Population dynamics of the Grey Partridge Perdix perdix 1793–1993: monitoring, modelling and management

Abstract

The longest available bag record of Grey Partridges Perdix perdix in Great Britain (1793-1993) reveals a collapse of stocks after 1952 despite considerable annual variation. The annual fluctuations were attributable largely to annual variations in chick survival rate. The Game Conservancy Trust's National Game Census revealed that chick survival rates averaged 49% before the introduction of herbicides and 32% once their use became widespread. On a study area in Sussex. where spring density declined from around 21 pairs per km2 in 1968 to under four pairs per km2 in 1993, annual chick survival rates averaged 28% with no demonstrable trend. The annual over-winter "survival" rates in the area improved during 1968-1993, whereas brood production rates declined. Simulation modelling showed that a reduction in chick survival rate from 49% to 32% had little effect on spring stocks as long as nest predation was controlled but that stocks collapsed when nest predation control was relaxed. The effect of such a change in chick survival rate on population status was investigated by reference to 36 other studies in the literature. Amongst 20 studied populations which were stable, adjusting mean chick survival rates downwards produced demographic parameters characteristic of declining populations in all but two cases. Conversely, adjusting chick survival rates upwards for 16 declining populations made all but two stable. Diagnosing and remedying the causes of population change require a testable understanding of density-dependent factors and compensatory processes, best approached by a combination of monitoring, modelling and management.

Demographic parameters of reintroduced grey partridges in central Italy and the effect of weather

“…Higher population levels were found only for some areas in northern France and in England (Potts and Aebischer 1994;Aebischer and Ewald 2004;Bro et al 2005), and lower breeding densities were recorded in Italy, Austria, France, and Finland (Meriggi et al , 1992Turtola 1998;Bro et al 2000;Reitz 2003).…”

“…In our population, CSR fluctuated widely, and its values were close to those recorded in Britain, on areas with land management for conservation purposes (Aebischer and Potts 1998;Sotherton et al 1993). Potts and Aebischer (1994) pointed out that an increase in offspring survival rate could stabilise but not reverse most of the declining populations. In our case, CSR affects the change of breeding population, but no weather conditions explain their annual fluctuations.…”

“…The European populations of Grey partridge (Perdix perdix Linnaeus 1758) declined from mid-1950s onwards with the reduction and the marked fragmentation of their historical range, especially along the range boundaries (Potts 1986;Potts and Aebischer 1994;Putaala and Hissa 1998;Meriggi et al 2002;Aebischer and Ewald 2004;De Leo et al 2004;Panek 2005;Meriggi et al 2007). Population decreases occurred to such an extent that the species was considered threatened and vulnerable and was classified in the list of the Species of European Conservation Concern in the third category (i.e.…”

Understanding changes in bird populations – the role of bird marking

“…Such studies are increasingly being complemented by analyses of extensive data gathered at much larger spatial scales, building on the pioneering work of former BTO Directors David Snow (1966), andRaymond O'Connor (1980), which eventually gave rise to the BTO's Integrated Population Monitoring Programme (Baillie 1990(Baillie , 2001; Fig 1). The results from such studies should ideally be combined to produce population models that allow the effects of environmental change and management options to be explored, taking account of interactions between key relationships (Potts & Aebischer 1995, Aebischer & Ewald 2004. Where possible, predictions from such field studies and modelling should be tested through experiments.…”

THE REAL PERIODIC POPULATION GROWTH AS A BASE FOR DETERMINING THE DEGREE OF EXPLOITATION OF GREY PARTRIDGE (Perdix perdix L.) POPULATIONS IN MACEDONIA AND COMPARATIVE ANALYSIS OF OTHER METHODS USED

“…The suggested reduction of shooting bags (Birkan & Jacob, 1988;Potts & Aebischer, 1995) or suspension of hunting does not solve the problem of decreasing population number (Farago, 1996;Bro et al 2000; Aebischer & Ewald, 2010). Neither the supplementation and (re)introduction of artificially produced birds, according to the researches made in Italy (Meriggi et al, 2002) and in R. Croatia (Tomljanović et al, 2013), do not provide satisfactory results, and in some cases can cause even the opposite the effect in terms of decreasing the productivity of wild populations (Putaala & Hissa, 1998).…”