The Short-Tailed Bats are a funny group, being from the family Mystacinidae, and are endemic to New Zealand. The Greater had a large distribution over the northern climes of the island which is known from sub-fossil bones. It was classified as a sub-species of M. tuberculata until 1962 when it left the other 3 sub-species of M. tuberculata to form its own species. Greaters did the job of small rodents on the island, moving on the floor with all four limbs and only flying when necessary. Lessers are slow flyers, rarely getting above 3 meters above the ground, so it is expected that Greaters, with their larger body size, could only live in the north where the temperatures were high enough to allow them to warm up and fly (all Mystacina bats allow their core body temperature to drop at night, so when they want to become active again they need to become hot). Below is the only photo of the greater short tailed bat.
Now here we have an interesting example of an animal going against Bergmann’s Rule (within a group of closely related animals with a large north-south range, species/sub-species nearer the poles are larger). This rule works for “normal” homeotherms (constant body temperature), but here the advantage of keeping the core temperature high by having a large body to retain heat (lower surface area to volume ratio – better heat conservation) is outweighed by the time it takes for the body to heat up again in the day; thus we have small bats nearer the pole, and larger bats further toward the equator.
I expect you are now thinking “How on earth did this bat keep its wings out of the way whilst it foraged?”. Very good question: both species did so by tucking the wing membranes under a different membrane on their body, leaving the bats to scurry around in and out of burrows and about on the forest floor as eagerly as a mouse. The illustration shown opposite shows the bat as it would probably have stood, with its wing folded out of the way. They were most likely insectivores like M. tuberculata, but this is not known for certain.