Volunteer medley: stories of our team’s work within the Ark and across Aotearoa

Wintertime bat-logging at Ark reveals a surprise.

Although they have not been seen, pekapeka tou roa (or long-tailed bats) have most definitely been heard this winter in the Ark in audio-recordings of their calls.  Long-time volunteer and resident bat-man Grant Capill explains, “while helping out with bat monitoring, the question was asked about bats’ winter activities: are they active or do they hibernate?” Curious, Grant set out to answer this question with the help of bat recording devices supplied by Auckland Council and Community Waitākere.

Winter hibernation in pekapeka tou roa is not a continuous period of sleep as it is in other animals, but rather alternating periods of torpor and activity to conserve energy over the cold winter months. Because pekapeka tou roa use high-frequency calls to echo-locate at night, recorders which pick up these signals can be used to ‘eavesdrop’ on the bats as they emerge after dusk, giving an idea of their winter activity.

In the Ark, pekapeka tou roa are particularly fond of roosting in cavities high within kauri trees, and so Cascade Kauri Park seemed like the natural choice of location for the study. Grant chose to position the loggers above Cascade Stream, knowing that pekapeka tou roa might capitalise on the clear space above the stream as a ‘highway’ for flight.

What was discovered was surprising. Bat loggers record a file every time bats move in and out of range, and over most of the nights in June that the loggers were deployed, only between 0-40 files were recorded. But over the two nights of June 26th and 27th, the bat loggers went crazy recording a whopping 1421 files in a single night! After that the loggers, and presumably pekapeka tou roa activity, returned to normal.

Experts in the bat-monitoring community were baffled. Apparently nobody had encountered such activity before. Initially thought to be a technical glitch, but the files were recorded consistently over the three loggers, suggesting that they were working properly. So what can possibly have happened? Could the pekapeka tou roa have been roused from their torpor by a spell of warm weather? Or could the bats (which can move roost regularly) have shifted to new roost trees right by the loggers? While the finding invites speculation, the answer remains a mystery for now. We think this demands further replication of the study to solve the mystery, and reveal the wintertime secrets of pekapeka tou roa at the Ark.

Michael Fox.

Michael joined the Ark as a trapper this winter.  He’s beginning his PhD project on the ōi or grey-faced petrels (Pterodroma macroptera gouldi) nesting on coastal headlands of the Waitākere Ranges. Michael says “these birds are interesting because they are one of the only burrowing seabird species to still breed on the mainland. They are susceptible to predation from introduced mammals, so my project will explore how different levels and types of these pests can affect breeding success”. The idea is that this information can help community trapping groups target their petrel protection efforts. As well, traditional Māori narratives, historic records, and archaeological evidence will be used to reconstruct former ranges of ōi and other seabirds, to see where future restoration could be headed. Because predator control has been credited in the success of ōi on the mainland, it’s hoped that as it continues in future the birds will naturally recolonise further reaches of their former range.

Christine Mansford.

A familiar face around Ark, Christine will be exploring tākoketai (black petrel – Procellaria parkinsoni) conservation and pig management on Aotea Great Barrier Island for her MSc. Christine says “wild pigs are a valued part of the culture and economy on Aotea, and so to be effective at protecting petrels, pig management also needs to be socially acceptable.  I’ll be interviewing hunters and their whānau to find out what options for managing pigs around petrel colonies they are supportive of”. The project will also gather camera trap data to understand how and when pigs are interacting with petrels, to further inform targeted strategies for petrel protection.

“I’m excited about trialing some pig deterrents (scent, sight and sound cues), as these hold promise as methods for protecting petrels which do not conflict with pig hunter values”, says Christine. “Hopefully this allows us to identify conservation options that are accepted by locals, and likely to be effective at protecting tākoketai long-term. This offers hope for seabird conservation on an island where pig eradication is currently not socially feasible”.