Sonia González-Braojos

Factors Affecting the Presence and Abundance of Generalist Ectoparasites in Nests of Three Sympatric Hole-Nesting Bird Species

Abstract. Nesting cavities constitute micro-environments very likely to be colonized by ectoparasites which feed on blood of the incubating female and the nestlings. Given the negative impact of ectoparasites on nestlings there will be selection on hosts to minimize ectoparasite loads through behavioural defenses. We have addressed the implications of ectoparasitism in three sympatric avian cavity-nesters, namely Pied Flycatchers Ficedula hypoleuca, Blue Tits Cyanistes caeruleus and Nuthatches Sitta europaea, to explore if differences in prevalence and abundance of generalist ectoparasites (blowflies, fleas and mites) can be related to interspecific differences in their nest size, nest composition and cavity microclimate. Furthermore, we have aimed at detecting if interspecific variation in the incidence and intensity of anti-parasite behaviours is a consequence of the abundance of ectoparasites. Differences in nest composition among host species appear not to be the main factor explaining ectoparasite loads, while nest size, breeding phenology, brood size and nest-cavity micro-climate may affect them in different ways for each host-parasite association. Behavioural defenses against parasites are exhibited by all host species but are more intense in the host species with the highest infestation levels (Blue Tits). This study shows different sources of variation in associations between three sympatric avian cavity-nesters and their generalist ectoparasites.

Plasma Antioxidant Capacity and Oxidative Damage in Relation to Male Plumage Ornamental Traits in a Montane Iberian Pied Flycatcher Ficedula hypoleuca Population

Abstract. Melanin-based plumage ornaments may express individual quality in the context of social and sexual selection. Oxidative stress and antioxidant defences may be expressed through melanin-based plumage traits. Male Pied Flycatchers Ficedula hypoleuca exhibit eumelanic dorsal plumage and white feather patches on forehead and wing feathers. Although these traits have been related to sexual selection in some populations, no physiological correlate of variation in these characters has been previously shown. Here we test if these plumage traits are related to plasma oxidative stress and antioxidant capacity. We captured males while feeding nestlings in a population breeding at high altitude (1200–1400 m) in central Spain and collected blood samples from brachial veins. Percentage black on dorsal plumage and extension of white on folded wing and forehead were obtained from digital photographs. Plasma samples were analysed in the laboratory to obtain lipid peroxidation as a measure of oxidative damage by quantifying malondialdehydes (MDA), and antioxidant capacity. When controlling for male mass, breeding date and brood size, only forehead patch size was negatively associated with plasma lipid peroxidation levels and positively related to antioxidant capacity. There was no association among different plumage traits. Thus forehead patch size in montane Iberian populations may signal male phenotypic quality through plasma oxidative stress and antioxidant capacity possibly due to altitudinal effects on oxidative stress.

Is nestling growth affected by nest reuse and skin bacteria in Pied Flycatchers Ficedula hypoleuca

Abstract. Bacteria may colonize avian nests with unknown repercussions on nestling growth and health, although bacteria on nest materials may easily colonize nestling skin and growing feathers. Cavity nesters may have to build their nests on top of used nest materials, given restrictions on cavity availability. Nest reuse may favour bacterial colonization of nest materials and nestling skin and thereby affect nestling feather growth. To test these possibilities, we conducted a study of Pied Flycatchers Ficedula hypoleuca breeding in nest-boxes in central Spain. We left a sample of nest-boxes without removing old nest materials in 2010 and compared bacterial loads of nest materials, control inert objects and nestling belly skin in reused nests with those in new nests in 2011. Nestlings raised in reused nests had higher bacterial loads on their belly skin than those in new nests, while no difference between nest types for nest materials and control inert objects were found. There was a marginally significant tendency for wing length before fledging to be lower in reused nests, but no trend for mass or tarsus length. The bacterial loads of nests showed a negative association with feather growth of nestlings as expressed through wing length but not with tarsus length or mass growth. These results indicate an association between nest reuse and bacterial growth on nestling skin not hitherto detected. They also suggest a possible impairment of flight capacity at fledging mediated by nest bacterial communities which are in direct contact with nestling skin and growing feathers.

Assessing the effects of climate on host-parasite interactions: a comparative study of European birds and their parasites.

Background Climate change potentially has important effects on distribution, abundance, transmission and virulence of parasites in wild populations of animals. Methodology/Principal Finding Here we analyzed paired information on 89 parasite populations for 24 species of bird hosts some years ago and again in 2010 with an average interval of 10 years. The parasite taxa included protozoa, feather parasites, diptera, ticks, mites and fleas. We investigated whether change in abundance and prevalence of parasites was related to change in body condition, reproduction and population size of hosts. We conducted analyses based on the entire dataset, but also on a restricted dataset with intervals between study years being 5–15 years. Parasite abundance increased over time when restricting the analyses to datasets with an interval of 5–15 years, with no significant effect of changes in temperature at the time of breeding among study sites. Changes in host body condition and clutch size were related to change in temperature between first and second study year. In addition, changes in clutch size, brood size and body condition of hosts were correlated with change in abundance of parasites. Finally, changes in population size of hosts were not significantly related to changes in abundance of parasites or their prevalence. Conclusions/Significance Climate change is associated with a general increase in parasite abundance. Variation in laying date depended on locality and was associated with latitude while body condition of hosts was associated with a change in temperature. Because clutch size, brood size and body condition were associated with change in parasitism, these results suggest that parasites, perhaps mediated through the indirect effects of temperature, may affect fecundity and condition of their hosts. The conclusions were particularly in accordance with predictions when the restricted dataset with intervals of 5–15 years was used, suggesting that short intervals may bias findings.

Age-related changes in abundance of enterococci and Enterobacteriaceae in Pied Flycatcher (Ficedula hypoleuca) nestlings and their association with growth

Bacteria have the potential to be important selective forces in the evolution of many aspects of avian biology, including nestling growth. We estimated abundances of two common gut bacterial types in birds (enterococci and Enterobacteriaceae) and their correlation with growth in tarsus length, mass and wing length of 102 nestlings (54 broods) of the Pied Flycatcher, Ficedula hypoleuca, in a population of central Spain. Chicks were weighed and measured on days 7–13 after hatching, at which ages fecal samples were obtained for detection and estimation of abundance of enterococci and Enterobacteriaceae. The loads of the two bacterial types were not correlated. Enterobacterial loads decreased from day 7 to 13, while loads of enterococci increased during the same period. On day 7, loads of Enterobacteriaceae among nest mates were similar whereas loads of enterococci were not similar. On day 13, nest mates did not have similar loads of either bacterial type. Loads of enterococci were positively correlated with body mass and wing length on day 7, but not on day 13. Tarsus growth between days 7 and 13 was negatively correlated with loads of enterococci on day 7.ZusammenfassungAlterungsbedingte Veränderungen in der Abundanz von enterokokken undEnterobacteriaceae und deren Assoziation mit dem Wachstum von Trauerschnäpperküken (Ficedula hypoleuca)Bakterien spielen potentiell eine wichtige selektive Rolle in vielen Aspekten der Evolutionsbiologie von Vögeln, einschließlich des Wachstums von Küken. Hier haben wir die Häufigkeit von zwei Darmbakterien (enterokokken und Enterobacteriaceae), welche in Vögeln vorkommen, geschätzt, ebenso wie die Korrelation dieser Bakterienabundanzen mit dem Wachstum von Tarsuslänge, Gewicht und Flügellänge von 102 Nestlingen (54 Bruten) einer Population von Trauerschnäppern (Ficedula hypoleuca) in Zentral-Spanien. Die Küken wurden an Tag 7 und 13 nach dem Schlüpfen gewogen und gemessen an denselben Tagen wurden, zur Erfassung und Abschätzung der Abundanz von enterokokken und Enterobacteriaceae, Kotproben entnommen. Die Abundanzen der beiden Bakterienarten waren nicht miteinander korreliert. Die Abundanz von Enterobacteriaceae verringerte sich von Tag 7 bis Tag 13, während die Abundanz von enterokokken im gleichen Zeitraum anstieg. Am Tag 7 ähnelten sich die Abundanzen von Enterobacteriaceae unter Nestgeschwistern während die der enterokokken variierten. Am Tag 13 waren de Abundanzen von Nestgefährten bei keinem der beiden Bakterienarten ähnlich. Die Abundanzen von enterokokken waren positiv mit Gewicht und Flügellänge am Tag 7 korreliert, jedoch nicht am Tag 13. Das Tarsuswachstum zwischen den Tagen 7 und 13 war negativ korreliert mit der Abundanz von enterokokken am Tag 7.

Oxidative damage in relation to a female plumage badge: evidence for signalling costs

Badges of status may be controlled by costs derived from increased aggression from dominant individuals. This cost could be translated into elevated metabolic levels and a concomitant disruption of oxidative balance. Some females in Iberian pied flycatcher Ficedula hypoleuca populations exhibit a white forehead patch similar to that exhibited by all males in this species, functioning in aggressive interactions between females when competing for breeding sites. To test if social stress imposes costs on signalling, we painted white patches on females without natural patches (NP) and compared them with females with natural control (NU). We also over-painted the natural patch in other females (FP) and compared to females with control natural patches (FU). We obtained for the whole sample of females data on reproductive investment, morphology and oxidative damage measured by blood malondialdehydes (MDA), and in a subsample of females variables related to parental care during incubation and the early nestling stage. FP and FU did not differ significantly in any variable which negates an effect of paint itself. However, NP females showed significant higher levels of MDA than NU females when controlling for breeding success for the whole sample, and for female incubation attendance for the parental care subsample. When including the four treatments, there was a significant interaction between the paint treatment and the presence/absence of badges before the experiment when controlling for the significant negative effect of incubation attendance on MDA. Addition of a badge to females without one leads to increased oxidative damage possibly mediated by social control. Badges of status in female pied flycatchers may operate as badges of oxidative status.

Handicapped females receive more feedings during incubation from their mates: support for the female nutrition hypothesis

The female nutrition hypothesis posits that provisioning intensity of incubating females by their mates may depend on female needs and ensure proper incubation and a corresponding high hatching and breeding success of breeding pairs. Here, we have handicapped female pied flycatchers Ficedula hypoleuca at the beginning of incubation by clipping two primaries on each wing and filmed nests during incubation and later nestling provisioning to estimate male involvement in incubation feeding at the nest and in offspring care. Incubation feeding was more frequent at late nests. Correcting for this seasonal effect, incubation feeding was significantly affected by treatment and twice as high at experimental as at control nests. There was no effect of the experiment on female incubation attendance. The handicap did not result in any effect on hatching and breeding success, nestling growth and male or female provisioning and mass at the end of the nestling period. Males adjust their incubation feeding activity at the nest to female energetic requirements during incubation.

Nest-dwelling ectoparasites reduce antioxidant defences in females and nestlings of a passerine: a field experiment.

Ectoparasites may imply a cost in terms of oxidative stress provoked by inflammatory responses in hosts. Ectoparasites may also result in costs for nestlings and brooding females because of the direct loss of nutrients and reduced metabolic capacity resulting from parasite feeding activities. These responses may involve the production of reactive oxygen and nitrogen species that may induce oxidative damage in host tissues. Our goal was to examine the effect of ectoparasites in terms of oxidative stress for nestlings and adult females in a population of pied flycatchers Ficedula hypoleuca. We manipulated the entire nest ectoparasite community by reducing ectoparasite loads in some nests through a heating treatment and compared them with a control group of nests with natural loads. A marker of total antioxidant capacity (TAS) in plasma and total levels of glutathione (tGSH) in red blood cells as well as a marker of oxidative damage in plasma lipids (malondialdehyde; MDA) were assessed simultaneously. Levels of tGSH were higher in heat-treated nests than in controls for both females and nestlings. Higher TAS values were observed in females from heat-treated nests. In nestlings there was a negative correlation between TAS and MDA. Our study supports the hypothesis that ectoparasites expose cavity-nesting birds to an oxidative challenge. This could be paid for in the long term, ultimately compromising individual fitness.

Extra-pair matings, context-dependence and offspring quality: a brood manipulation experiment in pied flycatchers

Extra-pair paternity (EPP) in socially monogamous species has been associated with the genetic benefits incurred by females through extra-pair mate choice. There is conflicting evidence in the literature concerning the importance of such benefits possibly due to their context-dependence. To ascertain if there are such context-dependent genetic benefits, we conducted a brood manipulation experiment in pied flycatchers (Ficedula hypoleuca) breeding in central Spain. We found that extra-pair mates (EPM) are frequently not nearest neighbours. Cuckolded males and EPM did not differ from other males in any measured trait, and were not different either when cuckolds and cuckolders were compared within broods. Within-pair offspring (WPO) and extra-pair offspring (EPO) did not differ with respect to heterozygosity and no association of heterozygosity of either offspring or males and females with EPP could be detected. Moreover, the competitive context in the nest induced by brood manipulations affected the growth of nestlings and showed an interaction with paternity differences in nestling mass but in the opposite direction to the prediction of context-dependence, i.e., EPO were lighter than WPO in enlarged broods but not in control broods. Furthermore, EPO had shorter tarsi than WPO in all treatments. Mortality in the nest showed an association with brood manipulation treatment, but not with paternity or its interaction with treatment. Thus, we have not found any evidence of genetic benefits, context-dependent or otherwise, of EPP in our study population. The evidence of poor quality EPO does not support a mixed reproductive strategy of females in our population.

Only Some Ectoparasite Populations are Affected by Nest Re-Use: an Experimental Study on Pied Flycatchers

Summary. Nest re-use in birds is rare but since appropriate cavities may be scarce, cavity-nesting birds may often re-use those that were occupied in previous seasons. Old nest material may contain and/or attract more ectoparasites than fresh material. Therefore it is important to understand the effects of nest re-use on the abundance of different ectoparasite species of different virulence and their impli cation for breeding parameters and nestling condition. We studied the consequences of nest re-use in a population of pied flycatchers Ficedula hypoleuca breeding in central Spain by offering them both nest-boxes with old nest material and cleaned nest-boxes. We monitored breeding activity from the early stages of nest construction until fledging, and then finally removed nests to estimate ectoparasite abun dances. Occupation rates were similar for both treatments. We found that blowfly and flea abundances were significantly higher in old nests than in new nests, but the abundance of mites, the most virulent ectoparasites on our host study population, was not affected by the presence of old nest material. Nestling growth with respect to tarsus length and mass was not affected by nest re-use although wing length was marginally and significantly reduced by nest re-use. There was no association between ectoparasite abundance and nestling growth and condition. These results question the generality of assumed higher infestations in re-used nests, on which a certain critique of nest-box studies has been based.