Although the habitat preferences of this species are incompletely known, it is presumed to have similar requirements to Mystacina tuberculata in that it was a forest species that was largely restricted to undisturbed old-growth forest. Remains of this species in limestone caves suggest that it commonly roosted in caves, and it is possible that the species also roosted in tree cavities, although there is no direct evidence for this (Lloyd 2001). The last remaining bats sighted on the southern Titi islands were seen in coastal sea caves (Bell et al. 2016).

This species is endemic to New Zealand. There have been no confirmed sightings of the species since 1967 when it was last found on Big South Cape Island (near Stewart Island). It might still persist on Big South Cape Island, the neighbouring Putauhinu Island, or on other small privately-owned islands near Stewart Island.

Formerly, it was known from widespread subfossil remains on both North Island and South Island (Worthy and Scofield 2004). It may have declined at mainland sites following introduction of Pacific Rats (Rattus exulans, kiore) by Māori. By the time of European arrival, ca 200 years ago, the species was probably already restricted to small islands off the coast of Stewart Island.

Ship rats have been eradicated from both Big South Cape (where the species was last seen) and neighbouring Putauhina Island. Following these eradications, there have been several reports of bat sightings from Putauhina, and in 1999. Colin O'Donnell recorded Mystacina-like echolocation calls from the island that do not belong to M. tuberculata (O'Donnell 1999). There have since been additional unconfirmed reports of bats being seen on Big South Cape. Surveys in 2009 on Big South Cape and on Putauhina in 2017 also failed to capture or record any bats (C. O’Donnell, M. Pryde pers. comm.). The identity of the bats being seen still must be confirmed, and although M. tuberculata is thought to have once inhabited these islands, the nearest populations of it or the only other New Zealand bat species (Chalinolobus tuberculatus) are more than 50 km away. For this reason, there is a real possibility that M. robusta still survives in low numbers (C. O'Donnell pers. comm.).

Rats continue to be eradicated from all islands in this group, and more surveys for M. robusta are planned (C. O'Donnell pers. comm.).