Alectoris Rufa Research Articles

Anatomopathological aspects of avian aspergillosis

Aspergillosis is a fungal disease caused by fungi of the genus Aspergillus, in particular A. fumigatus and A. flavus. This paper focuses on anatomopathological aspects resulting from a chronic infection from Aspergillus spp in the chicken (Gallus domesticus), in the herring gull (Larus cachinnans micaelli) and in the red-legged partridge (Alectoris rufa rufa). Microscopically, we observed some histological lesions that are related to the two typical forms of Aspergillosis: a deep nodular form, typical of organs with a non-aerated parenchyma, and a non-encapsulated superficial diffuse form typical of the serosae and the lung. The observed forms of aspergillosis have been found in animals raised in poor hygienic environmental conditions or malnourished animals (chicken); in wild birds from wildlife recovery centres (herring gull), which underwent some forms of stress, such as traumas, detention, starvation, extended antibiotic treatments; in game birds (red-legged partridge) used for restocking natural areas that had been negatively affected by such stressors as captivity in aviaries, containment and transport in cages, release in unsuitable environments and malnutrition. The observed anatomopathological and istopathological aspects can therefore be regarded as the outcome of a number of factors that have reduced the typical resistance of the species and impaired the efficiency of their immune systems.

Parasites, condition, immune responsiveness and carotenoid‐based ornamentation in male red‐legged partridge Alectoris rufa

Sexual ornaments might indicate better condition, fewer parasites or a greater immune responsiveness. Carotenoid‐based ornaments are common sexual signals of birds and often influence mate choice. Skin or beaks pigmented by carotenoids can change colour rapidly, and could be particularly useful as honest indicators of an individual's current condition and/or health. This is because carotenoids must be acquired through diet and/or allocation for ornamental coloration might be to the detriment of self‐maintenance needs. Here, we investigated whether the carotenoid‐based coloration of eye rings and beak of male red‐legged partridges Alectoris rufa predicted condition (mass corrected for size), parasite load (more specifically infection by coccidia, a main avian intestinal parasite) or a greater immune responsiveness (swelling response to a plant lectin, phytohaemagluttinin, or PHA). Redness of beak and eye rings positively correlated with plasma carotenoid levels. Also, males in better condition had fewer coccidia, more circulating carotenoids and a greater swelling response to PHA. Carotenoid‐based ornamentation predicted coccidia abundance and immune responsiveness (redder males had fewer coccidia and greater swelling response to PHA), but was only weakly positively related to condition. Thus, the carotenoid pigmentation of beak and eye rings reflected the current health status of individuals. Our results are consistent with the hypothesis that allocation trade‐offs (carotenoid use for ornamentation versus parasite defence needs) might ensure reliable carotenoid‐based signalling.

Assessment of game restocking contributions to anthropogenic hybridization: the case of the Iberian red‐legged partridge

AbstractAnthropogenic hybridization in wildlife has been identified as one of the main causes of genetic homogenization, highlighting the need for identification and evaluation of populations at risk. Relocation of wildlife for game management purposes is a widespread practice that may promote the admixing of genetically different populations, subspecies or species. We undertook a large‐scale study on the Iberian Peninsula to assess the extent of hybridization in red‐legged partridge Alectoris rufa populations, which have been subject to extensive restocking of farm‐reared individuals. Using a polymerase chain reaction‐restriction fragment length polymorphism technique to assess the prevalence of individuals with mtDNA from other species, we examined samples of A. rufa from museum specimens (229), extant wild populations (955) and game farms (530). We found widespread occurrence of chukar partridge Alectoris chukar mtDNA lineages in samples obtained from game farm partridges (63% of game farms) and from wild partridges (45% of populations), but no allochthonous mtDNA lineages were found in museum partridges. We also found that the probability of occurrence and the number of partridges with allochthonous lineages was higher in localities where recent restocking had occurred. In addition, investigation of trends in bag records and the numbers of game farms over the past 30 years suggests that the general decline of wild populations has been accompanied by an increase in game farm facilities. These results suggest that supplemental stocking practices are threatening the integrity of the wild population gene pool. We recommend that rural development policies and associated wildlife management programs focused on maintaining high stock densities for hunting also need to consider the impact of game management on the genetic integrity of game populations.

Predator abundance in relation to small game management in southern Portugal: conservation implications

The interaction between hunting interests and legally protected predators is often a contentious conservation problem, requiring detailed understanding of predator responses to game management. This issue was addressed in southern Portugal in a treatment-control natural experiment, whereby the abundances of small game, corvids, birds of prey and carnivores were compared in 12 game estates (>500 ha) and 12 matching areas with similar sizes and land uses but no game management. European rabbits (Oryctolagus cuniculus), Iberian hares (Lepus granatensis) and, less so, red-legged partridges (Alectoris rufa) were far more numerous in game estates than elsewhere. Among legally controlled species, there were less Eurasian jays (Garrulus glandarius) but more red foxes (Vulpes vulpes) in game estates, though the latter were primary targets of predator culling. Fox abundance within game estates varied inversely with an index of management intensity (density of small game feeding sites) and increased along with hare abundance. As for protected species, only common kestrels (Falco tinnunculus) and genets (Genetta genetta) were fewer in game estates. The abundance of raptors within game estates varied inversely with gamekeeper density, whereas that of common buzzards (Buteo buteo) increased along with rabbit abundance. Overall, there was little evidence that game management reduced local predator abundances, except in the most intensively managed estates. Game estates provided concentrations of prey that was scarce elsewhere, which may have favoured increased abundances of some predators. Further investigations are needed to find out whether high prey densities may attract predators to game estates with increased mortality risk, which may thus become population sinks for protected species.

Developmental stage of failed eggs in the red-legged partridge Alectoris rufa

Understanding whether egg failure occurs more frequently during laying or during incubation is important for determining the most vulnerable period of the egg phase in bird species with long laying and incubation periods. However, most studies compare nest failure during the egg stage and the hatchling stage. In this study we examined whether egg failure was higher during the laying period and early development than during the final stages of development in a population of red-legged partridge (Alectoris rufa) from northeast Spain. We collected 216 abandoned eggs in the field. Only 12% (n = 26) of the eggs were sufficiently intact to enable direct assessment of developmental stage, showing that 81% of 26 eggs were lost during early stages. The majority of eggs were depredated (n = 154, 71%), as evidenced by an opening hole. To take advantage of information contained in these eggs, we propose a simple method to assess their developmental stage by measuring the size of the opening of their hole. Based on this method, we estimated that the proportion of eggs lost during early stages ranged from 72 to 83%. We validated this result of a high percentage of egg failure during early developmental stages with a larger experimental sample. Nest losses in the partridge are higher during the laying period or early development. This result is important in that the direction of conservation efforts and their seasonal application should be adjusted to account for the most important factors affecting egg failure.

Learning ability of 1-d-old partridges (Alectoris rufa) from eggs laid by hens fed with different n-3 fatty acid concentrations

1. The diets of commercial strains of laying partridge are usually lower in polyunsaturated fatty acids (PUFA) and n-3 fatty acids than the diets of wild partridges. The aim of this experiment was to examine the effects of three different PUFA and n-3 concentrations in partridge laying diets. 2. Offspring learning ability (passive avoidance test of 1-d-old chicks) was used to assess the effect of three different maternal diets (144 chicks were tested for each diet). A negative experience, allowing the bird to peck a bead bathed in a bitter liquid (methyl anthranilate—MA), was used for this purpose. The adults had been fed one of three different diets with n-3 contents of 0·48, 4·04 or 7·60 g/kg. 3. There was better memory retention in the offspring of adults fed the intermediate n-3 content compared to those fed the lower content. Discrimination ratio (DR) of the latency time toward the wrong (red) bead was less for the lower n-3 content (0·48) than for the middle n-3 PUFA content (0·43). DR of the number of pecks toward the wrong beads was greater for the lower n-3 content (0·51) than for the middle n-3 PUFA content (0·71). 4. The partridges fed the diet containing the lowest concentration of n-3 and PUFA were unable to express the expected behavioural score (neural embryo development index) given the genetic characteristics of the animals.

Polymerase Chain Reaction-Restriction Fragment Length Polymorphism Authentication of Raw Meats from Game Birds

Polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) analysis has been applied to the identification of meats from quail (Coturnix coturnix), pheasant (Phasianus colchicus), red-legged partridge (Alectoris rufa), guinea fowl (Numida meleagris), capercaillie (Tetrao urogallus), Eurasian woodcock (Scolopax rusticola), woodpigeon (Columba palumbus), and song thrush (Turdus philomelos). PCR amplification was performed using a set of primers flanking a conserved region of approximately 720 base pairs (bp) from the mitochondrial 12S rRNA gene. Restriction site analysis based on sequence data from this DNA fragment permitted the selection of AluI and BfaI 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. However, the use of the PCR-RFLP technique described is limited to raw meat authentication. It is not suitable for cooked products because thermal treatment strongly accelerates DNA degradation leading to difficulties in amplifying the 720 bp fragment.

The oxidation handicap hypothesis and the carotenoid allocation trade‐off

The oxidation handicap hypothesis proposes that testosterone mediates the trade-off between the expression of secondary sexual traits and the fight against free radicals. Coloured traits controlled by testosterone can be produced by carotenoid pigments (yellow-orange-red traits), but carotenoids also help to quench free radicals. Recently, it has been shown that testosterone increases the amount of circulating carotenoids in birds. Here, a testosterone-mediated trade-off in the carotenoid allocation between colour expression and the fight against oxidative stress is proposed. Male red-legged partridges were treated with testosterone, anti-androgens or manipulated as controls. Testosterone-treated males maintained the highest circulating carotenoid levels, but showed the palest red traits and no evidence of oxidative damage. Increased levels of a key intracellular antioxidant (i.e. glutathione) indicated that an oxidative challenge was in fact induced but controlled. The trade-off was apparently solved by reducing redness, allowing increased carotenoid availability, which could have contributed to buffer oxidative stress.

Lead-Shot Exposure in Red-Legged Partridge (Alectoris rufa) on a Driven Shooting Estate

The goal of the study was to investigate the accumulation and spatial patterns of spent lead (Pb) shot pellets and the prevalence of shot ingestion in red-legged partridge in a driven shooting estate. Soil was collected using a regular sampling design perpendicular to three shooting lines. Factors involved in shot spatial distribution were investigated by a causal structural equation model (SEM). Shot ingestion prevalence and liver and bone Pb concentrations were studied in partridges hunted in 2004 and 2006. Shot soil-burden averaged 73,600 units/ha (i.e., 8.1 kg/ha). Shot density was significantly higher in front of than behind shooting lines, with greatest accumulation occurring at between 40-110 m and in certain ecotones (i.e., shrubland-dry cropland). Analyses revealed 7.8% of partridges with evidence of Pb shot ingestion. Particle size in diet, grit-size composition, and shot ingestion prevalence were significantly higher in 2004 than in 2006, indicating that supplying partridges with large seeds (i.e., corn) may increase the risk of Pb shot ingestion. Moving shooting lines into croplands and controlling seed size used for diet supplementation may reduce shot ingestion.

Factors affecting large‐scale distribution of the Bonelli's eagleAquila fasciatain Spain

AbstractWe analyzed the environmental determinants of the regional distribution of Bonelli's eagle (Aquila fasciata) in Spain (ca. 500,000 km2), taking into account its frequency of occurrence on UTM blocks of 50 × 50 km. We found that the distribution pattern of Bonelli's eagle was a highly predictable phenomenon based on climate, vegetation and interspecific relationships. The proportion of sunny, anticyclonic days, per year (i.e., high levels of solar radiation) was the main environmental predictor explaining the distribution and abundance pattern of the Bonelli's eagle. Sparse plant formations (mainly shrublands) had also a positive effect, while altitude, agricultural land and deciduous forests had a negative influence. The relative abundance of one of its main preys, the Red Partridge (Alectoris rufa), favored the probability of occurrence of Bonelli's eagle, but only in the less sunny areas located in the north of Spain. The relative abundance of its main competitor, the Golden eagle (Aquila chrysaetos), was slightly but positively correlated with both the distribution and the abundance of the Bonelli's eagle in the Spanish portion of the Iberian Peninsula, probably due to similarities in their habitat preferences. Finally, we did not find further regional effects of the variables describing the degree of human pressure (density of roads, urban cover, and length of power lines).

Cell-mediated immune activation rapidly decreases plasma carotenoids but does not affect oxidative stress in red-legged partridges (Alectoris rufa)

In animals yellow-orange-red sexual traits pigmented by carotenoids have been suggested to act as signals of current health. Because carotenoids have important physiological functions, individuals might trade-off allocating these pigments to self-maintenance versus coloration. Carotenoids may act as scavengers of free radicals that are released during an immune response. Here, we experimentally assessed whether a local cell-mediated immune response affects circulating carotenoids, antioxidant status, oxidative damage and the expression of a carotenoid-based trait. Male red-legged partridges (Alectoris rufa) were subcutaneously injected with phytohaemagglutinin (PHA) or with phosphate buffer solution (controls). The effect of the treatment on circulating carotenoids, total plasma antioxidant status (TAS), lipid oxidative damage in erythrocytes (TBARS) and ornamentation was assessed. Immune challenge induced a 13% decrease in circulating carotenoids within 24 h. However, this treatment did not affect TAS, TBARS or coloration. Coloration, circulating carotenoids and cell-mediated immune response were positively correlated, but these were not related to TAS or TBARS. Carotenoids were only weakly related to TAS after controlling for the effect of uric acid levels. These results suggest that carotenoid-based ornaments may honestly indicate immunocompetence but probably not antioxidant capacity in this species, and that carotenoids might be relatively weak antioxidants in the plasma. Furthermore, even a relatively harmless and locally elicited immune challenge had important effects on circulating carotenoids, but this effect did not appear to be associated with oxidative stress. Alternative mechanisms linking carotenoids to immunity (not necessarily relying on the use of these pigments as antioxidants) should be considered in future studies on birds.

Influence of the pairing system on the behaviour of farmed red-legged partridge couples ( Alectoris rufa)

Approximately four million red-legged partridges ( Alectoris rufa) are released in Spain each year for repopulation or hunting purposes, all produced on intensive farming facilities under a forced pairing system. We studied the ethological response differences between two types of red-legged partridges couples: free and forced, using an experimental protocol with two groups of 20 couples each one: (A) group of forced pairing, one male and one female randomly chosen were introduced in the same cage and (B) group of free pairing, a female had the opportunity to chose between four males, using as female choice parameter the time spent by the female near each male. The behaviour of the couples during the first week they were together was evaluated. Female red-legged partridges chose males of higher weight and this males display more frequently patterns of feeding and vigilance behaviour. In the red-legged partridge alert and vigilance behavioural patterns are closely correlated to other feeding and cohesive behavioural patterns that increase the reproductive success of the couple. There was not aggressive behaviour in the free couples and only 2 attacks in the forced couples. In conclusion to have the opportunity to choose a partner increase the display of patterns of cohesive and feeding behaviour that increase the welfare of the females red-legged partridge on farm, but the environmental conditions of this study were not able to demonstrate differences in welfare due to pairing methods because there was a practically absence of aggressive behaviour of the male in both pairing options. We consider the cage design and space allowance together with the pairing methods as important factors that should be study in the future to improve welfare of farmed red-legged partridges.

Xoloptes blaszakisp. nov. (Pterolichoidea: Pterolichidae) — A New Species of Feather Mite fromAlectoris rufa(Galliformes: Phasianidae) from Europe with DNA Barcode Data

Xoloptes blaszaki, a new species of the feather mite family Pterolichidae (Pterolichoidea), is described from wing feathers of the Red-legged Partridge Alectoris rufa (L., 1758) (Phasianidae). Fusion of epimerites I and presence of a retrograde ventrobasal apophysis on tibia II in males of the new species differentiate it from the only other described species of Xoloptes (X. claudicans (Robin, 1877)), in which males have free epimerites I and thickened apico-ventral parts of tibiae II. The standard morphological description is supplemented by cytochrome oxidase I sequence data (DNA barcode).

The influence of egg size and colour on egg consumption by the Algerian hedgehog (Atelerix algirus)

We tested the hypothesis that the Algerian hedgehog (Atelerix algirus) consumes smaller eggs in preference to larger ones and that the colour of the eggs (brown or white spotted) does not influence the egg consumption rate. Eggs of three galliform species (the quail, Coturnix japonica; the red legged partridge, Alectoris rufa; the chicken, Gallus domesticus) were offered to 14 individual hedgehogs under experimental conditions. Overall, the hedgehogs consumed 107 of the 225 eggs offered (48%) in 5 days. The colour of the eggs did not influence the rates of egg consumption. However, egg size had a significant influence on the rates of egg consumption. Generalized linear mixed models showed that hedgehogs preferred to consume smaller quail eggs (91%, n = 65) than intermediate partridge eggs (44%, n = 110), whereas the largest chicken eggs (n = 50) were not consumed at all. There was a strong inter-individual variation in egg consumption, particularly of partridge eggs, from 0 to 100%, whereas individual variation in consumption of quail eggs was lower, from 70 to 100%.

Carotenoid-based bill and eye ring coloration as honest signals of condition: an experimental test in the red-legged partridge (Alectoris rufa)

Carotenoid pigments cannot be synthesized by vertebrates but must be ingested through the diet. As they seem to be a limited resource, carotenoid-based ornaments are particularly interesting as possible honest signals of individual quality, in particular of foraging efficiency and nutritional status. Some studies have demonstrated the condition dependence of carotenoid-based plumage in birds. However, many other carotenoid-pigmented bare parts (i.e. skin, caruncles, bills, cere, and tarsi) are present in birds but, in comparison with plumage, little is known about these traits as indicators of individual quality. Here, we show that the eye ring pigmentation and bill redness of the red-legged partridge (Alectoris rufa) are positively associated to body condition and recent changes in body mass. Also, we found a negative relationship between these two traits and heterophil-to-lymphocyte ratio, an indicator of physiological stress (the relationship with bill redness being significant only for males). In an experiment, we found that after a period of reduction in food intake (with the consequent loss of body mass), food-restricted birds showed lower eye ring pigmentation than ad-libitum-fed birds. Therefore, different ornaments seem to reflect changes in body condition but at different speeds or intensities (eye ring, a fleshy ornament, appears to respond more rapidly to changes in the nutritional status than a keratinized structure as the bill). These results indicate that carotenoid-based ornaments are condition-dependent traits in the red-legged partridge, being therefore susceptible to be employed as honest signals of quality in sexual selection.

Human-mediated introgression of exotic chukar (Alectoris chukar, Galliformes) genes from East Asia into native Mediterranean partridges

Mediterranean red-legged (Alectoris rufa) and rock (Alectoris graeca) partridge populations are affected by genetic pollution. The chukar partridge (Alectoris chukar), a species only partly native to Europe, is the most frequently introgressive taxon detected in the genome of hybrid partridges. Both theoretical (evolutionary) and practical (resources management) matters spur to get insight into the geographic origin of the A. chukar hybridizing swarm. The phenotypic A. rufa populations colonizing the easternmost part of the distribution range of this species, the islands of Elba (Italy) and Corsica (France), were investigated. The analysis of both mitochondrial (mtDNA: Cytochrome-b gene plus Control Region: 2,250 characters) and nuclear (Short Tandem Repeats, STR; Random Amplified Polymorphic DNA, RAPD) genomes of 25 wild (Elba) and 20 captive (Corsica) partridges, disclosed spread introgression of chukar origin also in these populations. All mtDNA haplotypes of Elba and Corsica partridges along with those we obtained from other A. rufa (total, n = 111: Italy, Spain, France) and A. graeca (n = 6, Italy), were compared with the mtDNA haplotypes of chukars (n = 205) sampled in 20 countries. It was found that the A. chukar genes detected in red-legged (n = 43) and rock partridges (n = 4) of Spain, France and Italy as well as in either introduced (Italy) or native (Greece, Turkey) chukars (n = 35) were all from East Asia. Hence, a well-defined geographic origin of the exotic chukar genes polluting the genome of native Mediterranean A. rufa and A. graeca (inter-specific level) as well as A. chukar (intra-specific level), was demonstrated.

Habitat selection and home range size of red-legged partridges in Spain

To understand the factors contributing to the spatial behaviour of the red-legged partridge ( Alectoris rufa), a radio-tracking study of free living partridges was carried out in Spain. During 2000–2002, 275 individuals were captured in four areas with different environmental and management characteristics. Sixty-nine adults and 23 juveniles were used to study space use distributions, including home range size, core area size and habitat selection. According to a generalized linear mixed model, 63% of the variability in home range size was explained by three landscape variables: edge index, average patch size and agricultural disturbance. Habitat selection was not influenced by age or sex because parents and juveniles remained together for most of the year, except during mating. The decline of the red-legged partridge in Spain was preceded by agricultural transformations related to land holding concentration and an increase in cultivated surface per property, which increased patch sizes and decreased edge and marginal areas across Spain.

Corticosterone in feathers is a long‐term, integrated measure of avian stress physiology

1. Stress has pervasive consequences for the well-being of animals. Currently, understanding how individuals cope with stressors is typically accomplished via short-term quantification of blood glucocorticoids released after activation of the hypothalamic-pituitary-adrenal (HPA) axis. 2. We investigated whether the amount of corticosterone (CORT) deposited in growing feathers provides a long-term, integrated measure of HPA activity in birds using captive red-legged partridges Alectoris rufa as a model species. 3. We examined CORT levels in primary feathers induced to grow at the same time as stress series were performed with a capture and restraint protocol. Plasma CORT titres after stress-induced stimulation, but not baseline values, correlated with feather CORT. Feather levels showed the same pattern as plasma of decline across the breeding season, but more severely. 4. For females, CORT in naturally moulted flank feathers was highly and positively correlated with the number of eggs laid in the previous few months, but not clutch size of the following year. For males, the amount of black on a feather, known to be a social signal, was positively correlated with its CORT level. 5. The analysis of feather CORT is a novel methodology that allows for meaningful interpretations of how individuals respond to environmental perturbations and adjust to life-history stages. 6. The analysis of feather hormones has the unique advantages of allowing for experimentation and sampling at any time of the year with minimal investigator-induced impacts and artefacts, and shows the HPA activity of an individual with a flexible time frame from days to months depending on the length of time taken to grow the feather. As this technique can be applied to living or dead birds, or feathers picked up after moult, it provides the ultimate non-invasive physiological measure of considerable benefit in terms of animal welfare and sampling effort.

New perspectives on harvesting as one driver of ecosystem dynamics

New perspectives on harvesting as one driver of ecosystem dynamics

Carotenoid-based ornamentation as a dynamic but consistent individual trait

Carotenoid-based ornaments act as signals of quality in many animal species. In contrast to feathers, which are relatively stable structures, carotenoid-pigmented integuments (e.g. bills, lores, tarsi) can change colour rapidly and may better reflect changes in physiological condition. I studied the seasonal variations in plasma carotenoids in red-legged partridges (Alectoris rufa) kept on a constant diet and free of intestinal parasites. Furthermore, I analyzed whether seasonal changes in circulating carotenoids were mirrored by the carotenoid-based coloration of eye rings and bill of this species. Plasma carotenoids showed seasonal variation, with higher levels coinciding with the end of the mating and the start of the laying season. Eye ring pigmentation was related to plasma carotenoid levels, and changes in bill hue (but not changes in UV or red bill chroma) mirrored the variation in plasma carotenoids during the breeding season. Despite the seasonal variation, individual differences in eye ring pigmentation and bill hue, UV and red chroma were consistent throughout the breeding season. Similarly, individual differences in eye ring pigmentation and bill hue and red chroma remained consistent between consecutive years. These results suggest that carotenoid based integumentary colorations act as dynamic traits that accurately reflect the carotenoid-status of individuals, thus reliably indicating consistent differences in individual quality. Furthermore, variability in signal expression appears to have a relevant genetic/phenotypic basis independently of environmental conditions.