Kakadu National Park rangers win Ranger of the Year Award

From left, park manager Pete Cotsell with Fred Hunter, Joseph May, Timothy Henda, David Brown, Anthony Mann


How many people can honestly say they have worked non-stop on a project for 10 years? 15 years? Even 25 years?

For more than 25 years the Kakadu National Park Integrated Ferals Team has worked hard at keeping our World Heritage Areas free of what Ranger Fred Hunter calls the smartest plant in Australia.

On Thursday night (30 June 2016) they were formally recognised for their unwavering efforts in weed management, winning the NT Ranger Award for Outstanding Environmental Achievement.

We spent 10 minutes with one of the team, Ranger Fred Hunter, to talk about the work behind this recognition.

Kakadu National Park Ranger Fred Hunter is what you could call a natural resource super sleuth. He spends most days in crippling heat or pouring rain playing a game of ‘catch-me-if you-can’ with one of the world’s worst invasive species. It has been ranked as the tenth most problematic weed in Australia and is listed on the Weeds of National Significance.

The winning rangers with the Hon Bess Nungarrayi Price MLA

Mimosa pigra is the smartest plant in Australia,” Mr Hunter said. “It drops its seeds in the wet season, then they get buried when the water level drops in the dry season. Its seeds can stay viable on a floodplain for up to 23 years waiting for a fire to come along and crack them open.”

Brought to Kakadu as a cattle fodder with the introduction of water buffalo, the plant is wildly invasive. Each Mimosa pigra plant has up to 100 flowers. Each flower head produces a cluster of 10 to 20 seedpods, which then mature and break into segments, each containing an oblong shaped seed. The plant takes as little as four months to grow to reproductive age in the right conditions.

“Left unattended Mimosa pigra has the ability to choke wetlands with dense, thorny, impenetrable thickets that threaten Kakadu’s precious wildlife and world heritage biodiversity” Mr Hunter said.

The Integrated Ferals Team has been tackling this weed and maintaining a complete Mimosa pigra database across more than 120 sites in the park since 1983. The database provides evidence of the efforts of the Integrated Ferals Team in largely containing the spread in the park. Thanks to the tenacious efforts of our rangers, no new outbreaks have been recorded in the past four years.

This involves tackling Mimosa pigra using helicopters, quad bikes or airboats across Kakadu’s vast wetlands to access outcrops of the weed.

“While this sounds exciting, it’s dangerous work because we have to hand pull the seed heads in remote wetlands that are home to some of our largest saltwater crocodiles. Not to mention the floodplains are often over 40 degrees with suffocating humidity” Mr Hunter said.

Mr Hunter is concerned that changing climatic conditions and people illegally driving four wheel drives across the park could quickly undo their hard work.

“Tiny hairs on the seeds allow them to float on water and stick to hair or clothing, hence aiding in dispersal. Changes in flooding conditions due to climate change could increase the seed distribution to new areas and seeds stuck to four wheel drives and camping gear transport the seeds into areas we aren’t monitoring” he said.

Visitors to Kakadu National Park can help stop the spread of weeds by thoroughly checking their vehicles for weed seeds before entering the park, and by sticking to designated roads and camping areas.

It’s a good idea for road trippers coming to Kakadu to run their car through a car wash in Darwin or Katherine before heading out to the park.