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This article belongs to the Special Issue Zoonoses and Wildlife: One Health Approach., Coxiella burnetii, the causal agent of human Q fever and animal Coxiellosis, is a zoonotic infectious bacterium with a complex ecology that results from its ability to replicate in multiple (in)vertebrate host species. Spain notifies the highest number of Q fever cases to the ECDC annually and wildlife plays a relevant role in C. burnetii ecology in the country. However, the whole picture of C. burnetii hosts is incomplete, so this study seeks to better understand the role of micromammals in C. burnetii ecology in the country. Spleen samples from 816 micromammals of 10 species and 130 vaginal swabs from Microtus arvalis were analysed by qPCR to detect C. burnetii infection and shedding, respectively. The 9.7% of the spleen samples were qPCR positive. The highest infection prevalence (10.8%) was found in Microtus arvalis, in which C. burnetii DNA was also detected in 1 of the 130 vaginal swabs (0.8%) analysed. Positive samples were also found in Apodemus sylvaticus (8.7%), Crocidura russula (7.7%) and Rattus rattus (6.4%). Positive samples were genotyped by coupling PCR with reverse line blotting and a genotype II+ strain was identified for the first time in one of the positive samples from M. arvalis, whereas only partial results could be obtained for the rest of the samples. Acute Q fever was diagnosed in one of the researchers that participated in the study, and it was presumably linked to M. arvalis handling. The results of the study are consistent with previous findings suggesting that micromammals can be infected by C. burnetii. Our findings additionally suggest that micromammals may be potential sources to trace back the origin of human Q fever and animal Coxiellosis cases in Europe., This work was supported by grants CGL2011-30274 and CGL2015-71255-P of the Spanish Ministry for the Science and Innovation (MCI), and by the ‘Fundación BBVA’ Research Project TOPIGEPLA (2014 call). This is also a contribution to MCI-funded projects CGL2017-89866-R and E-RTA-2015-0002-C02-02. D.G.-B. was funded by MCI through Juan de la Cierva (FJCI-2016-27875) and ‘Sara Borrell’ (CD19CIII/00011) postdoctoral fellowships. GREFA provided partial financial support and invaluable logistic and workforce support for samplings in NW Spain, along with many students and staff from UAM.

It is known that the garden dormouse Eliomys quercinus includes meat in its diet, however, it is unclear if scavenging is a widespread behaviour, as it is difficult to observe in the wild. Here, we document scavenging behaviour for the species based on direct evidence. We captured five garden dormice with live traps using dead baits, which were partially or totally consumed. Additionally, a camera-trap recorded how at least one garden dormouse visited and actively consumed the bait on 12 occasions during the study. These observations suggest that carrion may play an important role in the garden dormouse's diet, opening a new ecological unexplored topic for this species., This study was funded by projects TOPIGEPLA (Fundación BBVA Research Projects, 2014 call) and Movi-Topi (I + D National Plan Project, CGL2015-71255-P). F. Díaz-Ruiz was supported by a “Juan de la Cierva” research contract (Ministerio de Ciencia e Innovación, Funder Id: 10.13039/501100004837, FJCI-2015-24949) from the Spanish Ministry of Economy, Industry and Competitiveness.

In conservation biology, population monitoring is a critical step, particularly for endangered groups, such as steppe birds in European agro-ecosystems. Long-term population monitoring allows for determination of species population trends and also provides insights into the relative roles that environmental variability and human activities have on priority species. Here, we compare the population trends of two sympatric, closely related farmland bird species, the Little Bustard Tetrax tetrax and Great Bustard Otis tarda, in a protected area of Central Spain, which is their main stronghold in Europe. Over 12 years of monitoring, the abundance of Little and Great Bustards shifted in opposite directions in our study area. Little Bustard abundance decreased significantly (both males [-56%], and harder-to-detect females [-55%]), while Great Bustard abundance increased significantly (1,800%). Future surveys should be more precise and frequent for Little Bustards to facilitate evaluation of their population status and trends. We recommend annual surveys in 2-3 important locations by region throughout the breeding range for Little Bustards, while for Great Bustard the current regional monitoring programmes would be sufficient., This work was supported by the Ministerio de Ciencia y Tecnología (MCYT-REN2003-07851/GLO, CGL2004-02568/BOS, CGL2007-66322/BOS and CGL2008-04282/BOS) and the Project ‘‘Steppeahead’’ funded by Fundación General del Consejo Superior de Investigaciones Científicas from Spain (FGCSIC) and Banco Santander. FC was supported by the Andalucía Talent Hub Program launched by the Andalusian Knowledge Agency, cofounded by the European Union’s Seventh Framework Program, Marie Skłodowska-Curie actions (COFUND–Grant Agreement n° 291780) and the Ministry of Economy, Innovation, Science and Employment of the Junta de Andalucía.

A significant restructuring of vineyards is currently taking place in the European Union (EU) as a result of the implementation of a restructuring and conversion of vineyards regulation (CE 1493/1999) in southwest Europe, so that trellis vineyards are rapidly replacing traditional vineyards (e.g., surface area from 18.1 % in 2010 to 34 % in 2015 in Castilla-La Mancha, Central Spain). These changes may influence patterns of space use in birds, which may avoid modified habitats. We assess how the location of traditional and trellis vineyards might influence the distribution of great bustard (Otis tarda), a globally threatened species. We estimate Resource Selection Functions (RSFs) to quantify the relative probability of use of different areas by the great bustards, and use the RSF’s to simulated scenarios of conversion from traditional to trellis vineyards (low - 10 %, medium - 30 %, and high rate - 60 %) to quantify the potential impact of such modifications on the availability of suitable great bustard habitat. Our results revealed that great bustards significantly avoid trellis vineyards, especially at closer distances. Transition scenarios show how an increase in the proportion of traditional vineyards converted to trellis vineyards greatly decrease the proportion of suitable habitat for great bustard. Compared to current conditions, the percentage loss of suitable habitat increased steadily with higher rates of converted vineyards, up to 60 % loss of suitable habitat at the highest rate of conversion. Because the effect of transforming traditional vineyards to trellis vineyards depends both on the amount of habitat available for bustards before the transformation occurs and on the overall area covered by vineyards, a correct estimation of transformable vineyard area will require a case-by-case assessment to assure a low impact on bustard populations. We identified alternative vineyard management options that would mitigate impacts on the great bustard populations., This work was supported by the Ministerio de Ciencia y Tecnología (MCYT-REN2003-07851/GLO and CGL2004-02568/BOS). FC was supported by the Andalucía Talent Hub Program launched by the Andalusian Knowledge Agency, cofounded by the European Union’s Seventh Framework Program, Marie Skłodowska-Curie actions (COFUND–Grant Agreement n° 291780) and the Ministry of Economy, Innovation, Science and Employment of the Junta de Andalucía, and by the University of Maryland.

The onset of incubation before the end of laying imposes asynchrony at hatching and, therefore, a size hierarchy in the brood. It has been argued that hatching asynchrony might be a strategy to improve reproductive output in terms of quality or quantity of offspring. However, little is known about the mediating effect of hatching asynchrony on offspring quality when brood reduction occurs. Here, we investigate the relationship between phenotypic quality and hatching asynchrony in Common Kestrel Falco tinnunculus nestlings in Spain. Hatching asynchrony did not increase breeding success or nestling quality. Furthermore, hatching asynchrony and brood reduction had different effects on nestlings’ phytohaematogglutinin (PHA)-mediated immune response and nestling growth. In asynchronous and reduced broods (in which at least one nestling died), nestlings showed a stronger PHA-mediated immune response and tended to have a smaller body size compared with nestlings raised in synchronous and reduced broods. When brood reduction occurred in broods hatched synchronously, there was no effect on nestling size, but nestlings had a relatively poor PHA-mediated immune response compared with nestlings raised in asynchronous and reduced broods. We suggest that resources for growth can be directed to immune function only in asynchronously hatched broods, resulting in improved nestling quality, as suggested by their immune response. We also found that males produced a greater PHA-mediated immune response than females only in brood-reduced nests without any effect on nestling size or condition, suggesting that females may trade off immune activities and body condition, size or weight. Overall, our results suggest that hatching pattern and brood reduction may mediate resource allocation to different fitness traits. They also highlight that the resolution of immune-related trade-offs when brood reduction occurs may differ between male and female nestlings.

We tested some predictions of parental investment theory by studying the aggressive behaviour of colonial nesting chinstrap penguins (Pygoscelis antarctica) against human intruders into their nesting territories. We tested for differences in the aggressive behaviour of penguins according to offspring age (eggs vs. chicks), offspring number, nest location in the colonies (central vs. peripheral) and sex. Offspring age was the main factor influencing nest defence, although nest location and sex were also important. Chicks were defended more strongly than eggs, in accordance with changes in the reproductive value of offspring, and this increase in aggressiveness was not related to revisitation of the same individuals. The level of aggression of penguins breeding in central sites was higher than that of peripheral birds, a difference that could be due to the lower residual reproductive value of central-nesting, probably older, birds. The stronger aggressiveness of males could be due to a combination of factors related to sexual selection and life-history traits. Offspring number did not affect the level of nest defence.

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., C.A.‐A. and L.P.‐R. were funded by a Ramon y Cajal Fellowship and a predoctoral Formación del Profesorado Universitario grant, respectively (Ministerio de Educación y Ciencia, Spain). The study was funded by Junta de Comunidades de Castilla–La Mancha (project PAI‐06‐0018) and Ministerio de Educación y Ciencia (project CGL2006‐10357‐C02‐02), both from Spain.

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 Partridges Alectoris rufa in 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.

An analysis of the orientation of 182 nest sites of the Black Kite Milvus migrans in two areas in south and central Spain found that orientations toward the east were preferred. In southern Spain an analysis of the relationship between nest orientation and hatching success showed that success was lower among the nests located in non-preferred orientations, with some inter-annual variation. The tendency to orientate nests toward the east was greater among the early nesting pairs and the effect that the orientation had on the hatching success was also greater than in late nesting pairs. The data suggest that rainfall and prevailing winds were the main factors conditioning nest orientation.

Parental favoritism in birds would be enhanced if parents can control any egg feature influencing the ontogeny of the embryo during incubation. Egg size and composition may influence the duration of incubation and hatching periods, and eggs bearing embryos of different sex may differ in size and composition. Therefore, the sex of the embryo could also influence its ontogeny before hatching. We tested this prediction by investigating the duration of the embryonic period of different-sex embryos in the Eurasian kestrel (Falco tinnunculus), a sexually dimorphic raptor in which adult females are approximately 20% heavier than are adult males. We found the first evidence of sex differences in the duration of the embryonic period in avian eggs. Female embryos had a shorter embryonic period than did male embryos, which allowed females to hatch earlier in the hatching sequence and assume a higher rank than that of males in the intrabrood size hierarchy. Embryos with a fast growth and development resulted in hatchlings with greater residual reserves and thus larger mass, which suggests that a shorter embryonic period requires less maintenance metabolism relative to growth. Our results also indicated that early hatching may be advantageous to gain a high rank in the size hierarchy within the brood independently of the effect of sex on fledgling mass. Sex differences in avian egg ontogeny may therefore be a factor shaping life-history traits associated with parental control of sibling competition, which should be addressed in any future work on optimal reproductive investment.

Capturing and marking free-living birds permits the study of important aspects of their biology but may have undesirable effects. Bird welfare should be a primary concern, so it is necessary to evaluate and minimize any adverse effects of procedures used. We assess short-term effects associated with the capture, handling and tagging with backpack-mounted transmitters of Pin-tailed Pterocles alchata and Black-bellied Pterocles orientalis Sandgrouse, steppe birds of conservation concern. There was a significantly higher mortality (15%) during the first week after capture than during the following weeks (, F. Casas was supported by a JAE-Doc contract funded by CSIC and the European Social Fund (ESF) and by the Steppe-Ahead project funded by FGCSIC. Funding came from the Dirección General de Investigación (projects CGL2007-66322/BOS and CGL2008-04282/BOS), Consejería de Educación y Ciencia de Castilla-La Mancha (projects PAI08-0171-9582 and PAC06-137) and Bardenas Reales Biosphere Reserve (projects UCTR09-0268, UCTR110053 and UCTR120308).

At least 19 hypotheses have been proposed to explain the evolutionary significance of avian hatching asynchrony, and hatching patterns have been suggested to be the result of several simultaneous selective pressures. Hatching asynchrony was experimentally modified in the black kite Milvus migrans by manipulating the onset of incubation during the laying period. Delayed onset of incubation reduced egg viability of first-laid eggs, especially when ambient temperature during the laying period was high. Brood reduction (nestling mortality by starvation or siblicide) was more commonly observed in asynchronous nests. The growth rate was slower in synchronous broods, probably due to stronger sibling rivalry in broods with high size symmetry. Last-hatched chicks in synchronous broods fledged at a small size/mass, while in control broods, hatching order affected growth rates, but not final size. Brood reduction, variable growth rates, and the ability to face long periods of food scarcity are probably mechanisms to adjust productivity to stochastic food availability in a highly opportunistic predator. The natural pattern of hatching asynchrony may be the consequence of opposing selective forces. Extreme hatching synchrony is associated with slow growth rates, small final size of last-hatched chicks, and low viability of first-laid eggs, while extreme hatching asynchrony is associated with high mortality rates. Females seem to facultatively manipulate the degree of hatching asynchrony according to those pressures, because hatching asynchrony of control clutches was positively correlated with temperature during laying, and negatively correlated with the rate of rabbit consumption.

In siblicidal species, hatching asynchrony could act to reduce sibling rivalry or promote the death of last-hatched chicks. The pattern of hatching asynchrony was experimentally altered in the black kite Milvus migrans. Hatching asynchrony in control broods was intermediate between those of experimentally synchronised and asynchronised broods. Sibling aggression and wounds on the chicks were more commonly observed early in the nestling period and in synchronous nests. Serious injuries were observed on last-hatched chicks in asynchronous nests, as were observations of intimidated or crushed chicks. Sibling aggression was related to food abundance, but some chicks died at an early age in nests with abundant food (cainism). Cainism was more commonly found in asynchronous nests. For species with facultative siblicide, moderate hatching asynchrony could be a compromise between reducing sibling rivalry and avoiding large size differences between sibs that would result in cainism. Female black kites preferentially fed the smallest chicks and exhibited behaviours to reduce sibling aggression, contrary to observations in other siblicidal species. In a highly opportunistic forager such as the black kite, a strategy may exist to protract the life of all the chicks in the brood, waiting for unpredictable situations of food overabundance. This would induce the appearance of a parent-offspring conflict over brood reduction, reflected in the existence of a possible anticipated response by some of the chicks (cainism) and in the appearance of special behaviours by the parents to selectively feed smaller chicks or reduce sibling aggression. In this facultatively siblicidal species, cainism does not seem to be the final stage of an evolutionary trend favouring the raising of high-quality chicks, but a manifestation of a parent-offspring conflict over brood size.

We evaluated the effect of conspecific abundance and habitat quality of leks on the territorial behaviour of males in an exploded lekking species, the Little Bustard (Tetrax tetrax). The hypothesis that males more intensely defend territories with higher conspecific abundance and better habitat quality was evaluated experimentally analysing the agonistic response of experimental males to male decoys placed on their displaying areas. Decoy experiments showed that the intensity of display territory defence by little bustard males is density dependent. The time experimental males took to return to their display sites after decoy placement decreased with abundance of both males and females. The strength of their final response was positively associated to local male and female abundance in the vicinity of their display sites. Habitat quality also influenced males' display territory defence since the intensity of male response increased with the degree of natural vegetation cover. Habitat quality was particularly relevant in explaining variation of experimental males' snort call rate, which decreased with the degree in plough cover and increased with the number of fields in the lekking area. Snort call rate decreased with the level of male aggregation and was lowest in males exhibiting the strongest aggressive response to decoys. These results add new evidence for the density dependence of species' breeding territorial behaviour, supporting density-dependent models of lek formation and reinforcing the role of resources defence in exploded lek mating systems., FC and JM-P were supported by a JAE-Doc contract funded by Spanish Research Council and the European Social Fund (ESF), and ELG was funded by a FPU grant from the Spanish Ministry of Education. This paper contributes to projects CGL2004-06147-C02-01, CGL2004-06147-C02-02 and CGL2009-13029/BOS of the Spanish Ministry of Science, as well as to the REMEDINAL2 network of the Community of Madrid (S-2009/AMB/1783).

Many animal species show ornaments with yellow-orange-red colors produced by carotenoid pigments. Such traits have evolved as reliable signals of individual quality because of the costs inherent to their production or maintenance. In animal tissues, carotenoids are often found combined with free fatty acids, as carotenoid esters, which may confer more stability to coloration than free carotenoids. Surprisingly, the potential relevance of carotenoid esterification in the expression of animal sexual signals has been virtually ignored. Moreover, the sources of variability of esterified carotenoid levels are barely known, because most studies have not quantified their concentrations. Here, carotenoids in the ornaments (bill, eye rings, and legs) of red-legged partridges Alectoris rufa were quantified in their free and esterified forms. Carotenoid ester levels were the best predictors of leg color, whereas the redness of the other traits was better explained by free carotenoids. Nonetheless, total carotenoid levels (the sum of free and esterified forms) were always significantly correlated to redness. Young partridges had lower levels of free and esterified carotenids in the legs than did older individuals. Also, wild animals had higher ester levels and a higher proportion of carotenoids in esterified forms in all traits than did captive partridges. Probable physiological mechanisms explaining these patterns are discussed., Esther García-de Blas was supported by a predoctoral grant (JAE-PRE program) from the Consejo Superior de Investigaciones Científicas cofinanced by Fondo Socia Europeo. Lorenzo Pérez-Rodríguez was supported by a “Juan de la Cierva” postdoctoral contract from the Spanish Ministerio de Ciencia e Innovación (JCI-2008-2059). This study was funded by Consejería de Educación y Ciencia, Junta de Comunidades de Castilla la Mancha (PII1I09-0271-5037), and Ministerio de Economía y Competitividad (CGL2009-10883-C02-02) from the Spanish government.

[EN] Previous studies have shown that the rabbit (Oryctolagus cuniculus) is the main prey of the Black Kite (Milvus migrans) in Matasgordas (Doñana National Park, southwestern Spain), and that the reproductive success of pairs is enhanced with increasing rabbit consumption. In our study area, rabbits live mainly in large warrens patchily distributed across the breeding area of Black Kites. Rabbit consumption was higher for Black Kite pairs having warren entrances close to their nests. During the 3 years of the study, this population of Black Kites suffered a considerable increase. New pairs in the area selected nesting trees inside areas with a high density of rabbits. The pattern of Black Kite aggregation in our study area, where they breed in a "colony" with a population density among the highest recorded, can be explained, at least partially, by rabbit aggregation. Defense of feeding resources could help to explain the territorial behavior of Black Kites. Coloniality and feeding territoriality are not mutually exclusive., [FR] Des études antérieures ont démontré que le Lapin de garenne, Oryctolagus coniculus, est la principale proie du Milan noir (Milvus migrans) à Matasgordas (par national Donana, sud-ouest de l'Espagne) et que le succès des couples d'oiseaux à la reproduction est meilleur lorsque la consommation de lapins est importante. Dans la zone étudiée, les lapins vivent surtout dans de grandes garennes à répartition contagieuse dans l'aire de reproduction de l'oiseau. La consommation de lapins était plus importante chez les couples dont les nids étaient situés près de l'entrée d'une garenne. Au cours des 3 ans qu'à duré notre étude, la population de milans a subi une augmentation importante. Les couples qui ont niché dans la zone d'étude ont construit leurs nids dans les zones de densité élevée de lapins. La répartition contagieuse des Milans noirs dans notre zone d'étude, où ils se reproduisent en une « colonie » au sein d'une population parmi les plus denses jamais recontrées, s'explique, du moins en partie, par la répartition contagieuse des lapins. La défense des ressources alimentaires peut contribuer à expliquer le comportement territorial des milans. La colonialité et la territorialité reliée à l'alimentation ne sont pas incompatibles.

Visual displays are signals that may be selected to increase visibility. Light is a crucial component in the transmission of visual signals, and white colour is very conspicuous when illuminated by sun and exhibited against darker backgrounds. Here we tested the hypothesis that orientation of sexual displays in male great bustard (Otis tarda) depends upon position of the sun, i.e., males direct their uplifted white tails towards the sun in order to maximise signal detectability to distant females. We recorded the orientation of 405 male displays in relation to the sun and to females at seven leks. Great bustard males signalled towards the sun more often than expected by chance in early morning, although this pattern was not obvious at other times of day, when males displayed more towards females. Our hypothesis was further supported by the fact that displays were more directed towards the sun when the sun was most visible. Males were more likely to direct their displays towards females during the most elaborate components of their courtship display and when there were fewer males on the lek. Pointing white plumage to the sun may be a behaviour selected in species living in steppe-like open landscapes if individuals obtain net fitness benefit by increasing the likelihood of mating., P.P.O. was partially supported by research project from the Ministerio de Educación y Ciencia (CGL2006-05047/BOS). F.C. was supported by a postdoctoral grant funded by the regional government of Castilla la Mancha (JCCM).

We studied the effect of growth rate, final size, hatching sequence, hatching asynchrony, and fledging asynchrony on the fledging age of Black and Red kites (Milvus migrans and M. milvus). Feather growth explained 43% and 38% of the variance in fledging age of Black and Red kites, respectively. Fledging age increased with hatching sequence and increased fledging asynchrony in relation to initial hatching asynchrony of both species, especially in broods of three chicks. Once the effect of growth was removed, no differences in fledging age related to hatching sequence were found in the Red Kite, but there was still a delay in fledging of third-hatched Black Kite chicks. Synchronous fledging of first- and second-hatched Black Kite chicks seemed to occur when both chicks had grown at a similar rate, and was caused by a delay in the fledging of the first-hatched chick. First-hatched Black Kite chicks did not delay fledging if second-hatched chicks experienced reduced growth. Differences between the two species in the third-hatched-chick fledging delay could be due to differences in nest provisioning by adults during the postfledging dependence period. Red Kites reduced provisioning to the nest as soon as the first chick fledged, while Black Kites maintained nest provisioning longer. No evidence was found supporting the idea that parents may reduce feedings to hasten first flight of their offspring, Funding was provided by project 944 CSIC-CAICYT and predoctoral fellowships of the PFPI (Ministerio de Educacion y Ciencia) for both authors.

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

Carotenoid pigments have become a central subject of research on animal signaling systems during the past decade. Thus, measurement of plasma carotenoid levels is widespread in the literature. Many plasma biochemical parameters tend to vary with the hour of sampling, which may be an important source of sampling error. However, little is known about this kind of variation for circulating carotenoids. With a sampling protocol that allowed us to separately analyze the effect of sampling hour and repeated blood extraction at the within‐individual level, we evaluated the effect of these two parameters on plasma carotenoid concentration in captive red‐legged partridges (Alectoris rufa). The hour of sampling did not show a significant influence on carotenoid variability. Nevertheless, carotenoid levels significantly decreased as a result of repeated sampling. In fact, carotenoid variability was positively related to hematocrit values, which also decreased throughout the experiment. Furthermore, the effect was evident from the second sampling event. These results suggest that blood samples for carotenoid analysis may be obtained at random during the daytime with no serious risk of adding variance to data obtained. However, the effect of hemodilution associated with repeated blood extraction should be carefully considered in those studies involving repeated sampling., Financial support was provided by the Research Project PAI‐02‐006 of the Junta de Comunidades de Castilla–La Mancha. L.P.R. was supported by a predoctoral grant of the Spanish Ministerio de Educacion y Ciencia. C.A.‐A. was supported by a Ramon y Cajal fellowship (Ministerio de Educacion y Ciencia, Spain).

Game bird farming is associated with high parasite levels that reduce farm productivity, reduce survival after releasing, and may pose a health risk for natural populations. The efficacy of albendazole (orally, 20 mg kg(-1) was evaluated in farmed red-legged partridges naturally infected with the nematodes Aonchotheca caudinflata and Heterakis gallinarum. In treated birds body condition improved, nematode egg deposition was reduced and the proportion of gravid A. caudinflata females was reduced, but not the overall worm burdens. Albendazole was found to be 36.8% and 17.1% effective against A. caudinflata and H. gallinarum, respectively. These results indicate that the anthelmintic treatment used normally in Spanish partridge farms is not effective enough to avoid the introduction of parasites into the field after release., This research contributes to the agreement IREC - Principado de Asturias. L. Pérez-Rodríguez has a FPU grant and O. Rodríguez a Torres Quevedo contract partly supported by MEC.

The immunocompetence handicap hypothesis posits that androgen-mediated signals honestly indicate the responsiveness of the immune system because of the immunosuppressive effect of androgens. How- ever, androgen levels may also be related to nutritional status, and differences in body condition could be a more parsimonious explanation for variation in the expression of the signal. We maintained captive male red-legged partridges, Alectoris rufa, under regulated food shortage until they reached 85% of their initial body mass. Controls were provided with food ad libitum. After food shortage, experimental birds had lower androgen and higher corticosterone levels than controls. The condition dependence in andro- gen levels suggests that androgen-mediated signals could be indicating general nutritional state rather than immune function specifically. We propose that androgen-dependent signals may act as indicators of body condition or indicators of immune system quality, depending on the nutritional status of the individual., Financial support was provided by the Research Project PAI-02-006 of the Junta de Comunidades de Castilla-La Mancha, and the Natural Sciences and Engineering Research Council of Canada (to G.R.B.), L.P.R. and J.B. were supported by a FPU and a postdoctoral grant, respectively, from the Spanish Ministerio de Educación y Ciencia. J.B. was also supported by the Isabel Maria Lopez Martinez Memorial Scholarship.

The study of host-parasite relationships usually requires reliable estimates of parasite intensity, which is often estimated from parasite propagule concentration in faeces. However, parasite excretion in faeces may be subject to variation due to endogenous or exogenous factors that must be identified to obtain reliable results. We analysed the effect of the hour of sample collection on propagule counts of 2 intestinal parasites infecting the red-legged partridge: the capillarid nematode Aonchoteca caudinflata and coccidia of the genus Eimeria (Protozoa). Also, we test whether there are differences in propagule counts between caecal and intestinal faeces. Individual faecal samples from infected birds were collected daily at 4 different hours during several days. The hour of the day exerted a very strong effect on propagule counts, excretion of both types of parasites showing a clear and constant increase from dawn to dusk. Also, capillarid eggs were more abundant in intestinal than in caecal faeces, whereas the inverse pattern was found for coccidian oocysts. Standardization of the hour of sample collection or statistical control of this variable is recommendable to prevent bias. Similarly, in bird species with long caeca, consistent collection of one type of faeces may avoid significant errors in parasite burden estimates. © 2006 Cambridge University Press., We thank Elisa Pérez, Salvador Jesús Luna and Paqui Talavera for assistance during sample collection and analysis and Jesús Martínez-Padilla for statistical advice. Financial support was provided by the Research Project PAI-02-006 of the Junta de Comunidades de Castilla-La Mancha and by the agreement between CSIC and Principado de Asturias. Lorenzo Pérez-Rodríguez was supported by a FPU grant from the Ministerio de Educación y Ciencia.

The use of green nest plants by birds has received much attention in recent years. Although many hypotheses have been put forward to explain the functional significance of this trait, three of them, the courtship hypothesis, the nest protection hypothesis and the drug hypothesis, have particularly captured the interest of researchers. In this paper we demonstrate that in the spotless starling, Sturnus unicolor (1) most of the green plants were carried to nests during the 10 d that preceded the start of egg laying, (2) males that controlled a greater number of nest boxes, so that they mated with more females, also carried a larger amount of green material to each of their nests, (3) males carried larger amounts of green plants in second than in first clutches, and (4) monogamous males did not exhibit this last tendency when they mated with inexperienced females. Thus, plants seem to exert a function during the female fertile period but not during incubation or nestling stages. The amount of green plants added by a male may be seen as a honest signal of attractiveness and status. We suggest that males uses green plants to stimulate females to breed in it so that they carry more plants in second clutches, when females might be more reluctant to breed. This strategy was apparently constrained in monogamous males mated with inexperienced females probably because parental duties, rarely recorded in polygynous males, limits the time available to carry plants to nests. We also discuss to what extent other hypotheses may further explain the evolution of green plants carrying in starlings., This study was funded by projects PB97-1249 (DGICYT), BOS2001-0703 (MCYT) and CGL-2004-00126/BOS. The present research has been conducted under licence of the Consejería de Medio Ambiente of the Comunidad of Madrid.

Arthropod abundance in most places across Europe has suffered a dramatic decline induced by modifications in agricultural practices, and this could induce changes in the selection of breeding habitat and foraging behaviour of several endangered raptor species. We studied a 6,500 ha Special Protection Area (SPA) in Spain created for the benefit of its important steppe bird populations and examined the patterns of land-use selection and use of vegetation structure by the Lesser Kestrel Falco naumanni in relation to prey-capture success. We also studied the spatial relationship between foraging sites and the location of colonies in that breeding area. The type of land-use most frequently used by foraging Lesser Kestrels was unploughed fallow (positively selected) while kestrels significantly avoided areas with cereal crops. The relationship between foraging sites and colonies (kestrels forage preferentially in areas close to the colonies) indicates that not only is farmland management important, but also the spatial relationships between foraging areas and breeding sites. Maintaining the Spanish traditional rotation of cultivation (called barbechos) may improve the correct habitat management for Lesser Kestrels in agricultural areas in Spain.

Rabbits are the staple prey for Black Kites in Matasgordas, south-western Spain. Because of their poor predatory skills, it has been considered that most of the Rabbits consumed by Kites were young and affected by myxomatosis. After rabbit haemorrhagic disease (RHD) arrived in Spain, and since most of the Rabbits affected were adults, it was expected that the raptor would benefit with the incorporation of larger Rabbits in its diet. In concordance with that prediction, during the immediate three years before the arrival of RHD (1987–89), average size of Rabbits consumed by nestling Black Kites were similar and corresponded to the size of those Rabbits affected by myxomatosis. However, after RHD arrival in 1990, sizes of Rabbits consumed by Kites increased, corresponding to the age more frequently affected by RHD.

1. Intraclutch egg-mass variation may be determined by nutritional constraints during the laying period, or may be adaptive. These hypotheses are not mutually exclusive, and may act simultaneously on the same species. For this study, egg mass variation was analysed in the black kite, Milvus migrans (Bodd.), a mid-sized Falconiforme. 2. Egg size showed consistent patterns of variation with laying order and clutch size (2-3 eggs); egg size was larger in three-egg clutches, smaller in last-laid eggs, and relatively smaller in last-laid eggs of three-egg clutches. 3. Inexperienced breeders laid smaller eggs. There were no significant effects of year or laying date on egg size, once the confounding effect of breeder experience was removed. 4. Egg size affected hatchability only in two-egg clutches, and it affected the probability of survival of last-hatched chicks, after the confounding effects of hatching order and breeder experience were removed. There was no significant effect of egg size on growth rates or asymptotic body size. 5. The relative sizes of last-laid eggs and of first-laid eggs were not correlated with hatching asynchrony. 6. Factors reflecting the degree of nutritional constraint during laying (year, laying date, breeder experience) did not affect the degree of intraclutch egg-size asymmetry. The slight intraclutch egg-mass variation in this species (less than 0.5% of female weight) cannot impose serious energy constraints. Pairs nesting in high-quality territories laid clutches with relatively large last-laid eggs, which could be an adaptive variation of egg size to food availability. 7. Although there may be nutritional constraints on egg size at the time of laying, intraclutch egg-size variation in black kites cannot be explained exclusively by this factor. Rather, the variation may reflect distribution of resources among eggs, based on their reproductive value relative to laying order. This is determined by higher mortality of last-hatched chicks and lower hatchability of first-laid eggs in three-egg clutches. Also, it may be a component of the brood reduction strategy of raptors. 8. Relative importance of nutritional constraints or adaptation in determining intraclutch egg-size variation may depend on life history traits of each species, mainly on how the resources for laying are gathered. Adaptive patterns could exist in species storing most of the resources in the prelaying period, while nutritional constraints could hamper the appearance of any adaptive variation in species gathering those resources during the laying period.

We studied the effect of hatching date on breeding performance (chick growth and mortality) and phenology (creching and fledging ages) of the chinstrap penguin during three years. The year affected every variable considered, probably due to pack-ice persistence and food availability differences between years. Hatching date had slight or no effect on mortality and early growth, but was negatively correlated with creching age, which, in turn, was positively related to final size. The decision to leave the chicks unguarded does not seem to be based on the condition of the chicks, but on that of adults. Fledging age was negatively correlated with hatching date, and this effect was more marked in the year with poor growth performance. Given the short time available for breeding in Antarctica, there must be conflicting pressures between investing in feeding chicks and advancing the period of premoult resource storage, this explaining the strong relationship between hatching dates and subsequent phenological events (creching and fledging). In this kind of study, it may be important to remove the effect of inter-year variation before assessing the possible effects of other variables.

This paper presents data on the winter diet of the Red Kite Milvus milvus in the Iberian Peninsula. The diet composition and its relationship with food abundance and habitat characteristics were studied in two areas (northern and southern plateaux) with different food availability and habitat composition. Red Kites showed a clear difference in diet between the two plateaux, with a higher consumption of carrion on the northern plateau and of game species on the southern plateau. Common Voles Microtus arvalis, despite being a very abundant prey on the northern plateau, did not appear in the diet in high numbers, but their frequency was related to the proportion of land occupied by nonirrigated (cereal) crops. High frequencies of “small” carrion (e.g. farmed Rabbits Oryctolagus cuniculus, poultry Gallus sp.) in the diet were correlated with a decrease in the trophic diversity which suggested an active choice of the food, at least in years with low vole densities. We suggest that the use of carrion is influenced not only by its abundance but by its availability to Red Kites. Refuse tips and muladares (dumps for dead livestock) and their management during the winter are important for the conservation of the species.