Spider's webs; the reinforcing and duct-tape used by Broadbills, Common Ioras, Hummingbirds, Kinglets, Gnatcatchers and Vireo bird species.

Humans have analyzed spider's webs to understand why it is five times stronger than steel while being 1000 times thinner than a human hair. Each strand is made up of thousands of nano strands to attain this remarkable strength. Spider silk has been likened to the man-made Kevlar which is used to make bullet-proof vests.

Some bird species are intelligent enough to utilize this strength in nest building.

Locally, in Malaysia, with over 20 years in the field I have observed several species of broadbill utilizing web  strands as well as the Common Iora, that has also been documented previously by a Singapore group. In the Americas; Hummingbirds,  Kinglets, Gnatcatchers and Vireos have also been observed to embrace the same mode of structural engineering.

Broadbills in Malaysia are birds of the forest that are not commonly seen during the non-breeding season but build loose pendulous nests near rivers, streams, or forest tracks during the nesting season. In Khao Yai national park in Thailand there are many Long-tailed Broadbill nests hanging from telegraph/power lines that are adjacent to paved roads through the park. Waterways or roads are thought to provide easier access to the nest during the frenetic breeding season.

I have observed Black and Red, Long-tailed and Silver-breasted Broadbills to draw the following conclusions. I have not observed Long-tailed Broadbills in the process of building their nests but have seen many nests and spider thread can be seen interwoven in all of them.

A pair of Black and Red broadbills were photographed building a nest near the Kinabatangan River in Sabah. The following images detail how the pair tease the web apart and then apply it to the outside of the rather loose nest, often entailing picking up the thread and spiraling around the nest to place it judiciously.

Black and Red Broadbill pair

Bringing in the Spider's web

Applying the spider silk

Spiraling around the nest with the spider silk

Applying the Spider silk while flying

There was a constant flow of material arriving at the nest under construction

Similarly,  Silver-breasted Broadbills were photographed nesting at Fraser's Hill and Bukit Tinggi in successive years. They were in an earlier stage of nest-building and seemed to gather some of the materials including spider web before construction started in earnest.

A pair of Silver-breasted Broadbills (the female has the necklace)

The materials were brought in and added constantly to the nest under construction.

The early phase of the nest building

More building material arrives

The spider's web was brought in, teased out and applied in a spiral motions around the nest's exterior. This seemed to be an earlier stage of the nest construction.

The spider silk arrives

It is teased out to single threads

The silk is applied around the nest

Another Silver-breasted Broadbill nest, with spider silk apparent, and three chicks within

At Fraser's Hill I also photographed a Long-tailed Broadbill pair nesting. The three chicks in the nest were about to fledge. Spider silk was apparent interwoven in the plant material of the nest.

Long-tailed Broadbill

A successful nest where all three chicks fledged

Adult Long-tailed Broadbill leaving the nest

Green Broadbill feeding the chicks....also evidence for presence of spider silk

Closer to home in Penang I was at Air Hitam Dalam when I saw a yellow bird behaving strangely at the edge of the disjointed forest. Identified as a Common Iora it appeared to be snapping at air. It was building a nest nearby and I observed it seemed to contain quite a few spider  silk. I realized that the adult bird was gathering these silk threads, which are just apparent in the photo below.

Common Iora

Common Iora gathering nesting material

Gathering Spider silk

There is a lot of spider silk apparent on this nest.

Common Iora with a chick in the nest

The use of Spider's silk to strengthen nests by various bird species is not confined to Malaysian species. Various relatively small species in the Americas have been recorded to re-purpose this fantastic strengthening material. Picture below are examples of some of these species. The spider's silk is apparent on each of these nests.

 Anna's hummingbird chicks

Warbling Vireo chicks

Warbling Vireo female on her nest

Blue-gray Gnatcatcher nest

Blue-gray Gnatcatcher and chicks

Ruby-crowned Kinglet in her nest

As a scientist I am the first to say that we need to have more evidence before collected observations become universally accepted. Others have investigated Broadbill nesting proclivities with many months of work and observations on hundreds of nests. Such a study was done in Vietnam by E.N. Zubkova who studied the nest constructions of Dusky Broadbills and Black and Red Broadbills. It is mentioned in the resulting publication that spider silk is applied at various stages of nest construction. It must be also considered that the other material used and the skill of the birds is also essential for a successful nesting. Also, a well constructed nest does not guarantee a successful nesting.

It is possible that the hummingbirds and others using the rice-bowl construction for their nest that  the spider silk plays a more central role. It can also play a role as a decoration.

Nesting Material and Nest Building Technique in Two Species of Broadbill (Cymbirhynchus macorhynchos) and Corydon sumatranus, Passififormes, Eurylaimidae) from South Vietnam. E.N. Zubkova Biology Bulletin Vol 44, No 7, pp769-786.