Nectar intake of white-bellied sunbirds (Cinnyris talatala): can meal size be inferred from feeding duration?
A positive relationship between feeding duration and meal size of avian nectarivores has often been assumed in earlier studies. We investigated whether feeding duration can be used as a surrogate for the amount of sugar solution ingested by white-bellied sunbirds, Cinnyris (Nectarinia) talatala. Feeding durations of sunbirds consuming three sucrose concentrations (10%, 20%, and 40% w/w) were measured using an infrared photodetection system, and the amounts consumed were recorded simultaneously by weighing the feeder throughout the experiment. For all three diet concentrations, a positive relationship was found between the time spent feeding per 30 min and the mass consumed. Therefore, feeding duration is demonstrated to be an index of the amount ingested on a particular sugar concentration. The rate of ingestion, however, depended on the sugar concentration, with the highest rate at the lowest concentration of 10% and the lowest rate at the 40% concentration. Less total time was spent feeding on the 20% solution than on the 10% solution, but time increased on the 40% diet because of viscosity effects. There appeared to be a weak relationship between feeding patterns and sex, but this was not significant, probably because of interindividual variation.
Köhler
Angela
A
Department of Zoology and Entomology, University of Pretoria, Pretoria 0002, South Africa. akoehler@zoology.up.ac.za
Verburgt
Luke
L
Nicolson
Sue W
SW
D000704:Analysis of Variance; D000818:Animals; D004435:Eating / Q000502:physiology*; D005247:Feeding Behavior / Q000502:physiology*; D005260:Female; D008297:Male; D046109:Passeriformes / Q000502:physiology*; D012737:Sex Factors; D013019:South Africa; D013395:Sucrose; D013997:Time Factors; D014783:Viscosity
D013395:Sucrose