Alectoris Rufa Research Articles

Nodular TROMBICULIOSIS Caused by Neoschoengastia simonovichi in a Group of Wild Red-Legged Partridges (Alectoris rufa)

Nodular TROMBICULIOSIS Caused by Neoschoengastia simonovichi in a Group of Wild Red-Legged Partridges (Alectoris rufa)

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.

Effects of Lead Exposure on Sperm Quality and Reproductive Success in an Avian Model.

Lead (Pb) poisoning via ingestion of shot pellets is a frequent cause of death in wild birds and also has a wide range of subclinical effects. Here we report on the sublethal effects Pb exposure has on the breeding performance of red-legged partridges (Alectoris rufa). We studied the effects of Pb exposure on sperm quality, reproductive success, egg properties, laying performance, antioxidant levels, and carotenoid-based coloration. Birds were exposed by oral gavage to one or three No. 6 Pb shot pellets (2.8 mm in diameter, mean mass ± SD: 109 ± 7.97 mg). We show that exposure to three pellets (330 mg) reduced the hatching rate of females and decreased the acrosome integrity and sperm motility of males. In addition, females exposed to 1 pellet (110 mg) produced heavier eggs and chicks, whereas males exposed to 1 pellet presented an increase in sperm vigor. Sperm viability, concentration, progressiveness or fecundation rate were not affected by Pb treatment. Pb exposure increased circulating antioxidant levels in males, whereas the percentage of carotenoid-pigmented eye-ring area decreased in exposed females. Several sperm parameters showed positive relationships with coloration and antioxidant levels, suggesting that males displaying redder ornaments may be more capable of protecting sperm from oxidative stress in the event of sublethal Pb exposure.

Specific carotenoid pigments in the diet and a bit of oxidative stress in the recipe for producing red carotenoid-based signals.

Colorful ornaments have been the focus of sexual selection studies since the work of Darwin. Yellow to red coloration is often produced by carotenoid pigments. Different hypotheses have been formulated to explain the evolution of these traits as signals of individual quality. Many of these hypotheses involve the existence of a signal production cost. The carotenoids necessary for signaling can only be obtained from food. In this line, carotenoid-based signals could reveal an individual’s capacity to find sufficient dietary pigments. However, the ingested carotenoids are often yellow and became transformed by the organism to produce pigments of more intense color (red ketocarotenoids). Biotransformation should involve oxidation reactions, although the exact mechanism is poorly known. We tested the hypothesis that carotenoid biotransformation could be costly because a certain level of oxidative stress is required to correctly perform the conversion. The carotenoid-based signals could thus reveal the efficiency of the owner in successfully managing this challenge. In a bird with ketocarotenoid-based ornaments (the red-legged partridge; Alectoris rufa), the availability of different carotenoids in the diet (i.e. astaxanthin, zeaxanthin and lutein) and oxidative stress were manipulated. The carotenoid composition was analyzed and quantified in the ornaments, blood, liver and fat. A number of oxidative stress biomarkers were also measured in the same tissues. First, we found that color and pigment levels in the ornaments depended on food levels of those carotenoids used as substrates in biotransformation. Second, we found that birds exposed to mild levels of a free radical generator (diquat) developed redder bills and deposited higher amounts of ketocarotenoids (astaxanthin) in ornaments. Moreover, the same diquat-exposed birds also showed a weaker resistance to hemolysis when their erythrocytes were exposed to free radicals, with females also enduring higher oxidative damage in plasma lipids. Thus, higher color production would be linked to higher oxidative stress, supporting the biotransformation hypothesis. The recent discovery of an avian oxygenase enzyme involved in converting yellow to red carotenoids may support our results. Nonetheless, the effect could also depend on the abundance of specific substrate carotenoids in the diet. Birds fed with proportionally higher levels of zeaxanthin showed the reddest ornaments with the highest astaxanthin concentrations. Moreover, these birds tended to show the strongest diquat-mediated effect. Therefore, in the evolution of carotenoid-based sexual signals, a biotransformation cost derived from maintaining a well-adjusted redox machinery could coexist with a cost linked to carotenoid acquisition and allocation (i.e. a resource allocation trade-off).

Age and Sex Ratios in a High-Density Wild Red-Legged Partridge Population.

The dynamics of a wild red-legged partridge population were examined over a 14-year period in Spain to identify patterns in age and sex ratios in relation to weather parameters, and to assess the importance of these parameters in population dynamics and management. The results gave age ratios of 1.07 (but 2.13 in July counts), juvenile sex ratios of 1.01 and adult sex ratios of 1.47. Overall, 12% more females were hatched and female juvenile mortality was 7.3% higher than in males. Sex differential mortality explains the 19.2% deficit in adult females, which are more heavily predated than males during the breeding period. Accordingly, age ratios are dependent on sex ratios and both are density dependent. Over time, ratios and density changes appear to be influenced by weather and management. When the habitat is well conserved, partridge population dynamics can be explained by a causal chain: weather operates on net primary production, thereby affecting partridge reproduction and predation and, as a result, age and sex ratios in the October population. A reduction in the impact of predation (i.e. the effects of ground predators on eggs, chicks and breeding females) is the key factor to improve the conservation of partridge populations and associated biological processes.

Influence of game crops on the distribution and productivity of red-legged partridges Alectoris rufa in Mediterranean woodlands

Red-legged partridges Alectoris rufa are one of the most important game species in extensively managed Mediterranean agro-forest systems. Population declines have led to management to increase their populations. This includes the creation of game crops, but their efficacy for red-legged partridges has not been tested. We developed in October 1996 an experimental introduction of 32 100 × 8 m plots in a 6.46-km2 mixed agro-forest system area in Portugal. These plots were planted with either lupin Lupinus sp., vetch Vicea sp. or triticale Triticum aestivum × Secale cereale. The main goal of this study was the evaluation of the potential effect of game crops on partridge distribution and productivity, after controlling for the effect of habitat or other management actions. Partridge abundance and distribution were assessed during spring and summer 1997 by intensive territory mapping. We compared characteristics of territory centres with those of random points in relation to land uses, game crops, and location of water points or supplementary grain sites. The most important variable explaining partridge’s location in spring was the density of supplementary water points. In summer, partridge territories were positively associated with the density of water points and lupin game crops, as well as olive trees. Productivity (number of young per territory in relation to adults observed) increased with the density of lupin game crops, but decreased with density of water points and vetch game crops and proportion of woodland within the territories. Overall, this study suggests that management for partridges in areas of agricultural abandonment, such as those in Mediterranean woodlands, would benefit from the introduction of leguminous game crops and water provision, though more studies are required for a more adequate optimization of these measures of habitat improvement, in particular about the specific cover of the crops and their spatial distribution so they provide adequate resources in summer for nestlings.

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

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

Prioritising Research in Steppe Bird Conservation: A Literature Survey

With the aim to identify priorities in conservation-oriented research, this paper reviews the level of scientific attention given to steppe birds in Spain during the last 50 years. We surveyed scientific literature using Thomson Reuters Web of Science and the journal Ardeola, using the English names of 28 species of steppe birds and the word “Spain” as search terms. Every species was assigned a Scientific Attention Index (SAI), based on the number of articles published on each of them. In addition, a vulnerability measure (Vulnerability Score; VS) was calculated for each species on the basis of the trend estimate provided by the Sacre or Noctua monitoring programmes, or according to expert criteria. The sample gathered (432 articles) was a significant and thus representative proportion of WOS and Ardeola contents on the species considered. The most studied species was the red-legged partridge Alectoris rufa, with 83 papers (20.15%); while the least studied was the short-eared owl Asio flammeus (1 paper; 0.24%). The most studied knowledge area was Habitat Selection (92 papers; 22.17%), while the least was Niche/Climate, with nine papers (2.17%). Preferred habitat (grass steppe, shrub steppe or mixed) was not a significant factor in the level of scientific attention given to the different species. However, large-sized species (non-Passerines) were significantly more studied than small-sized ones (Passerines), indicating a research bias for the former group. Finally, no significant relationship was found between SAI and VS, which suggests that research effort has been allocated irrespective of the species' conservation status. These results highlight the scarce scientific attention given to most steppe birds in Spain in spite of their overall high vulnerability, and for most of the knowledge areas considered. On the other hand, they also show the high relative importance of research carried out in Spain, in both the Mediterranean and world contexts. This work underscores the need to focus scientific effort on certain species, especially those that currently show more regressive trends or higher levels of vulnerability, and in most areas of knowledge.

Gender-related amino acid intake of adult wild Red-legged Partridge (Alectoris rufa)

The Red-legged Partridge (Alectoris rufa) is under an enormous hunting pressure. It is bred intensively in game farms. The hunting season is during the non-reproductive resting period when partridges are at maintenance conditions.There is a lack of information about the amino acid (AA) composition of the natural diet of the adult birds in their habitat or differences in dietary AA composition related to gender. The objective of this work was to establish a first approach to the AA composition of the natural diet of adult wild Red-legged Partridge.Food content in crops and gizzards of female and male birds hunted in the same hunting season and area was analysed for AA composition.Females food had higher concentrations of individual essential AA (EAA) and non-essential AA (NEAA) than males.There are important differences in the concentration of AA in the natural diet of wild females and males. It may be advisable to use diets differing in the proportion of individual AA in the game farms during the non-reproductive resting period.

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.

Identifying key habitats for the conservation of Bonelli's Eagle Aquila fasciata using radiotracking

Identifying the priority habitats of endangered species is crucial to implementing effective conservation actions. We characterize the key habitats used by Bonelli's Eagle Aquila fasciata, an umbrella and flagship species that is endangered in Mediterranean countries. We radiotracked 17 breeding individuals (10 males and seven females) in Catalonia (NE Iberian Peninsula) and used compositional analysis to determine the key habitats in home‐ranges of both sexes. The main habitats identified within the home‐range area were scrubland, coniferous forests, cropland, sclerophyllous forests, rock outcrops and urban areas, with little difference in habitat use between the sexes. Bonelli's Eagles preferred rocky habitats as breeding areas and scrubland as foraging areas, as these hold the highest abundance of their main prey, Rabbits Oryctolagus cuniculus and Red‐legged Partridges Alectoris rufa. Habitat selection varied seasonally in foraging areas: scrubland was the most preferred habitat type during the breeding season, whereas rocky areas were preferred during the non‐breeding season (although scrubland was also highly selected). Urban areas were avoided both as breeding and as foraging areas. Home‐range size was inversely correlated with the proportion of scrubland, suggesting that this is a key habitat for Bonelli's Eagle. To conserve this species effectively, policies that ensure the preservation of the cliffs used as breeding sites, as well as suitable management of the scrubland used for foraging, should be implemented in the areas inhabited by this species. The promotion of traditional land uses and management techniques that will enhance open areas in Mediterranean landscapes should in the future play an essential role in the conservation of Bonelli's Eagle in Mediterranean habitats.

Selenium and vitamin E diet inclusion for optimal reproduction performances of red-legged partridge (Alectoris rufa)

To date there is little knowledge regarding the requirements of Se and vitamin E of red-legged partridges (Alectoris rufa). For this reason, in the present study four different Se and vitamin E diet inclusions have been tested. A total of 360 parents were used and randomly divided into four groups; diets were supplemented with 0.2, 0.3, 0.4 and 0.5 mg/kg of Se and Se to vitamin E ratio was kept approximately constant in all groups. The effects of the diets on parents’ reproduction performances and on embryos visceral organs were investigated. The best laying rate was reached with 0.4 mg/kg Se diet supplementation while the best hatching rate was reached with 0.3 mg/kg (p < 0.05). The relative weight of duodenum, jejunum and ileum in embryo was higher (p < 0.05) in the groups fed 0.4 and 0.5 mg/kg Se compared to the other groups. Significant differences (p < 0.05) were also observed for jejunum and ileum length as animals were fed the highest Se to vitamin E ratios. The number and height of villi and goblet cells density of jejunum were higher (p < 0.05) in the groups fed 0.4 and 0.5 mg/kg of Se than in the group fed 0.2 mg/kg. Epithelial buds density in the Bursa of Fabricius of embryos was significantly higher (p < 0.05) for 0.4 and 0.5 mg/kg Se supplemented groups than in the others. In conclusion our results suggest that 0.4 mg/kg of selenium and 100 mg/kg vitamin E should be included in the parents’ diet in order to optimise red-legged partridges performances.

Diseases in gamebirds: an update

Since previous publications in In Practice on disease control in adult pheasants (Pennycott 2001) and diseases in young pheasants (Welchman 2008), the numbers of gamebirds reared and released in Britain...

Comparison of Three Temperatures for the Hatching Phase in the Artificial Incubation of Red-legged Partridge (Alectoris rufa) Eggs

This study aimed at investigating the effects of three incubation temperatures during the hatching period on egg weight loss, hatchability, chick weight at hatching and length of the incubation period of red-legged partridge (Alectoris rufa) under artificial incubation. One hundred and fifty eggs obtained from a red-legged partridge game farm were randomly allocated to three batches of 50 eggs each. Eggs were incubated at 37.8oC during the first 20 days, and subsequently at 37.0, 37.4 or 37.8oC until hatching. Fertility was 74.7% and a good hatching performance was obtained, characterized by 85.7% hatchability, 9.1% egg weight loss after 20 days of incubation, 13.8±0.1 g chick weight at hatching, and 23.2±0.1 days incubation length. Hatchability, egg weight loss after 20 days of incubation, and length of the incubation period were not affected by incubation temperature during the hatching period. However, hatching synchrony improved when the incubation temperature was increased from 37.0 to 37.8°C (p<0.05). Thus, hatching distribution became very leptokurtic and very positively skewed with the increase in incubation temperature during the hatching phase. In conclusion, higher hatching synchrony can be achieved in A. rufa when setting temperatures within the range 37.0 to 37.8oC to incubate eggs during the hatching period. Consequently, incubation temperature management during the hatching phase may have a direct impact on hatching synchrony and hatchling management.

Statistical Modeling of Hunting Success Using Hunter Surveys

Different methods are available to estimate the wildlife population development. In this paper a method based on hunter surveys of a Spanish game preserve is proposed. A Poisson model is fitted to estimate the relationship between hunting success and other independent variables. In order to find the most appropriate model, a model selection procedure based on repeated cross validation is used to determine which explanatory variables describe the hunting success better in terms of prediction ability. The estimatedmodel is successful in the case of the red legged partridge (Alectoris rufa). The model can be used for applying different management criteria in a game preserve. Some possibilities are demonstrated for particular scenarios.

Bird-bone modifications by Iberian lynx: A taphonomic analysis of non-ingested red-legged partridge remains

The Iberian lynx (Lynx pardinus) is a significant taphonomic agent in Iberian ecosystems. Its diet is based almost exclusively on rabbits and it is complemented mainly with birds from the Phasianidae, Anatidae and Corvidae families. We present here the results of actualistic taphonomic research conducted to assess modifications produced by Iberian lynx on non-ingested red-legged partridge (Alectoris rufa) remains. Through anatomical representation, breakage patterns and bone surface modifications we were able to establish the main characteristics of the taphocoenosis of the Iberian lynx regarding one of their complementary preys. The results revealed low survival of entire carcasses, remains mainly of offal and feathers – that are barely preserved in archaeological fossil records –, and some skeletal remains. Anatomically there was greater evidence of thoraxes, especially pelvis/synsacrum and adjoining ribs, and distal portions of wings and legs. Breakage was nominal with a high survival of whole elements, but none of the major long-bone remains were complete. The bones in the meaty parts (wings/humeri, drumsticks/femurs and tibiae and breasts/sternums), were very fragmented. Tooth marks were rare and occurred mainly in the form of notches on fractured edges none of which had opposite tooth marks. A comparison of our results with those obtained for the main prey of lynxes – rabbits – indicated a lower survival of bird remains. This differential taphonomic pattern must be related to the anatomy of the prey and the anatomical distribution of meaty parts which are the main interest of the predator.

Factors Affecting Red-Legged PartridgeAlectoris rufaAbundance on Big-Game Hunting Estates: Implications for Management and Conservation

The red-legged partridge Alectoris rufa is not only the most important bird game species but also an important prey species for many predators in Iberia. However, its populations have significantly declined in recent decades, principally as the result of agricultural intensification on arable land. Its abundance has also undergone a significant decline in forested areas over the last few decades, where wild ungulate management and abundance have increased. In this scenario, we aimed to test the factors that affect red-legged partridge abundance in relation to high wild ungulate (wild boar and red deer) abundance in south-central Spain. The factors included as predictors were carnivore, wild boar and red deer abundances, vegetation features, nest predation rate and invertebrate availability. Red deer abundance showed a negative relationship with partridge abundance in spring (non-significant negative trends were also evident for carnivore and wild boar), whereas variables related to food availability (grass biomass, Hemipteran abundance and total invertebrate mass) had a positive effect in the same season. Moreover, deer and carnivore abundances and spring nest predation rate were negatively associated with partridge abundance in autumn. Plant biomass and Hemipteran abundance were negatively correlated with wild boar abundance, whereas maximum pasture height was negatively related to red deer and wild boar abundance. Overall, our results show that high ungulate densities may negatively affect partridge abundance, which may be mediated by (i) a reduction in food availability (invertebrate and herbaceous plant biomass) and (ii) nest predation by wild boar. This research has shown that current intensive big-game hunting management schemes in south-central Spain are often incompatible with red-legged partridge conservation, and that these effects should be taken into account when defining big-game management and conservation policies.

Resource partitioning and niche segregation in a steppe bird assemblage

Niche theory predicts that coexisting species will partition resources to limit the effects of interspecific competition. We examined microhabitat partitioning in six sets of steppe birds associated to agroecosystems in central Spain (female and male Great Bustards Otis tarda, female and male Little Bustards Tetrax tetrax, Red-legged Partridges Alectoris rufa and Eurasian Stone-curlews Burhinus oedicnemus) to estimate realized niche breadth, overlap and segregation. Principal Components Analysis on data from used and random microhabitat locations produced two axes we retained for analysis related with two key factors: cover-visibility and food availability. Non-parametric kernel density functions were calculated for each of the PCA axes and species (or sexes), and niche overlap estimated as the area shared between species’ density functions. Null models were run to evaluate overlap significance. In analyses of microhabitat selection by the six sets of birds, 13 out of 15 pairs had significant resource partitioning and niche segregation, except for the pairs partridge and female Great Bustard and the two sexes of Great Bustard. Eurasian Stone-curlew showed wider trophic niche breadth, although segregated from the other species, probably because of its higher invertebrate requirements. Great and Little Bustards segregated in both niche axes, selecting microhabitat according to their body size. Accessibility to food resources and shelter seems to be similar for partridges and female Great Bustards, overlapping in their selection, which may indicate the existence of segregation in other niche factors (e.g., feeding habits). Great Bustard males showed niche overlap with females. Little Bustard males showed feeding microhabitat selection patterns similar to those of females, although they preferred more open microhabitats to meet their sexual display requirements. The entire assemblage had significantly less overlap than expected by chance, suggesting that differential microhabitat selection and realized niche partitioning may explain coexistence in steppe bird communities. Our results suggest that the maintenance of different microhabitat structure should be a priority in the management of agricultural environments.

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.

Assessing the Risk of Fipronil-Treated Seed Ingestion and Associated Adverse Effects in the Red-Legged Partridge.

Fipronil is an insecticide commonly used in agriculture, but there are growing concerns over its environmental impacts (e.g., harmful effects on pollinators). Fipronil-treated seed ingestion might threaten granivorous farmland birds, in particular, Gallinaceous birds that are particularly sensitive to this insecticide. We report here on exposure risk and effects in a game bird of high socioeconomic importance, the red-legged partridge (Alectoris rufa). We fed captive birds with untreated maize (controls) or with a mixture of untreated-treated maize (ratio 80:20; exposed birds) during 10 days at the beginning of the breeding period (n = 12 pairs in each group). We first show that exposed partridges did not reject treated seeds but reduced food intake and lost body condition. We further studied the effects of treated seed ingestion on adult survival, oxidative balance, plasma biochemistry, carotenoid-based coloration, cellular immune response, steroid hormone levels, and reproduction. Fipronil exposure altered blood biochemistry and sexual hormone levels and reduced cellular immune response, antioxidant levels, and carotenoid-based coloration. Exposed pairs also had reduced egg fecundation rate and produced eggs with fewer antioxidants and offspring that had reduced cellular immune response. These negative effects on adult partridges, their reproductive performance, and offspring quality highlight that fipronil-treated seed ingestion is a significant threat to wild birds.