The autumn 2013 platypus surveys marked the end of the fifth consecutive year of platypus monitoring conducted by cesar.
Since 2007, cesar have collaborated with Melbourne Water to undertake the Melbourne Water Urban Platypus Program, which monitors platypus populations in the greater Melbourne region.
Results of monitoring over the past five years have been mixed with the prolonged drought thought to have greatly impacted upon platypus populations and contributed to significant population declines.
After initial signs of recovery at the end of the drought, severe flooding in early 2011 was believed to have hampered post-drought recovery of platypus populations.
2012/13 platypus surveys have provided encouraging results
Encouragingly, overall results from 2012/13 surveys were the highest recorded since cesar established the core monitoring program in 2007.
It now appears that population declines observed at many locations around Melbourne have halted and in some instances populations are starting to increase.
The return of platypuses to areas where they had been absent for many years is also an encouraging sign of population recovery.
Despite this, some locations continue to decline and monitoring of these populations is essential to determine population health and the factors contributing to continued decline.
What about juvenile platypuses?
A total of 21 juvenile platypuses (50% of total captures) were captured during autumn 2013 surveys, the highest proportion of juvenile platypuses captured in the past five years (comparisons before 2007 are not possible due to differences in survey locations).
The high number of juveniles is an encouraging sign that successful breeding is taking place throughout many of Melbourne’s waterways.
It is not known what factors contribute to successful breeding conditions for platypuses around Melbourne however the return of reliable water flows are likely to have positively affected breeding.
Juvenile platypuses in Victoria emerge from the maternal burrow and become independent between February and May.
Many research questions remain surrounding recruitment of juvenile platypuses into populations including dispersal (where do they go to?) and survival.
Injured and dead platypuses increasing
Unfortunately, coinciding with the increase in population abundance we are seeing higher occurrence of platypuses found entangled and killed in litter and illegal fishing practices.
It is important to become aware that platypuses inhabit our local creeks and rivers and to raise awareness of the threats of litter and illegal fishing to platypuses and other aquatic organisms.
The next few years will be a crucial period of recovery of Melbourne’s platypuses and all of us need to ensure waterways remain healthy environments.