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Studies on the Two New Zealand Bats

IV. A Review of Field Observations on New Zealand Bats

IV. A Review of Field Observations on New Zealand Bats

Abstract

The present area of distribution of New Zealand bats is considerably less than it was over a century ago. The decrease is correlated with the restriction of forest during the last century and the failure of either species to survive in open country or to urbanise. The Urewera in the North Island and the Buller River drainage in the South Island appear to support the highest densities of bats in New Zealand. Field observations in relation to behaviour and ecology are reviewed, and probable species differences in hibernation, foraging times, and diet are indicated. Fur mites are reported as parasites of both species.

Introduction

During a recent investigation of the two New Zealand bats, Mystacina tuberculata Gray and Chalinolobus tuberculatus (Forster), an attempt was made to survey the distribution of these species, and to review the fragmentary knowledge of their ecology and behaviour. A brief account of some of the results of this survey has already been published (Dwyer, 1960) but it is felt that a detailed report of the data obtained may be of worth in providing a basis for future work. The author was unable to make any personal observations on living bats. During the three years ended 1959, numerous trips were made at all seasons to the Tararua and Rimutaka ranges (South Wellington). In addition the following localities were visited: Egmont (April, 1957), Marlborough Sounds (November, 1957), northern Ruahine Range (April, 1958), Kapiti Island (November, 1958) and Waitomo district (June, 1959). At the last named locality some skeletal material of Mystacina was obtained.

Distribution

Both species of New Zealand bat are endemic. The long-tailed bat, C. tuberculatus, is one of six species of the Australasian genus Chalinolobus (F. Vesper-tilionidae) ; a genus closely related to the southern African Glauconycteris. Tate (1946) suggests that the genus is of Australian origin and it appears that C. tuberculatus is a comparatively recent immigrant to New Zealand. The shorttailed bat, Mystacina tuberculata, is the sole species of the family Mystacinidae. Within New Zealand Mystacina is represented as two subspecies. M. t. tuberculata is recorded from the North Island and the northern parts of the South Island, while M. t. robusta is known only from the Stewart Island region.

There are some unconfirmed records suggesting the existence of other species of bat in New Zealand. Polack (1838) refers to the presence of "Pekapeka, or bats" and "various small batlets, but none of the vampire species". Stock (1876) claims sighting a large bat. at Paekakariki (South Wellington) in 1854. The "body was far larger than of a mouse and somewhat smaller than that of an ordinary sized rat; wing spread was certainly not less than 18 inches". He page 12records similar observations by others at Wanganui and at the Clarence River (Marlborough). Baker and Bird (1936) state that the range of Hipposideros cervinus (Gould) extends south to New Zealand, but I have been unable to find any evidence for this remark. Tate (1941) has reviewed the genus Hipposideros and does not include New Zealand within the range. It is possible that records such as these could be based on chance sightings of occasional wind-borne Australian species.

Sources

The information upon which the following account of distribution is based was derived from various sources. Records have been supplied by the Auckland Institute and Museum, Dominion Museum, Canterbury Museum and Southland Museum. Phillipps' file at the Dominion Museum, Internal Affairs Department file No. 46/108 and Animal Ecology Division (D.S.I.R.) file No. 6/24/2 have been valuable references. The reports obtained from the New Zealand Deer Stalkers' Association were summarized in 1959 issues of Roaring Stag. Several records have been supplied by the New Zealand Speleological Society.

Distribution records have also been obtained from the following: Buller (1893), Cheeseman (1894), Cockayne (1907), Drummond (1908), Forster (1844), Gray (in Dieffenbach, 1843a), Guthrie-Smith (1921), Hutton and Drummond (1904), Knox (1872), Martin (no date), Myers (1921), Parham (1959), Pascoe (1957), Roach and Turbott (1953), Stead (1937), Thomson (1921), Wilkinson (1952), Wilson (1959), Forest and Bird Journal (May, 1959). Dollimore (1957) has been used extensively to determine the whereabouts of numerous localities.

Interpretation of Data

Table I. Summary of bat distribution records for New Zealand
Colonies or large flights. Small flights and isolated sightings.
District Before 1930 After 1930 Before 1930 After 1930
M C U M C U M C U M C U TOTAL
N. Auckland - 2 - - - 1 - 2 1 - - 4 10
Gt. & L. Barrier ls. 1 - - - - 2 1 - - - - 5 8
S. Auckland - - 1 - - 2 4 1 5 3 3 7 26
Rotorua-Taupo - - 3 1 - 8 - - 7 3 2 16 40
Gisborne - - - - - 8 - - 4 - 1 11 22
Taranaki - - - - - 1 - - 2 - - 2 5
Hawkes Bay - - 2 - - 1 - - 2 - - 9 14
H. Wellington - - 1 - - - - - 5 - 5 12 23
S. Wellington - 1 4 - - - 2 - 3 1 - 16 27
Kapltl I. - - - - - - 1 - 1 - 2 5 9
Marlborough - 1 1 - - - - - 3 - - 5 10
Nelson - - 4 - - 1 1 1 9 3 3 30 52
Westland - - 1 - - - 3 1 6 - 3 10 24
Canterbury - - - - - - - 4 3 1 1 2 11
Otago - - - - - - - 1 3 - - 3 7
Southland - - - - - - 3 1 2 - 1 9 16
Stewart I. etc. - - - - - - 1 - 3 5 - 3 12
Totals: 1 4 17 1 - 20 17 11 59 16 21 149 316
page 13

Maps 1 and 2 record the localities from which sightings of bats have been reported, and Table I summarises the details of the distribution records for each of the seventeen districts shown on these plates.* It also incorporates details of the numbers of bats observed at a single time. "M", "C" and "U" are used for Mystacina, Chalinolobus, and unidentified bats respectively. Large flights are taken, quite arbitrarily, as those including twelve or more animals.

Date Locality District Species
About 1949 Eglinton Valley S. Unidentified
Dec., 1950 Doctor's Gamp, 6 miles from Te Whaiti R.T. Unidentified
Dec., 1952 Doctor's Gamp, 6 miles from Te Whaiti R.T. Unidentified
Dec., 1952 Dale's Run, Te Whaiti R.T. Unidentified
Apr., 1955 Hidden Falls R., Lower Hollyford Valley Ot. Unidentified
About 1957 Lake Marora S. Unidentified
Apr. 26, 1957 North branch Tutaki Valley, slopes of Mt Murchison N. Unidentified
Nov. 28, 1958 Morgano Flat on Durville River N. Unidentified
Dec., 1958 Leslie River area N. Unidentified
Dec. 26, 1958 Lake Rotoroa, mouth of Durville River N. Unidentified
Oct., 1959 Pourakino Valley S. Unidentified

Two individuals of Mystacina tuberculata on Little Barrier Island during early 1958 are recorded by Watson (in N.Z. Dep. Sci. Industr. Res. Bull. 137: 132-5, 1961). May (N.Z. Speleological Bull. 37: 175-176, 1961) refers to a live bat (probably Chalinolobus tuberculatus) sighted in a limestone tunnel (Wai-tomo district) during February, 1961.

Note that sightings along the Wanganui River on the boundary of Taranaki and North Wellington are considered in Table I as being in North Wellington.

* Details of the actual distribution records are included as an appendix to the thesis "Studies on New Zealand Ghiroptera", by P. D. Dwyer, deposited at Victoria University of Wellington, New Zealand. Since the completion of this thesis the following additional records have been made available by the New Zealand Deer Stalkers' Association. These records are incorporated in the totals of Tables I and II, but are not shown on the distribution maps.

page 14
Map 1.

Map 1.

North Island of New Zealand, showing distribution of bats.

Abbreviations: N.A., North Auckland; B.Is., Great Barrier and Little Barrier Islands; S.A., South Auckland; R.T., Rotorua and Taupo districts; G, Gisborne; T, Taranaki; H.B., Hawke's Bay; N.W., North Wellington; S.W., South Wellington; K.Is., Kapiti Island.

References to symbols as for Map 2. A larger circle indicates a series of records from a single locality.

page 15
Map 2.

Map 2.

South Island of New Zealand, showing distribution of bats.

Abbreviations: M., Marlborough; N., Nelson; W., Westland; C, Canterbury; Ot., Otago; S., Southland; S.Is., Stewart Island and subsidiary islets.

page 16
Map 3.

Map 3.

New Zealand, showing bat distribution and forest.

Only observations of bats since 1930 are shown. A large circle indicates a series of records from a single locality. Forest areas at 1955 are based on Masters, Holloway and McKelvey (1957).

page 17
Map 4.

Map 4.

New Zealand, showing bat distribution and rivers and lakes.

A large circle indicates a series of bat records from a single locality.

page 18

Maps 3 and 4 illustrate the relationship of observations to forested areas and to rivers and lakes. In Map 3 only observations since 1930 have been used, and the forested areas illustrate the position at 1955 according to Masters, Holloway and McKelvey (1957).

A number of problems in interpretation are at once apparent from an examination of the distribution records available. The most obvious of these is that records must tend to reflect the distribution of observers, and for animals such as bats which become active after dusk this is particularly relevant. Both species are forest inhabiting and the greater percentage of observations of bats in flight have been made over lakes, in river valleys, or in open clearings within or adjacent. to forest. It is only in such open areas that the rapid movement of the bats may be observed against the background of the sky. There is a tendency, therefore, for observations. to fringe the forests (post 1930 records of Map 3) or to follow major river valleys where these are surrounded by forest (Map 4). Thus in the North Island, Lake Waikaremoana (Gisborne), Lake Rotorua (Rotorua-Taupo) and the Wanganui River drainage (North Wellington) provide numerous records. It is obvious that the Urewera records (Rotorua-Taupo and Gisborne) lie along the settled Rotorua-Waikaremoana road route at the head waters of the Rangi-taiki and Whakatane Rivers. In the South Island, the Wairau and Pelorus River Valleys (Marlborough), the Buller and Grey River Valleys (Nelson), and the Lake Rotoroa district (Nelson) account for many records. Within forest, observations are usually of roosting animals or, rarely, the entry of solitary foraging animals into tents or huts.

Table II
Total number of records in five-yearly intervals
Myetaoina. Chalinolotous Unidentified Total
1870-74 2 0 3 5
1875-79 0 0 5 5
1880-84 0 1 5 6
1885-89 0 0 4 4
1890-94 2 5 4 11
1895-99 1 0 7 8
1900-04 4 0 5 9
1905-09 2 2 9 13
1910-l4 0 0 9 9
1915-19 1 0 1 2
1920-24 1 0 9 10
1925-29 1 0 13 14
1930-34 2 0 15 17
1935-39 0 0 17 17
1940-44 1 0 11 12
1945-49 2 6 47 55
1950-54 2 6 27 35
1955-59 10 8 51 69
Totals 31 28 242 301
page 19

Table II groups the total numbers of observations in five yearly intervals.* The sudden increase in the number of observations from 1945-49 is a direct result of a survey by Mr. W. Phillipps, Dominion Museum. The increase during the last five years results, in part, from the present survey as reflected by the numerous records from the New Zealand Deer Stalkers' Association and also from general public interest and the consequent accumulation of information by the Internal Affairs Department. The table certainly cannot be taken to suggest an increase in numbers during the last hundred years.

The second problem arising in interpretation of distribution records is that the total number of observations for different districts may give a false impression of the relative densities of bats in these districts. Thus a comparison of the records for the South Auckland and Gisborne districts (Table I) indicates fewer observations, 22 against 26, for Gisborne, but more colonies or large flights, 6 against 3. In addition the percentage of observations since 1930 is far greater for Gisborne than for South Auckland.

Sight records are not sufficient to enable species identification. Therefore most of the observations are of unidentified bats. Species records have only been accepted in the light of good evidence. Mystacina has long been popularly legarded as the rarer species, but I feel this stems from its structural peculiarities and the popular synonymy of "unusual" and "rare". There is no great difference between the numbers of records since 1930 for the two species; 17 for Mystacina, 20 for Chalinolobus.

With these problems in mind, I have attempted to assess the distribution of bats in New Zealand, in relation to time and physical characters of the environment.

* The discrepancies in the totals between Tables I and II and between the tables and the maps result from differences in the details supplied by individual records.

Conclusions

The present area of distribution of New Zealand bats is considerably less than it was over a century ago. Early records are available from many major urban centres such as Wellington and Dunedin and a well authenticated colony beneath a bridge over the river Avon in Christchurch persisted to the early 1900's. Smaller townships such as Dannevirke (Hawke's Bay) and Ross (Westland) also had their colonies.

Before 1930 sightings were scattered and were generally nearer the coast or townships than is now the case. They were seldom far distant from the extensive forest areas. The general pattern has been a decrease in the distribution correlated with the restriction of forest during the last century. Both species of bat have failed to urbanise, and small populations isolated from the forest generally have not survived.

There is no evidence that the density of bats has decreased within unmodified forest. Rivers and lakes provide an abundance of suitable insect food and clearings near bush provide favourable hunting grounds. Bat colonies have therefore survived in these localities. In open limestone country isolated colonies sometimes occur in caves. Such small colonies are present in the Te Kuiti-Waitomo district (South Auckland).

Altitudinally the bush line limits the distribution of bats. The single record. above this limit is at 3,460 feet in the Tararua Range (South Wellington).

In the North Island bats are regularly reported from southern South Auckland, Rotorua-Taupo, Gisborne and the northern parts of North Wellington and Hawke's Bay. Within. the Rotorua-Taupo and Gisborne districts the greatest number of sightings are from the Urewera and Lakes Waikaremoana-Rotorua districts. page 20A large colony is well established at Aniwaniwa (Waikaremoana) with flights of 40 or more bats being observed over the lake during the summer. Some recent records are derived from the Whakatane-Opotiki district. In North Wellington the upper reaches of the Wanganui River drainage system account for many sightings. The many records from South Wellington have usually been of isolated bats or small flights. It appears that here bats are restricted to a few small scattered colonies in the Rimutaka and Tararua ranges. Little Barrier Island and Kapiti Island have a long history of sightings, but again numbers appear to be relatively few.

In the South Island, north-western Marlborough, Nelson and northern West-land seem to be well populated. The Wairau, Pelorus, Motueka, Karamea, Buller and Grey River drainage systems account for these records. The few recent records for Canterbury come from the Geraldine County. In Southland the few records are perhaps deceptive and the recent nature of these, excepting those coastal, suggests that a general absence of observers in previous years accounts for an apparent absence of bats. Stewart Island and its subsidiary islets still support small but flourishing colonies.

I would suggest that the Urewera in the North Island and the Buller River drainage in the South Island support the highest densities of bats in New Zealand. For only two localities is it possible that one species may occur in the absence of the other. In the North Island only Chalinolobus has been recorded from the Wanganui River drainage, and in the Stewart Island region only Mystacina has been taken.

General Biology

Little has been recorded of the behaviour or general ecology of the New-Zealand bats. Chance encounters with colonies, often as a result of felling timber, provide some information relating to habitat and gregarity. Stead (1937) gives a report of observations on Mystacina near Stewart Island, and a few brief accounts, such as Roach and Turbott (1953) and Parham (1959), record the behaviour of captive bats. The present survey reviews all past accounts and includes some recent data.

Activity

Fig. 1 records the activity of bats in terms of the number of observations for each month of the year. The basic pattern, reflected in the value for unidentified bats, is of low numbers during the winter months (May to August) followed by a steady increase in numbers from September to mid-summer and autumn. Though values are low, it is noticeable that records of Mystacina are lacking for only two months, March and September, whereas Chalinolobus is not recorded during five months, three of these being the winter months, May, July and August. Fig. 2 records the yearly activity of a small colony of unidentified bats at Puke-titiri, Hawke's Bay, observed by Miss P. Lewis during the years 1956 to 1959. An almost complete absence is noticeable for the winter, the single observation for the months May to July being of a solitary bat in the early dawn.

Of the numerous observations of unidentified bats, 22 record dusk, 22 evening and 10 summer evenings as the sighting time. A few claim that the bats were seen after dark. Confirmed sightings of Chalinolobus state evening as being the period of activity. Roach and Turbott (1953) record this time as the active period for a captive specimen. At Orakei-Korako (Rotorua-Taupo) on the 19th-20th February, 1948, Phillipps (Dominion Museum file) noted the appearance of the first bat from a cave colony at 7.30 p.m., and of the second a little later. No further bats emerged, and both these bats returned at 1.30 a.m.

page 21

There are few references to Mystacina in flight. Two records of the entry of this species into lighted huts, and Stead's (1937) reference to the activity of this species in the Stewart Island region after 10 p.m., are relevant. During late February, 1959, a captive Mystacina in the Rotorua-Taupo district consistently roosted till 8 or 8.30 p.m. in the early stages of its capture.

Fig. 1.—Yearly activity of New Zealand bats in terms of the number of sightings recorded every month.

Fig. 1.—Yearly activity of New Zealand bats in terms of the number of sightings recorded every month.

The abbreviations "M", "C", and "U" are used for Mystacina, Chalinolobus and unidentified bats respectively.

Fig. 2.—Yearly activity of bats at Puketitiri, Hawke's Bay.

Fig. 2.—Yearly activity of bats at Puketitiri, Hawke's Bay.

page 22
Fig. 3.—Appearance of Puketitiri bats in relation to sunset time.

Fig. 3.—Appearance of Puketitiri bats in relation to sunset time.

Fig. 3 shows the relationship between the times of appearance of the Puketitiri bats and the times of sunset for 1958. Although affected to some extent by weather conditions, the animals generally appeared between five and twenty-five minutes after sunset. This time is comparable with the data reported for Chalinolobus. Phillipps' record for the 19th February coincides with the Puke-titiri times for the corresponding period of the year. A winter sighting of an unidentified bat in the Rotorua-Taupo district during June, 1958, was at about 14 minutes before sunset.

The duration of the foraging period is difficult to assess. Observations of bats usually last between a few seconds and fifteen or twenty minutes. Longer observations are seldom possible because of the rapidly failing evening light. Captive animals are usually active for only short periods each day. McKay (Internal Affairs file) records that for a captive Mystacina feeding, drinking, and exercise usually occupied three hours. Stead (1937) claimed a two-hour flight period for this species. Roach and Turbott (1953) record 10 minute evening flights for a Chalinolobus specimen. Phillipps' Chalinolobus remained away from the roost for six hours. At Puketitiri sightings have been made at 4.45 a.m. in January, 5 a.m. in March, and early dawn in June.

Influence of Weather Conditions on Activity

Bats are generally reported on fine warm nights. Miss Lewis (personal communication) states that no bats are seen at Puketitiri on misty damp evenings and suggests that on cloudy evenings the bats appear earlier than usual. A record of bats flying high in drizzle, and a record of an injured Chalinolobus found on the floor of a shed after a rough night, are the only reports of activity in adverse conditions.

Range and Foraging Areas

At Puketitiri the bats appear regularly from the same section of forest. Feeding areas are established and are not more than about 800 yards from the point at which the bats appear. Three areas serve as the main feeding grounds. These page 23are: a paddock about 120 yards from the forest edge; a dam about 220 yards from the forest edge; and a grass paddock about 350 yards from the forest edge. A stream runs along the south-western boundary of the paddocks. Feeding areas nearer the forest are more often frequented and, although some variation occurs from year to year, the sites of these areas generally have close relation to the stream and dam.

A few other evening observations record the following distances from the nearest forest: 150 yards and 350 yards, ¼, ½, and ¾ of a mile. Of fifty reports which include details of the habitat, 28 refer to the presence of water either as swamps, lakes, streams, etc., and 25 refer to the presence of forest. Of these latter, all but three indicate that the bats were observed at the forest margin or in open areas adjacent to forest. The remaining three are sightings in dense forest.

Flight, Crawling and Roosting

The flight of both species is erratic. Colenso (1890) describes the short zig-zag turns and the irregular rising and falling of feeding animals. Cheeseman (1894) describes the flight of Chalinolobus as quick, soft, and noiseless. It is unaffected by full daylight. When resting between flights this bat hangs upside-down with the wings furled.

Frequent changes of direction are also characteristic of Mystacina but Stead (1937) claims that the flight of this species is not so rapid or twisty as that of Chalinolobus. Mystacina may pursue insects in the vicinity of lights, flying at times quite close to the ground, and a number of specimens have been captured in forest when stunned after hitting against torches or lanterns, or after flying into lighted tents or huts. In captivity this species may rest between flights with the wings partially extended. When roosting it suspends itself upside down, using the recurved claws of both feet. The head extends straight downwards. The thigh is directed outwards from the body, at right angles to it, and the shank extends posteriorly and slightly medially. The foot is turned only slightly outwards from the line of the shank.

A number of structural peculiarities in Mystacina have been interpreted as adaptations suitable for terrestrialism (Dobson, 1876). Some information relating to terrestrial locomotor behaviour in this bat is available. Stead (1937) refers to seven specimens of Mystacina taken on Solomon Island. "They were placed in a box with a wire-netting front, and were most active in their efforts to escape, running head first with a curious stiff action and quite fast, using their folded wings as forelegs, the wrist joints coming in contact with the ground. They climbed the wire-netting or the smooth wooden sides tail first and with remarkable agility."

Mr H. E. Grubner (Whakatane) who kept a single bat of this species for two weeks during October, 1958, described the bat as particularly agile and able to run on top of or beneath a branch. He reports the ability of this bat to. take flight from a level surface.

Voice and Reaction to Sound

A slight "clacking" emitted during flight has been noted for Mystacina. Stead (1937) mentions the shrill squeaking of Mystacina when handled, and Grubner (personal communication) describes ear twitching as a reaction to light scratching or high pitched sounds. He describes the reaction of this bat to radio static as "panic", and describes a behaviour pattern before flight in which the animal "opened its mouth and turned its head from side to side". This latter would facilitate echo-orientation. Phillipps (Dominion Museum file) records a high pitched squeak and a low grunt from a colony of Chalinolobus.

page 24

Food and Feeding

The numerous evening observations of bats above water suggest that adult instars of insects with aquatic larvae may form a major portion of the diet. Bats hunting the forest margin in the evening probably obtain moths. Moths, mosquitoes, and midges are all recorded as food items by observers, and Colenso (1890) notes that small flies were readily accepted by a captive bat.

Cheeseman (1894) records the capture of insects on the wing by Chalinolobus, and Roach and Turbott (1953) fed a bat of this species with mealworms and liver fragments. A praying mantis was readily accepted. The jaw motion in feeding was described as very rapid, food items being quickly reduced to a pulp. The faeces of Chalinolobus are small, about 4 to 8 mm long and, though usually tapered at either end, they may be somewhat irregular. Droppings from the surface of a cave pool at Orakei-Korako (Rotorua-Taupo district) consisted almost entirely of lepidopterous and dipterous remnants.

Items accepted as food by captive specimens of Mystacina include earwigs, spiders, moths, grasshoppers, crickets, wood grubs, and wire worms. Of these, spiders, moths and crickets were apparently most acceptable. McKay (Internal Affairs file) states that crickets "were quickly killed and, like all other insects that were offered, they were devoured head first with a distinct crunching noise". Spiders and crickets were readily taken from the floor of the cage.

Stead (1937) records the flesh of a skinned diving petrel being eaten by Mystacina and carcasses of mutton birds hung out overnight to dry have been damaged by these bats. The strong transverse tongue ridges (Knox, 1872) would facilitate such feeding habits. The specialization of this bat for terrestrialism and the recorded flesh-eating habits suggest that a scavenging habit could provide a winter food source.

Parham (personal communication) describes drinking habits of Mystacina. "The animal was offered half a teaspoonful of water. It would take a drink, then wipe its mouth on the floor of the cage before taking the next. This process was repeated four or five times. During this period it was sitting with the toes of each foot splayed out, and the arms resting on the floor."

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.

Predators

Moreporks have been frequently reported as bat predators. Stead (1937) found a dead Mystacina in a morepork's nest. The bat had a small claw puncture in its neck. A pair of moreporks nested for a number of seasons at the entrance to a cave known to support a colony of Chalinolobus. Grubner (personal communication) has observed a bat escape an attack from a morepork by flight in a fast upward spiral.

Two records, one for each species, are known of capture by cats. Three page 26Mystacina were killed by a dog when a tree containing a colony was felled. Stead (1937) considers that in the Stewart Island region black rats may prey on Mystacina. Mustelids could similarly cause extensive loss to accessible colonies, but there are no confirmed records of predation by any of these mammals.

Parasites

Both species of New Zealand bat carry external parasites. Fleas are known from both, but till now records of mites exist only for Mystacina. Several observers refer to this bat as being "infested with vermin" and Grubner (personal communication) , who reports "a large spidery thing, reddish brown, and about ⅛in or more in size" from a captive bat, states that the animal was able to scratch any portion of its back with the foot.

Most specimens, juvenile and adult, of Chalinolobus examined during this study carried fleas (Order Aphaniptera). These occurred in the fur on all portions of the body, being commonest on the ventral surface in the axillary and pubic regions. From four animals (3 females, 1 male) which were thoroughly combed 23 fleas (17 females, 6 males) were obtained. All were Porribius pacificus described by Jordan (1947) for New Zealand bats. Only one flea was obtained from the twelve Mystacina examined. It was a female P. pacificus. Jordan includes five species in the genus Porribius, all as parasites of Australasian bats. Host species include Eptesicus pumilus, Nyctinomus (= Tadarida) australis, and Chalinolobus morio (Rothschild, 1936). Although the number of specimens from which the fleas were obtained was small the striking difference in infestation between the species could suggest that P. pacificus is at present in the process of transferring to Mystacina.

Grubner's description of a parasite of Mystacina as "spidery" and "about ⅛th inch or more in length" is strikingly suggestive of the family Nycteribidae, Order Diptera. Allen (1939) describes these bat parasites as being spidery in appearance and states that they are a common parasite, especially of Old World bats.

Mites (Order Acarina) were common on Mystacina, as many as 15 being obtained from a single specimen. The three species recognised belonging to the family Laelaptidae (Mesostigmata), suborder Sarcoptiformes (perhaps family Acaridae) and the group Parasitoidea (Mesostigmata). The laelaptid mite species was the most common. Only a single specimen of the last was obtained. Mites were present in the fur and none were found on the membranes.

A single specimen of a large mite was obtained from a juvenile Chalinolobus from Pelorus Valley (Marlborough). A member of the suborder Trombidiformes, the extremely dense coat of setae on the dorsal surface of this mite suggest that it belongs to the family Trombiculidae. Three genera of this family are recorded (Domrow, 1959) from Australian bats with Trombicula thomsoni known from Chalinolobus gouldii.

Acknowledgments

I would like to thank Professor L. R. Richardson for his guidance throughout this investigation and Professor A. F. O'Farrell and Dr J. le Gay Brereton for suggestions during the preparation of the manuscript.

Numerous persons have provided the information upon which this survey is based, and in particular acknowledgment is due to Mr W. J. Phillipps, who amassed most of the early records discussed here. Other important records have been provided by the Dominion Museum, Canterbury Museum, Internal Affairs Department, Animal Ecology Division, New Zealand Deer Stalkers' Association, New Zealand Speleological Society, Miss Pam Lewis, Mr D. Arthur and Mr W. Parham.