Nectar Intake of White‐Bellied Sunbirds (Cinnyris talatala): Can Meal Size Be Inferred from Feeding Duration?

Abstract

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 whitebellied 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.

Interruptions in nectar availability: responses of White-bellied Sunbirds (Cinnyris talatala) and Brown Honeyeaters (Lichmera indistincta)

“…Feeding duration is positively related to meal size in this species (Köhler et al 2008a), i.e. the longer the birds feed the more they ingest during one feeding event.…”

Do sunbirds use taste to decide how much to drink?

“…A meal can be thought of as the total nectar consumed from multiple flowers from when a bird first starts feeding until it leaves a food source. Like hummingbirds, sunbirds also typically consume less per meal when sucrose concentrations are higher than when they are lower (Köhler, Verburgt & Nicolson ). Volumetric intake of higher concentrations may also be lower than intake of lower concentrations: more concentrated sucrose solutions take longer to pass through the gut, limiting capacity for further food intake (Downs ; Savory ).…”