Examinando por Autor "Macias Garcia, Constantino"

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Cosmetic enhancement of signal colouration: experimental evidence in the house finch
(Oxford Academic, 2010) López-Rull, Isabel; Pagán, Iluminada; Macias Garcia, Constantino
Plumage coloration plays an important role in visual communication by signaling aspects of individual quality. It has been proposed that the need for preserving plumage condition and hence signaling content may have promoted a novel signaling mechanism: cosmetic coloration. Here, we investigated whether preen waxes may act as cosmetics by affecting feathers’ ornamental coloration in male house finches (Carpodacus mexicanus). We (1) blocked the access to uropygial gland of a group of males and compared their coloration with a control group and (2) applied preen wax extracted from live individuals to museum skins and measured color before and after wax application. We found that red feathers of control males were more colorful than those of experimental males and that applying waxes to museum skins’ red feathers increased their color saturation. Our results provide evidence that preen waxes act as cosmetics by enhancing plumage ornamentation, thus revealing the existence of novel mechanisms operating in signaling coloration. Although preen waxes per se would not constitute a signal, selection for signal efficacy might favor individuals that are able to increase signal intensity beyond the optimum necessary for plumage maintenance. Our results support the hypothesis that preen waxes reinforce the honesty of signals, which may be particularly useful in a social context where interactions between individuals are mediated by the intensity of the signals.
Incorporation of cigarette butts into nests reduces nest ectoparasite load in urban birds: new ingredients for an old recipe?
(The Royal Society, 2013) Rodríguez Suárez, Montserrat; López-Rull, Isabel; Macias Garcia, Constantino
Birds are known to respond to nest-dwelling parasites by altering beha-viours. Some bird species, for example, bring fresh plants to the nest,which contain volatile compounds that repel parasites. There is evidencethat some birds living in cities incorporate cigarette butts into their nests,but the effect (if any) of this behaviour remains unclear. Butts fromsmoked cigarettes retain substantial amounts of nicotine and other com-pounds that may also act as arthropod repellents. We provide the firstevidence that smoked cigarette butts may function as a parasite repellentin urban bird nests. The amount of cellulose acetate from butts in nests oftwo widely distributed urban birds was negatively associated with thenumber of nest-dwelling parasites. Moreover, when parasites were attractedto heat traps containing smoked or non-smoked cigarette butts, fewer para-sites reached the former, presumably due to the presence of nicotine.Because urbanization changes the abundance and type of resources uponwhich birds depend, including nesting materials and plants involved inself-medication, our results are consistent with the view that urbanizationimposes new challenges on birds that are dealt with using adaptationsevolved elsewhere.
Male quality and conspecific scent preferences in the house finch Carpodacus mexicanus
(Elsevier Sciencedirect, 2012) Amo, Luisa; López-Rull, Isabel; Pagán, Iluminada; Macias Garcia, Constantino
There is increasing evidence that birds use chemical cues in different contexts, and this is changing the traditional view that birds are the only largely olfaction-free vertebrates. We performed a choice experiment to examine whether male house finches exhibit any preferences for the sex of conspecifics when only their chemical cues are available. When exposed during the breeding season to the scent of a male and a female, males appeared to respond indiscriminately to both odours. However, when we analysed a posteriori the choices of males in relation to their relative quality, males with worse quality than scent donor males avoided the male-scented area, whereas males with better quality moved towards the male-scented area. Our results suggest that in the context of mate choice/competition for mates, house finches may obtain information via olfaction to assess the quality of rival males