On the tongue of a hummingbird: Its role in the rate and energetics of feeding

Abstract

1. 1. Rate of intake of hummingbirds (3·1 and 7·9 g) visiting a feeder was greater for larger hummingbirds but was not dependent on sugar concentration up to 1 ·0 molar sucrose. 2. 2. Most flowers produce nectarwith concentrations (0·24-1·48 molar sucrose) that should not influence rate of nectar intake. 3. 3. Rate of tongue licking was independent of body size (2·6-3·8 licks/sec), but the larger hununingbird obtained more nectar per tongue lick. 4. 4. Morphological studies indicated that the grooves on the tongues of hummingbirds may play a minor role in determining rate of nectar intake at a feeder with large nectar volumes, but they could be important in emptying small nectar volumes from flowers. 5. 5. Adding a “corolla” to the feeder resulted in a linear decrease in rate of intake with increasing “corolla” length. However, corolla curvature, position and the volume of nectar in flowers are also important for determining rate of nectar extraction from flowers.