Weather and demographics affect Dactylanthus flower visitation by New Zealand lesser short-tailed bats

Dactylanthus taylorii is thought to be the only ground-flowering plant to be pollinated by a bat; the New Zealand lesser short-tailed bat (Mystacina tuberculata). This unique mutualistic relationship is poorly understood despite both species being threatened. We placed dataloggers around distinct clumps of D. taylorii inflorescences to monitor bats with implanted passive integrated transponders (PIT-tags) and quantify visitation rates and demography during the late-summer flowering season. Adult males and juveniles visited flowers more frequently than adult females. Adult males may have visited flowers to feed on nectar and offset the energy demands of advertising, lek defence and mating, and/or reduced foraging time during summer. Juvenile bats may be under increased energetic burdens due to naïve foraging behaviour and use nectar to augment low energy reserves. The frequency of visits correlated positively with mean night ambient temperature, likely because of increased prey, and therefore, bat activity. Our study is the first to examine the demographics of M. tuberculata visiting D. taylorii and serves as a baseline for future studies considering these unique and vulnerable New Zealand species.