During an extreme heat-stress event at Melbourne's Yarra Bend Grey-headed Flying-fox (Pteropus poliocephalus) colony, where temperatures exceeded 43°C, in a desperate search for somewhere cooler and less exposed, Grey-headed Flying-fox (Pteropus poliocephalus) descend from the safety of the tree canopy looking for a cooler place. Ironically and sadly, this behaviour results in what experts call 'clumping' - where the number of bats in close proximity means that the animals get even hotter. It is often a precursor to mass deaths. On the ground there were already many dead bats that had succumb to this heat-stress event. Park Ranger and Grey-headed Flying-fox Project Officer Stephen Brend estimated that during this day, over 4,500 Grey-headed Flying-foxes died at the Melbourne Yarra Bend colony as temperatures exceeded 43°C. 56% being infants and a significant part of the next generation. Yarra Bend Golf course, Fairfiele, Victoria, Australia. December 2019.