How Tiny Marsupials Crack the Toughest Sandalwood Seeds

A new study has revealed how two critically endangered bettong species crack the ultra-hard seeds of Santalum (sandalwood) trees. These small marsupials, no larger than rabbits, use specialised jaw techniques to break open shells that would normally resist such force. The findings, published in the Zoological Journal of the Linnean Society, highlight an unusual feeding behaviour that also plays a key role in Australia's ecosystems. Brush-walled bettongs, including the brush-tailed bettong (Bettongia penicillata), have evolved reinforced jaw structures to tackle Santalum seeds. Unlike their usual diet of soft fruits, fungi, and tubers, these seeds demand extreme biting power. The animals grip the seed with their premolars, then repeatedly bite down while rotating it with their forepaws. The Lesueur's bettong (Bettongia lesueur) even has a short snout, which gives it extra leverage for cracking.

Before European settlement in the late 18th century, species like Bettongia lesueur and Bettongia tropica likely helped spread sandalwood by caching and consuming seeds. They would bury or defecate them, aiding plant growth across arid and tropical regions. Today, however, all four living brush-walled bettong species face critical endangerment, with their habitats drastically reduced.

Beyond seed dispersal, these bettongs improve soil health as they forage. Their digging turns over the earth, boosting water retention and nutrient cycling. Researchers stress that understanding their diets is crucial for conservation efforts, including potential reintroduction schemes. The study confirms that brush-walled bettongs perform a unique ecological function by cracking Santalum seeds. Their decline has likely disrupted natural seed dispersal and soil processes in Australian landscapes. Conservation programs may now use these dietary insights to support the recovery of remaining populations.