Alectoris Rufa Research Articles

Does fox control improve red–legged partridge (Alectoris rufa) survival? An experimental study in Northern Spain

This work evaluates the effectiveness of fox control as a method to improve the survival of red–legged partridge (Alectoris rufa). We radio–tracked 89 adult partridges and their chicks (62 few days old chicks and 46 over one–month–old chicks) and monitored their nests (N = 45) on two hunting estates in northern Spain over two years. Generalist predators (red fox, Vulpes vulpes, and magpie, Pica pica) were selectively controlled on one half of each estate during the first year, and on the other half in the second year. We estimated the effect of predator control on survival rates. Predator control did not improve survival rates for adult partridges and nests, but it improved chick survival, especially for chicks over one–month old.

Does the use of playback affect the estimated numbers of red–legged partridge Alectoris rufa?

The red–legged partridge Alectoris rufa lives in a situation of potential conservation risk for its long–term preservation in Italy as its habitat is increasingly threatened by the disappearance of traditional agriculture–related environments. In such a situation, it is important to use effective and appropriate monitoring methods to assess population changes over time and to identify potential conservation threats. The objective of this study was to evaluate the effectiveness of the playback method to estimate the density of calling males. We compared playback method with spontaneous calling of males at dawn and direct observations along transects. The results on raw count data of playback counts revealed a strong underestimation rate compared to the method that gave the best results: count of spontaneous calls at dawn. Our study provides a critical evaluation of a method that is widely used even though data about its effectiveness are scarce. Our data do not evaluate detection probability of the three methods. Our aim was only to evaluate which methods give the best results in term of population size estimation under the same field condition (same population density, same period, same monitoring area). The results raise some doubts about the ability of the playback method to monitor red–legged partridge populations. The implications of our results for red–legged population management are discussed.

Experimental exposure of red-legged partridges (Alectoris rufa) to seeds coated with imidacloprid, thiram and difenoconazole

Pesticide coated seeds are commonly used in agriculture, and may be an important source of food for some birds in times of scarcity, as well as a route of pesticide ingestion. We tested the lethal and sub-lethal effects of treated seed ingestion by the red-legged partridge (Alectoris rufa), a game bird of high socio-economic value in Spain. One year-old partridges (n = 42 pairs) were fed for 10 days in spring (prior to breeding) with wheat treated with difenoconazole (fungicide), thiram (fungicide) or imidacloprid (insecticide), using two doses for each pesticide (the one recommended, and its double to represent potential cases of abuse of pesticides). We investigated the direct and indirect effects on the body condition, physiology, immunology, coloration and subsequent reproduction of exposed partridges. For the latter, eggs were collected, measured and incubated and the growth and survival of chicks were monitored. Thiram and imidacloprid at high exposure doses produced mortalities of 41.6 and 58.3 %, respectively. The first death was observed at day 3 for imidacloprid and at day 7 for thiram. Both doses of the three pesticides caused sublethal effects, such as altered biochemical parameters, oxidative stress and reduced carotenoid-based coloration. The high exposure doses of imidacloprid and thiram also produced a decrease in cellular immune response measured by the phytohemagglutinin test in males. Bearing in mind the limitation of the small number of surviving pairs in some treatments, we found that the three pesticides reduced the size of eggs and imidacloprid and difenoconazole also reduced the fertilization rate. In addition, both thiram and imidacloprid reduced chick survival. These experiments highlight that the toxicity of pesticide-treated seeds is a factor to consider in the decline of birds in agricultural environments.

Natural Bagaza virus infection in game birds in southern Spain

In late summer 2010 a mosquito born flavivirus not previously reported in Europe called Bagaza virus (BAGV) caused high mortality in red-legged partridges (Alectoris rufa) and ring-necked pheasants (Phasianus colchicus). We studied clinical findings, lesions and viral antigen distribution in naturally BAGV infected game birds in order to understand the apparently higher impact on red-legged partridges. The disease induced neurologic signs in the two galliform species and, to a lesser extent, in common wood pigeons (Columba palumbus). In red-legged partridges infection by BAGV caused severe haemosiderosis in the liver and spleen that was absent in pheasants and less evident in common wood pigeons. Also, BAGV antigen was present in vascular endothelium in multiple organs in red-legged partridges, and in the spleen in common wood pigeons, while in ring-necked pheasants it was only detected in neurons and glial cells in the brain. These findings indicate tropism of BAGV for endothelial cells and a severe haemolytic process in red-legged partridges in addition to the central nervous lesions that were found in all three species.

First Evaluation of Different Captive Rearing Techniques for the Re-Establishment of the Red Legged Partridge Populations

In Tuscany, the red-legged partridge (Alectoris rufa) became extinct at the beginning of the 20th century. Recently, some attempts have been made to re-establish wild populations in Tuscany using farm reared birds, but in most cases the released populations have shown difficulties in reaching sufficient viability, even in areas where the habitat can be considered suitable. Modern technologies for rearing game-birds may be not suitable for reintroduction purposes. For this reason we carried out preliminary research to evaluate the survival of red legged partridges reared under natural condition (Natural) compared to those farm reared (Artificial). Natural rearing occurred in a large pen where birds were allowed to mate freely and to nest. Natural reared birds reached a larger size than artificially-reared birds. Partridges were released in a 7.56 sq km protected area located in the province of Leghorn (western Tuscany, Italy). We followed the fate of 22 young radio-tagged red-legged female partridges (half Natural and half Artificial) and 56 young red-legged partridges (25 Artificial and 31 Natural) marked with different coloured ponchos. The survival of Natural radio-tagged red-legged partridges was double that of the Artificial red-legged partridges. After six months, the re-sighting rate of the Natural poncho-marked birds reached 22.6% whereas none of the Artificial stock was re-sighted. The preliminary results of this research suggest that Natural rearing may be an important tool to improve the success of partridge reintroduction.

Occurrence of avian pathogenic Escherichia coli and antimicrobial-resistant E. coli in red-legged partridges (Alectoris rufa): sanitary concerns of farming

Red-legged partridges (Alectoris rufa) are a significant part of the culture, diet and income for many people in central and southern Spain. Due to declining populations in the wild, intensive farming is common and 4 million juvenile partridges are released each autumn. Intensive management and high densities result in high prevalence of enteric disease and the use of antimicrobials as preventive measures on partridge farms and prior to restocking in the wild. We determined the occurrence of avian pathogenic Escherichia coli (APEC), and screened phenotypic resistance of E. coli against enrofloxacin, gentamicin and cefotaxim in farmed, restocked and wild partridges. Prevalence of APEC in farmed and restocked red-legged partridges was significantly higher than in natural populations. Phenotypic resistance against both gentamicin and enrofloxacin was significantly more frequent in farmed (75%) and restocked (43%) partridges than in wild partridges, while most E. coli isolated from natural populations were susceptible to all three antimicrobials tested (65%). This indicates that farmed and restocked partridges carry APEC that could be a reason for disease outbreaks on farms, and that E. coli carried by farmed and restocked partridges can acquire resistance to frequently used antimicrobials, thus being a concern for the environment, wild birds and consumers. Management in farms and restocking procedures may create a hazard not only for spreading APEC, but also as a potential source of resistant E. coli in the environment.

Real-time fluorogenic reverse transcription polymerase chain reaction assay for the specific detection of Bagaza virus

In September 2010, an outbreak of disease in 2 wild bird species (red-legged partridge, Alectoris rufa; ring-necked pheasant, Phasianus colchicus) occurred in southern Spain. Bagaza virus (BAGV) was identified as the etiological agent of the outbreak. BAGV had only been reported before in Western Africa (Central African Republic, Senegal) and in India. The first occurrence of BAGV in Spain stimulated a demand for rapid, reliable, and efficacious diagnostic methods to facilitate the surveillance of this disease in the field. This report describes a real-time reverse transcription polymerase chain reaction (RT-PCR) method based on a commercial 5'-Taq nuclease-3' minor groove binder DNA probe and primers targeting the Bagaza NS5 gene. The method allowed the detection of BAGV with a high sensitivity, whereas other closely related flaviviruses (Usutu virus, West Nile virus, and Japanese encephalitis virus) were not detected. The assay was evaluated using field samples of red-legged partridges dead during the outbreak (n = 11), as well as samples collected from partridges during surveillance programs (n = 81). The results were compared to those obtained with a pan-flaviviral hemi-nested RT-PCR followed by nucleotide sequencing, which was employed originally to identify the virus involved in the outbreak. The results obtained with both techniques were 100% matching, indicating that the newly developed real-time RT-PCR is a valid technique for BAGV genome detection, useful in both diagnosis and surveillance studies.

Do pairing systems improve welfare of captive Red-Legged partridges (Alectoris rufa) in laying cages?

Although animal welfare has become an important premise in poultry, little attention has been paid to the effects of present-day rearing methods on the welfare of game birds, species released for hunting and re-establishment purposes. This work studied the effect of pairing methods on the welfare of the Red-Legged partridge kept in laying cages (4,500 cm2), a commonly hunted game species in Western Europe. Agonistic behavior and possible injuries caused by aggression were studied during the pairing and laying period in 2 types of couples: the forced type (n=24), 1 male and 1 female randomly chosen and placed in the same cage, and the free type (n=24), where the female had the opportunity to chose between 4 males, using the time spent by the female near each male as female choice parameter. Welfare of partridges was affected by pairing system, as aggressive behavior, divorces and injuries were observed in a higher rate in forced pairs (25% of pairs did not finish the productive cycle) than in free pairs (16.6%). In addition, more females were attacked in forced pairs, whereas in free pairs, the number of attacked males and mutual aggression was increased. Males tended to display more aggressive behavior than females, pecking mainly on the head and back of females. Although injuries were observed in a minor rate in free pairs, a higher mortality was reported in females compared with males from both free and forced pairs (6 females died in total). The poor welfare in a high percentage of laying pairs hampers the development of sustainable rearing methods for the species. Thus, farmers should consider avoiding forced pairing.

Impact of land-use changes on red-legged partridge conservation in the Iberian Peninsula

SUMMARYRed-legged partridge (Alectoris rufa) populations have significantly declined in the Iberian Peninsula (by > 50% between 1973 and 2002). This decline has been attributed to the drastic changes that have occurred in traditional agricultural landscapes, among other factors. This paper assesses the relationship between landscape change and the changes in areas favourable to partridges. The areas favourable to partridges in Andalusia (southern Spain), and the environmental and land-use factors that determined these areas, were identified for both the 1960s and the 1990s. Land-use changes were analysed both throughout the study area and for areas where favourability for partridges has either improved or worsened during recent decades. Both the location and the factors determining areas favourable to red-legged partridges have changed substantially over recent decades. In the 1960s, areas favourable to partridges were associated mainly with natural vegetation in mountainous areas, whereas, by the 1990s, favourable areas were associated with large low-lying croplands; such change may be attributable to regional land-use changes. The percentage area of the main natural vegetation variables positively correlated to partridge favourability in the 1960s model (mainly pastures and open scrubland) had decreased in areas that had become unfavourable to the species (such as mountain areas), and risen where partridge favourability increased. By the 1990s, the land area favourable to partridges had decreased byc. 10% (c. 6000 km2) in southern Spain, whereas land use unfavourable to partridges markedly increased (> 100%; an increase ofc. 3000 km2). Landscape suitable for partridges has thus become severely impoverished over recent decades in the Iberian Peninsula. Management measures aimed at improving the landscape for farmland birds should be encouraged to conserve red-legged partridge populations in southern Spain.

Harvest of red‐legged partridge in central Spain

A basic rule to attain sustainable use of harvested resources is to adjust take to availability. Populations of red-legged partridges in Spain have decreased in recent decades, and releases of farm-bred partridges to improve short-term availability are increasingly common. We used questionnaires and bird surveys to assess whether harvest was related to availability of wild partridges or intensity of farm-bred partridge releases. We studied 50 hunting estates, including 6 administratively labeled as intensive (with few numerical and temporal restrictions to releases). In addition, we considered hunting pressure (number of hunters × hunting days/km2) and habitat as explanatory variables in the analyses. In intensive estates, annual harvest was exclusively related to release intensity, indicating that in these estates hunting is detached from natural resources and approaches an industrial activity based on external inputs. In non-intensive estates, harvest was affected by wild stock availability, walked-up shooting pressure, and habitat (greater harvest in estates with more Mediterranean shrubland). In these estates, releases did not increase annual harvest, and can be considered an inefficient practice. Additionally, the relationship between abundance estimates and harvest disappeared in estates with low partridge abundance estimates, suggesting possibilities for overharvesting in a large proportion of estates. Increasing the abundance of wild red-legged partridge through techniques like habitat management, and improving the adjustment of harvest to availability, may be a good strategy to increase long-term harvest in non-intensive estates. Additionally, Government and managers must create ways to segregate and label the estates where only wild red-legged partridges are managed from those where releases are used, to reduce ecological costs of management decisions. © 2012 The Wildlife Society.

Evaluation of radiotagging techniques and their application to survival analysis of Red‐legged Partridge Alectoris rufa chicks

A better knowledge of chick survival rates is required to enable understanding of the population dynamics of gamebirds and to develop management measures to conserve their populations. The Red‐legged Partridge Alectoris rufa is a highly valued game species in Spain but its populations have declined in recent decades. A lack of appropriate monitoring methods has been a limitation in gaining information on the mortality of Red‐legged Partridge chicks. We developed methods for the effective radiotagging of chicks in captivity and applied these methods in the field in northern Spain to estimate survival during the first 5 months of life. The most effective method for radiotagging captive chicks between 3 and 8 days old involved gluing small tags directly to the skin in the interscapular space using cyanoacrylate adhesive. Backpack harness tags attached with elastic bands were the most effective method of radiotagging 4‐week‐old chicks. Predation was the main cause of chick mortality identified during the field experiments. Survival between hatching and 5 months of age was estimated to be 16–21%. The lowest survival rates occurred during the first 7 days of life (62–70% cumulative survival) and this period seems to be a major determinant in the life history of the species.

Distribution patterns of influenza virus receptors and viral attachment patterns in the respiratory and intestinal tracts of seven avian species

This study assessed the presence of sialic acid α-2,3 and α-2,6 linked glycan receptors in seven avian species. The respiratory and intestinal tracts of the chicken, common quail, red-legged partridge, turkey, golden pheasant, ostrich, and mallard were tested by means of lectin histochemistry, using the lectins Maackia amurensis agglutinin II and Sambucus nigra agglutinin, which show affinity for α-2,3 and α-2,6 receptors, respectively. Additionally, the pattern of virus attachment (PVA) was evaluated with virus histochemistry, using an avian-origin H4N5 virus and a human-origin seasonal H1N1 virus. There was a great variation of receptor distribution among the tissues and avian species studied. Both α-2,3 and α-2,6 receptors were present in the respiratory and intestinal tracts of the chicken, common quail, red-legged partridge, turkey, and golden pheasant. In ostriches, the expression of the receptor was basically restricted to α-2,3 in both the respiratory and intestinal tracts and in mallards the α-2,6 receptors were absent from the intestinal tract. The results obtained with the lectin histochemistry were, in general, in agreement with the PVA. The differential expression and distribution of α-2,3 and α-2,6 receptors among various avian species might reflect a potentially decisive factor in the emergence of new viral strains.

Monitoring of the Bagaza Virus Epidemic in Wild Bird Species in Spain, 2010

By the end of August 2010, high mortalities in red-legged partridges (Alectoris rufa) and pheasants (Phasianus colchicus) were detected in several hunting states in the province of Cádiz (southern Spain). Retrospective epidemiological studies revealed that the first clinical signs had been observed in late July-early August. The most common clinical signs were incoordination, disorientation and ataxia. The estimated mean morbidity rates were 37% in partridges and 11% in pheasants. The estimated mean mortality rates were 23% in partridges and 6% in pheasants. The estimated mean case-fatality rates were 38% and 8% in partridges and pheasants, respectively. A total of 19 clinically affected birds from 18 affected hunting states were analysed between August and November 2011. Histopathological analyses revealed encephalitis, myocarditis, leiomyositis, meningoencephalitis and neuritis as the most frequently observed lesions. Molecular analyses identified Bagaza virus (BAGV) as the causative agent of the epidemic. Further studies are needed to determine the source of introduction of the virus into Europe and to elucidate whether wild birds play a role in the epidemiology of BAGV. Surveillance in susceptible bird species, including partridges and pheasants, may be useful for the early detection of BAGV in an area.

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.

Adjustment of female reproductive investment according to male carotenoid-based ornamentation in a gallinaceous bird

Carotenoid-based ornaments (many yellow–orange–red colourations) may signal the genetic or parental quality of the bearer. Thus, their expression could influence the amount of resources/energy that the mate will invest in the production of offspring, thereby optimising its reproductive fitness. The differential allocation hypothesis (DAH) predicts that females mated with more attractive males should lay more and better eggs. This has been explored only in few bird species with carotenoid-based traits. We tested this hypothesis in the red-legged partridge (Alectoris rufa), a gallinacean with very variable laying capacity. Both sexes display carotenoid-based ornamentation that gradually fades throughout the laying period. Here, the redness of beak and eye rings of captive males was intensified after mating by means of paint. The proportion of females that laid eggs did not differ between treatments. Amongst laying females, those mated with colour-enhanced males (experimental females) tended to lay earlier and produced significantly more eggs than controls, but of similar quality (egg mass and composition). We additionally investigated whether male attractiveness influenced egg components depending on the clutch size and laying sequence. The testosterone level in eggs from experimental females was positively related to the laying order, whereas control eggs did not show any trend. Our results provided mixed support for the DAH, but nevertheless revealed that female red-legged partridges may adjust their breeding investment according to male carotenoid-based ornamentation.

Water-site selection and behaviour of red-legged partridge Alectoris rufa evaluated using camera trapping

This paper explores watering patterns of wild red-legged partridges at water troughs (WT) during three consecutive summers on a farm-land area of Spain where drought periods are frequent. Camera trapping was used in order to assess climatic effects on weekly and daily watering patterns, investigate the influence of shrub cover on water-site selection, evaluate behavioural patterns displayed when using WT, and describe age and number of birds observed at WT. Red-legged partridges used WT throughout the study period, but significant use did not occur until August, decreasing dramatically in mid September, and ending in October. A circadian watering pattern was observed during daylight hours with most photographs taken from 08:00hours to 11:00hours (54.8%). Partridges displayed different behaviours (drinking, feeding/dusting, vigilance, moving/unknown), but patterns did not vary significantly throughout the day. WT were used mostly by adult birds with only 26.5% of photographs also depicting young partridges. WT selection was strongly influenced by the presence of surrounding vegetation as partridges preferred troughs with shrub cover. We also found a significant negative relationship (P<0.05) between the percentage of vigilant birds and covey size at water sources with shrub cover. Given the high predation rates observed in this species, security risk is likely an important factor involved in water-site selection.

Are reclamo hunting seasons for the Spanish red‐legged partridge off the mark?

AbstractThe red‐legged partridge (Alectoris rufa) is abundant in a number of regions in Spain and one of the most commonly hunted small game species in the country. Partridge hunting generates substantial income in rural areas where agriculture is less profitable. A traditional hunting method, reclamo hunting, is currently under revision by the European Commission's (EC) Birds Directive because hunting may fall within the reproduction period of the species. So far, only limited data on the reproductive phenology of the species exist to inform a policy change. In this study, we present reproduction data for red‐legged partridges from 9 hunting estates in Andalusia during 1 year, and over 3 consecutive seasons from a control estate. We used direct nest and partridge chick covey observations to estimate 165 egg‐laying dates. We found significant differences between sites related to altitude during reproduction periods. Using our pooled data, we showed that reproduction occurred between the last 10 days in January and the middle of February; beyond 31 January we observed an exponential increase in birds reproduction. According to these data and current EC legislation, reclamo hunting should not extend beyond 31 January. © 2012 The Wildlife Society.

Systemic candidiasis in farm-reared red-legged partridges (Alectoris rufa) caused by Leucosporidium spp.

BackgroundThis report describes the results of radiological, histological and molecular examination of three farm-reared red-legged partridges (Alectoris rufa) affected by candidiasis.Case presentationThree juvenile farm-reared red-legged partridges in a batch of 100 of the same species were sent for clinical and pathological investigations. The owner referred of a sudden isolation of the sick animals, with apathy, diarrhea, ruffled plumage and respiratory rattles. Post mortem total body lateral projection radiograph showed an increased perihilar interstitial pattern and air bronchogram signs due to lung edema. At necropsy, carcasses showed cachexia; the pericloacal region was soiled by diarrheic fecal material. From the mouth to the intestine, a mucous yellowish fluid was present on a slightly reddish mucosa. Histopathology showed slight edema and congestion with different free fungal elements, referable to blastospores, hyphae and pseudohyphae. Biomolecular exam identified the most similar sequences as belonging to Leucosporidium scottii.ConclusionTo our knowledge, this case report describes for the first time this fungal species as a causative agent of candidiasis in birds.

Pathological Findings in Red-legged Partridges ( Alectoris rufa) and Common Pheasants ( Phasianus colchicus) Naturally Infected with Bagaza Virus (BAGV) in Spain

Pathological Findings in Red-legged Partridges ( Alectoris rufa) and Common Pheasants ( Phasianus colchicus) Naturally Infected with Bagaza Virus (BAGV) in Spain

Contrasted effects of an oxidative challenge and α-melanocyte-stimulating hormone on cellular immune responsiveness: an experiment with red-legged partridges Alectoris rufa

Oxidative stress is increasingly recognized as a key selective force shaping evolutionary trade-offs. One such trade-off involves investing in immunity versus combating oxidative stress. While there is broad evidence that mounting an immune response causes increased oxidative stress, the effect that increased oxidative stress during development has at a later stage on immune responsiveness remains little known. The production of melanin-based coloration in vertebrates is influenced by oxidative stress and by hormones, such as the alpha-melanocyte-stimulating hormone (α-MSH). Oxidative stress could impair immunity, and this might be a cost associated with the production of melanin traits. α-MSH has immunomodulatory effects, with most evidence pointing towards an improvement of immunity (improved pro-inflammatory activity). Here, we investigated the effects of an oxidative challenge (exposure to a pro-oxidant compound, diquat) and of experimentally elevated α-MSH on the cell-mediated immune responses (CMIR) of growing young (1 month old) red-legged partridges Alectoris rufa in captivity. CMIR were assessed in response to primary and secondary challenges with phytohemagglutinin (PHA). We specifically tested whether an oxidative challenge during growth and development had a delayed effect (4 months after exposure) on immunity. We found that the diquat treatment did not affect primary CMIR, but significantly reduced secondary CMIR. Elevated α-MSH increased primary CMIR in males, but not in females. Our experimental results are consistent with a trade-off between investing in activities that generate oxidative stress (e.g., growth, reproduction, production of ornaments) versus investing in immunity, and shed new lights onto the inter-relationships between immunity, oxidative stress and the expression of melanin-based coloration in vertebrates, revealing a novel, delayed physiological cost that can contribute to ensuring honest signaling.