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.
Spotlight on seabird scientists at Ark.
Despite the main focus of Ark being terrestrial birds, the avian interests of Ark volunteers and staff are quite diverse. A number of the Ark team are involved in protecting wetland species pāteke (brown teal), matuku (bittern) and puweto (crake) with our close neighbours Matuku Link, in Te Henga. Other volunteers and staff have a particular interest in petrels (Pterodroma spp.) – seabirds endemic to Auckland’s West Coast and islands in the Hauraki Gulf – and which form the focus of their postgraduate studies supervised by Professor James Russell, at the University of Auckland. Here, we introduce these two ‘petrelheads’ and their projects:
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.
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”.
Ark volunteer develops models which prioritise pest eradications.
Volunteer and PhD student Zachary Carter has taken a maths-based approach to conservation, in his work developing models that help prioritise pest control. These models, based on statistics and machine-learning, take data on the factors which affect eradication success and utilise it to produce predictions about eradication outcomes in future. Zach says “this can help prioritise management actions for invasive species. By identifying where pest control should be conducted, and what tools should be used, Predator Free 2050 may be achieved in a timely manner”.
“New Zealand has a uniquely rich biological heritage that can be found nowhere else in the world and it is my hope that my research provides conservation decision makers with solutions to preserve that biological heritage indefinitely”.
The Auckland University Tramping Club, and a winning photographer.
During the first weekend of August we welcomed 15 mostly new volunteers to the Ark from the Auckland University Tramping Club (AUTC). Their team has permanently adopted one block on the far side of the Ark, and their leaders organise a team of students to bait this entire block every baiting round. One volunteer new to the Ark, Frank, has since signed up as a regular Ark volunteer and was inspired to go one step further!
After submitting some amazing photos to AUTCs photography competition and winning multiple categories, he chose to donate all of the prize money to Forest & Bird and become a member in the process! After sharing the news of his generosity with the Ark team, he also agreed to share how he found his first day at the Ark:
“I began my PhD in Auckland against a backdrop of sporadic coronavirus scares, and consequently have led quite a sedentary life. As such, I feel grateful to have joined Auckland University Tramping Club (AUTC) a few weeks ago.
Volunteering at the Ark was actually my first time out with AUTC, and I enjoyed my time there thoroughly. The scenery out west was memorable, the interpersonal atmosphere was welcoming and supportive, (the soup lunch was DELICIOUS), and I do believe I got to contribute to some cool, long-term, work. I do hope that I will come often and make the Waitākere Ranges a familiar place to me one day.
As a physics student and an amateur travelling photographer, I deeply appreciate the new opportunities to connect with nature that the Ark (and AUTC in general) provides. I think late astronomer Carl Sagan’s words describe my motivation quite well. In a remark of a picture of planet earth taken from far, far away (aka. the “Pale Blue Dot”), he wrote “the distant image of our tiny world … underscores our responsibility to deal more kindly with one another, and to preserve and cherish the pale blue dot, the only home we’ve ever known.” My photography portfolio can be found at fwphys.com/lux.“