As regular CFZ-watchers will know, for some time Corinna has been doing a column for Animals & Men and a regular segment on On The Track... particularly about out-of-place birds and rare vagrants. There seem to be more and more bird stories from all over the world hitting the news these days so, to make room for them all - and to give them all equal and worthy coverage - she has set up this new blog to cover all things feathery and Fortean.

Friday 21 December 2018

Birds can mistake some caterpillars for snakes; can robots help?

Researchers observe a defense mechanism for caterpillars can attract unwanted attention
Date:  December 17, 2018
Source:  Ecological Society of America
When a caterpillar disguises itself as a snake to ward off potential predators, it should probably expect to be treated like one.
This is exactly what happened in Costa Rica earlier this year, when researchers witnessed a hummingbird defending its nest from what it interpreted to be a snake, but was actually a larva of the moth Oxytenis modestia. The encounter is described in a new paper published in the Ecological Society of America's journal Ecology.
These moths -- sometimes called the dead-leaf moth or the Costa Rica leaf moth -- resemble flat dried leaves as adults. The caterpillars can inflate the top of their heads to expose a pair of eyespots. When disturbed, they raise their head up and move from side to side, increasing the snake-like appearance. In particular they resemble a green parrot snake, known to prey on nesting birds.
The attacking hummingbird's nest with eggs was about 10cm away from the caterpillar in a small tree. When the researchers went to look for an assumed snake, they instead found the caterpillar feeding on a leaf immediately above the nest.
"Hummingbirds have a few stereotypical styles of flying: visiting flowers, preying on swarms of tiny insects, chasing each other, and mating/territorial display flights," says lead author James H. Marden, professor with the Department of Biology at Pennsylvania State University. "Mobbing behavior directed against a threat to their nest is much less common but distinct and easy to recognize if you know their other flight behaviors... One can recognize this from a distance and only notice the source of their agitation upon close inspection."

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