India, Oct. 10 -- Arun Khanna was engrossed in photographing nest construction by baya weaver in the Saketri grasslands. "Then I spotted an interesting object on a babul branch: an elongated, blackish, tube-like object. My first thought was amusing: maybe some kid had flung an old bicycle tube up the tree. The 'tube' moved. The weavers got agitated. It was a rat snake, manoeuvring to a nest," recalled Khanna.

Rat snakes can climb incredibly high trees to gobble eggs and nestlings. However, weaver nests are challenging. The weaver can build two entrances, a false and a concealed real one, or a very narrow one to the nest, which frustrates the serpent. Nests can be tactically sited on branches hanging over a waterbody or a well to increase...