As storks make nests for owls, scientists gain green wisdom

Chandigarh, April 3 In the farmlands of southern Haryana, a pair of woolly-necked storks get ready to leave their nest along with their chicks who had just started flying.

The large ungainly stick nest of the storks was still surprisingly intact after three months of use. The nest, however, was not left empty for long after the storks left. A pair of large dusky eagle owls took over almost immediately. And raised their chicks in the same nest.

In itself, this occurrence of a large owl reusing a large nest was not entirely remarkable.

Most large owls do not build their own nests, instead using natural features such as cliffs or nests built by other birds to breed on.

The remarkable elements of the waterbird-large raptor story played out as researchers of the Nature Conservation Foundation watched hundreds of stork nests for over nearly a decade.

Woolly-necked storks have a thriving population in Haryana's farmlands. This defies conventional assumptions. This stork species was wrongly assumed to need protected forests and wetlands to breed.

While studying these storks, researchers noticed the large dusky eagle owls reusing the nests after the storks had completed their breeding. They began to carefully piece together an inter-species association that had never been documented before.

Explaining the stork-owl bond, Gopi Sundar, the lead scientist of the project, told that most of the owls' reused nests were in areas that had more woolly-necked storks nesting.

The owls did reuse large nests of other birds such as eagles and ibises in the same area but did so very rarely. The entire goings-on were very unusual since it suggested that the owl was tracking the storks' breeding rather than use any old nest that it encountered.

This was the first time anyone had discovered a large predatory bird being reliant on nests built by one species.

Such a relationship where one species, in this case the owl, relied on the resources created by another species, the nests of the stork, without harming the species is called commensalism.

This study documented the first instance of commensalism involving a large owl and a large waterbird anywhere. The research was recently published in the international journal "Biotropica" that accepts original research on species in tropical ecosystems.

The authors of this research paper include Rakesh Ahlawat and Devender Singh Dalal who were field associates on the project.

In India, it is very unusual for field associates to be included as full co-authors of scientific papers published in international journals.

Scientists usually relegate their field staff to the acknowledgements.

Sundar, and his colleague Swati Kittur, carried out the mapping and analyses for this work.

The scientists noted other fascinating aspects during the study.

Woolly-necked storks made their nests largely on the very common tree, sheesham or Dalbergia sissoo. Sheesham is a native tree species treasured by farmers and villagers for its hard wood being used even to make yokes for farming and for furniture.

The storks also made many nests on the large Peepal