杏吧原创

A south-east Australian bat that was thought to mainly eat insects also sometimes consumes other bats, according to an analysis of its droppings.

The greater broad-nosed bat (Scoteanax rueppellii) mostly lives along the coast and foothills of New South Wales. It is poorly understood because it is difficult to capture and its echolocation calls overlap with those of other bat species, making it tricky to detect, says at the New South Wales government鈥檚 Department of Primary Industries.

鈥淭hey鈥檙e hard to catch because they mostly fly above the height at which we can set our traps,鈥� he says.

Over a 12-year period, Law and his colleagues managed to catch 12 individuals at several sites in New South Wales using a variety of traps made from thin fishing line or fine mesh. The bats accidentally flew into the traps because they couldn鈥檛 detect them with their echolocation calls.

The bats were kept in capture bags for no more than a day before being released, and any droppings they left inside were analysed in a lab to see what they had eaten. This was done by sequencing DNA in the droppings and studying their contents under a microscope.

The bats appeared to mainly eat beetles, which was consistent with the findings of a 1977 study that . But large amounts of hair that matched that of other bats 鈥� such as the little forest bat (Vespadelus vulturnus) and free-tailed bats (Ozimops spp.) 鈥� were also found in four of the individuals鈥� droppings, suggesting they had preyed on them.

Law had suspected that greater broad-nosed bats sometimes ate other bats after he and others occasionally found them in traps alongside the half-eaten remains of other bats, but the faecal analysis provides the most conclusive evidence yet, he says.

Greater broad-nosed bats are bigger than many other bat species, weighing roughly 25 to 30 grams, and have sharp teeth for crunching insect exoskeletons, meaning they would be equipped to attack smaller bats, says Law.

They may do this when beetles are less abundant or to get a large dose of nutrients like protein or calcium from other bats鈥� flesh and bones, he says.

鈥淏ut there鈥檚 still a lot we don鈥檛 know, including whether they鈥檙e able to catch other bats while they鈥檙e out flying around, or if they get them in the daytime while they鈥檙e roosting in tree hollows,鈥� he says.

Some carnivorous bats like the spectral bat (Vampyrum spectrum) in Central and South America and the ghost bat (惭补肠谤辞诲别谤尘补听驳颈驳补蝉) in northern Australia are known to sometimes eat other bats in addition to their usual prey of birds, frogs, lizards and rodents. However, it is surprising to discover a bat that mostly eats insects snacking on other bats too, says Law.