Platypus Re-wilding in Royal National Park – Dr Gilad Bino

Community engagement is a significant part of Bino’s work. Platypuses are widely loved, making them a popular focus for education. He has been involved in numerous outreach programs, particularly with school students and community volunteers in the Illawarra region.

Regarding language, the word “platypus” means “flat foot.” The correct plural would be “platypodes” in Latin, but in English, we commonly use “platypuses” (though “platypi” remains a popular misconception).

There are several excellent resources available for further reading, including the book Platypus by Tom Grant and an open journal titled The Platypus: Evolutionary History, Biology, and an Uncertain Future.

Unique Traits of the Platypus

Platypuses are fascinating creatures with many unusual characteristics. They are one of only five egg-laying mammals (monotremes), along with four species of echidna. Their ancestors diverged from other mammals around 200 million years ago, with fossil evidence of platypus-like creatures found in South America.

Interesting Facts:

• Female platypuses dig burrows up to 10 meters from the water’s edge to lay eggs. They line these burrows with nesting material carried across the water using their tails.

• Platypuses have mammary glands but no teats; instead, milk is secreted through the skin.

• They have grinding pads instead of teeth. Hatchlings are born with a single tooth, which helps them break out of the egg before disappearing.

• Both males and females are born with spurs. In females, the spur is tiny (1–2 mm) and disappears, while in males, the spur remains and delivers venom capable of causing severe pain, reportedly lasting up to six months with little relief available. Males mainly use these spurs in fights.

• Their webbed feet aid in swimming, but on land, they walk on their knuckles.

• They have highly sensitive bills that detect electro-mechanical signals in the water. When diving, they close their eyes and ears, relying entirely on their bills to locate prey.

• Humans have one pair of sex chromosomes per cell (XX in females, XY in males), but platypuses have five pairs—an unusual genetic trait.

Lifecycle and Habitat

Platypuses follow a distinct seasonal cycle. Males establish territories in September and may fight rivals for dominance. Females seek out safe nesting areas before mating, engaging in a courtship display where pairs swim in circles. They typically lay one or two eggs from November to January, but they do not breed every year. The young hatch in January, and platypuses have a lifespan of around seven years.

Platypuses have a body temperature of about 32°C. Males are about 50% larger than females, and size varies with climate. The largest specimens (up to 3 kg) are found in Tasmania, whereas those in Queensland average around 1.5 kg. Males can grow up to 60 cm long, while females reach about 50 cm.

Ideal platypus habitat includes:

• Creeks with deep (1–4 meters) and broad water bodies that do not dry out.

• Earthen banks (preferred over rocky banks) for burrow construction.

• Overhanging and intact fringing vegetation, which provides food and shelter.

• Good spatial connectivity between water sources.

Suitable watercourses can support anywhere from 1 to 12 platypuses per kilometer, with an average of 4 per kilometer in prime habitat.

Population and Conservation Efforts

The exact number of wild platypuses is uncertain, with estimates ranging from 30,000 to 300,000. Bino has used drones and environmental DNA (eDNA) sampling to improve population tracking and predict where platypuses might be found.

Threats to Platypuses:

• Historical hunting: Platypus fur was once in high demand, with records of hunters killing over 10 per day.

• Habitat destruction: Land clearing, farming practices, and soil erosion reduce suitable environments.

• Water pollution: Nutrient enrichment from agriculture affects creeks.

• Dam construction: Alters water flow and disrupts breeding grounds.

• Predators: Foxes prey on platypuses during droughts.

In South Australia, platypuses are listed as endangered, while they are considered vulnerable in Victoria. However, they are not yet listed as threatened in other states or under Commonwealth legislation. A national assessment found a 30% decline in occurrences since 2000, yet the scientific committee requested further data before revising their conservation status. Historical records suggest platypuses were once far more abundant, with accounts of dozens being seen in single river stretches in the 1800s.

Rehabilitation and Re-introduction

Some platypuses have been rescued from drought-affected waterways. Taronga Zoo has built a special Platypus Rehabilitation Centre at Dubbo Zoo to care for rescued individuals.

Bino led a reintroduction project in Royal National Park, focusing on the Hacking River and Kangaroo Creek, where platypuses had disappeared possibly due to pollution or toxic spills. In May 2023, his team released 10 platypuses (6 females and 4 males) from different parts of NSW. These were tagged for tracking. In April 2024, a juvenile platypus was recorded—confirmation of successful breeding!

Out of the 10 introduced individuals, 7 were detected, while 3 went off the radar. This could be due to malfunctioning tags, or possibly mortality. More platypuses will be introduced in the future to ensure population success.

Protecting Platypus Habitats

Bino reminds us of the importance of keeping our creeklines clean, vegetated, and free of contaminants. Protecting water quality, maintaining connectivity between waterways, and monitoring urban impacts are crucial to their survival. Community efforts, including eDNA sampling, can help track populations and support conservation.