STORIES
SCRUB TURKEYS
Darryl
Darryl Jones is an ecologist and Associate Professor at Griffith University in Brisbane.
You would not have to spend very much time on Tamborine Mountain before you encountered a Brush Turkey. In fact my first visit to the Mountain was looking for a site where I could study the species. I ended up spending a very large amount of time there, studying them and it was the first study of this species conducted anywhere, and basically everything that I found out was new, to the extent that some people did not believe what I found. I started studying these things when people were absolutely convinced that the group they belonged to, the megapodes, were all thoroughly monogamous.
I did a tiny study when I was an undergraduate and I thought there is a chance that these things really aren’t monogamous. They just don’t look like they are and that was based on the fact that I saw one male mate with three different females over a period of about half and hour, and I thought here is something that really needs to be studied at length. I discovered that megapodes in general, and Brush Turkeys in particular, are a really remarkable group of birds, especially how they incubate their eggs. Unlike every other type of bird, they don’t use their body heat to incubate their eggs. They construct what is effectively a compost heap where the heat generated by micro-organisms breaking down organic matter inside that big mound of sticks, leaves and dirt, (containing up to 4 tons of material) produces the required heat and all the female has to do is dig a hole in the mound and deposit her egg and leave it there. The male’s job in life is to build a compost heap that will attract as many females as possible. He requires any female that wants to lay her eggs in his compost heap to mate with him and a really successful male will mate with up to twelve different females over a period of time. Once laid, the eggs of megapodes are abandoned by the females and the male, maintaining the mound, has nothing further to do with the eggs.
The eggs are very large. They have among the largest yolk content of any bird species and that is because the chicks that are going to hatch are so well developed, so advanced at the time that they hatch. In fact, we make the claim that megapodes, exemplified by Brush Turkeys, are the most precocial of all chicks of any bird. No other bird, at the time of hatching, has fully developed flight feathers. The rest of their bodies are still covered in down, but they have fully developed flight feathers, so that they can fly on their first day of hatching. Every Brush Turkey will spend its first night sitting in a tree somewhere having flown there. No other species is that advanced, so we call this species superprecocial.
The chicks hatch about a metre below the surface and the first thing they have to do is dig their way to the surface. It’s absolutely remarkable. Other birds might be hatched in a warm, feather-lined nest with attentive parents waiting to help them through life. A baby Brush Turkey hatches at the bottom of a pile of sticks and dirt and leaves, has to dig its way to the surface and should it get to the surface (98% of them succeed), and if it met one of its parents, the parent wouldn’t even recognise it. The chick then runs off alone into the rainforest, where it has to fend for itself, find food, evade predators, find a place to roost for the night. Everything alone. Scrub turkeys are the only vertebrate with no parental care of any sort. Truly remarkable. And so we have been studying these birds now for a very long period of time, looking at as many of these aspects as we can and it all started on Tamborine Mountain.
You will find an image of a Scrub Turkey here
Peter Kuttner interviewed Darryl Jones on 3 July 2008, after the completion of ’Archive Part Six – The Interviews’.