Natures wonders: fungus in nest protects chicks (Introduction)

by David Turell , Tuesday, August 16, 2022, 23:38 (828 days ago) @ David Turell

In some African nests:

https://www.newscientist.com/article/2333846-tropical-birds-build-nests-from-fungi-that...

"Fungi woven into birds’ nests may not only help keep nests flexible and intact, but also control nestling-attacking parasites by releasing antibiotics and volatile chemicals.

"Baby birds, especially when naked and newly hatched, should be vulnerable to skin infections and parasites. Yet even in the stuffy confines of a nest in a steamy tropical rainforest, nestlings generally manage to remain fester-free. Why this is has long puzzled scientists, but Catherine Aime at Purdue University in Indiana and her colleagues wondered if they may derive protection from the long strands of fungal material many tropical birds weave into their nests.

"Called rhizomorphs, these long, pliable and highly decay-resistant structures protect the feeding parts of a fungus, the hyphae, inside a sheath so they can grow from one hospitable place to another. But their length and flexibility also make them ideal as the basic scaffolding for nests under construction. As a result, they are common components of nests throughout the tropics.

"Rhizomorphs are also known to be potent producers of defensive chemicals, designed to keep insects, slugs and even other fungi at bay while the rope-like extensions seek out new spots of decomposable succulence.

***

"...they collected rhizomorphs from just-vacated nests built by 22 bird species in Iwokrama rainforest, Guyana, cleaned the fungal strands and then placed then on agar, a fungal growing medium. They found that, far from being dead, the cord-like strands were active and capable of producing chemical substances.

“Rainforests are challenging places, so rhizomorphs produce a huge variety of protective chemicals,” says team member Rachel Koch Bach, also at Purdue University.

"Many of these chemicals are volatile, meaning they easily evaporate and travel through the air, so they could protect nestlings in the close confines of a nest, says Aime.

"The team considers it highly likely that birds actively choose rhizomorphs as strong supports but also for keeping their nestlings free of the skin-infesting parasites so abundant in the humidity of a tropical rainforest."

Comment: there is no question birds will find strong twigs and strands for the nests, but the birds did not actually reason as the study authors did about the protective values. Not in the beginning at least. They may have come to recognize the value later on.