The decline of the grey partridge in Europe: comparing demographies in traditional and modern agricultural landscapes

The Grey Partridge Perdix perdix is a European Species of Conservation Concern and a priority species under the UK Biodiversity Action Plan. The Game & Wildlife Conservation Trust (GWCT) launched a major programme to help partridge recovery in the UK, built on the GWCT’s Partridge Count Scheme (PCS) and including a demonstration site from 2002. We contrast the national picture of no population change since 1999 from BTO monitoring with a doubling of spring pair density on PCS sites. At the demonstration site, where set‐aside was used for habitat creation, Grey Partridge breeding density increased six‐fold, to 18 pairs/km2, then fell back. The drop coincided with bad weather but also with the disappearance of rotational set‐aside when the set‐aside rate fell to zero, which halved the amount of brood‐rearing habitat. Non‐rotational set‐aside remained unchanged, as did the amount of nesting habitat that it provided. Grey Partridge density was significantly linked to rotational set‐aside, especially wild bird cover, but not to non‐rotational set‐aside. The demonstration project also showed that, with appropriate precautions, it was possible to shoot over 60% of Red‐legged Partridges Alectoris rufa while maintaining Grey Partridge losses below 5%. On PCS sites, the annual change in spring density in recent years differed in relation to neither shooting pressure nor intensity of Red‐legged Partridge releasing. Provision of brood‐rearing habitats and game cover increased with the latter, and probably counteracts the shooting losses of Grey Partridges on Red‐legged Partridge shoots when, as on PCS sites, active measures keep those losses below 20%. Targeted personal advice channelled through the PCS has been fundamental to these successes and must be expanded.

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“…In parts of Europe, Grey Partridge shooting has been unsustainable (Renzoni 1974, De Leo et al. 2004).…”

Section: Discussionmentioning

confidence: 99%

Grey Partridge Perdix perdix in the UK: recovery status, set‐aside and shooting

Aebischer

Ewald

2010

Ibis

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“…Percentage of deaths from lead shot ingestion for the common buzzard, red kite, and grey partridge were modeled as 0, 9, and 4%, respectively for direct proximal cause of death. The data sources for these estimates of mortality caused by lead shot and other causes were: a wild common buzzard population in the UK [ 22 ], a reintroduced red kite population in the UK [ 21 ], the partridge population in continental Europe for hunting mortality [ 10 ], and a mix of wild and released partridges for non-hunting mortality in the UK and France [ 20 , 23 , 25 ]. For potential ultimate cause of death, the percentages were modeled as 5, 16, and 7% for the buzzard, kite, and partridge, respectively (using raptor elevated subclinical [≥ 6.5 mg/kg dw] liver lead concentration and partridge “bad” body fat data [ 21 – 23 ], Fig 1 ).…”

Section: Methodsmentioning

confidence: 99%

“…Quasi-extinction is the probability of a population size declining below a specified threshold of concern greater than zero. We focus on probabilities of quasi-extinction rather than ultimate extinction (i.e., when no individuals remain) because of phenomena that act on very small population sizes such as inbreeding, the Allee effect, and demographic stochasticity [ 37 ], which our models do not take into account [ 10 ]. Therefore, our estimates of extinction probability are higher than estimates of probability of ultimate extinction.…”

Section: Methodsmentioning

confidence: 99%

“…For the grey partridge, we first ran the stochastic, demographic population model published by De Leo et al [ 10 ] for the continental population of grey partridges in Europe (equations in their appendix and S1 Fig ). This partridge population was at a relatively high steady-state density in the 1930s to 1960s and then decreased to a lower steady-state density until 1995, when it appeared to decrease again to an even lower steady state [ 10 , 14 , 38 ]. De Leo et al [ 10 ] parameterized their model and density-dependent relationships for spring population growth rates and autumn/winter mortality using empirical data for the middle period of 1965 to 1993 [ S1 Fig ].…”

Section: Methodsmentioning

confidence: 99%

“…Population-level changes were evaluated by (1) estimating the proportion of total mortality attributable to lead shot ingestion or poisoning using empirical mortality data from field studies in the United Kingdom (UK) or France and (2) comparing change in population size and extinction risk with and without such mortality using population viability analysis models. This approach is often taken to assess effects of stressors on wildlife population trends [ 8 – 10 ]. Data from laboratory toxicity studies are less useful than empirical mortality data because laboratory studies cannot provide exposure or annual mortality rates of lead shot or poison ingestion for populations; instead, they only provide mortality rates of individuals exposed to chemicals at laboratory-selected intensities, durations, and frequencies.…”

Section: Introductionmentioning

confidence: 99%

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Can Ingestion of Lead Shot and Poisons Change Population Trends of Three European Birds: Grey Partridge, Common Buzzard, and Red Kite?

Meyer

Francisco

et al. 2016

PLoS ONE

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Little is known about the magnitude of the effects of lead shot ingestion alone or combined with poisons (e.g., in bait or seeds/granules containing pesticides) on population size, growth, and extinction of non-waterbird avian species that ingest these substances. We used population models to create example scenarios demonstrating how changes in these parameters might affect three susceptible species: grey partridge (Perdix perdix), common buzzard (Buteo buteo), and red kite (Milvus milvus). We added or subtracted estimates of mortality due to lead shot ingestion (4–16% of mortality, depending on species) and poisons (4–46% of mortality) reported in the UK or France to observed mortality of studied populations after models were calibrated to observed population trends. Observed trends were decreasing for partridge (in continental Europe), stable for buzzard (in Germany), and increasing for red kite (in Wales). Although lead shot ingestion and poison at modeled levels did not change the trend direction for the three species, they reduced population size and slowed population growth. Lead shot ingestion at modeled rates reduced population size of partridges by 10%, and when combined with bait and pesticide poisons, by 18%. For buzzards, decrease in mean population size by lead shot and poisons combined was much smaller (≤ 1%). The red kite population has been recovering; however, modeled lead shot ingestion reduced its annual growth rate from 6.5% to 4%, slowing recovery. If mortality from poisoned baits could be removed, the kite population could potentially increase at a rapid annual rate of 12%. The effects are somewhat higher if ingestion of these substances additionally causes sublethal reproductive impairment. These results have uncertainty but suggest that declining or recovering populations are most sensitive to lead shot or poison ingestion, and removal of poisoned baits can have a positive impact on recovering raptor populations that frequently feed on carrion.

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Spatial movements of grey partridge Perdix perdix: male-biased spring dispersal and effect of habitat quality

Šálek

Marhoul

2008

J Ornithol

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The Grey Partridge Perdix perdix is a sedentary species with a surplus of males in spring populations. It experienced a dramatic decline in Europe primarily due to habitat loss that may have forced the species to modify its dispersal behaviour, a less transparent source of populations threats. We analysed the dispersal patterns of Grey Partridges during pre-and post-breeding periods in two landscapes with different habitat quality in the Czech Republic. Grey Partridges tended to pair off quickly, with most pre-breeding movements executed in pairs. The birds usually dispersed over a few hundred metres indicating that the habitat conditions in a landscape with a carrying capacity of 2-5 pairs/1 km 2 was not below the threshold initiating strong dispersal, as observed in extreme habitats and at the northern limits of the specieś distribution range. A few single males that had remained unpaired until April also finally bred. However, the high level of sedentariness of males in a good landscape suggested that males prefer to stay near wintering sites unless habitat sources become limited. Unlike the males, the females dispersed in a wide range of distances with an extensive overlap in both landscapes. Autumn movements did not differ between the sexes, but were longer than the pre-breeding movements and increased in a poor landscape. We conclude that both reduced habitat availability and reduced mating opportunities initialise primarily male-biased breeding dispersal in Grey Partridge populations.

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The decline of the grey partridge in Europe: comparing demographies in traditional and modern agricultural landscapes

Cited by 29 publications

References 60 publications

Grey Partridge Perdix perdix in the UK: recovery status, set‐aside and shooting

Grey Partridge Perdix perdix in the UK: recovery status, set‐aside and shooting

Can Ingestion of Lead Shot and Poisons Change Population Trends of Three European Birds: Grey Partridge, Common Buzzard, and Red Kite?

Spatial movements of grey partridge Perdix perdix: male-biased spring dispersal and effect of habitat quality

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