Whiskered Bat (Myotis mystacinus) in captivity, Oldham 1899
No. 692.— February, 1899.
WHISKERED BAT (MYOTIS MYSTACINUS) IN CAPTIVITY.
By Charles Oldham.
The observation of Bats in a free state is, owing to their nocturnal habits and peculiar mode of life, a matter of considerable difficulty, and but very little is known of the economy of even our common British species. Many of their actions may be studied in captivity, but it is not easy to maintain the supply of insect food essential to the welfare of the little creatures, which seldom survive confinement long. These considerations are perhaps sufficient excuse for the publication of the following notes on a Bat which I kept alive for nearly five weeks last winter.
On Nov. 27th I obtained a male Whiskered Bat, Myotis mystacinus (Leisler), from one of the tunnels of the disused copper mines on Alderley Edge. It would not eat some meal-worms I offered it, although it greedily lapped water from a camel-hair pencil and from the palm of my hand. Five days later, after many unsuccessful attempts to induce the Bat to feed, I procured some moths (Scotosia dubitata) from the copper mines, and placed them in a box with it; but no attention was paid to them. On the evening of the following day I placed the Bat under a bell-jar with six of the moths, and, on going to look at it an hour afterwards, found that it had caught and eaten them all, rejecting only the wings and legs. The available supply of moths was exhausted in a few days, and I began to despair of keeping my little captive alive, as it still ignored the mealworms, even when they crawled over its face and wings. On Dec. 5th I fastened a moth's wing to half a mealworm, and moved it about just in front of the Bat's nose. This ruse succeeded admirably; the Bat made a dash at the imitation moth, and speedily devoured the mealworm. From that time it took the mealworms readily, and soon learned to look for them if I held my finger-tips near its face. I fed it nearly every day, and for so small a creature it had an enormous appetite. On one occasion, although it had eaten seven mealworms on the previous evening, it ate, between two and eight o'clock, eight mealworms, a large spider, and six S. dubitata; after which it merely snapped at the moths, but would not eat them. During the ensuing night, however, it ate seven more moths which I had left with it under the bell-jar. On another evening it ate two fragments of raw rabbit, seven mealworms, one S. dubitata, and two thick-bodied moths (Gonoptera libatrix). On Dec. 28th the Bat appeared to be in good health, and ate seven mealworms. I did not feed it on the 29th, and on the morning of the following day it was hanging as though asleep, except that its legs were straight instead of flexed; but, on touching it, I found that it was dead.
The Bat bit me viciously when I took it from the roof of the tunnel and warmed it in my hand, but it never showed any temper subsequently, and in a few days had become absurdly tame. It evinced little disposition for flight, especially after feeding, and if compelled to take wing would, after one or two turns round the room, drop on to the floor, or pitch on a curtain, chair, or my head or body. When settling on a vertical surface it used to pitch head upwards, then quickly shuffle round and hang suspended by its toes in a convenient position for taking wing again. It could rise from a flat surface by making a sudden spring upwards and expanding its wings immediately. Although loth to fly, it seemed never tired of running about among the papers and other objects on the table, and was seldom stationary unless it was eating. The bell-jar in which I kept it was raised above a stand on supports rather more than ¼ in., or, to be exact, just 7 mm. in height, and whenever the perforated zinc guard was removed from the intervening space the Bat would creep out at once. The bright light of the lamp on my table seemed to cause it no inconvenience, for it used to sit, supported on feet and wrists, eating mealworms within a few inches of the flame, and never showed any desire to retire to dark or shaded places. Sometimes it would creep under my hand, or up my sleeve, but this, I think, was on account of the sensation of warmth it experienced in nestling against my skin.
The sense of sight seems to be but feeble in the Whiskered Bat. The example under notice could not see, or at all events recognize, a mealworm or wet paint-brush if more than an inch from its face. As this species is more diurnal than any other British Bat, and may frequently be seen abroad at midday in summer, the inability of my captive to see objects an inch away cannot be attributed to the dazzling effects of too strong a light, especially as this inability existed equally in the daytime and in the artificial light of a lamp. Its hearing also appeared to be dull, as it never showed by any movement of its head that it perceived a sudden noise, such as the snapping of my fingers, or the click of a watch-lid being closed. It sometimes slept prone upon the floor with wings folded and pressed closely to its sides, at other times suspended by its toes to the rim of a wooden box. During sleep, which was always profound, its temperature fell considerably, and it felt, as all Bats do in this state, extremely cold. It usually wakened in the evening, but exceptionally in the daytime without being roused; while, as a rule, it was necessary to warm it into activity by holding it for a minute or two in my hand if I wanted to feed it by daylight. It was constantly thirsty, and would readily lap milk or water even when not sufficiently roused from sleep to seize food. Its voice, often used, was a feeble squeak, less shrill than that of the Long-eared Bat. My captive used to tuck its head away under its body directly it had seized an insect, at the same time bringing its feet forward, so far indeed that it sometimes lost its balance and toppled over on its back. This habit, practised from the very first, was evidently one of old standing, and not a trick acquired in confinement. By feeding the Bat on a sheet of glass so that I could see it from beneath, or, better still, by giving it an insect as it hung suspended by its toes, the reason of its action was at once apparent. The tail being directed forward beneath the body, the interfemoral membrane formed a pouch into which the Bat thrust its head, and was thereby enabled to get a firmer grip of its prey without any danger of dropping it. When the Bat was on a flat surface the lower side of this pouch was pressed closer to its belly than would be the case during flight, so that it sometimes failed to get its head into the pouch, and let a mealworm drop. When this was the case it never made any attempt to seize its prey again, and the mealworm would escape by crawling out from beneath its wings or tail. When the Bat was suspended, however, the bag was wide open, and the insect never escaped. Experience seemed to teach it that the mealworms were incapable of escape by flight, and latterly it did not always thrust its head into the interfemoral pouch after seizing one, but devoured it without this preliminary. In a free state Bats, capturing the greater part, if not all, of their food on the wing, must often fail to grip large insects securely at the first bite, and it would be a manifest advantage to have some means of adjusting their hold without alighting. An insect accidentally dropped during flight could hardly be recovered, and would probably be abandoned without further thought, as was the case when my Whiskered Bat dropped a mealworm. A Long-eared Bat which I kept for a few days invariably thrust its head into the interfemoral pouch on seizing a moth. Both Long-eared and Whiskered Bats have the tail curved beneath them during flight, although they are usually figured with it held straight behind them; and I have little doubt that when on the wing they actually use the method I have described for securing their prey. Further observation will probably show that this curious habit is common to all our British species, with the possible exception of the Horseshoe Bats, in which the interfemoral membrane is comparatively small, and the tail, during repose at any rate, is carried in a very different way.
Having firmly secured its prey, whether moth or mealworm, by the head or tail, my Whiskered Bat used to swallow it lengthwise, crunching it thoroughly by rapid movements of the jaws as it slowly disappeared. Neither foot nor carpus was ever used in any way to assist it in capturing or holding an insect. The use of either would of course be quite impossible during flight. Moths and spiders moving near it were pounced upon and captured, but mealworms dissociated from my fingers seemed to puzzle it, and only once did I see it capture one itself, although the creatures frequently crawled just before its eyes and over its wings and feet. The wings and legs of moths were always dropped, but once or twice a wing accidentally encountered in the Bat's ramble about the table was picked up and eaten. The mealworms were, as a rule, entirely consumed, but sometimes the horny heads were left.
After being fed or handled, the Bat always went through a rather elaborate toilet. It used to hang by one foot and comb the fur of its face and body with the other, often sucking its toes first, and always moving the free foot with great rapidity. It would then change the foot used for suspension, and repeat the operation. It paid much attention to the wings and interfemoral membrane, licking them inside and out, and distending the membranes by thrusting its nose among the folds. When washing itself, as well as when securing prey in the manner described above, it displayed remarkable suppleness.
Despite its cleanliness it was the host, as every Bat seems to be, of some external parasites. I removed a large tick from the upper surface of the interfemoral membrane near the root of its tail, and caught two fleas (which Mr. Edward Saunders has identified as Typhlopsylla hexactenus) in its fur.