Parental care does not vary with age-dependent plumage in male Saffron Finches Sicalis flaveola

PALMERIO, A.G; MASSONI, V.

IBIS

WILEY-BLACKWELL PUBLISHING, INC

Año: 2011

0019-1019

Abstract. The delayed acquisition of definitive nuptial plumage until after an individual´s first potential breeding season (Rohwer et al. 1980, Hill 1996), is typically associated with age, condition or social context (Galeotti et al. 2003). The drab-color plumage may signal their status in species where males hold simple territories (Status Signalling Hypothesis, Lyon & Montgomerie 1986), thus advertising their youth and lower competitive ability to obtain females (Senar 2006) and receiving less aggression from full coloured adult males (Hill 1989, Muether et al. 1997, Karubian et al. 2008), though females regularly prefer brightly coloured males (Saethre et al. 1994, Green et al. 2000). Indeed, there are obvious advantages to females in assessing the age of a male, given that older individuals will often have more breeding experience and presumably also good genes because they have survived longer (Forslund and Pärt 1995, Kokko and Lindström 1996). However, there is scant information on the parental care provided by immature and mature plumaged males and their respective females in species with delayed plumage maturation (but see Flood 1984, Sætre et al. 1995, Karubian 2002).             Saffron Finch males, Sicalis flaveola, show age-related delayed plumage maturation: from our data on males banded as nestlings, we know that they retain the immature plumage through the entire year of hatching, and all acquire the golden-yellow colour with olive-streaked black upperparts after their first potential breeding season is over while they still are second year males (SY males, thereafter). Yellow mature-plumaged males (after second year males, ASY males, thereafter) develop an orange crown during the breeding season. While their first potential breeding season, SY males look like females, grayish, streaked with black above, with breast and flanks whitish, streaked brownish (Narosky and Yzurieta 1987). Saffron Finches’ SY males are able to attract females and reproduce successfully in a nestbox system (Palmerio and Massoni 2009). While females paired to SY males probably know the youth of their partners, we wonder if they pay the cost of lower parental investment by their younger mates who might be allotting less investment to the current progeny and saving residual reproductive effort for the future (Williams 1966). If the ASY yellow plumage discloses male’s ability and willingness to provide parental investment, as predicted by the good parent hypothesis (Hoeltzer 1989), we expect ASY males to feed their incubating females and nestlings at higher rates than the SY males. Females paired to ASY males may either contribute less, taking advantage of the male’s effort, or contribute equally well or more, if engaged in age assortative mating. We compared the ASY and SY male’s feeding rate to incubating females, the nestling feeding rate delivered by each sex and sanitation rate, and whether they differed depending on the age of the attending male; we also considered other potentially important variables such as egg lay date, number of brood in the season, brood size, and parent’s body condition.