Alectoris Rufa Research Articles

Serologic Testing for Avian Influenza Viruses in Wild Birds: Comparison of Two Commercial Competition Enzyme-Linked Immunosorbent Assays

Serologic testing of wild birds for avian influenza virus (AIV) surveillance poses problems due to species differences and nonspecific inhibitors that may be present in sera of wild birds. Recently available competitive enzyme-linked immunosorbent assay (cELISA) kits offer a new species-independent approach. In this study we compare two commercial competitive cELISAs, using a total of 184 serum and plasma samples from 23 species of wild birds belonging to 10 orders. Thirteen samples were from experimentally high pathogenicity AI and low pathogenicity AI infected red-legged partridges (Alectoris rufa), 77 samples were from a flock of sentinel hybrid ducks confirmed infected by AI by real-time PCR, and 94 samples were from wild birds admitted to a rehabilitation center. Both ELISAs detected AI antibodies in the experimentally infected partridges, whereas hemagglutination inhibition (HI) was negative. Concordance in results between the two ELISAs was 51.5%. When specific subtype-H5/H7 HI-positive samples were considered for comparison, ELISA 1 appeared to perform better on ducks, whereas ELISA 2 appeared to perform better in other wild bird species. Overall, 68.2% of H5/H7 positive samples tested positive by ELISA 1 and 36% by ELISA 2. Both ELISAs detected AIV-antibody-positive samples negative by specific HI against 9 of the 16 existing hemagglutinin (HA) subtypes. Presumably this reflects either higher sensitivity of cELISA when compared to HI, presence of antibodies against HA subtypes not tested, or unspecific reactions. Performance of ELISA 1 on ducks appears to be comparable to in-house cELISA previously used by other authors in wild birds, but requires a relatively large sample volume. Alternatively, although ELISA 2 required a smaller sample volume, it was less effective at identifying HI-positive samples. The results reflect the necessity of validation of cELISA tests for individual species or at least families, as required by the OIE.

Effect of long-term storage on the hatchability of red-legged partridge (Alectoris rufa) eggs

The effect of 0-, 7-, 14-, 21-, 28-, and 35-d storage periods on hatchability and weight loss during storage and incubation of red-legged partridge (Alectoris rufa) eggs stored at 15 degrees C and 80% RH was studied. There was a significant effect of storage period on egg weight loss during storage (P<0.001), a significant increase occurring in weight loss for each additional week the eggs were stored, and this weight loss amounted to more than 3% for the eggs stored for 35 d. Storage period affected egg weight loss during incubation (P<0.05). An increase in egg weight loss during incubation occurred, increasing from 21 d of storage and amounting to more than 10% for the eggs stored for 35 d. Storage period had a significant effect on hatchability (P<0.05). Storage of red-legged partridge eggs up to 28 d does not affect subsequent hatchability, but a significant decline in hatchability occurs when the eggs are stored for 35 d. This research confirms, as occurs in other Alectoris species, that long-term storage of red-legged partridge eggs (to 28 d) does not have a negative effect on hatchability. These findings will be useful in terms of successful hatchery management, mainly by allowing prolonged storage of eggs while gathering a sufficient-sized batch to be incubated, and shipment of long shelf life hatching eggs at game farms while losing little hatchability until further incubation.

Age and Breeding Effort as Sources of Individual Variability in Oxidative Stress Markers in a Bird Species

Oxidative stress is the imbalance between the production of pro-oxidant substances and the level of antioxidant defenses, which leads to oxidative damage. It has been proposed that senescence is the result of accumulated oxidative damage throughout life. In birds, the sources of individual variability in oxidative stress are still poorly understood. Among these sources, age, as related to senescence, should be particularly relevant. Furthermore, recent findings suggest that breeding effort may also deeply influence susceptibility to oxidative stress. However, there is still no evidence of a link between breeding effort and oxidative damage in any vertebrate. Here we analyzed 288 captive red-legged partridges (Alectoris rufa) across a wide age range (i.e., 1-8 yr old), thus including potentially senescent birds. In spite of limitations due to the cross-sectional approach, results revealed that old birds produced less offspring and endured higher levels of oxidized glutathione and peroxidized lipids in erythrocytes than did middle-aged individuals. Old birds also showed higher plasma total antioxidant status and uric acid levels than did younger birds, but lower amounts of circulating carotenoids. Furthermore, hatching success was negatively correlated to lipid peroxidation in females but not in males, supporting the hypothesis that breeding effort promotes oxidative damage.

Influence of the breeding system on the escape response of red-legged partridges (Alectoris rufa)

This study aimed to determine the influence of the breeding system on the escape response of red-legged partridges comparing 147 free-born partridges captured in the wild (W) and 164 partridges from a commercial hunting farm with an intensive production system (F). All birds were individually released to the natural environment using wooden cages; the escape response was recorded with a high resolution video camera and 4 behavior parameters were analyzed: reaction time or latency, escape type, angle at the moment of flight start, and distance flown. There were significant differences on the mean reaction time depending on the origin of the partridges: 0.43 s, with a maximum of 9 s, for the W and 52.90 s, with a maximum of 120 s, in 32.3% of the F birds. Only one of the W partridges (0.68%) escaped by walking, whereas all the other W birds, and 69.5% of the F partridges, flew; the differences in the type of escape reaction between origins were significant. Considering the angle of flight start, the differences were also significant because 98.6% of W partridges showed less than 45 degrees angles, whereas 37.7% of F birds showed angles of more than 45 degrees. Thus, we can conclude that the breeding system has a great influence on the escape response of the red-legged partridges. The intensive management production systems used on the commercial game farms produced obvious changes in the escape reaction of the red-legged partridges, and this could explain the low ability of these birds to integrate and to survive in the wild due to the high predation pressure they undergo when they are used in repopulation processes.

Small game water troughs in a Spanish agrarian pseudo steppe: visits and water site choice by wild fauna

This paper studies the visits of wild fauna, the influence of vegetal cover and fencing at water site election, and consumption tendency in water troughs designed for small game species distributed in an agricultural Mediterranean area during the summers from 2002 to 2005. Red-legged partridges (Alectoris rufa), lagomorphs (Oryctolagus cuniculus, Lepus granatensis), and other autochthonous species (birds and wild canids) visited water sources throughout the study. The number of visits by target species was higher than non-game. Lagomorphs preferred protected troughs (with surrounding vegetal cover) while partridges opted for open ones (without cover). Fencing had no effect on the visits of birds and lagomorphs, but it did reduce the visits of wild canids. Harsh climatic conditions determined an increase in water consumption in summer. Before designing a water trough device for this fauna, managers should consider that (1) target and non-target species could try to make use of it, (2) water points should be adapted to target species self protection, (3) fencing can prevent undesirable visitors (particularly predators), and (4) water requirements increase in the harsh moments of the dry season.

New single nucleotide polymorphisms in Alectoris identified using chicken genome information allow Alectoris introgression detection

Using the chicken genome, 114 polymorphisms (109 SNPs and 5 INDELs) were identified in the Alectoris genus by polymerase chain reaction-single strand conformation polymorphism. Using these, a panel of SNPs is described, which allows easy detection of introgression of Alectoris chukar in wild Alectoris rufa populations, when used with a primer extension protocol. The selected polymorphisms were genotyped and their allelic frequencies estimated on 98 A. rufa partridges sampled from nonrestocking Spanish areas, and 63 A. chukar partridges from Greek and Spanish farms. Power calculations to determine an optimum subset of markers for a given significance level were performed.

Nervous signs associated with otitis and cranial osteomyelitis and with Ornithobacterium rhinotracheale infection in red-legged partridges (Alectoris rufa)‡

A case of nervous signs in red-legged partridges (Alectoris rufa) associated with a severe otitis and osteomyelitis is reported. The outbreak was characterized by abnormal head position, torticollis and difficulty in standing, walking and flying. Pathological, microbiological and molecular genetic data supported an association with Ornithobacterium rhinotracheale (ORT) infection. Clinical signs persisted for several days and were accompanied by weight loss leading to death. Morbidity was approximately 20% and most birds died if untreated. Lesions were mainly characterized by a severe osteomyelitis of the cranial bones and purulent inflammation of the external, middle and inner ears. O. rhinotracheale was isolated from ear samples, skull and brain stem in pure culture. Genetic characterization by pulsed-field gel electrophoresis of the clinical isolates showed that the outbreak was caused by a single strain of ORT. This appears to be the first report of otitis associated with ORT in an avian species.

Double‐nesting behaviour and sexual differences in breeding success in wild Red‐legged PartridgesAlectoris rufa

Double‐nesting behaviour, a rare breeding system in which females lay in two nests, one incubated by herself and the other one by her mate, could be considered an intermediate stage in the evolutionary trend from biparental to uniparental care of single clutches. We examined the occurrence and success of double‐nesting behaviour in Red‐legged PartridgesAlectoris rufain Central Spain. Clutch size and hatching success were recorded, as well as the variation in these between years and between incubating sexes. Participation in incubation was higher for females (94.76%) than males (41.0%), and the proportion of incubating males varied markedly between years, with no incubating males in one dry year and approximately 50% of males incubating in other years. There was significant variation among years and between sexes in laying date, clutch size and hatching success. Clutch size decreased with later laying date in males and females. The probability of clutch loss to predation differed between sexes, being much higher for nests incubated by females. Our results suggest that both rainfall and predation influence the occurrence and success of double‐nesting.

Survival and causes of mortality among wild Red‐legged Partridges Alectoris rufa in southern Spain: implications for conservation

Knowledge of intrinsic and extrinsic factors associated with survival rates and the underlying causes of mortality is essential to understand both population dynamics and the causes of population declines. We studied the influence of habitat variables and body condition on survival of 151 radio‐tracked Red‐legged Partridges Alectoris rufa in four areas of Spain, representing a gradient from natural unmanaged areas to highly managed areas. We examined the effects of differences in game management practices, and seasonal and geographical variations in survival and causes of mortality over 4 years, from 1999 to 2002. Monthly survival rate was consistently over 90% for both sexes in the natural area. However, in two areas managed intensively for both hunting and agriculture, survival was low during the hunting period (72% for females and 79% for males), high during the breeding period for males (99%), and intermediate for females (89%) due mainly to diseases. Hunting was the main cause of Red‐legged Partridge mortality in both hunting areas where driven partridge shooting was performed, affecting 50% of radio‐tagged individuals, and was the main cause of mortality over all areas during both breeding and hunting periods. Disease was the next most common cause of mortality in managed areas, affecting mostly females during the breeding period, whereas predation was the main cause of mortality in unmanaged populations. Finally, we compared the habitat associations and body condition of living and dead individuals with varying causes of mortality. In general, high survival rates were associated with diverse vegetation, habitat edges and a good body condition index. Habitat diversity and a high edge index were also negatively associated with mortality due to predation and diseases. On the other hand, hunting mortality decreased with the proportion of scrubland and increased with the proportion of agricultural land. These results suggest that preventing declines of wild Red‐legged Partridge populations might best be achieved by increasing landscape complexity and connectivity, and promoting game management practices to limit both partridge bags and long‐term densities.

Noninvasive Genotyping of the Red-Legged Partridge (Alectoris rufa, Phasianidae): Semi-Nested PCR of Mitochondrial DNA from Feces

DNA-based studies using avian feces are scarce and deal only with large-sized species. The red-legged partridge, Alectoris rufa, is a medium-sized member of the order Galliformes. Our goal was to set up a fast, noninvasive procedure for mitochondrial DNA (mtDNA) genotyping of A. rufa fecal samples. We focused on the protected population from Elba Island (Tuscan Archipelago National Park, Italy). Dry A. rufa fecal samples (n = 30) were collected in winter. Both the cytochrome b gene (1,092 bp) and the control region (ca. 1,155 bp) were amplified by means of semi-nested PCRs. Twenty-five samples were successfully sequenced for both genes: 8 showed A. rufa mtDNA lineage and 17 chukar partridge (A. chukar), an exotic species. Mixed maternal ancestry suggests A. rufa x A. chukar hybridization. Our protocol allows noninvasive mtDNA genotyping of any Alectoris species and appears suitable to investigate protected populations as well as those existing either at very low density or inhabiting poorly accessible regions.

The expression of melanin-based plumage is separately modulated by exogenous oxidative stress and a melanocortin

Melanin-based traits involved in animal communication have been traditionally viewed as occurring under strict genetic control. However, it is generally accepted that both genetic and environmental factors influence melanin production. Medical studies suggest that, among environmental factors influencing melanization, oxidative stress could play a relevant role. On the other hand, genetic control would be exerted by the melanocortin system, and particularly by the alpha-melanocyte-stimulating hormone (alpha-MSH), which triggers the production of eumelanins (black pigments). To determine how the melanocortin system and an exogenous source of oxidative stress interact in the expression of melanin-based plumage, developing red-legged partridges (Alectoris rufa) were manipulated. Some partridges were injected with alpha-MSH, while other birds received a pro-oxidant molecule (diquat) in drinking water. Controls and birds receiving both treatments were also studied. Both alpha-MSH- and diquat-treated individuals presented larger eumelanin-based traits than controls, but alpha-MSH+diquat-treated birds showed the largest traits, suggesting that oxidative stress and melanocortins promote additive but independent effects. Diquat also induced a decline in the level of a key intracellular antioxidant (glutathione), which is associated with high expression of eumelanin-based signals in other bird species. Some scenarios for the evolution of melanin-based traits in relation to oxidative stress are proposed.

Long-term changes in the prevalences of caecal nematodes and histomonosis in gamebirds in the UK and the interaction with poultry

From 1912 to 2003, 12,056 grey and red-legged partridges and pheasants found dead in the UK were examined. The trends in their infection rates with Heterakis species and histomonosis were...

Temporal and Spatial Differences in the Feeding Ecology of the Spanish Imperial EagleAquila adatbertiDuring the Non-Breeding Season: Effects of the Rabbit Population Crash

The paper describes the diet of territorial Spanish Imperial Eagles during the non-breeding season, comparing prey identified across different regions (Central, Western and Southern), breeding season vs non-breeding season, and periods (1983–1985 or pre-viral haemorrhagic disease [RHD] vs 1991–2000 or post-RHD). Comparison of the nonbreeding with the breeding season revealed a slight variation in the diet. The Rabbit Oryctolagus cuniculus continues to be the most important prey species in the eagle's diet during the non-breeding season, followed by pigeons and the Red Partridge Alectoris rufa, although this varies from one region to another. In general, the decrease in the rabbit population after the epizooty (RHD) does not appear to have had an impact on the occurrence of this prey species in the Spanish Imperial Eagle's diet. Although this species is generally considered to be specialised in the capture of rabbits, the variability found between regions suggests that when the main prey (wild Rabbit) is scarce, the Spanish Imperial Eagle's diet is based on alternative prey such as pigeons or carrion.

Application of indicator kriging to the complementary use of bioindicators at three trophic levels

The use of biological indicators is widespread in environmental monitoring, although it has long been recognised that each bioindicator is generally associated with a range of potential limitations and shortcomings. To circumvent this problem, this study adopted the complementary use of bioindicators representing different trophic levels and providing different type of information, in an innovative approach to integrate knowledge and to estimate the overall health state of ecosystems. The approach is illustrated using mercury contamination in primary producers (mosses), primary consumers (domestic pigeons and red-legged partridges) and top predators (Bonelli's eagles) in southern Portugal. Indicator kriging geostatistics was used to identify the areas where mercury concentration was higher than the median for each species, and to produce an index that combines mercury contamination across trophic levels. Spatial patterns of mercury contamination were consistent across species. The combined index provided a new level of information useful in incorporating measures of overall environmental contamination into pollution studies.

Is the Nature 2000 Network associated with small-game bag results?

Small-game hunting is of great economic importance in Portugal. Game managers claim that game management restrictions regarding shoots inside the Nature 2000 Network negatively influence small-game bags, particularly of hare, wild rabbit and red-legged partridge. We analyse whether different habitat and game management practices are associated with game bags of those species in Alentejo (Portugal). Game bag records from five hunting seasons referring to shoots both inside and outside Nature 2000 sites were analysed. Significant differences concerning habitat and game management descriptors were found between shoots inside and outside Nature 2000 sites. However, this ecological network does not seem to correlate with hare and red-legged partridge game bags, whilst it may negatively influence wild rabbit hunting results. Considering that habitat quality for wild rabbit is rather poor inside the studied Nature 2000 sites, further investigation is needed of the possible negative influence of this ecological network on the species’ game bag. Hare game bags increase with extensive non-irrigated agricultural fields and orchards. Besides these two habitats, red-legged partridge game bags are also favoured by cork oak montado where predators are controlled. The game bags of the three small-game species studied increase with hunting effort. Further, our results suggest that there is a positive relation between hunting effort and small-game population abundance.

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.

Testosterone-mediated trade-offs in the old age: a new approach to the immunocompetence handicap and carotenoid-based sexual signalling

The immunocompetence handicap hypothesis proposes that testosterone mediates a trade-off between sexual signalling and immunocompetence in males. Such a trade-off could favour the reliability of sexual signals on the basis that testosterone required for signal expression also promotes immunosuppression. However, the immunosuppressive activity of testosterone has not been convincingly demonstrated. We propose that the optimal solution to the testosterone-mediated trade-off should change with age, explaining ambiguous results in the past. Testosterone and ageing would promote two simultaneous immunosuppressive challenges unaffordable for low-quality males. Oxidative stress, as intimately related to ageing and immunosenescence, could contribute to enhance signal reliability. In this context, traits coloured by carotenoids (yellow-red traits) could play a crucial role due to the immunostimulatory and antioxidant properties of these pigments. Here, old and middle-aged male red-legged partridges were treated with testosterone or manipulated as controls. In the presence of high-testosterone levels, middle-aged males increased both circulating carotenoid levels and colour expression, whereas their cell-mediated immunity was not significantly altered. However, in old males, neither circulating carotenoids nor sexual signalling increased when treated with testosterone, but immunosuppression was detected. The link between testosterone and carotenoids could favour the reliability of sexual signals throughout the life.

Eggshell Thickness Variation in Red-legged Partridge (Alectoris rufa) from Spain

Eggshell thickness is commonly used as an indicator of habitat quality and effects of environmental pollution on avian reproduction. We present the first data available on eggshell thickness for Red-legged Partridge (Alectoris rufa) in Spain. We compared eggshell thickness between eggs collected in an agricultural area (wild eggs) and eggs from game farms (farm eggs). Wild eggs had shells significantly thicker (x̄ = 0.32 mm, n = 74) than farm eggs (x̄ = 0.28 mm, n = 89), despite game farm partridges being fed a diet rich in calcium and not exposed to agricultural pollutants. Eggshell thickness did not affect hatching success of wild partridges, and population decline observed in this species cannot be linked to reduction in egg viability due to eggshell thickness.

Improving Management Plans by Downscaling Hunting Yield Models: A Case Study with the Red‐Legged Partridge Alectoris rufa in Southern Spain

The aim of our work is to predict potentially optimal areas for red‐legged partridge Alectoris rufa hunting success in Andalusia (southern Spain) according to topographic, climatic and vegetation factors and their interaction. We analysed 32,134 annual hunting reports from the period 1993–2001 reported by 6,049 game estates to estimate the average hunting yields of red‐legged partridge in each Andalusian municipality (N= 771). We modelled the favourability for obtaining good hunting yields using generalised linear models (GLM) on a set of climatic, topographic, land use and vegetation variables. The variables that affected hunting yields of red‐legged partridge were dry herbaceous and wood crops, annual number of frost days, altitude and mean annual temperature. Vegetation was the most important factor of those considered in our study explaining the distribution of good hunting yields of the red‐legged partridge in Andalusia. The favourability equation was used to create a downscaled image representing the favourability of obtaining good hunting yields for the red‐legged partridge in 1 × 1‐km squares in Andalusia, using the Idrisi Image Calculator. Downscaling the model from municipalities to 1 × 1‐km squares provided a much higher spatial resolution when predicting the optimal areas for good hunting yields for the red‐legged partridge.

Identification of raw and heat-processed meats from game bird species by polymerase chain reaction-restriction fragment length polymorphism of the mitochondrial D-loop region

Polymerase chain reaction-RFLP analysis has been applied to the identification of meats from quail (Coturnix coturnix), pheasant (Phasianus colchicus), red-legged partridge (Alectoris rufa), chukar partridge (Alectoris chukar), guinea fowl (Numida meleagris), capercaillie (Tetrao urogallus), Eurasian woodcock (Scolopax rusticola), and woodpigeon (Columba palumbus). Polymerase chain reaction amplification was carried out using a set of primers flanking a conserved region of approximately 310 bp from the mitochondrial D-loop region. Restriction site analysis based on sequence data from this DNA fragment permitted the selection of Hinf I, Mbo II, and Hpy188 III endonucleases for species identification. The restriction profiles obtained when amplicons were digested with the chosen enzymes allowed the unequivocal identification of all game bird species analyzed. Consistent results were obtained with both raw and heat-processed meats.