The differential allocation hypothesis posits that individuals should invest in the current reproductive attempt according to the attractiveness of their mate, but studies of allocation by males when female traits are manipulated to be more attractive are lacking. In the current study, we experimentally enhanced and reduced the plumage brightness of female tree swallows (Tachycineta bicolor) relative to controls to examine whether males adjust investment in parental care according to female attractiveness, while simultaneously performing a brood size manipulation. Contrary to our predictions, we found no evidence that males provisioned nestlings according to the plumage brightness of females. However, we found that nestling quality and fledging success were lowest when female plumage brightness was reduced and brood size was enlarged. This may be due to the plumage brightness treatment influencing agonistic interactions with other females, and may suggest that plumage brightness is a signal assessed by females.
Site- and sex-level differences in adult feeding behaviour and its consequences to offspring quality in tree swallows (Tachycineta bicolor) following brood-size manipulation. —
Can. J. Zool.85:
Age-related differences in plumage characteristics of male tree swallows Tachycineta bicolor: hue and brightness signal different aspects of individual quality. —
J. Avian Biol.39:
The importance of microclimate variation in determining size, growth and survival of avian offspring: experimental evidence from a cavity nesting passerine. —
Defeat is a major stressor in males while social instability is stressful mainly in females: towards the development of a social stress model in female rats. —
Brain Res. Bull.50:
Condition- and parasite-dependent expression of a male-like trait in a female bird. —
Female blue tits with brighter yellow chests transfer more carotenoids to their eggs after an immune challenge. —
The evolution of female ornaments and weaponry: social selection, sexual selection and ecological competition. —
Philos. Trans. Roy. Soc. Lond. B: Biol. Sci.367:
Stress and success: individual differences in the glucocorticoid stress response predict behavior and reproductive success under high predation risk. —
Tree swallow (Tachycineta bicolor). — In:
Birds of North America (
PooleA. ed.) retrieved from Birds of North America Online at http://bna.birds.cornell.edu/bna/species/011. Cornell Lab of OrnithologyIthaca, NY.