Updated 

PHOTO: Thousands of spectacled flying foxes dropped dead from trees during a week of record-breaking heat in Cairns. (Supplied: David White)

An extreme heatwave in far north Queensland last month is estimated to have killed more than 23,000 spectacled flying foxes, equating to almost one third of the species in Australia.

The deaths were from colonies in the Cairns area where the mercury soared above 42 degrees Celsius two days in a row, breaking the city’s previous record temperature for November by five degrees.

Ecologist, Dr Justin Welbergen from the Hawkesbury Institute for the Environment (Western Sydney University) is collating the numbers of bat deaths and said it was the second-largest mass die-off of flying foxes recorded in Australia and the first time it had happened to this species.