With UQ Professor of Zoology, Craig Franklin, at the helm of the UQ scientific research team, the collaborative annual croc research trip with the Irwin family and Australia Zoo is going from strength to strength.
The team continues Steve Irwin’s work to uncover the mysterious lives of crocodiles. This work has been greatly assisted through the use of GPS satellite tracking technology, time depth recorders and temperature recorders. Much of the information recorded has been merged with existing information from various sources to produce incredible insights into the lives of these secretive creatures.
Acoustic telemetry is used to track the estuarine crocodiles (commonly known as “salties”) in the Wenlock River. Once captured, an acoustic tag is surgically implanted in the crocodile’s armpit. These acoustic tags send a signal to an array of more than 60 hydrophone receiving stations positioned throughout the Wenlock River and some surrounding water bodies. These acoustic signals are logged by the hydrophones and, when analysed, enable us to discover how the crocodiles are using the river and interacting with each other.
To date, the acoustic tag project is tracking over 190 estuarine crocodiles, providing critical data and contributing to the knowledge base of these incredible apex predators.
Another exciting part of our research on the Steve Irwin Wildlife Reserve is isotopic analysis. Isotopic analysis identifies markers in bloods/muscle/bone to give us an insight into what makes up the natural diet of the estuarine crocodile and highlighting their important role within their natural environment.
This is just the tip of the iceberg for us as there are many questions that remain unanswered. This vital research has provided insights into the travel range of a single crocodile, their ability to return to their habitat after relocation, revolutionary findings on their ability to remain submerged and their behaviour during flood events. All this information is critical in learning how to successfully manage our wild crocodile populations and, most importantly, keep people safe.
Each research trip to the Steve Irwin Wildlife Reserve continues to break new ground in crocodile research globally and is central to managing the co-existence of crocodiles and people.
Educating local communities
Each year, the Irwin family take what has become almost a pilgrimage up to the Steve Irwin Wildlife Reserve and, as part of their conservation work there, they venture into local schools in Weipa area to conduct talks with the children, to educate them on how to safely live alongside crocodiles. It is the Irwin family and Australia Zoo’s belief that individual culling and relocation are not effective ways to manage crocodile/human co-existence; rather, research and educating people are the key.
At the end of the 2019 crocodile research trip, the study has 191 crocodiles being tracked in the Wenlock River and over 10 million data recordings have been collected.
From the data collected since 2008, scientists have made the following discoveries:
- Identified crocodile movement patterns between ‘wet’ and ‘dry’ seasons – for some animals showing routine movements each season
- Isotopic analysis is identifying the specific animal species crocs are feeding on
- Dive duration data has identified dive times of up to seven hours
- Movement data analysis of large males has shown distinct territorial zones along the river
- Crocodiles will utilise tidal currents to facilitate travel within the river system
- Crocodile travel distances can extend to up to 60 kilometres per day
- Relocated crocodiles can navigate their way back to their original river system
- Successfully used GPS tracking data to identify female nest location and collect egg shells for genetic sampling
- Measurements of recaptured crocodiles now provide data for further analysis of growth rates
Research topics to be incorporated into our next crocodile research trip include investigation into the social contact between crocodiles, utilising hydrophones to record crocodile vocalisations and further identification of nesting sites to investigate tracking of juvenile crocodiles.
Additional Crocodile Research by Professor Craig Franklin:
- Remote Monitoring of Crocodilians
- Home Range Utilisation and Long Range Movement of Estuarine Crocodiles during the Breeding and Nesting Season.
Other Research on the Steve Irwin Wildlife Reserve
We also aim to continue our research with other predatory species living in the river, which involves deploying acoustic tags in animals such as bull sharks, whip-tail rays, golden catfish, spear-tooth sharks and barramundi. We aim to eventually track over 230 animals in the river, and this will allow us to monitor them for the next 7-10 years.
We are honoured to be working with GRIDD, a drug discovery research centre at Griffith University, who have been collecting plants from the Reserve since 2014 as part of an ongoing study for life-saving medical research. Initial studies have proven some positive indications toward extracted compounds that may be useful in a treatment for Parkinson’s disease.