Birds Incubate Eggs With Heat From Compost

brown white and black fowl bird stands on top of pike of sticks against a natural forest background

Biological Strategy

Mallee fowl

AskNature Team

Image: Donald Hobern / Flickr / CC BY - Creative Commons Attribution alone

Regulate Reproduction or Growth

Reproduction and growth are two physiological processes that occur in all living systems. There are situations when conditions are right for both, and other situations when continuing either harms the living system because both have a very high energy cost. Reproduction and growth are unique in that both can stop until conditions improve, although stopping either for an extended time can cause problems. An example of regulating reproduction is a process called delayed implantation or embryonic diapause found in some mammals, such as otters. An otter’s embryos sometimes temporarily cease developing and won’t develop further until the female senses that conditions are suitable.

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Protect From Temperature

Many living systems function best within specific temperature ranges. Temperatures higher or lower than that range can negatively impact a living system’s physiological or chemical processes, and damage its exterior or interior. Living systems must manage high or low temperatures using minimal energy, which often requires controlling responses along incremental temperature changes. To do so, living systems use a variety of strategies, such as avoiding high or low temperatures, removing excess heat, and holding heat in. Insulation is a well-known example of managing low temperatures by retaining heat using thick layers of hair, fur, or feathers to hold warm air next to the skin.

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Transform Thermal Energy

Heat is necessary for survival, but too much of it can be damaging to an organism. Explore the ways different living things have adapted to use or transform different types of thermal energy.

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Birds

Class Aves (“bird”): Eagles, hawks, sparrows, parrots

Birds are evolutionary engineering marvels. They are descended from dinosaurs, but are far from our idea of heavy, scaly reptiles. Of the specific adaptions that set them apart, most notable is flight—although some mammals can fly, birds take the prize for abundance in the skies. Many birds have hollow, lightweight skeletons and specially-designed wings to help them stay aloft. They also have feathers made of keratin that help them stay warm, attract mates, and improve navigation and aerodynamics in flight. In contrast to their dinosaur ancestors, they lack true teeth and have replaced them with specialized beaks and bills.

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The nests of mallee fowl provide warmth for eggs by use of rotting vegetation and insulating layers of soil.

Introduction

The mallee-fowl, Leipoa ocellata Gould, is an intriguing bird native to the arid and semi-arid regions of southern Australia. It has adapted to its harsh environment through an extraordinary nesting behavior. Instead of incubating its eggs through body heat, the mallee-fowl constructs large nesting mounds, utilizing the heat generated by fermenting plant material mixed with soil. These mounds are carefully engineered to maintain optimal temperature conditions for egg incubation, demonstrating a remarkable natural strategy for temperature regulation.

Image: Glen Fergus / CC BY SA - Creative Commons Attribution + ShareAlike

A mallee fowl nest mound rises above ground level in Coorong, South Australia.

The Strategy

Mallee-fowl mounds are not merely piles of earth and leaves but are sophisticated structures designed to leverage the natural process of fermentation for heat production. The birds start by digging a large pit, which they fill with plant material—mainly leaves and twigs. This organic matter begins to ferment, producing heat, which is crucial for warming the eggs buried within the mound.

The true ingenuity of the mallee-fowl lies in its ability to regulate the temperature of the mound meticulously. By adding or removing layers of soil, the mallee-fowl ensures that the temperature within the mound stays within the narrow range suitable for egg development. This process of adjustment is almost daily, with the birds frequently checking and modifying the insulation of their nests.

As the season progresses and external temperatures rise, the mallee-fowl’s task shifts from primarily generating to dissipating heat. The birds cleverly open parts of the mound to allow excess heat to escape and close it up to conserve heat during cooler periods. This active management helps in maintaining a stable thermal environment, essential for the successful development of the eggs.

The Potential

The temperature regulation strategy of the mallee-fowl could inspire innovative approaches to sustainable building practices. For instance, the concept of using bio-based materials for heat production through composting could be applied to eco-friendly housing. These homes could utilize compost heat recovery systems to naturally warm living spaces in colder months, reducing reliance on fossil fuels.

Additionally, the mallee-fowl’s method of adjusting insulation could inform the development of dynamic insulation materials for buildings. These materials would automatically adjust their thermal resistance in response to changes in external temperatures, improving energy efficiency.

In agriculture, similar strategies could enhance passive solar greenhouses, using fermenting organic matter not only to enrich the soil but also to regulate temperatures, extending the growing season in colder climates without additional energy costs.

By studying the mallee-fowl’s natural engineering skills, we can develop systems that are both energy-efficient and environmentally friendly, reflecting the bird’s seamless integration into its habitat.

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Last Updated April 24, 2024

References

Journal article

Temperature regulation in the nesting mounds of the mallee-fowl, Leipoa ocellata Gould

CSIRO Wildlife Research | 1956 | HJ Frith

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Reference

“One family of birds has, in the most ingenious way, managed to avoid the hazardous duty of sitting on its eggs throughout the incubation period. The mallee fowl of eastern Australia lays its eggs in a large mound built by the male. The core is composed of rotting vegetation and the whole is covered with sand. The breeding season is a very long one, spread over five months, and during all this time, the male has to remain in constant attendance probing the mound with his bill to test the temperature. In spring the newly gathered vegetation at the centre is decaying rapidly and producing so much heat that the mound may get too warm for the eggs within it, in which case he industriously removes sand from the top to allow heat to escape. In summer, there is a different danger: the sun may strike the mound and over-heat it. Now he must pile more sand on top as a shield. In autumn, when the decaying core has lost much of its strength, he removes the top layers to allow the sun to warm the centre where the eggs are and then covers it in the evening to retain the heat.” (Attenborough 1979:196-197)

Book

Life on Earth: A Natural History

01/01/1970 | David Attenborough

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Reference

Book

How Life Learned to Live: Adaptation in Nature

01/01/1983 | Helmut Tributsch

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