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Studies on the Two New Zealand Bats

Habitat and Gregarity

Habitat and Gregarity

The number of bats flighting together varies considerably. Table III is prepared from 132 sightings. Nearly all the larger flights have been noted above water. Pairs of bats and solitary bats are frequently seen hunting along the forest margin.

Stead (1937) records the discovery of a small colony of Mystacina. The seven bats, including both males and females, were packed closely together. In
Table III.—Number of Bats Flighting Together.
No. of Bats Seen No. of Records No. of Bats Seen No. of Records
1 38 7-12 5
2 24 About 14 1
2 or 3 2 20-30 3
3 7 Above 30 3
3 or 4 3 A few or several 22
4 1 Numerous 2
4or 5 2 Large numbers 4
5 2 Dozens 1
5 or 6 2 Scores 2
6 6 Hundreds 1
6 or 7 5
page 25the Stewart Island region he found accumulations of droppings, amounting to several bushels, in caves and hollow trees. Solitary specimens of Mystacina have been taken from beneath tree bark and, in one recent instance, a bat was present between the folds of a sack hanging from a shed rafter.

Stead's small colony was at the end of a hole in a rata limb. The hole, about I8in long, with the opening about five inches in diameter, was five feet from the ground. Other colonies are recorded from hollow ratas, totaras and puriri trees, as well as from caves. A musty smell is usually associated with long standing colony sites. The colony of thirty or more bats discovered at Matahina during October, 1958, was in a large totara. The cavity occupied was near the base of the tree. It was about three or four feet long and was eight inches in diameter.

Many of the bats from this last colony flew directly to a neighbouring totara when they were disturbed. Stead (1937) records that bats vacated one roosting site for a fortnight and then returned. The capture of several Mystacina in Milford Sound in 1871 when. the sails of H.M.S. "Clio" were loosed for drying is an additional suggestion that there is a measure of flexibility in the choice of roosting sites.

The body of Mystacina is cold to the touch during the roosting hours and if disturbed at this time movements are extremely sluggish. Waking involves stretching and head shaking. The animals are difficult to rouse when cold but become very active and quite warm after handling.

There are several records of large colonies of Chalinolobus in trees and caves. A colony numbering several hundreds is mentioned by Buller (1893) and Cheeseman (1894) also refers to several large colonies. One colony of more than thirty bats was present amongst creepers and epiphytes in the upper branches of a large tree. The bats were clinging together in clusters. Cheeseman found that bats liberated in a room settled in groups of four and five. Phillipps (Dominion Museum file) reports a colony from a cave at Orakei-Korako: Air temperature within the cave was about five degrees centigrade higher than that of the entrance. Several "bat holes" in the form of short tunnels were present in the roof. Smaller colonies of this species have been reported, six bats being obtained from a small hollow in a non-native tree. Two records of a pair of bats found beneath tree bark are also known. In one instance the tree was a dead kahikatea. A hibernating bat was discovered in a dead wattle tree at Matarawa (North Wellington). Roach and Turbott (1953) state that waking involves a period of warming up lasting several minutes. The process commences with a yawn or snarl, the jaws opening to nearly ninety degrees.

Colonies of unidentified bats have been found in caves and hollow trees and in the leafy upper portions of tall trees. Totara, rimu, kahikatea, pukatea and rata are all recorded as sites; totara being reported most frequently.* Large accumulations of droppings are sometimes present and colony sites may be characterised by a strong smell. Colenso (1890) records finding clusters of bats in hollow trees during the winter.

* Specific identification of trees was not available in any instance.