By day Mr Tonga is an East Fremantle building maintenance and pest control operator.
But his personal passion for the past decade has been to save the microbat species by building special bat boxes.
Calling on his carpentry skills, Mr Tonga builds boxes for bats and possums funded by grants obtained by environmental groups or local governments.
Each box is wedge-shaped and made of thick plywood with a metal roof designed to last at least 13 years.
Inside, the bat pads are furnished with galvanised mesh.
A reflective strip, visible even in daylight, allows the presence of bats to be monitored as their silhouette shows against the strip.
‘It’s my contribution to the environment,’ Mr Tonga said.
‘They are a species that are becoming rarer and normally require hollows, which are being removed by development.
‘We put 30 boxes in Bibra Lake and are starting to see an increase there.’
In 2012, Mr Tonga installed five bat boxes, which can each fit as many as 50 microbats, at Adachi and Hardey parks using a $1000 donation from the Rotary Club of Welshpool to encourage the breeding of the white-striped freetail bat known to be in the Rivervale foreshore area.
Microbats eat insects, consuming about 1000 mosquitoes a night.
Some are just 4cm, and weigh just five grams, although most weigh about 30g.