Yearly variation in the structure and diversity of a non-breeding passerine bird community in a Mediterranean wetland

Background:The dynamics and structure of many bird communities are changing due to the global warming and changes in the land use and management.The Ebro Valley constitutes one of the chief wintering areas for several passerine species in Iberia,and the reed beds spread across this Valley concentrate huge numbers of birds that use them to roost,while the surrounding agricultural areas serve as main foraging habitats.The aims of this work are(1)to quantify how variable a non-breeding passerine bird community associated to a reed bed area in the Ebro Valley is,and,(2)to test for the effect of weather on possible annual fluctuations in species’proportions at a regional/local scale.Methods:We used for that ringing data collected at Badina de Escudera lagoon(Navarra)over a 12-year period.Results:Though,overall,the assemblage did not vary strongly among years(most similarity values were>0.8),we still found a significant linear effect of year on the proportion of captures of Reed Buntings(Emberiza schoeniclus),i.e.,the dominant species detected in our passerine community.The increasing loss of weight of Reed Buntings in the community was due to a progressive decrease in its abundance.Conclusions:The structure and diversity of passerine community in Badina Escudera was not influenced by meteorological conditions at a local scale,suggesting that local weather would not have an impact on numbers of Reed Buntings in winter.

Bigger or long-winged male common crossbills exhibit redder carotenoid-based plumage coloration

Carotenoid-based ornaments are often considered reliable(honest)individual condition signals because their expression implies physiological costs unaffordable for low-quality animals(handicap signals).Recently,it has been suggested that efficient cell respiration is mandatory for producing red ketocarotenoids from dietary yellow carotenoids.This implies that red colorations should be entirely unfalsifiable and independent of expression costs(index signals).In a precedent study,male common crossbills,Loxia curvirostra,showing a red plumage reported higher apparent survival than those showing yellowish-orange colors.The plumage redness in this species is due to ketocarotenoid accumulation in feathers.Here,we correlated the male plumage redness(a 4-level visual score:yellow,patchy,orange,and red)and the body morphology in more than 1,ooo adult crossbills captured in 3 Iberian localities to infer the mechanisms responsible for color evolution.A principal component analysis summarized morphometry of 10 variables(beak,wing,tarsus length,etc.).The overall body size(PC1)and the length of flight feathers regarding body size(Pc3)showed significant positive relationships with plumage redness.Plumage redness was barely correlated with bill shape measures,suggesting no constraint in acquiring carotenoids from pine cones.However,large body sizes or proportionally long flying feathers could help carotenoid acquisition via social competition or increased foraging ranges.Proportionally longer flight feathers might also be associated with a specific cell respiration profile that would simultaneously favor flying capacities and enzymatic transformations needed for ketocarotenoid synthesis.Such a phenotypic profile would agree with the hypothesis of ketocarotenoid-based colors acting as individual quality index signals.