested whether density dependence occurred through competition or habitat heterogeneity by examining the relationship between the variability of per capita reproductive success and pair density. Our results support both alternative hypotheses depending upon the area of concern. In terms of population and habitat management our findings have implications for hunting interests. The best strategy to maximise the hunting quota when reproductive success is depressed with increased density recommends intermediate values of both pair density and reproductive success, which conciliates hunting interests and conservation objectives. To alleviate density dependence, habitat management should supply limited resources that are homogeneously distributed in space when density dependence operates through competition, and should improve habitat quality of the poorest patches when density dependence operates through habitat heterogeneity.

Interannual variations of reproductive parameters in a booted eagle (Hieraaetus pennatus) population: the influence of density and laying date

“…abiotic variables, food availability) (Newton 1998). For example, the negative relationship between density and productivity is a widely observed pattern in many bird species (Ferrer and Doná zar 1996;Bro et al 2003;Sillet et al 2004), usually driven by a territorial behaviour mechanism with regulatory consequences for the populations (Rodenhouse et al 1997). The timing of breeding is another important factor influencing reproductive parameters (Aparicio and Bonal 2002).…”

Decoupling of component and ensemble density feedbacks in birds and mammals

“…No deviance is calculated for predictors that are not in top-ranked models. (Bro et al 2002), or the African elephant, Loxodonta africana, in Addo National Park, South Africa (Gough and Kerley 2006) (Table 4, Fig. 3).…”

Impact of habitat management on grey partridge populations: assessing wildlife cover using a multisite BACI experiment

“…First, they were located in a region where partridges were most abundant in the early 1980s and still abundant in the late 1990s (10-30 pairs km − 2 ; Reitz 2003). Secondly, they were part of the French grey partridge network so that historical data sets were available (Reitz 2000;Bro et al . 2003).…”

“…habitat management on managed areas), data were collected within the context of the French national grey partridge network, the objective of which is to survey partridge populations in central northern France (Reitz 2000): a time series of 10 -20 years exists for some areas (Bro et al . 2003).…”