Until late November 2018, we thought our flying foxes in far north Queensland would be spared the disaster of a heat stress event because the high humidity levels tend to keep temperatures down. We had not allowed for climate change and were unprepared for the scale of the event. About 23,000 Spectacled flying foxes died, estimated to be up to 30% of their population and the second largest die-off of flying foxes ever recorded in Australia. Read about it here from the ABC website, and on our website.
Heat stress has been increasingly affecting southern colonies for the last two decades, the largest killing over 45,000 in south east Queensland in 2014. A lot of work has been done developing protocols for government and carer groups to monitor and respond to such an event. Flying-fox heat event management guidelines 2018. Flying-foxes show a predictable sequence of thermoregulatory behaviours with rising temperatures (clockwise: wing fanning, clustering, salivating, panting). Beyond 42º C, thermoregulatory mechanisms become overwhelmed and this is soon followed by death – go to the Animal Ecology Lab to read more about this.
(Right) There are about 70 flying foxes in this photo. Multiply this number by over 10 to 750 and that is the record number of orphans we released in early 2019, 500 from heat stress and 250 from tick paralysis.