The Living Hollow: Mycelium-Based Habitat for Hollow-Dependent Wildlife

Land clearing, bushfires, and logging have drastically reduced Australia's natural tree hollows, pushing gliders into crisis. While traditional nest boxes provide a stopgap, they are limited in replicating the thermal regulation and organic complexity these animals require. A mycelium-based hollow could offer a more ecologically appropriate solution, but no manufacturing precedent existed. Mycelium is typically grown in rigid moulds, incompatible with a hollow where the interior cavity exceeds the entry opening. Long-term outdoor durability of mycelium composites remains largely untested, and its poor tensile strength makes conventional tree-fixing structurally inappropriate. The team faced a challenge simultaneously ecological, biological, and fabrication-driven.

Internal geometry follows glider biology. The 3D-printed wood-composite scaffold serves as both permanent structure and formwork, eliminating demoulding and reducing formwork waste. Mycelium is cultivated directly over the scaffold, fusing with exposed wood fibres to form a layered composite. Modular components are geometrically interlocked and left for mycelium to grow across each join, fusing them into a seamless whole. A critical discovery, that a high-CO2 growing environment drives aerial mycelium spread across exterior surfaces, achieved full exterior colonisation. The result is a physically deployable, tree-mounted mycelium hollow: proof of concept for an entirely new bio-fabrication approach to wildlife habitat design.

The Living Hollow establishes a new bio-fabrication approach to wildlife habitat design with broad conservation implications. Environmentally, it offers a biodegradable, carbon-friendly alternative to synthetic nest boxes, directly addressing hollow shortages for gliders in fire-affected and logged landscapes. Societally, the project advances habitat restoration practice through an interdisciplinary model combining architecture, ecology, and material science, in partnership with WWF-Australia. The manufacturing approach, mycelium grown over a 3D-printed scaffold, is scalable and adaptable beyond gliders to other hollow-dependent species, positioning The Living Hollow as a replicable conservation tool for Australia's hollow-depleted forests.

The Living Hollow integrates several innovations across design, biology, and fabrication.Scaffold as formwork: The 3D-printed wood-composite scaffold eliminates conventional demoulding by remaining permanently embedded. This resolves a fundamental fabrication constraint, that a hollow where the interior cavity exceeds the entry opening cannot be conventionally demoulded, while simultaneously reducing material waste and enabling complex organic geometries.Biological joint fusion: Modular components are geometrically interlocked and biologically sealed as live mycelium colonises across each joint, creating a seamless composite structure without adhesives or mechanical fasteners.Hypercapnic colonisation: Early trials in open greenhouse conditions failed to achieve exterior mycelium growth. A critical discovery established that restricted gas exchange, achieved with sealed polypropylene bags containing microporous filter patches, drives aerial mycelial spread across exterior surfaces, achieving full colonisation without conventional substrate filling.Species-informed design: Internal geometry, entry aperture, tunnel angle, and surface texture are derived directly from glider biology, maximising habitat suitability and grip for arboreal movement.Carbon-friendly lifecycle: The mycelium-wood composite is biodegradable, returning to the soil at the end of life with no synthetic waste.Field deployment: The prototype is ethics-approved under Swinburne University's Animal Ethics Committee and deployed on a living eucalyptus at Birdsland Reserve, Victoria, in partnership with WWF-Australia.