H U S B A N D R Y 175

in a long pair of forceps and shaken to incite the snake to bite. Never allow l ive rodents to remain inside the enclosure overnight or for prolonged periods as the rodent may bite and injure, or, on rare occasions, inflict a fatal wound on the snake.

It should be remembered that snakes are creatures that generally respond to basic stimuli, and this should be kept in mind when attempting to elicit the de- sired behaviour. Quite often, the mere mechanics o f biting and injecting venom are sufficient to inspire an associated feeding response. Rabbits appear to be the favourite food. Wild-caught diamondbacks in o u r collection have al- most invariably responded t o the odour of rabbits in preference to that of mice and rats. Once the animal starts feeding on rabbits, it is an easy matter t o convert it to rats and mice, using odour manipu- lation. Persistence is important. If initial attempts at this type of feeding d o not work, do not be discouraged, but instead, explore other possibilities. Kauffeld ( I ) points out the value of using partially decomposed prey as a stimulus. Not only should a variety of foods be offered, but each of these items should be presented in various ways, i.e., live, pre-killed o r partially decomposed; sometimes a piece of skin torn from the

nose of the prey, o r allowing the snake to contact fresh blood in some other way will excite it and trigger a feeding response. The latter technique has been extensively used b y Louis Pistoia at Col- umbus Zoo.

Temperature for the Eastern diamond-back is not particularly critical, and it will do quite well within a range o f 19-28"C and at humidities ranging be- tween 5 0 4 0 % . I repeat, the most impor- tant single factor is isolation and solitude in the initial stages of captivity. Once the specimen has fed several times, the hid- ing places and the darkened enclosure may gradually be eliminated and the animal eventually placed on public dis- play. A reasonable period should be al- lotted during which it can acclimate to the activity of keepers, etc., behind the scenes. Once on exhibition, a log or rock can be positioned in the cage so that the rattlesnake is clearly visible but is wil- lingly anchored as far from the viewing public as possible.

K E F E R E N C E 1. KAUFFELD. C . F. (1953): Methods of feeding cap- tive snakes. Herpetologica9 (3): 129-131. 2. S H A W . (;. E. (1969): Longevity of snakes in North American collections as of 1 January 1968. Zool Carl.. 1 . p ~ (N .F . )37 : 193-196.

Manuscript submitted 1 1 February 1974

The bushmaster Lachesis muta

in captivity P A T R I C K B U R C H F 1 E I . D General Curator, Gladys Porter Zoo, Brownsville, Texm 78520, USA

'Deceptively lethargic' is a graphically Many authorities refer to its savage dis- apt description of the bushmaster position, depicting unprovoked attacks Lacheszs muta. Belying its size and notori- on the hapless passer by. But in my many e ty , it is a rather secretive species and is years of collecting, handling, extracting seldom seen in its natural habitat except venom, shipping and maintaining by the most experienced of hunters. numerous bushmasters, only once have I

176 H U S B A N D R Y

had occasion to observe their awesome lunge and been pursued, and then only after much provocation.

In San Jose, Costa Rica, researchers at the Institute Chdomiro Picardo relate much the same experience, stating that bushmasters rarely offer to bite, and if prodded continuously, will usually hide their heads beneath a body coil (H. Flow- ers & R. Taylor, pers. comm.). Accounts of bushmaster attacks are normally the result of encounters with ?? guarding the defensive perimeter of the nest site and dutch. The young are much more pugnacious than adults and possess a red tail tip which they vibrate when annoyed. When irritated, the animal draws into a loose 's' coil, with the head 1-aised as it distends and inflates the throat ventrally.

Its spectacular aspects have long made Lachv.sis a popular, if transient, exhibit in zoo collections. In this respect the species is not unique in the management difficul- ties which it presents. Over the years, reptile experts arid enthusiasts have chilled, overheated, and otherwise suc- ceeded in killing it. As is often the case, we search for complex solutions to what prove to be very basic problems. Within the last ten years, however, there has been considerable progress in bushmas- ter husbandry. Many specimens have been kept for more than three and four years under varying conditions in differ- ent collections, although usually in a cool environment and off-exhibit rather than in a public display. T o the best of my know ledge , the cu r re n t Ion gev i t y record for the species is held by a specimen belonging to the private collection of Henry A. Molt Jr, of Philadelphia-5 years X months 17 days. I t had been imported as a 2 m long adult and had the typical noose scar. N o special provisions were made for temperature or enclos- ure, and the animal fed from the outset; it died of acute nephritis.

Like some of the Southeast Asian crotalids, the bushmaster is elongated and rather slender in conformation.

This delicacy of form, in comparison with its length, is one of the principal reasons why the species has rarely sur- vived in zoos in the past. The trauma o f capture, particularly when a noose was used, usually resulted in some sort o f injury. Much of the present degree of succe5s with the species can be attributed to the Tcquisition of younger, uninjured specimens. Mishandling, mechanical in- jury and stress during transport are other common causes of death.

The three subspecies, L. m. muta, L. m. noctivaga and L. m. stenophryb range from Costa Rica to Brazil; both muta and stenophrys have been kept here at Brownsville. Bushmasters are primarily nocturnal ( I ; 2), venturing forth during the cooler hours of darkness in their jungle and tropical rainforest habitats. Although in the wild changes in tern- peratlire will initiate activity, such fluctuations are not normally essential in captivity, other than as a possible tool to stimulate feeding. A general range bet- ween 21-27°C is sufficient, and a 30- 60% humidity is acceptable, except when the snake is due to shed.

Total isolation and seclusion are vital in the first stages of captivity, preferably in an opaque-fronted cage located in a darkened cabinet or room, and with a hiding box inside the cage. The box should be small enough to make the snake feel secure when it retreats inside. In the initial attempts at feeding, small, furred live rats have proved to be the single most acceptable food. If the speci- men is either too timid to feed or be- comes too disturbed by the activity of its prey, the rat should after a reasonable waiting period be removed and killed, and then, while it still shows some mus- cular twitching, it may be used to stimu- late the snake into biting-and so to begin feeding.

We have had reasonable success in initiating feeding in captive bushmas- ters. However, a notable exception was a certain specimen of the Central Ameri- can race L. m. stenophrys, which we re-

11 I! S R A N I) H Y 177

ceived in poor condition. It had several broken ribs and a noticeable concavity in the posterior third of the body. At first, w e quite naturally assumed that it was this internal damage and the stress to which the animal had been subjected which inhibited voluntary feeding. All other external indications were good and the specimen was quite alert, even a little aggressive. For a period of three or four months w e tried various food items, and various methods of introducing them. Rut taking its internal injuries for granted, we were never surprised at its refusal to cat.

At five months, as the specimen exhi- bited a marked weight loss, we decided to begin force-feeding, using the standard forceps insertion procedure. Pre-killed rats, smaller in size than those normally offered, were dipped in egg; their mouths had previously been sewn u p so as to prevent the sharp incisors from lacerating the snake's mucous mem- branes. They were fed primarily toopen and lubricate the tract for the larger items which were to follow. Once the food was in the throat, the animal was released in the hope that it would follow through and swallow of its own accord. Regurgitation can be averted in most instances by stimulating the animal to crawl forward, so that involuntary peris- talsis takes over. If this fails, the snake may be immersed into a can of tepid water; swimming activates the same re- sponse but provides an additional shock to the animal's system.

Force-feeding presented no problem other than the ever present possibility of mechanical injury. During the ensuing months it was continued, together with intermittent attempts to provoke spon- taneous feeding. Rats and mice of all sizes and colours, several species of birds, lizards, snakes, opossums, rabbits, fish, frogs, and even bats were all offered, with equal lack of success; they were presented alive, dead and in various stages of decomposition. Hiding boxes, change of cage, temperature and humid-

ity variations, vitamin BI2 and Ad- remarnone were also tried at different times. None of our methods was particu- larly innovative, but what was surprising was the fact that we had managed to keep the specimen alive with force-feeding for a whole I f years

Eventually, we moved the cage unit into the Administrative Office, which represented a radical drop in tempera- ture. An adult dead rat was offered, and some time during the night it was con- sumed. After that the snake fed, re- gained weight and was returned to the Herpetarium bushmaster exhibit, where it joined another specimen received in the same shipment.

Another frequently encountered hus- bandry problem concerns shedding. Once the old skin has dried on a bush- master, it is extremely difficult and often traumatic to remove. In the hot and arid conditions of captivity this is a hazard experienced by many snake species. Sur- prisingly enough, to the alert reptile man. the process of ecdysis can be a useful tool of management, rather than a problem. Many keepers maintain accu- rate records on feeding, defaecation, growth and shedding of their charges. Where good, detailed shedding records have been kept in the past, and the interval between when a specimen first becomes opaque and final ecdysis has been carefully noted, it is a simple matter with most species to make an exact pre- diction of the day o f shedding. T h e duration of opaqueness has proved to be a valuable guide in, for example, the prevention of prolonged soaking or spraying, both of which can jeopardize a snake's health. P R o i ) " c r M F . N . I I O N F D I N T H E T E X T

Adreapmom: respiratory corucotropin injection, manufactured by Armour-Baldwin laboratories, Omaha, Nebraska 68103, IJSA. REFER F. N C E S 1. DOWIJNG, H . G. (1960): A bushmaster in the zoo again. Anim. Kingd. 63(3): 109-1 1 1 . 2. OLIVER, j. A. (1957): How to feed a bushmaster. Anim. Kingd. 60(6): 175-177.

Manuscript submitted 1 1 February 1974