Abstract
Parents should allocate parental investment in relation to the expected reproductive value of their offspring. We used a cross-fostering experiment to see whether factors influencing offspring reproductive value (brood size, nestling sex, age or paternity) were related to parental investment in nest defence in the blue tit, Cyanistes caeruleus . Although brood size and the incidence of extrapair paternity did not influence the nest defence behaviour of parents, we found a significant difference in the way male and female parents responded to the experimental change in sex ratio of the brood; the nest defence response of males was faster at nests with an increased proportion of sons, but the response of females was unrelated to changes in brood sex ratio. Furthermore, there was no relation between the original sex ratio of the brood, before manipulation, and the nest defence response of the male, indicating that paternal investment in this behaviour was a direct response to the manipulated brood sex ratio.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
