Managing the UK Grey Partridge Perdix perdix recovery: population change, reproduction, habitat and shooting

In 1995, the UK Government designated the Grey Partridge Perdix perdix as a priority species under its Biodiversity Action Plan (BAP). The Game Conservancy Trust (GCT), nominated as lead partner for the species, launched a programme to help Grey Partridge recovery by (1) raising awareness among the shooting and farming communities, (2) encouraging land managers and local BAP groups to conserve Partridges by setting numerical targets and offering feedback from counts on how to increase numbers, and (3) motivating by example by setting up a site demonstrating management techniques and the increase in Partridge abundance that ensues. Building on past research, we quantify the amount of habitat management required to achieve the BAP targets of halting the decline and achieving population recovery. Using three major GCT databases, (1) the National Gamebag Census, which collates data on shooting bags and gamebird releasing in the UK, (2) the Partridge Count Scheme, which monitors national Partridge density and reproduction, and (3) the Sussex Study, which monitors local Partridge population dynamics over 37 years, we emphasize the importance of good breeding success for increasing densities, review the evidence that management can be successful and evaluate the impact of shooting on Grey Partridge conservation.     

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

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.     

Species differences in diet and the development of seed digestion in partridge chicks Perdix perdix and Alectoris rufa

Chicks of both the Grey and the Red-legged Partridge feed on arthropods and plant material, mainly leaves and seeds. Fully grown partridges are mainly herbivorous and the proportion of plant material eaten increases rapidly during early life in both species, but plant material predominates in the diet of the Red-legged Partridge from an earlier age than for the Grey Partridge. Red-legged Partridge chicks are also able to disrupt grass seeds efficiently during passage through the digestive tract from an earlier age (2 days) than Grey Partridge chicks (10 days). It is suggested that the difference in timing between species in the development of herbivory is associated with this difference in digestive ability.     

Impacts of birds of prey on gamebirds in the UK: a review

The influence of predators on the distribution, density and dynamics of their prey species has long been of interest to ecologists and wildlife managers. Where the prey population is also utilized by humans, conflicts may arise through competition for a limited resource. Because gamebird shooting in the UK provides employment, recreation and income, the impact of birds of prey on gamebird populations has been the subject of intense debate for many years. Various approaches have been used to assess the impacts that raptors have on gamebird populations. Here we review the applicability and limitations of the methods used and assess the scientific evidence for population-level and economic impacts of raptors on gamebird populations in the UK. Raptors may, in some situations, take large numbers of gamebirds and may be an important proximate cause of mortality, although few studies have addressed the impacts of raptors on either breeding or pre-shooting densities. Two exceptions are studies of Hen Harrier Circus cyaneus , Peregrine Falcon Falco peregrinus predation on Red Grouse Lagopus lagopus scoticus on moorland in Scotland and Sparrowhawk Accipiter nisus predation on Grey Partridge Perdix perdix on farmland in England. Both these studies suggested that raptors could have population-level impacts when their gamebird prey was already at low density. Studies on predation of captively bred gamebirds suggest that numbers taken by raptors at release pens vary considerably and in a few cases raptors have been documented killing relatively large numbers. On the whole, however, it appears that raptors account for a relatively small proportion of mortality among released birds and the impact on subsequent shooting bags is unknown. We summarize important gaps in current knowledge and recommend specific areas for future research.     

Comparing call-playback to an observation-only method to survey Grey Partridge Perdix perdix on hill farms in northern England

Capsule: Call-playback in spring can be a practical method to survey Grey Partridges Perdix perdix in rough grasslands with abundant cover. However, further research is required to investigate movements and other responses to call-playback.

Aims: To compare call-playback with an observation-only method to survey Grey Partridges in rough grasslands with abundant cover, and to undertake a pilot study to consider whether bird behaviour conforms to point distance sampling assumptions.

Methods: Grey Partridges were surveyed using two separate methods: call-playback and observation-only, at 10 equally spaced points along 14 independent 4?km routes at 3 study sites in northern England. Surveys were undertaken at dawn and dusk in spring (March and April) and again in summer (August and September).

Results: In spring, call-playback registered at dusk fourfold and at dawn almost twice as many Grey Partridge encounters as the observation-only method. Methods did not differ in summer. In spring, using call-playback registered three times more encounters in rough grasslands with tall, dense cover than the observation-only method. Methods did not differ in summer. Grey Partridge encounter density estimates did not differ significantly between methods or seasons.

Conclusion: Using call-playback in spring increased the numbers of Grey Partridge encounters and can be a practical survey method, but further research is required to compare results against known populations and to investigate movements and other responses to call-playback, which may violate distance sampling assumptions.     

The survival of gamebird (Galliformes) chicks in relation to pesticide use on cereals

Field experiments were carried out to test the effects of cereal pesticides (herbicides, fungicides and insecticides) on chick survival of Grey Partridge Perdix perdix , Red-legged Partridge Alectoris rufa and Pheasant Phasianus colchicus. On fields in experimental plots the outer 6 m of cereal (the headland) were not sprayed with pesticides from 1 January 1984, whereas control plots were fully sprayed. Gamebird brood counts were carried out after the cereal harvest. In addition, nine Grey Partridge broods were radio-tracked for 21 days after hatching (four in sprayed plots and five in unsprayed plots) to determine their movements, home range size and survival in relation to pesticide spraying.
The mean brood size of Grey Partridge and Pheasant was significantly higher on plots where field edges were unsprayed than on fully sprayed control plots. Data for Red-legged Partridge were inconclusive. The survival of individually marked Grey Partridge broods was negatively related to the distance moved between successive nocturnal roost sites. Survival was significantly higher, the distance moved between roost sites significantly shorter and the proportion of home range including headland significantly greater for broods feeding in spring barley fields with unsprayed field edges compared with broods feeding in fully sprayed fields.     

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

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 km² was not below the threshold initiating strong dispersal, as observed in extreme habitats and at the northern limits of the species′ 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.     

Reproductive conditioning of the partridge (Perdix perdix) with GnRH and an increase in the photoperiod

Follicular growth and egg deposition were induced in the Grey Partridge (Perdix Perdix) after stimulation with Gn-RH and artificial light. The experiment was carried out from November to December 1983, during the short day period, and during the non egg laying period for this bird-sp. Two groups consisting of ten pairs of Grey Partridge each (female and male), received 3.8 mcg of Gn-RH (pGlu-His-Trp-Ser-Tyr-Gly-Leu-Arg-Pro-Gly-NH2) every 8 hours for 10 and 15 days, respectively. With interruption of the Gn-RH treatment we observed follicular regression. For this reason the birds were stimulated with artificial light daily from the 15th day of treatment until egg deposition. Fifty-five days after the start of the Gn-RH treatment the Grey Partridge laid eggs. Forty days of this period the birds were supplemented with artificial light. Twenty pairs of Grey Partridge were used as controls. Periodically two experimental female subjects (treated and control) were sacrificed to observe the development of ovary and oviducts.     

Long-term changes in chick survival rate and brood size in the Grey Partridge Perdix perdix in Poland

Data from 4801 Grey Partridge Perdix perdix broods collected in Poland during1987–2013 show that, over the 27 years of study, average brood sizes declined from 10.2 to 6.7 and chick survival fell from 57% to 34%. A probable cause of these trends was a 2.5 fold increase in the use of pesticides over the same time period.     

The impact of agro‐pastoral abandonment on the Rock Partridge Alectoris graeca in the Apennines

Human depopulation of rural mountain areas and the consequent abandonment of traditional land management are among the greatest driving forces behind changes in mountain ecosystems in Western Europe. Tree and shrub encroachment lead to an increase in landscape matrix uniformity and habitat fragmentation. For some animal species, this represents an unusual case of habitat loss caused by secondary succession. The animal species associated with this agro‐pastoral habitat may suffer from decreased connectivity as a consequence. The Rock Partridge Alectoris graeca is a species endemic to European mountains that represents a model for investigating the impact of habitat loss. We compared the habitat suitability of the Apennine Rock Partridge prior to abandonment of traditional agro‐pastoral activities by aerial photography with the current landscape, in order to investigate the effect of secondary succession on the distribution and viability of the species. We assessed the historical distribution (c. 1900–1950) by quantifying anecdotal evidence from interviews, and the current distribution (2005) from survey data. We applied ecological niche factor analysis and connectivity approaches to evaluate change in habitat suitability over this time scale. Moreover, to quantify landscape connectivity, we evaluated the relative importance of each patch in the two periods. Results indicated that to maintain a viable population in the Apennines, the species requires an ensemble of ecological conditions considerably different from the current situation. We observed a drastic decrease in connectivity as a result of a reduction in numbers and size of high suitability patches. This is most probably the primary cause of the current decline of the Rock Partridge population in the Apennines.     

A field assessment of the success of moorland restoration in the rehabilitation of whole plant assemblages

Question: How successful is restoration that is focused on a single dominant plant at enabling the reassembly of the whole vegetation assemblage and what factors affect the relative success of such restoration? Location: Moorlands in England and Scotland, UK. Methods: Vegetation composition was sampled in grassdominated (degraded), restored and long established Calluna vulgaris‐dominated (target) areas within eight moorland restoration sites. Additional soil and biogeographic data were collected. Data were analysed by Canonical Correspondence Analysis, which allowed the impact of moorland management to be examined. Results: All sites showed good restoration success when the dominant managed species (Calluna vulgaris, Molinia caerulea and Nardus stricta) were considered. Restoration success of the remainder of the plant assemblage, disregarding these dominant species, was lower with restored samples at some sites differing little from their respective degraded samples. Moors restored solely by grazing exclusion were more similar to their respective targets than were those restored by more intensive mechanical means. The most important factors in explaining vegetation assemblages were management status (i.e. whether samples represented degraded, restored or target parts of the moor) and latitude. Conclusions: The project demonstrates that, where possible, restoration should be attempted by grazing exclusion alone. Furthermore the importance of applying local restoration targets and of monitoring the whole plant assemblages when assessing the success of moorland restoration is highlighted.     

The influence of different aspects of grouse moorland management on nontarget bird assemblages

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Quantifying the importance of multi‐scale management and environmental variables on moorland bird abundance

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The changing status of the Chalkhill Blue butterfly <Emphasis Type="Italic">Polyommatus coridon</Emphasis> in the UK: the impacts of conservation policies and environmental factors

The Chalkhill Blue Polyommatus coridon is a widespread butterfly of lowland calcareous grassland in southern Britain and is considered a good indicator of habitat condition. Polyommatus coridon has been identified as a Species of Conservation Concern in the UK Biodiversity Action Plan due to a greater than 25% decline in range size since the 1950s, with losses due to the combined effects of habitat destruction, agricultural intensification and neglect. Analysis of annual butterfly monitoring data (transects) collected at 161 sites from 1981 to 2000 show a three-fold population recovery had occurred. The increases were at established sites, with no re-colonisations or range expansion detected. The 1980s population increase coincided with increases across the species range in stock and rabbit Oryctolagus cuniculus grazing, as well as greater protection and management of sites through protected areas and nature reserves. During the 1990s agri-environment schemes were thought to be the main conservation and policy mechanism driving the favourable conservation status of P. coridon, by facilitating appropriate habitat restoration and management. Weather played a part in the species recovery, with warm, but wet summers associated with increases in abundance. The research provides strong evidence of an important conservation success with the UK Biodiversity Action Plan, with implications for other specialist biodiversity.     

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Farmland bird invertebrate food provision in arable crops

Invertebrates are an essential food source for most farmland birds yet their relative abundance and biomass in the most commonly grown arable crops are poorly understood. Dvac suction sampling was used to determine the abundance, biomass and community composition of those invertebrate groups considered important in the diet of farmland birds for the commonest arable crops. Approximately 40 fields were sampled at the edge and mid‐field over 2 years in three different locations in England. In cereals, the fauna was primarily comprised of Araneae (10%), Coleoptera (30%) and Hemiptera (58%), whereas the oilseed rape fauna was dominated by Coleoptera (65%) and peas and potatoes by Hemiptera (89%). Beans contained a high proportion of Coleoptera (39%) and Hemiptera (49%). Aphididae were the most abundant family (20–86% of total), although in oilseed rape and beans, Chrysomelidae, Curculionidae and Nitidulidae formed ca 20% of the fauna. Aphids only formed a small proportion (7%) of the total biomass, except in peas (32%). Instead, Araneae, Carabidae, Heteroptera, Homoptera and Tipulidae formed much larger and more equal proportions. The highest abundance and biomass of invertebrates were recorded in cereals and least in potatoes. The Grey Partridge chick‐food index in all crops was only a half or less of the level required to ensure that chick survival is sufficient to maintain numbers of this red‐listed species. The total number of invertebrates, their biomass, diversity and the Grey Partridge chick‐food index were higher at the crop edge compared to mid‐field. Conservation measures are needed to help reverse the long‐term declines of invertebrates on farmland, which should include developing further invertebrate‐rich, agri‐environment scheme options and management techniques to encourage invertebrates considered important as bird food within arable crops.     

Climatic and geographic effects on the spatial genetic pattern of a landbird species (Alectoris rufa) on the Iberian Peninsula

Understanding the spatial pattern of genetic diversity may be pivotal to adaptive conservation management of a given taxon. The red-legged partridge (Alectorisrufa, Linnaeus 1758) is naturally widely distributed from the Mediterranean to humid temperate zones. According to a recent study, the genetic structure of this species comprises five clusters, three of which are in the Iberian Peninsula (glacial refugia). Partridge demographic expansion events and climatic shifts during Pleistocene glaciations have been used to test the hypotheses concerning Iberian red-legged partridge distribution. We tested the existence of climatic and geographic relationships on genetic diversity/distances. We employed markers from two different genetic systems, such as part of the mitochondrial DNA control region (n = 113) and 20 species-specific microsatellite DNA loci (n = 377), including climatic and geographic factors from the 14 Iberian localities where A. rufa populations were sampled. Our results showed a mitochondrial genetic diversity pattern associated with a thermic gradient, and a decrease of genetic diversity in peripheral populations that concurred with the ‘abundant centre’ hypothesis. Overall, current climatic variables reliably described genetic variation and differentiation in the red-legged partridge, which may be a result of local species adaptation.     

Plasmodium japonicum,P. juxtanucleare and P. nucleophilum in the Far East*

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Combination of 6-Benzylaminopurine and Thidiazuron Promotes Highly Efficient Shoot Regeneration from Cotyledonary Node of Mature Peanut (<i>Arachis hypogaea</i> L.) Cultivars

Efficient in vitro plantlet regeneration is an important step to successfully transform genes for the improvement of agronomic traits. A combination of 6-benzylaminopurine (BAP) and thidiazuron (TDZ) plant growth regulators was applied to evaluate shoot regeneration capacity whereas α-naphthalene acetic acid (NAA) combination with 6-benzylaminopurine (BAP), and 2, 4-dichlorophenoxyacetic acid (2, 4-D) with 6-benzylaminopurine were tested to optimize root induction for two peanut cultivars. The result showed combination (BAP with TDZ) was found to be effective in promoting shoot. The highest shoot regeneration frequency (93%) was obtained on a medium supplemented with 4 mg/L BAP and 0.5 mg/L TDZ while an average regeneration frequency (87%) was achieved in a medium containing combinations of 2 mg/L BAP with 1 mg/L TDZ. The shooting rate increased for both cultivars as the concentrations of BAP increased and TDZ decreased. The highest rooting rate (93%) was obtained on a medium supplemented with 3.5 mg/L NAA with 2.5 mg/L BAP for both cultivars. The rooting rate increased as the concentration of auxin to cytokinin ratio increased. The maximum rooting rate (83%) was obtained on MS medium supplemented with 0.3 mg/L 2, 4-D with 0.2 mg/L BAP for the cultivar N3. The result indicated that BAP with NAA was much better than BAP with 2, 4-D in rooting rate. Thus, the protocol developed was genotype independent and effective for peanut tissue culture.