| female starlings adjust primary sex ratio in response to aromatic plants in the nest. | adjustment of offspring sex ratios should be favoured by natural selection when parents are capable of facultatively altering brood sex ratios and of recognizing the circumstances that predict the probable fitness benefit of producing sons and daughters. although experimental studies have shown that female birds may adjust offspring sex ratios in response to changes in their own condition and in the external appearance of their mate, and male attributes other than his external morphology are als ... | 2004 | 15347516 |
| genome of a novel circovirus of starlings, amplified by multiply primed rolling-circle amplification. | the genus circovirus comprises small non-enveloped viruses with a circular single-stranded dna genome. by using pcr with degenerate primers, a novel circovirus (starling circovirus, stcv) was detected in spleen samples of wild starlings (sturnus vulgaris and sturnus unicolor) found dead during an epidemic outbreak of septicaemic salmonellosis in northeastern spain. using a specific pcr, stcv was also detected in apparently healthy birds from the same population. the genome was amplified using mu ... | 2006 | 16603520 |
| adaptive developmental plasticity in growing nestlings: sibling competition induces differential gape growth. | sibling competition has been shown to affect overall growth rates in birds. however, growth consists on the coordinated development of a multitude of structures, and there is ample scope for developmental plasticity and trade-offs among these structures. we would expect that the growth of structures that are used in sibling competition, such as the gape of altricial nestlings, should be prioritized under intense competition. we conducted an experiment in the spotless starling (sturnus unicolor), ... | 2008 | 18089540 |
| do spotless starlings place feathers at their nests by ultraviolet color? | a considerable number of bird species carry feathers to their nests. feathers' presence in the nests has traditionally been explained by their insulating properties. recently, however, it has been suggested that feathers carried to the nests by females of the spotted starling (sturnus unicolor l.) could have an ornamental function based on their ultraviolet (300-400 nm) and human-visible longer wavelength (400-700 nm) coloration. in our population, 95.7% of feathers found inside next-boxes occup ... | 2010 | 19941130 |
| wild birds, frequent carriers of extended-spectrum β-lactamase (esbl) producing escherichia coli of ctx-m and shv-12 types. | to get a better insight into the role of birds as reservoirs of extended-spectrum β-lactamase (esbl) and plasmidic ampc β-lactamase (pampc) escherichia coli producers, 100 fecal samples belonging to 15 different wild avian species from northern spain were analyzed. cefotaxime-resistant (ctx(r)) e. coli isolates were identified in 16 of the 100 tested birds, which corresponded to 9 animal species (gyps fulvus-griffon vulture, larus michahellis-yellow-legged gull, milvus migrans-black kite, milvus ... | 2016 | 26687342 |
| measuring oxidative stress: the confounding effect of lipid concentration in measures of lipid peroxidation. | lipid peroxidation products are widely used as markers of oxidative damage in the organism. to properly interpret the information provided by these markers, it is necessary to know potential sources of bias and control confounding factors. here, we investigated the relationship between two indicators of lipid mobilization (circulating levels of triglycerides and cholesterol) and two common markers of oxidative damage (plasma levels of malondialdehyde and hydroperoxides; the latter estimated from ... | 2015 | 25860832 |
| feathers at nests are potential female signals in the spotless starling. | although the presence of feathers in the nest is widespread among birds, it has not been previously suggested that feathers can be used as sexual signals. females of the spotless starling (sturnus unicolor) regularly carry feathers to their nest, mostly during laying and incubation. we show that the arrangement of these feathers was non-random with respect to the side (obverse or reverse) placed upwards (which can be viewed from the nest entrance). feathers of the wood pigeon (columba palumbus) ... | 2005 | 17148200 |
| avian malaria infections in western european mosquitoes. | in the complex life cycle of avian malaria parasites (plasmodium sp.), we still have a poor understanding on the vector-parasite relationships. this study described the community of potential avian malaria vectors in four portuguese reedbeds. we tested if their geographical distribution differed, and investigated on their plasmodium infections. the mosquitoes' feeding preferences were evaluated using co(2), mice, and birds as baits. the most abundant species were culex pipiens, culex theileri, a ... | 2012 | 22427023 |
| mixed life-history strategies in a local population of the ectoparasitic fly carnus hemapterus. | a major issue for the proper understanding of the evolution of life-cycle histories is the regulation of voltinism and its variation. diapause characteristics are known to regulate voltinism, but the underlying mechanisms are poorly understood. this paper studies diapause duration and voltinism variation in a haematophagous diptera parasitizing 2 sympatric hosts with very different breeding phenologies. we hypothesize that bivoltinism will be more frequent in carnid flies parasitizing an early b ... | 2012 | 22716907 |
| sex-specific effects of high yolk androgen levels on constitutive and cell-mediated immune responses in nestlings of an altricial passerine. | avian embryos are exposed to yolk androgens that are incorporated into the egg by the ovulating female. these steroids can affect several aspects of embryo development, often resulting in increases in overall size or the speed of growth of different traits. however, several studies suggest that they also entail immune costs to the offspring. in this study, we explored whether variation in yolk androgen concentration affected several measures of the constitutive and cell-mediated immune axes in t ... | 2017 | 28051945 |
| nest material shapes eggs bacterial environment. | selective pressures imposed by pathogenic microorganisms to embryos have selected in hosts for a battery of antimicrobial lines of defenses that includes physical and chemical barriers. due to the antimicrobial properties of volatile compounds of green plants and of chemicals of feather degrading bacteria, the use of aromatic plants and feathers for nest building has been suggested as one of these barriers. however, experimental evidence suggesting such effects is scarce in the literature. durin ... | 2016 | 26871451 |
| context-dependent effects of yolk androgens on nestling growth and immune function in a multibrooded passerine. | female birds may adjust their offspring phenotype to the specific requirements of the environment by differential allocation of physiologically active substances into yolks, such as androgens. yolk androgens have been shown to accelerate embryonic development, growth rate and competitive ability of nestlings, but they can also entail immunological costs. the balance between costs and benefits of androgen allocation is expected to depend on nestling environment. we tested this hypothesis in a mul ... | 2015 | 26079258 |
| diverse dose-response effects of yolk androgens on embryo development and nestling growth in a wild passerine. | avian egg yolks contain various amounts of maternally derived androgens that can modify offspring phenotype and adjust their development to the post-hatching environment. seemingly adaptive variation in yolk androgen levels with respect to breeding density conditions or male attractiveness has been found in numerous studies. one important consideration that has been overlooked in previous research is the likely non-linear nature of hormone effects. to examine possible complex dose-response effec ... | 2015 | 25987739 |
| are female starlings able to recognize the scent of their offspring? | although there is growing evidence that birds may have individual chemical profiles that can function in several social contexts, offspring recognition based on olfactory cues has never been explored. this ability should be more likely evolved in colonial birds and/or species suffering brood parasitism, in which the risk of being engaged in costly misdirected parental care is high. | 2014 | 25299305 |
| the pha test as an indicator of phagocytic activity in a passerine bird. | several techniques in ecological immunology have been used to assess bird immunocompetence thus providing useful information to understand the contribution of the immunological system in life-history decisions. the phytohaemagglutinin (pha)-skin test has been the most widely employed technique being interpreted as the sole result of t lymphocytes proliferation and hence used to evaluate acquired immunological capacity. however, the presence of high numbers of phagocytic cells in the swelling poi ... | 2013 | 24391896 |
| differential effects of yolk testosterone and androstenedione in embryo development and nestling growth in the spotless starling (sturnus unicolor). | yolk androgens in avian eggs play a significant role in embryo and nestling development. however, few studies have examined the differential effect of two of the main yolk androgens, testosterone (t) and androstenedione (a4). here, we injected eggs of spotless starlings with physiological levels of either t, a4, the combination t+a4 or vehicle substance (control), to examine the differential ability of these steroids to influence nestling development. we found that the duration of the embryonic ... | 2013 | 24090611 |
| can starling eggs be useful as a biomonitoring tool to study organohalogenated contaminants on a worldwide scale? | large-scale international monitoring studies are important to assess emission patterns and environmental distributions of organohalogenated contaminants (ohcs) on a worldwide scale. in this study, the presence of ohcs was investigated on three continents (europe, north america and australasia), using eggs of starlings (sturnus vulgaris and sturnus unicolor) to assess their suitability for large-scale monitoring studies. to the best of our knowledge, this is the first study using bird eggs of the ... | 2013 | 23220015 |
| sex recognition by odour and variation in the uropygial gland secretion in starlings. | 1. although a growing body of evidence supports that olfaction based on chemical compounds emitted by birds may play a role in individual recognition, the possible role of chemical cues in sexual selection of birds has been only preliminarily studied. 2. we investigated for the first time whether a passerine bird, the spotless starling sturnus unicolor, was able to discriminate the sex of conspecifics by using olfactory cues and whether the size and secretion composition of the uropygial gland c ... | 2012 | 22220811 |
| sexually selected egg coloration in spotless starlings. | it has been recently proposed that the blue-green coloration in eggs of many avian species may constitute a sexually selected female signal. blue-green color intensity would reflect the physiological condition of females, and hence it might also affect the allocation of male parental care. in this study, we use three different experimental approaches to explore the importance of sexual selection on blue-green egg coloration of spotless starling (sturnus unicolor) eggs. first, experimental deteri ... | 2008 | 18197771 |
| increased sibling competition does not increase testosterone or corticosterone levels in nestlings of the spotless starling (sturnus unicolor). | nestling begging in passerine birds is a complex behaviour that is shaped by a multitude of ecological factors and could be physiologically mediated by varying levels of steroid hormones. previous research has shown links between sibling competition and testosterone and corticosterone in several bird species. the spotless starling (sturnus unicolor) is a medium sized passerine in which nestlings compete intensively for resources, often resulting in marked size hierarchies that can have profound ... | 2008 | 18190915 |
| dark nests and egg colour in birds: a possible functional role of ultraviolet reflectance in egg detectability. | owing to the conspicuousness of ultraviolet (uv) colour in dark environments, natural selection might have selected uv egg coloration because it would enhance egg detectability by parents in murky nests. here, we tested this hypothesis by using comparative and experimental approaches. first, we studied variation in egg coloration of 98 species of european passerines measured using uv-visible reflectance spectrometry (300-700nm) in relation to nesting habits. analyses based on raw data and contro ... | 2006 | 17015364 |
| nest ornamentation by female spotless starlings in response to a male display: an experimental study. | 1. the use of behavioural traits by females in signalling condition has been practically ignored in evolutionary theory. however, females may also exhibit ornaments and behavioural displays, although less elaborated than those of males. 2. in this study we suggest that the carrying of feathers by spotless starlings sturnus unicolor temminck females to decorate the nest represents an elaborated and costly behaviour that is displayed in response to a courtship male behaviour: the carrying of nest ... | 2006 | 17009757 |
| experimentally increased testosterone affects social rank and primary sex ratio in the spotless starling. | it has been suggested that the amount of maternal testosterone allocated into the eggs might be implicated in the process of sex determination. however, recent findings on the effect that female social rank has on the level of egg testosterone suggest that reported associations between male-biased sex ratios and yolk testosterone may represent an indirect hormonal effect mediated by the interdependence among maternal hormones, female social rank, and sex ratio. here, we report the results of a f ... | 2004 | 15215041 |
| the diffusely-infiltrated lymphoid tissue of the bursa of fabricius of sturnus unicolor. histological organization and functional significance. | in the present study we confirm and extend previous reports about the existence of a t-dependent area in the bursa of fabricius of some birds, analyzing ultrastructurally the cell content of the so-called diffusely-infiltrated lymphoid tissue of the bursa of the spotless starling, sturnus unicolor. it consists of lymphocytes, plasma cells, macrophages (mphis) and interdigitating cells (idcs) in a supporting reticular stroma which, apart from blood capillaries, contains postcapillary high-endothe ... | 1994 | 8075494 |
| erythropoiesis in the thymus of the spotless starling, sturnus unicolor. | although previously described in other avian species, intrathymic erythropoiesis is a remarkable feature of the thymus of sturnus unicolor. in discrete stages of the life cycle of this species, erythroblasts and mature erythrocytes occupy large areas of the thymic cortex and cortico-medullary border. simultaneously, degenerated thymocytes and epithelial-reticular cells occur in the same areas. the relationship between intrathymic erythropoiesis, degeneration of cortical lymphocytes and epithelia ... | 1983 | 6883452 |
| ultrastructural study of interdigitating cells in the thymus of the spotless starling, sturnus unicolor. | interdigitating cells (idc) in the thymus of the spotless starling, sturnus unicolor, were examined by electron microscopy. they occur principally in the thymic medulla and corticomedullary border. they possess an irregular nucleus and a perinuclear area of cytoplasm, containing most of the membranous organelles, surrounded by a peripheral electron-lucent zone. clusters of smooth golgi vesicles and complicated labyrinthine membrane-membrane contacts are the most characteristic cytological featur ... | 1982 | 7127413 |
| ectoparasite activity during incubation increases microbial growth on avian eggs. | while direct detrimental effects of parasites on hosts are relatively well documented, other more subtle but potentially important effects of parasitism are yet unexplored. biological activity of ectoparasites, apart from skin injuries and blood-feeding, often results in blood remains, or parasite faeces that accumulate and modify the host environment. in this way, ectoparasite activities and remains may increase nutrient availability that may favour colonization and growth of microorganisms inc ... | 2018 | 29332150 |
| dna integrity estimated via the comet assay reflects oxidative stress and competitive disadvantage in developing birds. | abstractincreases in dna degradation have been detected in numerous situations in which organisms are exposed to pollutants. however, outside of the ecotoxicological literature, few studies have investigated whether there exists important variation in dna integrity in free-living, healthy animals. using the alkaline version of the comet assay to estimate dna integrity in blood samples, we aimed to evaluate whether dna integrity during early life is associated with nestlings' age, body mass, with ... | 2020 | 32780628 |
| antimicrobial activity of nest-lining feathers is enhanced by breeding activity in avian nests. | the use of feathers as nest material has been proposed as a kind of self-medication strategy because antimicrobial-producing microorganisms living on feathers may defend offspring against pathogenic infections. in this case, it is expected that density of antimicrobial-producing bacteria, and their antimicrobial effects, are higher in feathers that line the nests than in eggshells. moreover, we know that feather pigmentation and breeding activity may influence density and antimicrobial productio ... | 2019 | 30985888 |
| harsh conditions during early development influence telomere length in an altricial passerine: links with oxidative stress and corticosteroids. | stress during early development can induce substantial long-term effects in organisms. in the case of birds, despite growth compensations, nestlings reared under harsh conditions typically show reduced survival chances in adulthood. it has been proposed that environmental early-life stressors could affect longevity via effects on telomere length, possibly mediated through oxidative stress. however, the link between these processes is not clear. in this study, we experimentally manipulated brood ... | 2019 | 30387533 |
| molecular characterization of avian malaria in the spotless starling (sturnus unicolor). | we studied the prevalence and genetic diversity of malaria parasites in the poorly investigated spotless starling (sturnus unicolor) breeding in central spain, aiming to describe the phylogenetic relationships among them and with other haemosporidians infecting the genus sturnus. a total of 180 nestlings and 180 adult individuals from four different breeding seasons were screened for haemosporidian parasites using a nested pcr approach for the genera plasmodium and haemoproteus. although the mal ... | 2018 | 29327322 |
| the role of the mating system and intraspecific brood parasitism in the costs of reproduction in a passerine bird. | limited resources trigger trade-offs in resource allocation. reproduction is one of the most demanding activities in terms of energy, and costs related to reproduction can be apparent either as reduced future reproduction or as survival. however, costs are not always detected, because individual heterogeneity in quality and resource acquisition may explain variation in costs among individuals. we conducted a comprehensive study in spotless starlings (sturnus unicolor) nesting in central spain to ... | 2017 | 29018951 |