My Grandad is an old school farmer in Central Hawkes Bay. Although he is quick with a dry joke, he is a man of few words.
However, my Grandad is extremely knowledgeable in the ways of the natural world. He seems to know substantial information on the functionality of New Zealand ecosystems without the blood, sweat and tears of lectures, labs and assignments that I participate in. He often supplies me with stories about his experiences with hunting and farming. One of these was when he was on the chainsaw clearing trees for firewood: just as he was about to cut into a decayed section, out flies a bat.
This incident of his has stuck with me throughout the years as the idea of a native bat residing on my Grandad’s farm made me extremely inquisitive. It opened my eyes on how novel ecosystems, such as a farming community in Central Hawkes Bay, are able to support a habitat for a rare and specialised native bat.
I am unsure what species of bat my Grandad witnessed, but it was very likely to have been the long-tailed bat (Chalinolobus tuberculatus).
New Zealand’s native long-tailed bat is not the scary, dangerous, blood-sucking creature that Dracula has lead us to believe in. Instead, these bats are insectivorous, chestnut brown in colour with tiny ears, are thumb-sized and only weigh 8-11 grams. This creature is an utterly adorable fluffy golf ball. Despite their minuscule size, they can fly at up to 60kmh, range 20km from roosting sites and can emit a call that some people can even hear.
Although there were once one or two other bat species, the long-tailed bat and unrelated short-tailed bat are now New Zealand’s only remaining species of native land mammal.
Long-tailed bats were once common throughout New Zealand in the 1800s with colony sizes often numbering in the hundreds. Their population drastically declined by 1900-1930. Predation and competition by introduced predators or browsers, disturbance of roost sites, habitat loss and degradation have all been factors influencing the bat population reduction.
Since 1990, monitoring suggests that the bat is now rare or absent in many sites in the South Island, where they were once plentiful. The long-tailed bat is considered vulnerable to extinction nationally with their overall population numbers in the hundreds.
How difficult is it to monitor an extremely rare, cryptic, thumb-sized, speedy, nocturnal mammal? Not too difficult for former Lincoln University student Richard Griffiths. He published an article in the New Zealand Journal of Zoology in 2007 called “Activity patterns of long-tailed bats (Chalinolobus tuberculatus) in a rural landscape, South Canterbury, New Zealand“.
Griffiths investigated nightly activity patterns of long-tailed bats and how these patterns vary with seasonal change, habitat and other external factors in Geraldine, South Canterbury. This added to knowledge of the bats’ spatial and temporal activity enabled an understanding of their ecology, and ultimately their conservation.
I was specifically interested in how the bat exploited different South Canterbury environment habitat types. This would enable targeted resource protection measures and inspire further research.
Griffith used a variety of methods for monitoring to ensure that the different factors affecting the bats nightly patterns were assessed. The monitoring was performed between over 68 consecutive nights in the mid 90s.
Bat activity was monitored using automatic monitors placed in each of the four represented habitat types in the study site; limestone escarpment, open water, willow or other riparian vegetation and regenerating shrub-land in farmland. These automatic monitors received ultrasonic echolocation calls of bats within the area supplying an index of the areas bat activity.
Radio transmitters were also attached to five bats and sex, reproductive status, age, weight and ear, wing and tail measurements recorded. The radio-telemetry monitoring determined the nightly activity pattern of individual bats. Moon phase, cloud cover, wind and rain scales, and time and temperature of sunset and sunrise were also measured.
Griffith discovered that the peaks of bat nocturnal activities were in the second hour after sunset and a few hours before sunrise. This bimodal activity during the warmer months changed to a single peak after sunrise in activity from April onwards.
What I was most curious about was the long-tailed bats preferred habitat type. All of the five radio transmitted bats fed often in the willow or other riparian vegetation and occasionally the shrub-land habitat type, and all avoided open farmland. Wetland areas appeared more valuable foraging areas for insectivorous bats as they harbour high insect densities. These tagged bats were a good representation of the habitat preference for the wider colony population.
The article explained how the temperature influenced the insect activity and duration of activity, insect number and diversity of species. This was illustrated through the decreased activity of the tagged bats throughout the seasonal change from January to June. Bat activity responded to the insect activity, which was in turn determined by the temperature – warm temperatures leads to more insects and more bat activity. So maybe global warming isn’t so bad if it could be beneficial for some species!
Habitat loss and degradation are huge threats for our long-tailed bat due to their tiny size profile and expensive foraging strategy. Removing or manipulating supportive foraging sites for bats and insects decreases survival opportunities.
Although South Canterbury and Central Hawkes Bay are extremely different environments, both have a history of the transformation of ecosystems, yet they both contain supportive elements for bats. Conserving the long-tailed bat in these farming communities is possible and very beneficial for other indigenous species. The long-tailed bat is an umbrella species that indirectly supports many other species that make up the ecological community.
Conservation can be achieved by providing preserved areas that consist of fenced off wetland areas with riparian vegetation. Fencing will keep out disturbing factors such as humans and livestock . Fencing, and developing vegetations may become a barrier for insects and bats so it is suggested that these fences contain minimum wiring and at a distance from riparian vegetation to decrease contact occurrence. This strategy will allow undisturbed foraging, roosting sites and supported habitats for dependent insects and overall will drastically impact the conservation of our long-tailed bat.
This article has impacted numerous subsequent research for conservation management by supplying monitoring methods, habitat selection and colony reduction theories within New Zealand. Griffith’s research gives an insight about how these species actually are vulenable and also allows movement for better conservation strategies for influential people like my Grandad – who isn’t batty.
My Grandad witnessed the bat in a riparian plantation area of willows and has since increased the native vegetation in this area to cater for the bats and other species within the community.
Ruby Macgillivray is an undergraduate student completing a Bachelor of Science with a double major in Conservation and Ecology & Environmental Science. He wrote this article as part of his assessment for ECOL 608 Research Methods in Ecology.