The Self-Composting Nest!
I learned today about another amazing avian nesting habit (other favorites here and here). This is bird-nerd stuff, to be sure, but also interesting in terms of an architectural innovation that makes use of the energy generated by microbes breaking down vegetable matter. The Malleefowl of Australia (Leipoa ocellata) builds a massive nest mound (the one below is 5 meters wide!) and stuffs it with vegetation. This vegetation then rots, and produces heat, which incubates the eggs. Neat!
(Gluepot Reserve, SA (Apr, 2010), Photo © Vik Dunis)
I came across this amazing nesting strategy because I was reading about the wider affects of climate change on bird survival rates and population declines. In drought stricken parts of Australia, these nesting mounds dry out too quickly, so the vegetation doesn’t continue rotting, I assume because the microbes that drive the process require moisture. Slowing microbe activity means the nests cool down, and the eggs die. There have been attempts to intervene by pouring water over the mounds, which have been marginally successful, but most birds still abandon nesting sites in dry conditions (see Bird Conservation: Evidence for the Effects of Interventions- pdf).
One of the reasons this struck me is because I’ve run into a few folks lately who are working on projects using microbial fuel cells from soil for power. I haven’t been able to dig up too much info about the process, but according to Wikipedia…
Soils are naturally teeming with a diverse consortium of microbes, including the electrogenic microbes needed for MFCs, and are full of complex sugars and other nutrients that have accumulated over millions of years of plant and animal material decay.
This rich build up of microbes is needed for us to be able to tap into the electron transport chain that generates the power derived from a microbial fuel cell. It apparently takes 1 cubic meter of good, rich soil to light an LED, so the birds seem to have us beat on this for now. Below, a diagram for a basic soil MFC, and a photo of a mature Malleefowl on a giant nest mound.
Coorong National Park, SA (Feb, 2012), © Kay Parkin
