Long-tailed Parakeet and the Dendrophthoe pentandra mistletoe

An earlier post on the Long-tailed Parakeet (Psittacula longicauda) feeding on the fruits of the semi-parasitic tropical mistletoe, Dendrophthoe pentandra suggested that the parakeet aids in seed dispersal. However, observations on 28th February 2011 have proven this wrong.

That evening, a female Long-tailed Parakeet flew into my noni tree (Morinda citrifolia) accompanied with loud, shrill cries. She stayed very still for some time before chewing on a short rotting branch (left). She then moved off and began picking the ripe fruits of the mistletoe (D. pentandra) that grows on the noni branches.

The mistletoe fruit is single seeded turning red on ripening. When picked, the seed slips out of the fruit coat on a bed of thick, white and sticky mucilage. When the parakeet ate the seed, it discarded the fruit coat that dropped off, still attached to a string of mucilage (below).

Unlike flowerpeckers that swallow the mistletoe seeds, the Long-tailed Parakeet chews on it. In the process the seed is destroyed, although a very few may be swallowed whole to be excreted some distance away where they germinate on some branches or other. A long-section of the seed shows the green embryo (below right).

The image above (left) shows the crushed seeds between the mandibles of the parakeet. Note the greenish pieces that are the remains of the embryonic seed. The whitish pieces are parts of the endosperm together with the mucilage. The fruit coat is intact, still attached to the seed mass by the presence of the sticky mucilage.

In the process of picking the mistletoe fruits, the parakeet cut off the leaf stalks of the mistletoe leaves that get in her way (right). I have always suspected that some birds or other are responsible for the many whole green leaves that regularly litter the ground below my noni tree but it was only this time that I actually observed the parakeet clipping off the leaves.

YC Wee
Singapore
March 2011