Anatomy of a nest: Oriental White-eye

This is the nest that the pair of Oriental White-eyes (Zosterops palpebrosus) built in Yen Lau’s potted Australian Bottlebrush (Callistemon rigidus) plant in December 2006-January 2007 (above left). The nest on the right is that of July 2006.

The current nest is a small and extremely flimsy, cup-shaped, asymmetrical nest. Circular in outline, the nest has a diameter of 65 mm and depth of 45 mm. The cup diameter is 55 mm and cup depth 35 mm.

The nest is sited about 2 metres up the potted plant. It is attached at three points to three very slender (3 mm) branches of the bottlebrush plant with the help of what looks like spider web or its cocoon silk (above). These pieces of silk are also found scattered on the outer surface of the nest.

The outer layer of the nest is woven from narrow strips of vegetable matters, probably grass leaves, a few strips of transparent raffia with a few bottlebrush leaves incorporated. The inner lining is made up mostly of very fine, black and shiny ‘stem’ pieces that are loosely placed around, not carefully weaved or even crudely interlocked.

The base of the nest is extra flimsy and see-through. Looking into the nest, it is possible to see through it (top right). Thus it was possible to see the eggs while the nest was still attached to the potted tree. The image at bottom right shows the rather asymmetrical nest as seen from below.

The nest diameter of the earlier nesting on July 2006 is 56 mm and depth 42 mm. The cup diameter is 42 mm. The nest is quite symmetrical. There are a lot of single strand silk, probably spider cocoon silk and larger blobs of probably spider’s web. The basal part has mosses incorporated. The nest lining is of fine fibre.

It would appear that the nest dimensions are slightly larger in the later nest. However, the earlier nest has more materials and appear stronger. Although the difference between the outer and inner diameter is about the same, the rim of the later nest is as thick as before but the nest wall proper is made up of less materials.

The conclusion by Yen Lau that the birds were not able to get enough nesting materials for their year-end nest is further confirmed.

Input by YC, nest provided by Yen Lau through the good office of KC Tsang. Images by YC except top right by KC.