One of the joy of birding is to observe behaviour of birds in the field and then having done so, be educated by a fellow birder as to what it all meant.
I had the opportunity to observe a family of Oriental Pied Hornbills (Anthracoceros albirostris) flying towards a kampung house at Pulau Ubin. One of the adult proceeded to land on a large papaya tree. This tree happen to have one ripe papaya fruit.
Soon enough the hornbill dug into the fruit itself and then retrieve the flesh using its large bill. It then proceeded to flip the morsel up and then with the mouth wide open, swallowed it whole. It did this repeatedly after obtaining a solid morsel.
This method of feeding is call “ballistic transport feeding” and was just been discovered recently. Using high speed cameras, researchers have discovered that hornbills, toucans and cassowaries all have a unique way of eating, where food is tossed upwards, and on its way down, the bird open its “mouth” (from the tips of the bill to the pharynx) and the food is then swallowed whole. All this is accomplished without the tongue getting involved, which is a unique adaptation for swallowing large and variable sized food. Imagine that these birds do not taste, nor grind their food before swallowing.
The hornbill using its powerful bill to tear into the ripened papaya fruit.
The flip and swallow routine caught in action
A closer look at another instance. Notice the shape of the morsel is different.
Yet another instance, this time at a different, steeper head angle.
Next frame, just enough to capture the morsel going down.
After one side is done, it goes for the other side. A messy eater.
All the while, the juvenile is perched quietly just below the papaya tree. As it has the same pose, you can compare its relative proportion.
Soon after these photos were taken, a group of weekend cyclist came by a bit too close. The whole family flew off to another location, and the papaya was left half eaten.
In summary, we know that Oriental Pied Hornbills like ripe papaya fruits, they tear into the fruit using their powerful bill to retrieve morsels of flesh, are messy eaters and then use ballistic transport to feed themselves.
Gallery
This post was originally written in my blog at: https://fryap.wordpress.com/2014/05/26/oriental-pied-hornbill-ballistic-transport-feeding and expanded upon.
References:
1. Blog: Ballistic transport (“flip and catch”) feeding in hornbills
2. Baussart S, Korsoun L, Libourel PA, Bels V. (2009) “Ballistic food transport in toucans”. J Exp Zool A Ecol Genet Physiol. 2009 Aug 1;311(7):465-74.
3. Baussart S & V. Bels (2011) “Tropical hornbills (Aceros cassidix, Aceros undulatus, and Buceros hydrocorax) use ballistic transport to feed with their large beaks.” J Exp Zool A Ecol Genet Physiol. 2011 Feb:72-83
4. M. Harte , P. Legreneur, E. Pelle, M-A. Placide & V. Bels (2012) “Ballistic food transport in birds: the example of Casuarius casuarius” Computer Methods in Biomechanics and Biomedical Engineering, 15:sup1, 137-139