While the Sydney suburb of Penrith was grabbing headlines on Sunday with temperatures of 47C, it was to the southwest of the city that the extreme heat was taking its greatest toll.

In Campbelltown, which is home to a large colony of flying foxes, the hot weather caused some of the bats - mainly youngsters - to succumb to heat stroke, and more than 200 reportedly died.

The local wildlife rescue group, WIRES, was on hand to rescue those bats found alive. The group rescued and rehydrated 120 bats, reuniting them with their mothers. Another 40 were brought to intensive care.

Young flying foxes are vulnerable to temperatures above 35C, and their parents also suffer once temperatures exceed 40C.

According to veterinary scientist Tania Bishop, the bats seek shade and begin to fan themselves as temperatures rise. Blood vessels in their skin widen to allow heat to radiate out and cool their bodies.

This effect is limited, as fanning tends to increase core body heat due to the energy produced by the pectoral muscles, and eventually this outweighs any cooling from fanning. Volunteers sometimes spray the trees where bat colonies shelter in an effort to keep them cool.

Ongoing problem

As recently as last February, more than 2,000 flying foxes reportedly succumbed to temperatures in excess of 45C in the Richmond Valley area of New South Wales.

Recent studies have shown that such heatwaves are likely to become more frequent in the years ahead.

A 2014 report by Australia's Climate Council stated that heatwaves were becoming stronger, longer and more frequent across the country. The southeast is believed to be at particular risk.

Australia is home to four species of flying fox: black, grey-headed, spectacled and little red. Numbers of the latter two species have fallen by 95 percent over the last century.

Habitat loss, shooting and man-made hazards such as power lines, barbed wire and backyard fruit tree netting all take a toll. The addition of climate change to the list of hazards makes the long-term outlook for these creatures appear bleak.