Female penduline tits (Remiz pendulinus) choosing high quality nests benefit by decreased incubation effort and increased hatching success

Female penduline tits preferably choose males with relatively bigger nests. Nest size is a reliable indicator of thermal nest insulation capacity and hence nest quality. In this study we investigate possible benefits for females choosing larger nests. Possible benefits of choosing well insulated nests could be a) increased time-off the eggs, i.e., more time for food gathering and activities for self maintenance, and b) increased hatching success due to maintenance of a stable thermal environment. Field observations and results from aviary experiments revealed that females adjust their attentive period according to ambient temperature, whereby time-off increases with higher ambient temperature. Data corrected for ambient temperature and clutch size demonstrated that lime-off during incubation is positively correlated with nest size. However, body condition of incubating females did not increase with time-off Despite increased time-off hatching success is higher in larger nests. Thus, female mate choice for larger nest size may evolve from decreased incubation requirements with no loss in hatching success.