Richard White documented a Hummingbird Hawk Moth (Macroglossum sp.) harvesting nectar at the Singapore Botanic Gardens around August 2015. The hawk moth’s feeding behavior reminded him of a hummingbird hovering in front of flowers to harvest their nectar. In both cases they excrete excess water from from their liquid diet while hovering. Richard further brought up the question of whether nectar-feeding sunbirds excrete excess water.
We do not have hummingbirds in this part of the world. Instead we have the Old World’s equivalent – sunbirds. Sunbirds also feed on nectar, sometimes even hovering in front of flowers to get at it.
Both hummingbirds and sunbirds take in large amounts of nectar. And as their diet consists mainly of liquid food, both need to get rid of excess water, thus defecating frequently. However, whereas hummingbirds absorb all the ingested water, sunbirds do not. Again, while the kidneys of hummingbirds do not have the ability to concentrate urine, those of sunbirds do. Thus hummingbirds, like the Hummingbird Hawk Moth, need to eject excess water regularly. Not so in the case of sunbirds – see HERE
This post is a cooperative effort between Birds, Insects N Creatures Of Asia and BESG to bring the study of birds and their behavior through photography and videography to a wider audience.