I was trimming my starfruit tree (Averrhoa carambola) to remove the branches that were infringing on to my neighbour’s airspace. When collecting the branches, I was surprised to find a small nest attached to one of the end branches. So the nest was constructed high up the tree.

It was a smallish, oval nest, 14 x 8 cm, had a round opening 4 x 4 cm near the top (left). It was an untidy structure, with fibres sticking out all over the surface, looking like a mass of dried plant matters stuck to the branch.

The nest was firmly attached tied to the branch with masses of fibres. The round opening was lined with a defined rim of twisted fibres forming a distinct rim.

The fibres were carefully removed, identified and counted. Most of the fibres came from banana (Musa) and palms, making a total of 637 pieces, the longest being 31 cm. There were also 4 raffia strands and a single grass inflorescence branch. Loose lalang grass (Imperata cylindrical) floss scattered about the inner lining of the nest. There were also a few pieces of what looked like yellow spider cocoon silk, not specifically used to bind the fibres.

The Common Tailorbird (Orthotomus sutorius) has always been around the tree, foraging for insects, mostly ants. So the nest was most probably that of the tailorbird. The bird is about 11-13 cm in length and appears to fit the nest.

Also, earlier postings of Common Tailorbirds’ nests appear to be of similar size and shape. However, they were always built inside one to a few leaves stitched together like leaves of simpoh air (Dillenia suffruticosa), ginger plant or garden creeper.

Can it be that this nest is incomplete? And that when completed one or more larger leaves (taken from somewhere else) would be incorporated?

“Round and oval objects are hanging on the branches of a mangrove tree, swinging slightly when the wind blows (above). These are the nests of the Baya Weavers (Ploceus philippinus) (below top). There are more than ten of them, hanging from the branches of a tree in Sempadan swamp along Bogowonto river in the coastal village of Pagak Purworejo, Indonesia. This is a favourite nesting area of these birds.

“The nest architecture is complicated. Each nest is constructed from grass leaves, plaited in a very complex way.

“The nest is as big as a soccer ball, oval, stretched with a hallway and an entrance with a 10 cm diameter opening (left bottom). This entrance is on the underside of the nest with less dense plaited grass. The upperside of the nest is spherical and the grass plaited is thick and dense.

“Other nests seem to have different shapes - rounded with two openings beneath. Nest construction here seems to be incomplete, probably the male Baya Weaver is having a rest or cannot find enough nest materials? Or probably the male does not want to continue building his pretty house for the female, because she is not pleased with the house he built and has to be abandoned by the architect.

“It is not only humans that have special courtship behaviour. Baya birds, in order to attract a female, needs to pay a “bride price” or a guarantee of a home to raise the young. The male has to build a “castle” for the female before the copulation is allowed.

“Not just weavers but many other birds that live in the tropics such as Indonesia, have to build a nest before copulation.

“The many male birds can be seen competing with one another to collect materials and construct the nest. They are all busy arranging the grass leaves piece by piece, plaiting them carefully to slowly construct the nest before presenting to the female for approval.

“The bird that builds the most “beautiful and comfortable” nest will win a female for the current breeding season.”

Text by Oka Dwi P., images by Swiss Winasis.
This post was received courtesy of Sunaring Kurniandaru, Kutilang Indonesia Foundation, Yogyakarta, Indonesia.

Lin Yangchen documented a male Dark-necked Tailorbird (Orthotomus atrogularis nitidus) collecting fruits of the lalang grass (Imperata cylindrical) for its nest (above; field of lalang bottom). These fruits provide the floss that is probably incorporated with other plant materials as nest lining - seen in the nest of the Common Tailorbird (Orthotomus sutorius) and the Olive-backed Sunbird (Cinnyris jugularis), where there is a distinct lining of floss.

As Yenchen writes: “He made several trips to and fro (until the stalk was almost stripped of the fruits) but seemed to come from different directions sometimes (left and right). I am speculating that these ‘detours’ may be a behavioural adaptation to evade enemies.

“As the stalk was very flimsy, he hovered for short moments while plucking the fruits. These abundant fluffy things could provide thermal insulation for the chicks and are possibly less expensive (per unit insulating capacity) for the parents than using their own down, although the cheapness is offset by the energetic expense incurred in flying around looking for it.

“The actual nest seemed to be only about 1m away in a bush (which makes the search flights less expensive), but I didn’t try to locate it, so that he and his beloved wife could enjoy their private lives together.”

Image of bird by Yangchen, that of lalang by YC.

On 5th May 2008, Tan Teo Seng sent me a used munia nest that he collected from his fruit farm in Johor while pruning his jambu air or water apple (Syzygium aqueum) tree. The nest was lodged between the narrow forks of two pairs of slender branches about 3 metres from the ground.

The nest, a roundish structure of 150×150 mm, has a small oval opening of 35×40 mm near the top, about half way up (above left, arrow). The entrance is slightly directed downwards and not at all obvious, with an untidy overhang of dried leaves to camouflage it. The image on the right, above, shows the nest from the back.

The nest proper sits on a 50 mm thick base of leaves and twigs, comprising of a total of 34 pieces of branch tips, each with two to five leaves still attached. Mixed with these are 18 pieces of short twigs, most of which are short-branched rather than single pieces.

The outer layer of the nest is made up of a total of 220 dried grass leaves, mostly 300 mm long, the longest being 450 mm. These are weaved together to provide a firm shell. The removal of these leaves exposes the inner oval ball, 140×110 mm, made up entirely of grass inflorescence branches, complete with spikelets.

The grasse are Buffalo Grass (Paspalum conjugatum) 281 pieces (left top); Creeping Panic Grass (Panicum repens) 79 pieces; Elephant Grass (Pennisetum purpureum) 17 pieces (left middle and bottom); Lalang (Imperata cylindrical) 22 pieces; and Panicum humidorum 73 pieces.

The nest chamber is 60×50 mm. Inside are three eggs, one of which hatched while two remained unhatched, with ants around one that has cracked (below).

The total number of the different nesting materials that make up the nest is 744. This is very much less than the usual number of pieces of materials of this size. Why? Because most of the materials are extremely long, especially the grass leaves.

According to Restall (1996), “In most, if not all species, the male brings the nesting material to the nest, while the female inside works it into place by pushing. This pushing may extend to a kind of weaving when a length of grass may be pulled back into the structure and thus loops, catching hold, but the munias are not authentic weavers.”

What this means is that the male bird would need to make a total of around 679 trips to bring all the materials to the female to construct the nest. The female would be working just as hard to get the materials brought by the male into place to construct this large nest.

An earlier nest looks about the same but made of slightly different materials.

Reference:
Restall, R. (1996). Munias and mannikins. East Sussex: Pica Press.

Willis photographed this Common Iora (Aegithina tiphia) collecting spider silk for its nest (above). It can be a messy job as seen in the image but spider silk plays an important role in the makeup of small nests of many small birds. The silk helps bind up the nesting materials, making the nest a more sturdy structure.

An earlier post on the Black-naped Monarch (Hypothymis azurea) nest shows whitish spider cocoon silk on the nest surface together with mosses and liverworts.

Now, there is a difference between spider silk and spider cocoon silk. Spider silk comes from the web proper (top left). It is commonly believed that the sticky silk helps bind the superficial nesting materials together, just like in a sticky tape. However, according to Hansell (2007), only some spiders coat their webs with sticky droplets to trap prey, but these soon dry out. So the sticky tape idea is out.

It appears that the silk is used according to the Velcro principal. The silk provides the Velcro “loops” and the tiny leaves of the mosses and liverworts the “hooks”.

Another interesting point is that most of the silk that are seen on nests come from spider cocoon silk, the silk that is used to enclose the spider eggs (above right). Thus we see masses of white rather than single strands of white silk.

Image of iora collecting silk by willis; those of spiders by YC.

References:
1. Hansell, Mike (2000). Bird nests and construction behaviour. Cambridge University Press.
2. Hansell, Mike (2007). Built by animals. Oxford University Press.

This post is a cooperative effort between NaturePixels.org and BESG to bring the study of bird behaviour through photography to a wider audience