Bat Staging Caves, Central Queensland
ANDYSEZ Number 15 (Journal 19, June 1995 pp 34-35)
Di Vavryn responded to some remarks of mine in the last newsletter regarding the movements of the Eastern or Large Bent-wing Bat, Miniopterus schreibersii, to their summer maternity sites from the so-called staging caves. I am grateful for her interest and have asked her that she allow me to use her note as an ANDYSEZ to which she has graciously agreed.
I heartily endorse her remarks about recording and publishing observations of natural phenomena. Speleology is still an area where amateurs are able to contribute an enormous amount - the term 'amateur' should have no derogatory meaning.
We hear a lot about the need for monitoring environmental variables to ensure that we understand what we are doing to our caves. Often it is not necessary to spend enormous amounts of money. Simple observations using cheap devices are often as useful as measurements using one or two high tech pieces of whiz-bang black box. It is important that if things such as water levels or drip rates are monitored that it be done systematically, preferably routinely, are relateable to rainfall or whatever and that things are recorded consistently and are accessible.
You can't start too soon either. I recall being asked perhaps ten or twelve years ago about a problem at one of our show cave operations. Part of the advice I gave was to install some very inexpensive devices that could be noted by guides on their tours (and perhaps used as part of the interpretive experience). This never eventuated and the same questions are being asked again. We could have had data on which to base hypotheses about what was happening. We don't so we are still guessing. I am not suggesting either, that we all turn our caves into physics labs and produce more work for ourselves.
Note that I have followed modern practice and refer to Miniopterus schreibersii as the Eastern or Large Bent-wing Bat rather than as the Common.
Bat Staging Caves, Central Queensland
Dianne Vavryn
I read with great interest Andy's comments in ACKMA Journal No. 18 regarding the mass transport of sizeable numbers of newly born young from so-called staging caves to the maternity sites. I did not realise that the literature indicated that this was an unusual event. I do not know what the situation is in New South Wales or the species of bat mentioned. Here in Central Queensland the occurrence of Little Bent-wing Bats, Miniopterus australis, being born in such caves is well known to some people. I can see the wisdom now in recording and publishing such observances, something Dr. Les Hall has for many years been encouraging us amateurs to do. You never know how vital that information might be to those trying to make sound decisions in managing our native wildlife. There is a lot of information around in people's minds that has never been recorded.
Just to add a little more confusion in this area the caves spoken of by Andy are known as 'assembly caves' or to some as 'acclimatising caves'. Those that are known to me are Flogged Horse at Cammoo, the Deep Vault at Olsen's and Dragons Head on Limestone Ridge, and no doubt there would be others in the area. The sections of these caves used by the bats before the maternity season are humid and warm up due to the heat generated by the bats, with some of the heat dispersing during the night while the bats are out feeding.
Baby bats are known to have been born in Flogged Horse many times. One such incident was recorded by Dr Peter Dwyer (Dwyer 1969). One of the previous owners of Cammoo Caves was very excited to find a lot of baby bats in their cave and recorded this in an article in the Morning Bulletin, the local paper. At first they thought that Bat Cleft was not as important as was being stated and they had another maternity cave on their property.
The following day there were no baby bats there as they had all shifted to Bat Cleft, as was, the norm. When this article first appeared I was told by Jeff Simmons there was no need for concern, as this was not unusual and the baby bats would be seen carried by their mothers into the maternity cave. At this time Jeff was the Conservation Secretary of the Central Queensland Speleological Society - a position he held for many years. Jeff also lead tours to Bat Cleft, from 1974, for fifteen consecutive years. Those doing these tours at that time did so at their own expense. A guide who once worked at Cammoo mentioned to me seeing baby bats in this cave in the late 1980s. Baby bats are known to me to have been born in Olsen's Cave also. On 26th November 1991, about a thousand bats moved from the Deep Vault (acclimatising cave) after heavy rain into the Harp Cave, (not a acclimatising cave) and were there for a couple of days before moving. Thinking they had all vacated that area of the cave I went in on tour. Three or four bats flew off and on the ceiling were three hairless young, all of which later died. Had I known they were there I would not have switched on the lights and entered. A lot of baby bats were noted in the Deep Vault late November 1993 - there one day and gone the next.
Speaking from a human perspective, and with three times experience, when a baby is ready to be born there is no stopping its arrival. There are many hours between dawn and dusk and many baby bats will be ready to be born during these hours in the acclimatising caves. These caves are obviously warm enough during the day. When dusk again comes the mothers can carry their young to the maternity cave where many others have already given birth and warmed it up sufficiently. It is my belief the acclimatising caves do not retain heat for long enough after the adults emerge to be suitable to leave the young for any length of time unless the mothers remain with the young giving them the benefit of their body warmth. Of course I have not proved this. In late November 1988 I took a lady up to Bat Cleft to view the emergence. While we were there we witnessed many bats flying into Bat Cleft at dusk, we waited till well after dark and no bats emerged.
I feel that the birth of some young in acclimatising caves is a very normal activity and happens as part of the natural cycle, each year. Both Joe and I have for some years felt that these caves need to be identified and some protection given the bats at that crucial time of year. In particular the caves on the National Park where many people from different walks of life go caving. They could be totally unaware of the damage they could cause to the newly born bats by entering those caves at that time, and others would not care.
I can also understand the dilemma for the management body in looking after the needs of all the cave users, fauna and humans alike, from what I have witnessed locally. Johannsen's Cave is closed to the public for eight months of the year to protect a vulnerable species: the Ghost Bat, Macroderma gigas. It is twelve years now since the cave was first gated. I don't think there has been one year yet when the gate has not been vandalised. On one occasion I am told that the hinges were blown off from within. After so long the resentment held by some over the gate still remains.
It has long been established that it is important to protect bats in their wintering caves, in particular when in hibernation. I have noticed that the Little Bent-wing and Eastern or Large Bent-wing Bats can also be found in torpor during the summer months, in periods of heavy rainfall. From December 27th 1990 to the 5th January 1991, 925.5 mm of rain was recorded in The Caves District. The floor of the Belfrey Cave at Olsen's, a large multiple entranced cavern, was covered in pools of water several inches deep with water pouring in, in numerous areas. During this period of heavy rain the ceiling very close to the large entrance was covered in very large clusters of both Little Bent-wing bats and Eastern Bent-wing Bats in a state of torpor. I can't say the exact time the bats remained there in that state but it was for many days. A number of dead bats were noted in the water under the roost. On the 5th January 1991 at 5.00 p.m. during a break in the weather bats were out feeding, presumably from this cave, in broad daylight. I believe this behaviour was a sign of starvation, and perhaps it is also an important time for the protection of our furry friends. At Olsen's Capricorn Caverns tours cease going to some sections of the cave when bats are in residence, so as not to disturb them.