PUBLICACIÓN CIENTÍFICA

On the oxidative cost of begging: antioxidants enhance vocalizations in gull chicks

Enlace mardeaves Larus michahellis,PUBLICACIÓN CIENTÍFICA,REPOSITORIO ,,,

Noguera, J.C., Morales, J., Pérez, C. & Velando, A., 2010. On the oxidative cost of begging: antioxidants enhance vocalizations in gull chicks. Behavioral Ecology, 21(3), pp.479-484.

Offspring solicit food to their parents by begging displays, which are important in the parent–offspring communication. Most theoretical approximations on this behavior have centered on the view of begging as an honest signal of need or as a form of scramble competition for resources. In both signaling models, costly begging is necessary to stabilize the begging strategy at equilibrium. Nevertheless, evidence supporting begging as costly behavior remains scarce. We investigated whether oxidative stress may represent a general form of proximate cost of begging and also whether begging is related to offspring nutritional condition. To test this, we experimentally modified the chicks’ nutritional condition and vitamin E availability and measured the effects on different begging components. The intensity of all begging components increased in chicks that were intake restricted, whereas vitamin E specifically enhance the total number of chatter calls given by chicks, mainly in those with a lower body size. Our results suggest that begging behavior is an antioxidant demanding activity and support the idea that oxidative stress may be a cost of begging. Our findings also suggest that begging behavior may be an honest signal of the nutritional and oxidative status of the chicks.

Effect of testosterone on the behaviour of yellow-legged gulls (Larus cachinnans) in a high-density colony during the courtship period

Enlace mardeaves Larus michahellis,PUBLICACIÓN CIENTÍFICA,REPOSITORIO ,,,,,

Alonso-Alvarez, C. & Velando, A., 2001. Effect of testosterone on the behaviour of yellow-legged gulls (Larus cachinnans) in a high-density colony during the courtship period. Ethology Ecology & Evolution, 13(4), pp.341-349.

Yellow-legged gulls breed in high density areas, and the condition dependent hypothesis suggests that birds with high physical condition can obtain breeding benefits in high-density areas because they are able to pay off the energetic costs of aggressive behaviour and territory defence. This study and others showed a relationship between aggressiveness or copulation behaviour and nest-density during the pre-laying period in gulls. The link between density and behaviour can be explained by the strong competition for space and mates. Testosterone regulates male behaviour and can play an important role in the condition-dependent hypothesis. We tested the effects of testosterone implants on male breeding behaviour. In a high-density colony, testosterone-implanted male yellow-legged gulls showed higher aggression and copulation frequencies than controls during the courtship period. In addition, these testosterone-treated birds acquired larger territories than the controls. Thus, a high testosterone level can increase individual fitness in densely populated areas given the benefits derived, on the one hand, from a large territory and, on the other, from an increased copulation rate that would guarantee the male’s paternity of the chicks born in his own nest. Since testosterone increases energetic requirements, only high-quality males would be able to pay off the costs of high levels of testosterone and so obtain the benefits of breeding in high-density areas. Testosterone could therefore provide a proximate mechanism regulating nest density in gull colonies.

Age-dependent changes in plasma biochemistry of yellow-legged gulls (Larus cachinnans)

Enlace mardeaves Larus michahellis,PUBLICACIÓN CIENTÍFICA,REPOSITORIO ,,,,,

Alonso-Alvarez, C., 2005. Age-dependent changes in plasma biochemistry of yellow-legged gulls (Larus cachinnans). Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, 140(4), pp.512-518.

The study of avian plasma chemistry is providing useful reference values for the management of endangered and game species, supporting veterinarians in their diagnostics, and also bringing to light relevant physiological adaptations during periods of food-shortage. Age is an important source of variability for plasma chemistry. Here I report plasma chemistry of yellow-legged gulls Larus cachinnans from different ages, between post-independence and adulthood, a 5-year interval. Increase in plasma cholesterol concentration and decreases in uric acid, inorganic phosphorus and alkaline phosphatase values were seen. Body mass corrected by body size (i.e. body condition) increased with age, plasma cholesterol being positively correlated in females, but not in males. Moreover, cholesterol was also positively correlated to gonad size in both sexes. Long-term developmental changes in this species, such as gonad development and the acquisition of an optimal body mass for reproduction, could explain these findings. Finally, inorganic phosphorus and alkaline phosphatase, both traditionally related to osteogenesis, were not associated to deferred skull ossification, as originally was suggested in other species.

Effects of testosterone implants on pair behaviour during incubation in the Yellow‐legged Gull Larus cachinnans

Enlace mardeaves Larus michahellis,PUBLICACIÓN CIENTÍFICA,REPOSITORIO ,,

Alonso‐Alvarez, C., 2001. Effects of testosterone implants on pair behaviour during incubation in the Yellow‐legged Gull Larus cachinnans. Journal of Avian Biology, 32(4), pp.326-332.

The Yellow-legged Gull Larus cachinnans is monogamous with bi-parental incubation. In this study, the effects of high levels of plasma testosterone in male Yellow-legged Gulls during the incubation period were analysed. Free-living male gulls were implanted with testosterone (T-males), and their sexual behaviour within the pair was observed and compared with that of control pairs. Egg temperatures, length of incubation and hatching success were also analysed. T-males and their mates displayed more sexual behaviour than the controls. T-males engaged in mounting behaviour with their mates, whereas control males did not. Proportionally less time was spent incubating (in relation to time present in the colony) by T-males than control males. However, the mates of T-males did not spend more time incubating than control females to compensate for male neglect, although they did spend more time on the territory. Egg temperature in T-male nests was significantly lower than in control nests, but no significant difference in the length of incubation or hatching success between the two groups was found. In birds, the effects of high testosterone levels on male behaviour during incubation have only been analysed in a polyandrous species whose females usually do not contribute to incubation. The present results thus suggest that those males of a monogamous species with biparental incubation that sustain high testosterone levels after laying, thus reducing their contributions to incubation, will be confronted with a lack of compensation from their mates during incubation. Finally, this lack of female compensation seems to be mediated by behavioural interactions with the male rather than by her absence
from the colony.

Female control in yellow-legged gulls: trading paternity assurance for food

Enlace mardeaves Larus michahellis,PUBLICACIÓN CIENTÍFICA,REPOSITORIO ,,

Velando, A., 2004. Female control in yellow-legged gulls: trading paternity assurance for food. Animal Behaviour, 67(5), pp.899-907.

Females in many socially monogamous birds copulate hundreds of times more than necessary for fertilization, although little is known about the benefits of this excess. Females may not directly benefit from high copulation rates, but instead may exploit male interest in copulating to obtain benefits. In species with courtship feeding, females may trade copulations for food (immediate benefits hypothesis). I tested this hypothesis by analysing female behaviour during courtship in yellow-legged gulls, Larus cachinnans. Female gulls to some extent controlled sperm transfer, because they moved during copulation bouts, and this behaviour influenced the number of cloacal contacts per mounting that the male achieved. Female control was related to previous feeding by the male, and hence the male courtship feeding rate correlated with the cloacal contact rate. Males that give more food probably enhance their chances of fathering offspring. By analysing within-individual female behaviour, I also found that the number of cloacal contacts was higher when the male fed the female than when he did not, which indicates that female gulls followed a decision rule to resist copulation when food is not given. Overall, these results support the hypothesis that female gulls manipulate their mates to obtain food.

The evolution of multicomponent begging display in gull chicks: sibling competition and genetic variability

Enlace mardeaves Larus michahellis,PUBLICACIÓN CIENTÍFICA,REPOSITORIO ,,,,,,,
Kim, S.Y., Noguera, J.C., Morales, J. & Velando, A., 2011. The evolution of multicomponent begging display in gull chicks: sibling competition and genetic variability. Animal Behaviour, 82(1), pp.113-118.

The evolution of begging display may be influenced by gene–environment interaction, through the mechanisms that adjust begging behaviour to environmental conditions of offspring, including intensity of sibling competition within broods. We decomposed the complex begging display of yellow-legged gull, Larus michahellis, chicks into two different functional components: begging for food (pecks) and drawing the attention of parents (chatter calls). We examined these begging components in 2-day-old chicks that hatched and grew up in foster nests, by performing a begging test for each chick alone without the hindrance of its foster siblings. Male chicks and those with poorer body condition begged for food at higher rates than females and those with better body condition, respectively. Chicks from larger broods begged for food more frequently, but chicks from male-biased broods begged less frequently. If begging is costly, chicks may adjust their begging efforts to the intensity of sibling competition. Frequency of chatter calls varied with sex, chick order within broods and body condition: females, the third chicks and those with poorer condition produced chatter calls more frequently. Genetic origin had a significant effect on frequency of chatter calls but not on begging for food, while foster nest effect was null in both traits. Therefore, chatter calls (but not pecks) can be subject to evolution under directional selection. Different begging components may have evolved through different evolutionary pathways.

Which subspecies of Shag occurs in Galicia?

Enlace mardeaves Phalacrocorax aristotelis,PUBLICACIÓN CIENTÍFICA,REPOSITORIO

Yesou, P., Buchheim, A., & Bermejo, A. 2005. Which subspecies of Shag occurs in Galicia?. British Birds, 98: 369-370.

Juvenile Shags Phalacrocorax aristotelis with whitish underparts and pale legs, characteristics typically attributed to the Mediterranean subspecies P. a. desmarestii, may occur within the range of nominate aristotelis (BWP). Such pale individuals are extremely rare in Britain, however, and account for only a small proportion of the Shags breeding in Brittany, western France…

Yolk testosterone reduces oxidative damages during postnatal development

Enlace mardeaves Larus michahellis,PUBLICACIÓN CIENTÍFICA,REPOSITORIO ,,

Noguera, J.C., Alonso-Alvarez, C., Kim, S.Y., Morales, J. & Velando, A., 2011. Yolk testosterone reduces oxidative damages during postnatal development. Biology letters, 7(1), pp.93-95.

Conditions experienced during early life can influence the development of an organism and several physiological traits, even in adulthood. An important factor is the level of oxidative stress experienced during early life. In birds, extra-genomic egg substances, such as the testosterone hormone, may exert a widespread influence over the offspring phenotype. Interestingly, testosterone can also upregulate the bioavailability of certain antioxidants but simultaneously increases the susceptibility to oxidative stress in adulthood. However, little is known about the effects of maternally derived yolk testosterone on oxidative stress in developing birds. Here, we investigated the role of yolk testosterone on oxidative stress of yellow-legged gull chicks during their early development by experimentally increasing yolk testosterone levels. Levels of antioxidants, reactive oxygen species and lipid oxidative damage were determined in plasma during nestlings’ growth. Our results revealed that, contrary to control chicks, birds hatched from testosterone-treated eggs did not show an increase in the levels of oxidative damage during postnatal development. Moreover, the same birds showed a transient increase in plasma antioxidant levels. Our results suggest that yolk testosterone may shape the oxidative stress-resistance phenotype of the chicks during early development owing to an increase in antioxidant defences and repair processes.

Hatching hierarchy but not egg-related effects governs behavioral phenotypes in gull chicks

Enlace mardeaves Larus michahellis,PUBLICACIÓN CIENTÍFICA,REPOSITORIO ,,,,,

Diaz-Real, J., Kim, S.Y. & Velando, A., 2016. Hatching hierarchy but not egg-related effects governs behavioral phenotypes in gull chicks. Behavioral Ecology. doi: 10.1093/beheco/arw110

In many bird species that practice parental care, siblings often compete for resources and care provided by their parents, although their strategies differ according to hatching rank and condition. Differences in offspring strategies are generally attributed to hatching order and maternal effects, which are difficult to separate because these effects are often correlated. For example, third-hatched chicks of large gull species receive more egg testosterones and corticosterone, which influence early behavioral patterns. In this study, we carried out a cross-fostering experiment with first- and last-laid eggs of the yellow-legged gull (Larus michahellis) to test whether the within-brood variation in behavioral strategies for competing with siblings and coping with stress are due to maternal effects or to hatching order. Chicks hatched in the last position within the experimental brood emitted more chatter calls to attract parents’ attention, were less prone to respond to warning of danger, and had a lower breathing rate while restrained than first-hatched chicks. Egg laying order did not affect chick behaviors or breathing rate. Thus, we concluded that the different behavioral strategies of chicks were determined by their posthatching experience and not by the original egg position within the clutch. Last-laid eggs were smaller and chicks from those eggs grew slower than chicks from first-laid eggs. Independently of the original laying order, chicks that hatched first in the experimental brood grew faster than their siblings. Overall, our results indicate that behavioral strategies of chicks are plastic and influenced by their early social

Dioxins and dl-PCBs in gull eggs from Spanish Natural Parks (2010–2013)

Enlace mardeaves Larus michahellis,PUBLICACIÓN CIENTÍFICA,REPOSITORIO ,,,,

Morales, L., Martrat, M.G.R., Parera, J., Bertolero, A., Ábalos, M., Santos, F.J., Lacorte, S. & Abad, E., 2016. Dioxins and dl-PCBs in gull eggs from Spanish Natural Parks (2010–2013). Science of the Total Environment, 550, pp.114-122.

The aim of this study was to evaluate the presence and distribution of polychlorinated dibenzo-p-dioxins, dibenzofurans (PCDD/Fs) and biphenyls (PCBs), concretely those so-called as dioxin-like PCBs, in yellow-legged gull eggs (Larus michahellis) collected from five Natural Parks (some of them National Parks) in Spain during the period 2010–2013. PCDD/Fs and dl-PCBs were detected in all the samples. Due to the proximity to important urban and industrial areas higher concentrations were determined in colonies located in the Northern Mediterranean coast than those found in the Southern Mediterranean or Atlantic colonies where a softer anthropogenic impact occurs. Mean ∑ PCDD/F concentrations ranged from 49 to 223 pg/g lipid weight (lw) and ∑ dl-PCB concentrations varied from 146 to 911 ng/g lw. In the Natural Park of the Ebro Delta (Northern Mediterranean coast) two gull species share habitat: yellow-legged and Audouin gull (Larus audouinii). Eggs from both species were collected and PCDD/F and dl-PCB levels compared. The species that feeds exclusively on pelagic fish (L. audouinii) had significantly higher PCDD/F and dl-PCB levels than the scavenger L. michahellis, pointing out the diet-dependent differences in the accumulation of persistent organic pollutants between similar cohabitant breeding species. Finally, mean TEQ values were in general below those considered as critical for toxicological effects in birds.