Farm-reared Partridges Research Articles

Genomic diversity and signals of selection processes in wild and farm-reared red-legged partridges (Alectoris rufa)

The genetic dynamics of wild populations with releases of farm-reared reinforcements are very complex. These releases can endanger wild populations through genetic swamping or by displacing them. We assessed the genomic differences between wild and farm-reared red-legged partridges (Alectoris rufa) and described differential selection signals between both populations. We sequenced the whole genome of 30 wild and 30 farm-reared partridges. Both partridges had similar nucleotide diversity (π). Farm-reared partridges had a more negative Tajima's D and more and longer regions of extended haplotype homozygosity than wild partridges. We observed higher inbreeding coefficients (FIS and FROH) in wild partridges. Selective sweeps (Rsb) were enriched with genes that contribute to the reproductive, skin and feather colouring, and behavioural differences between wild and farm-reared partridges. The analysis of genomic diversity should inform future decisions for the preservation of wild populations.

Gastrointestinal parasites in red-legged partridges (Alectoris rufa) hunted in Spain: a warning to game managers

Red-legged partridge (Alectoris rufa) populations are currently declining in the Iberian Peninsula, mainly due to habitat degradation and hunting pressure. In addition, the release of farm-reared partridges may introduce pathogens, including parasites, to wild populations. The presence of digestive parasites in red-legged partridges hunted in fifteen Spanish provinces was studied. Fecal samples and gastrointestinal tracts were collected, analyzed, and the morphometric identification of parasites was carried out. Eimeria spp. oocysts, nematode, cestode and trematode eggs were observed in fecal samples. Adult nematodes (Ascaridia galli, Ascaridia compar, Heterakis gallinarum, Heterakis tenuicauda, Trichostrongylus tenuis, Subulura spp., Cyrnea spp. and Aonchotheca caudinflata), tapeworms (Raillietina tetragona, R. echinobothrida, R. micracantha, Rhabdometra nigropunctata, and Choanotaenia infundibulum), and trematodes (Brachylaima spp., Brachylecithum spp., Dicrocoelium spp.) were identified in the gastrointestinal tracts. Significant statistical differences were found among climatic regions in the prevalence and intensity of Eimeria spp. infection, median intensity and the prevalence of indirect life cycle helminths, with Southern areas always showing higher infection values. The study provides information of the health status of red-legged partridges in Spain, highlighting the risk associated with the release of farm-reared partridges for restocking purposes. This should be taken into account to improve management strategies for the long-term conservation of the species.

Risk of Infection, Local Prevalence and Seasonal Changes in an Avian Malaria Community Associated with Game Bird Releases

Anthropogenic activities, such as the translocation or introduction of animals, may cause a parallel movement of exotic parasites harboured by displaced animals. Although introduction and/or relocation of animals for hunting purposes is an increasingly common management technique, the effects of gamebird release as a major vehicle for the introduction of parasites into new geographic regions have rarely been reported. We examined the prevalence and distribution of avian malaria parasites infecting resident avian hosts (red-legged partridge Alectoris rufa) at a local scale, with a particular emphasis on the effects of releasing farm-reared birds for hunting on the spatial and temporal structure of the parasite community. We collected blood samples from adult partridges from two game estates with partridge releases and two sites without releases over two periods (spring and autumn). We tested the probability of infection and differences in the parasite community in relation to the management model (releases vs. non releases) and sampling period, comparing autumn (when farm-reared birds are released) and spring (after hunting season, when mostly wild birds can be found in the population). We found a high prevalence (54%) of Plasmodium spp., and substantial differences in the spatial and temporal distribution of parasite lineages among the populations studied. Some parasite lineages occurred at high frequencies in game estates without introduction of farm-reared partridges, while other lineages were more abundant in game estates with releases than in those without releases. Overall, the prevalence of avian malaria was similar between spring and autumn at non-release sites, whereas in sites with releases, it was higher in autumn than in spring—probably due to artificial restocking with infected farm-reared birds at the onset of the hunting season. In short, humans may be an important agent driving the alteration of the spatial structure of local parasite fauna via the introduction of exotic parasites by gamebird release, which could cause avian malaria outbreaks with severe repercussions for native avifauna.

Red-legged partridge Alectoris rufa productivity in relation to weather, land use, and releases of farm-reared birds

Productivity (offspring production) is a key demographic parameter influencing population dynamics, particularly in r-strategy species, and thus critical for implementing well-based management of populations. Accordingly, the study of factors influencing productivity is useful to develop management strategies in species of conservation concern or subject to exploitation. We studied productivity (covey size and young/adult ratio) of red-legged partridges (Alectoris rufa) in Spain through a large-scale sampling in Andalucia and Castilla-La Mancha, two large areas in central-southern Spain, the core of the distribution of the species. We evaluated potential environmental factors related with productivity that have been considered important in previous local studies (weather, land use, and intensity of releases of farm-reared partridges), using a dataset of 15,357 observations of partridges over three breeding seasons (2010, 2011, and 2012). Average productivity at the end of July was 3 young/adult, indicating 50% chick mortality between hatching and fledging and high breeding failure. We found marked effects of weather, year, and land use on partridge productivity, confirming some previous results at local scale and supporting widespread and simultaneous effects of these factors. We also detected a large-scale negative relationship with farm-bred partridge release intensities, with lower young/adult ratios in areas with high release intensity. This suggests that partridge releases may be contributing to the decline of wild populations. Our results support that correcting the effects of agricultural intensification is the main key to the long-term conservation of the species and suggest that, in dry spring years (leading to low average productivity), many populations could be exposed to overhunting. These results stress the importance of both small- and large-scale adjustments of hunting pressure to partridge productivity, in order to preserve wild populations. Poor hunting bags in “bad” years, along with the increasing demand in the hunting market, may have stimulated the widespread use of releases, further reducing productivity and leading to the current compromised conservation status of wild populations. We discuss some potential solutions to this conflicting situation from the socioeconomic and environmental points of view.

Reconciling economic and ecological sustainability: can non-intensive hunting of red-legged partridges be economically profitable?

The red-legged partridge (Alectoris rufa) is the most important gamebird in Spain. Due to population declines in recent decades, management approaches increasingly include the release of farm-reared partridges and the establishment of so-called intensive estates, where hunting is based on put-and-take partridges. The release of farm-reared partridges is controversial because these birds negatively affect wild populations. However, according to managers, releases are necessary to maintain commercial hunting. We analysed economic parameters using data provided by 20 red-legged partridge hunting estates with different management and economic aims in central Spain. We calculated total revenues, total expenses, benefits and profitability of these estates and simulated results under two different scenarios (prices for buying farm-reared partridges being 15 % higher and prices for hunting in estates not using releases being 15 % higher) attempting to mimic the internalization of some ecological costs of farm-reared birds or possible rewards from using wild populations sustainably. Non-commercial estates (n = 5), as expected, just broke even, with almost no benefits. Benefits of intensive estates, where massive releases throughout the hunting season allow a much higher harvest, were on average an order of magnitude higher (20,404 ± 24,413 €/km2, n = 8) than those of other commercial estates (1713 ± 1280 €/km2, n = 7). Benefits of non-intensive commercial estates using releases were on average lower than those of commercial estates without releases. In fact, profitability of non-intensive commercial estates not using releases was similar to that of intensive estates. Any of the two price scenarios considered led to non-intensive commercial estates not using releases being the most profitable on average. Thus, efforts should be made to identify ways of improving economic profitability of non-intensive estates, which may be important for promoting hunting management styles that are ecologically more beneficial.

Anti-predator behaviour of adult red-legged partridge (Alectoris rufa) tutors improves the defensive responses of farm-reared broods

The aim of this work was to improve natural anti-predator behaviour of farm-reared gamebirds.We evaluated the anti-predator behaviour of reared red-legged partridge Alectoris rufa chicks kept in brooder houses in large groups (>350 chicks), trained and not trained by parent red-legged partridges acting as experienced tutors.The experiment consisted of two conditioned tests (a raptor model and a human) and two control tests, which were conducted during three consecutive phases of life (1–4, 15–17 and 30–32 d after hatching). The motor anti-predator behaviour, its duration, the intensity of response in chicks and alarm calls elicited by adults were recorded.Tutors elicited aerial alarm calls (76% of tests) and showed prolonged crouching (59% of tests) in response to the raptor model whereas uttering the ground alarm call (73% of tests) and showing vigilance behaviour (78% of tests) was the main pattern during the human test.Trained and not trained chicks showed similar motor behaviour in response to the raptor model (crouching) and the human test (escaping), but frequency of strong responses (all chicks responding) from chicks trained with tutors was double that of chicks trained without them, and chicks trained with tutors showed a higher frequency of long responses (41–60 s).This study indicates that anti-predator training programmes before release may improve behaviour of farm-reared partridges which may confer benefits to survival of birds.

Are farm-reared red-legged partridge releases increasing hunting pressure on wild breeding partridges in central Spain?

Wild red-legged partridge populations have experienced important declines in recent decades. With an aim to increase or maintain hunting quotas, releases of farm-reared red-legged partridges have concomitantly increased. However, the sustainability of this management practice is increasingly questioned. Farm-reared partridges suffer a high mortality rate immediately after release, and many released birds may already be dead before hunting takes place. Therefore, it is possible that if hunters adjust harvest to the number of farm-reared released birds, this may lead to an overhunting of the wild breeding stocks. We investigated here whether autumn mortality by hunting of radio-tracked birds that bred in the previous summer differed between hunting estates that use or do not use releases as part of their management practices. Although our sample size was limited (32 radio-tagged birds monitored throughout the hunting season in four estates, with only one conducting releases), our results report novel data that support this cause for concern. We found that hunting was the main cause of mortality and that the proportion of hunted partridges was much higher in the estate with releases of farm-reared birds than in the three estates that did not use releases. Therefore, the release of farm-reared partridges, instead of reducing hunting pressure on the breeding stock through a potential dilution effect, may have an opposite effect. This should be confirmed with more spatial replicates, but raises serious concerns regarding the long term sustainability of wild partridge populations and their exploitation for hunting purposes in estates that overhunt partridge populations due to releases.

A quantitative assessment of the release of farm-reared red-legged partridges (Alectoris rufa) for shooting in central Spain

The release of farm-reared game is considered a conflictive management tool because of its potential harmful ecological effects on wildlife and associated habitats. Estimates of the number of animals released and the area where this game management takes place could give an idea of the magnitude of their potential impacts. We aimed to quantitatively assess the release of farm-reared red-legged partridges (Alectoris rufa) in the province of Ciudad Real, central Spain, one of the main hunting areas in this country. We analysed the official permits that the regional government granted to the hunting estates to release farm-reared partridges between 2006 and 2012. Our results show that an average of 800,000 partridges were released annually in the study area. A decrease in the number of hunting estates that used this game management practice, as well as in the number of red-legged partridges officially released, was observed during the last years within the study period. This might be a consequence of the current economic crisis, rather than a change in management styles. Release intensity was spatially heterogeneous, being higher in the southeast of the study area, where historically red-legged partridge was more abundant. Most of the red-legged partridges released came from only four farms placed in northern Spain. Our results suggest that this management activity should be better monitored and that spatial regulations should also be considered.

Does hunters’ willingness to pay match the best hunting options for biodiversity conservation? A choice experiment application for small-game hunting in Spain

• Hunters place economic value to the ecological characteristics of the estate. • Hunters’ willingness to pay for shooting an additional farm-reared partridges was low. • The diversity of small game and the presence of natural vegetation were appreciated. • The presence of protected non-game species was less valued than other attributes. • The views of hunters are apparently close to those of conservationists. In southern Europe, traditional hunting has been frequently replaced by models based on more intensive management. These systems include management strategies like the release of farm-reared animals that can cause harmful effects on biodiversity. However, little is known about the hunters’ views of this activity, and about their preferences for the ecological attributes of the hunting estates. We present the results of a choice experiment exercise evaluating the willingness to pay of Spanish hunters regarding different aspects of walked-up red-legged partridge ( Alectoris rufa ) shooting, including partridge quality (farm-reared vs. wild) and other attributes related to the ecological characteristics of the estate. We find that, when given the choice, hunting an additional wild partridge in a walked-up shooting day was valued more than 20 times higher than hunting an additional farm-reared bird. The diversity of small game available and the presence of natural vegetation in the landscape in which the walked-up hunting takes place were also significantly valued. Hunters also attributed economic value (albeit lower than other attributes) to the presence of protected non-game fauna in the estate. Overall, our results show that hunters are willing to pay more for hunting on estates that have better ecological characteristics, which may be indicative of good conservation status. This suggests that identifying and promoting such estates could lead to systems that are both ecologically and economically sustainable.

La perdiz roja (Alectoris rufa) en España: especie cinegética y amenazada

Vinuela, J., Casas, F., Diaz-Fernandez, S., Delibes-Mateos, M., Mougeot, F., Arroyo, B. (2013). The red-legged partridge ( Alectoris rufa ) in Spain: a threatened game species. Ecosistemas 22(2):6-12. Doi.: 10.7818/ECOS.2013.22-2.02 We review scientific knowledge on red-legged partridge ecology and management, focusing on recent studies. Red-legged partridge is a greatly valued game species, whose conservation status has been, and probably still is, poor. In small-game hunting estates, great efforts are devoted to red-legged partridge management, but many practices are applied without knowing their real consequences for partridge populations. Reviewed studies show that the most successful management options to increase the abundance of the species, allowing a sustainable harvest, would include an adequate adjustment of annual harvest to partridge abundance, appropriate habitat management promoting the presence of natural vegetation within the farmland matrix and field edges, and water and food supplementation. Information about the efficacy of predator control to increase red-legged partridge abundance is inconclusive. Releases of farm-reared partridges are putting at risk the genetic integrity of the species. Furthermore, when few partridges are released, releases do not increase annual harvest or estate profitability, and negatively affect the productivity of wild red-legged partridges. Despite leisure and economic movement generated by red-legged partridge hunting, inadequate management is currently reducing the potential benefits of this activity.

Phenotypic differences in body size, body condition and circulating carotenoids between hybrid and “pure” red-legged partridges (Alectoris rufa) in the wild

In the last decades, the release of large numbers of farmed-reared birds became a widespread management practice for game species. The red-legged partridge (Alectoris rufa) is a quarry species with a high economic impact in rural areas of southwest Europe. In order to increase productivity and produce heavier birds, farmed red-legged partridges have often been hybridized with Chukar partridges (A. chukar), although these species have allopatric distribution ranges. During restocking, hybrid birds may be released into wild populations and may subsequently successfully breed, thus threatening the genetic integrity of native A. rufa populations. In this study, we compared several phenotypic indicators (body size, body condition and physiological state) between “pure” and hybrid partridges in order to evaluate the possible consequences of A. chukar genetic introgression into A. rufa. For this purpose, we captured 115 wild red-legged partridges during the breeding seasons 2003–2005 in four game estates of central Spain. We observed a greater occurrence of hybrid A. rufa × A. chukar partridges nearby the sites where the release of farmed-birds took place. We also found that hybrid males were smaller and hybrid females had better body condition and lower plasma carotenoid concentration than pure partridges of the same sex. Low carotenoid levels in blood plasma might be a limitation for female reproduction (fewer carotenoids available for ornamentation or to allocate to eggs). Overall, our results showed a greater occurrence of hybrids near restocking areas and phenotypic differences between hybrids and “pure” partridge in the wild. Genetic controls of farm-reared partridges should be a key step to prevent the releases of hybrids and ensure the maintenance of the genetic integrity of wild red-legged partridge populations.

Market value of restocking and landscape in red-legged partridge hunting: a study based on advertisements

Context In Spain, the release of farm-reared partridges to hunt is increasingly used, despite being thought to affect sustainability of wild stocks and to reduce the need of natural habitats for game. Aims To explore the market value as a possible incentive for current management, we evaluated within a segment of the red-legged partridge hunting market whether the use of farm-reared birds (as opposed to wild stock) or the naturalisation of landscapes are affecting the hunt market price. Methods We considered estates that sell individual hunting days and contacted buyers through advertisements. We gathered all advertisements for the 2010 season in four top hunting magazines and two websites, and conducted a telephone survey to record price and associated characteristics of hunts. We looked for relationships between price and the characteristics of sold hunts, using general linear models. Key results Hunts varied largely in price, but neither restocking nor naturalisation of the landscape explained price variation, at least within our sample of estates. The absence of price difference between wild or released partridges could be reflecting the current difficulty to distinguish both kinds of products in the market. Conclusions Market forces alone might not be promoting the public interest of the sustainable use of wild stocks versus industrial hunting based on farm-reared birds. Implications If promoting conservation and sustainable use of wild stocks is considered a major goal of official institutions in charge of biodiversity conservation and game management, they should promote reliable ways of identifying estates selling wild or restocked partridges, and they should also evaluate benefits and costs associated with hunting farm-reared birds relative to wild birds, so as to help internalise these costs and benefits if necessary. A study of the determinants of hunter demands would also help explain variation in supply and market prices.

Hunting management in relation to profitability aims: red-legged partridge hunting in central Spain

Game management is widely implemented in Spain, affecting more than 70 % of land cover. Management intensity may be linked to the financial aims of hunting estates, but no study of these aspects has been developed in Spain, where commercial hunting is common. Through interviews with game managers and field surveys, we quantified physical and economic traits, management techniques, and hunting methods in a sample of 59 small-game hunting estates located in south-central Spain (where red-legged partridge hunting has the highest socioeconomic importance in the country). We compared non-commercial estates (aimed for leisure, managed mainly by local hunting societies) and commercial estates (aimed at financial benefit); among the latter, we also assessed “intensive” estates (a special category of commercial estates licensed to release farm-reared partridges without temporal or numerical limits throughout the hunting season). Commercial estates had more intensive management, including more and larger partridge releases, higher density of supplementary feeders and more intensive predator control. Thus, any positive or negative effects on biodiversity of these management techniques would be higher in commercial than in non-commercial estates. Commercial estates also retained more natural vegetation, which may help to enhance the landscape and biodiversity value of farmland in central Spain. On the other hand, differences in management and hunting styles were most marked between intensive and other type of estates (both commercial and non-commercial); this indicates that intensive estates are qualitatively different from other small-game estates, both ecologically (hunting based on releases and driven shooting) and economically (higher inputs and outputs). It would be desirable to find ways to quantify the environmental or social costs and benefits of different management techniques, and integrate them in the economics of hunting estates.

Fitness consequences of anthropogenic hybridization in wild red-legged partridge (Alectoris rufa, Phasianidae) populations

Hybridization is a widespread phenomenon, which plays crucial roles in the speciation of living beings. However, unnatural mixing of historically isolated taxa due to human-related activities has increased in recent decades, favouring levels of hybridization and introgression that can have important implications for conservation. The wild red-legged partridge (Alectoris rufa, Phasianidae) populations have recently declined and the releases of farm-reared partridges have become a widespread management strategy. The native range of the red-legged is limited to the south-west of Europe (from Italy to Portugal). This species does not breed in sympatry with the chukar partridge (A. chukar), whose range is Eurasian (from Turkey to China). However, red-legged partridges have often been hybridized with chukar partridges to increase the productivity of farmed birds, and game releases may have spread hybrid birds into the wild. In this study, we investigated the fitness (survival and breeding) differences between hybrid and “pure” red-legged partridges in a wild population located in central Spain. Incubation probability was similar in hybrids and “pure” partridges. Hybrid females laid larger clutches than “pure” ones, but hatching success did not differ between hybrid and “pure” partridges. Hybrid birds had lower survival rate than “pure” ones, mainly because of higher predation rates. Our results show that, despite lower survival, hybrid partridges breed in natural populations, so this could increase extinction risk of wild pure partridge populations, through releases of farmed hybrid birds. The consequences of continued releases could be of vital importance for the long term conservation of wild red-legged partridges.

Prevalence of Escherichia coli, Salmonella sp. and Campylobacter sp. in the intestinal flora of farm-reared, restocked and wild red-legged partridges (Alectoris rufa): is restocking using farm-reared birds a risk?

For hunting purposes, several millions of red-legged partridges (Alectoris rufa) are released each year in Spain, and these releases have the potential to introduce new parasites and disease into wild populations. We studied the prevalence of Escherichia coli, Campylobacter sp. and Salmonella sp. in the intestinal flora of red-legged partridges from three different husbandry groups: farm-reared, restocked and natural populations. Prevalence of E. coli was significantly higher in farm-reared (45%, p = 0.01) and restocked partridges (60%, p 0.05). The prevalence of Campylobacter sp. (23%, 100 out of 444) did not differ significantly between these three husbandry groups, and Salmonella sp. was only detected in a group of partridge chicks on one of the farms studied (0.9%, 5 out of 544). These results suggest that farm-reared and restocked partridges can act as carriers of these three enteropathogens and highlight a potential risk of transmission to natural populations via the releases of farm-reared partridges. However, future investigations are needed regarding the relation of the isolated bacteria with zoonotic strains and dissemination of antibiotic resistant microorganisms, especially E. coli, and to better evaluate the effect that these three enteropathogens have on partridge health and on the success of restocking with farm-reared birds.

Diseases of the Red-Legged Partridge (Alectoris rufa L.): a review

In spite of the ecological and socio-economical importance of the red-legged partridge (Alectoris rufa) as a prey of threatened species and as a gamebird, and the reported influence that pathogens have in other populations of galliform birds, information about diseases of the red-legged partridge is still scarce. Very little is known about the importance of the diseases in the dynamics of free-living partridge populations. However, enzootic avian poxvirus may be causing the death of partridge chicks in some natural populations. In contrast, more evidences support that the intense management of partridges (trough release of farm-reared partridges, supplemental feeding, or predator control) are promoting the release and transmission of infectious and parasitic diseases. Infectious and protozoan agents and monoxenous helminths typical from farmed galliforms (Ascaridia sp., Eucoleus contortus, or Heterakis gallinarum) are extremely frequent in partridge rearing facilities. The presence of such helminths but also other disease outbreaks (e.g. salmonellosis) in wild partridges may be related with the release of farm-reared partridges. Other cases of disease in the wild, such as avian tuberculosis, may be favoured by the aggregation of partridges and other birds around feeders and water points, and by the absence of predators that should remove sick partridges. Intense supplementary feeding may also promote patho-physiological troubles, such as an incorrect development and eventual massive deaths of juvenile wild partridges in summer months. These and other available reports of infectious and parasitic agents and other diseases of diverse aetiology are reviewed.