Nest size affects clutch size and the start of incubation in magpies: an experimental study |
| |
Authors: | Soler Juan Jose; Neve Liesbeth de; Martinez Juan Gabriel; Soler Manuel |
| |
Institution: | a
Estación Experimental de Zonas Aridas,
C.S.I.C., General Segura 1, E-04001 Almería,
Spain
b
Departamento de Biología Animal y
Ecología, Facultad de Ciencias, Universidad de
Granada, E-18071 Granada, Spain |
| |
Abstract: | Nest size has been suggested to be a sexually selected traitindicating parental ability of both males and females. To testwhether a female's reproductive decisions (e.g., clutch sizeand starting incubation) change in relation to experimentalmanipulation of nest size, as would be predicted if nest sizeis a sexually selected signal reflecting the male's parental
quality, we manipulated nest size in a population of monogamousmagpies before laying by adding or removing about 20 cm oflarge sticks in the roof of magpie nests. On the one hand,we found that clutch size of reduced nests was smaller thanthat of control or enlarged nests. Moreover, clutch size was
significantly related to nest size after manipulation, whichindicates that females adjust clutch size to the final sizeof the nest, nest size thereby being a good candidate for asexually selected trait. On the other hand, number of eggshatched during the first day is hypothesized to be related to
the expected available resources during nestling growth, andsubsequent nestlings hatched are likely to die due to broodreduction if resources are not sufficient to raise well-developednestlings. Nest size is hypothesized to inform females abouta male's willingness to invest in reproduction, and we foundthat in broods of experimentally reduced nests, females startedto incubate earlier in the laying sequence than they did inbroods of control or enlarged nests. Moreover, in experimentallyreduced nests, fewer nestlings hatched during the first day,and the difference in body mass between the first and the fourthnestling hatched increased. This result is in accordance withthe hypothesis that the female's decision of when to start incubationin the laying sequence is mediated by nest size, a sexuallyselected trait signaling parental quality. We discuss alternativeexplanations for the results such as the possibility that nestsof different treatments may differ in their thermoregulationproperties or in their protection against predators. |
| |
Keywords: | clutch size female decision making magpies nest building parental investment Pica pica sexual selection |
本文献已被 Oxford 等数据库收录! |
|