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Full Terms & Conditions of access and use can be found at https://www.tandfonline.com/action/journalInformation?journalCode=tnzr20 Journal of the Royal Society of New Zealand ISSN: 0303-6758 (Print) 1175-8899 (Online) Journal homepage: www.tandfonline.com/journals/tnzr20 A radiological study of the kiwi (Apteryx australis mantelli) Graham Beale To cite this article: Graham Beale (1985) A radiological study of the kiwi (Apteryx australis mantelli) , Journal of the Royal Society of New Zealand, 15:2, 187-200, DOI: 10.1080/03036758.1985.10416843 To link to this article: https://doi.org/10.1080/03036758.1985.10416843 Published online: 12 Jan 2012. 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The rate of skeletal maturation has been analysed from radiographs (x-ray photographs). Other aspects of the skeleton have been assessed, particularly the cervical spine. The results suggest that the thorax of the ancestors of the kiwi was more cephalically placed than at present and that four vertebrae classified as cervical were then in the thorax and carried ribs. Even in the modern kiwi vestigial ribs can be seen on the fifteenth cervical vertebra. Studies of the gastro intestinal tract have been carried out on other kiwis using a barium solution with videotaping and radiographic procedures. Anatomical and physiological observations, e.g., temperature, pulse and respiration studies have been made. On those birds requiring anaesthesia the effects of anaesthetic agents have been recorded. Some blood analysis has been done and there are observations on air sacs, the diaphragm and eggs. There is an appendix detailing the radiographic procedures used and the total amount of radiation administered, which was not significantly greater than natural gamma radiation over the same period. Keywords: X-rays, skeletal maturation, evolutionary history, anatomy, physiology, anaesthesia, air sacs, diaphragm, blood, eggs, radiographic technique, radiation. INTRODUCTION There are excellent descriptions of a kiwi skeleton by Owen (1841, 1849, 1871) and Parker (1888 a and b, 1891, 1892), and an up-to-date summary by Reid and Williams (1975). It is not my intention to reduplicate these, but rather to make some specific comments, redefine points of error and document new findings. I have used the terminology of modem human anatomists because I have found the terminology of recent and old zoological literature confusing. Each winter, kiwis injured in opossum traps are brought to the Wildlife Branch of the Internal Affairs Department. Birds that can be treated are often retained in captivity in designated stations, one of which is the Rainbow and Fairy Springs Tourist Resort in Rotorua, and some of the birds from the Resort have been made available for study. The live chick described here was handed into the Tourist Park with its father in December 1979. It was nurtured by Mr Brent Calder, and through a combination of his skill and some luck it has been reared in captivity to adulthood. The luck came with the age of the chick. We believe it was aged between five and six days at the time of capture, and had had no wild diet "imprint". It therefore accepted diced meat as its proper food. Had it been seven days older or more it would have become accustomed to a different diet in the wild and may not have accepted the food offered in captivity. The condition of the male also suggested that the chick was very young. The father had a large, very bald egg patch on its abdomen and the lack of any feather regrowth suggested that the chick was being cossetted. Fig. 1 shows the squatting position that the chick originally maintained; this characteristic vanished within the next two or three days. Initially the chick was radiographed in its pen with a portable x-ray unit. Later it was transferred to our Radiological Rooms in a carrying box. The initial programme was to take radiographs once a week; but the interval has been gradually extended so that now, after four and a half years, radiographs are taken only every six months. On each X-ray Rooms, 66 Haupapa Street, Rotorua, New Zealand. 188 Journal of the Royal Society of New Zealand, Volume 15, 1985 occasion the films were of the whole bird (Fig. 2); infrequently, limbs were stretched, out and specific areas examined. Fig. lA-Seven day old chick. It had not yet adopted the standing position, preferring to squat. The maintenance of the squatting posture gave a false impression of frailty and impending demise. Fig. 1 B - The kiwi chick at seven days old. Its size can be judged against the fingers supporting the bird. Notable is the absence of grit in the stomach, because it had not yet started to forage for food. Other live birds from the Rainbow and Fairy Springs Tourist Park have been used for other aspects of the study, and post-mortem material was obtained from birds dispatched because of severe injuries. Fig. 2 - The kiwi chick at two years. The direct measurement of the beak was 111 mm. Beale - Radiological study oj the kiwi 189 As the study unfolded and earlier published works were obtained and read, I developed a great respect for the skill and diligence of Owen and Parker. Both the breadth and depth of their investigations and their records are greatly to be admired. THE MATURATION OF THE SKELETON Skull By examination of the sutures of a human skull, either radiographically or at death, it is possible to estimate age with an accuracy of about a decade or less. By adolescence the human cranium is fully established, with the cranial sutures well defined and still open. By twenty-five the suture line between the basi-occiput and the sphenoid has closed, and sutures elsewhere in the skull close slowly and progressively over the next twenty five years. By early middle age suture closure is complete, and the human skull then remains stable till death. Parker (1891), in his description of the kiwi skull, uses the cranial sutures to define "young", "sub-adult" and "adult" skulls, without stating the ages represented in each group. "Young" skulls have all the sutures open, or at most only some are closing. "Sub-adult" skulls show a more advanced state of suture closure, and in "adult" skulls the sutures are closed. The similarity to the human cranial sutures can be readily seen. The fronto-parietal suture line of the kiwi skull is the only suture line easily visible in lateral radiographs (Fig. 3) so this suture has been radiographically monitored in the growing chick. Observations on the behaviour of the bird suggested that it achieved puberty at one year. (Its calling became clearly that of a male, and Brent Calder felt that its attitude to other birds had changed.) Therefore as a four year old it is certainly a mature bird. However, at four the frontoparietal sutures are still clearly defined; yet byParker's definition, using the state of the cranial sutures, it would be classed as a "young" or "young adult" bird. Parker's criterion of maturity based on skull sutures must therefore be used with caution. It will require a number of years of further radiographic study before the age that this suture finally closes is established, but I suggest that this event will mark the bird's middle age. The state of the cranial suture will therefore reflect only whether the bird is middle-aged or not. The presence of an open suture does not necessarily indicate an immature bird. Fig. 3 - A lateral radiograph of a young kiwi's skull. The longest internal diameter measured 33 mm on the film. Parker's assessment of the state of the "facial" bones of the skull must also be examined. He accurately describes slender connections between the maxillae and the frontal and temporal bones, and between the hard palate section of the maxillae and the vomer. However, he is incorrect in inferring that the maxillae can hinge away from the skull. The implication of his statements is that the upper jaw is mobile in life, but this is not so. The upper jaw is an integral part of the skull, and only in a young dried specimen can the maxillae be levered away from the remainder of the skull. In birds younger than middle age the articulations between the various facial and skull bones are unfused, as 190 Journal of the Royal Society of New Zealand, Volume 15, 1985 are the cranial sutures, and if the sutures are open, the upper jaw may be easily separated from the base of the dried skull. Once the sutures close the maxillae are firmly fused. Forelimbs Although the kiwi is flightless it does have wings. These diminutive structures have retained the major bones in readily identifiable forms (Fig. 4). Beak grooves in the feathers of the thorax show that a kiwi sleeps with its beak beneath a wing. The grooves show that some birds choose always to sleep with the beak beneath the same wing, while others have grooves on both sides. Fig. 4-A kiwi wing. The dry radius measured 23 mm. h-humerus, r-radius, u-ulna, c-carpus, fn-spur, claw or fingernail Knee Joints and the Patella The significant difference between the juvenile and adolescent forms of the knee is the development of a bony ossicle close to the expected position of the patella. Ossification commences at twelve months and it is seen radiographically as a bony spot (Fig. 5a). At two to two and a half years it is a well formed triangular-shaped bone (Fig. 5b). At three to three and a half years the ossicle starts to fuse with the upper tibia, and fusion is complete by four and a half years (Fig. 5c). Fig. 5A-A lateral radiograph of an adolescent kiwi knee at one year. The patella epiphysis has recently appeared and is a round dot. f-femur, p patella, t - tibia Fig. 5B-A lateral radiograph of a young adult kiwi at two years. The patella has a clear, sharp triangular form, and measured 8 mm in its longest axis. p-patella Fig. 5C - A lateral radiograph of a kiwi at least 4 liz years old. The patella has fused with the upper tibia. p - patella Owen's (1841) comment about the patella was brief; he referred to it only as "a small cartilagenous patella". This indicates that the bird he examined was less than a year old. Beale - Radiological study of the kiwi 191 Anatomically the patella is a sesamoid·bone placed within the quadrate femoral ligament where the ligament passes over the femoral condyles to its tibial insertion. A study of Fig. 5 shows that the bony ossicle does not articulate with the femoral condyles. I have called the ossicle a patella, but with slight reservation about the accuracy of this interpretation. Patello-tibial fusion does not occur in man (or in other mammals,) nor does fusion occur in the domestic fowl. The Ankles and Feet The human ankle joint is the combined articulation of the lower ends of the tibia and fibula with the upper surface of the talus. A mid tarsal joint exists between the calcaneus and talus proximally and the cuboid and scaphoid distally, but it is not a joint in the functional sense - rather it is an area of slightly increased mobility . • Fig. 6A - A frontal view of the juvenile ankle of a kiwi aged under one year. The ankle joint is between the proximal and distal row of tarsal bones. The tibia can be seen articulating with the proximal row, and the three metatarsals articulating with the distal row. d-distal tarsal bones, j - ankle joint, m - metatarsals, · p - proximal tarsal bones, t - tibia Fig. 6B-A frontal view of an adult kiwi's ankle and foot, showing fusion of the tarsals to their adjacent long bones and fusion of the metatarsals to each other. This kiwi is 5 years old or more. j - ankle joint, m - metatarsals, t - tibia Fig. 7 - A lateral view of the ankle joint of a kiwi at least 1 liz years old. The sesamoid measured 4 mm in its longest axis. m - metatarsal, m - meta tarsal, s-sesamoid posteriorly in the ankle joint, t - tibia 192 Journal oj the Royal Society oj New Zealand, Volume 15, 1985 Fig. 6a shows the kiwi ankle joint. It is a mid tarsal joint bounded proximally by the proximal row of tarsal bones and distally by the distal row of tarsal bones. It is important to establish these relationships, for the two sets of tarsal bones look very much like epiphyses of the growing lower tibia and fibula and the upper ends of the metatarsus. (No kiwi long bone had a radiologically identifiable epiphysis). These two groups of tarsal bones do ultimately fuse to their adjacent long bones, and the fusion process includes the amalgamation of the upper shafts of the metatarsals with each other (Fig. 6b). Fusion starts before four and a half years of age, and it will be useful to establish the age at which fusion is complete (I think by five years). Parker (1892) described a sesamoid behind the ankle joint, and implied that its form was inconsistent. However, this apparent inconsistency is an age-related feature, not a variation in form. The sesamoid does not ossify until puberty. When ossification begins, one may develop earlier than the other, and this Parker misinterpreted as inconsistency in form. Ossification is completed bilaterally by fifteen months (Fig. 7). Although I have regarded the bone as a sesamoid, it could be developmentally part of the calcaneus. Summary Table 1 summarises the. data on maturation of the skeleton of the kiwi chick, derived from regular radiological examinations of the same chick over four and a half years. Table 1 - Maturation of the skeleton of a kiwi chick determined from radiography. Hatching: 1 Year: 2 Years: 3 Years: 4 Years: 4Y/ Years: Ankle The tarsal bones are well defined. No ankle joint sesamoid is visible The tarsal bones are unchanged. The ankle joint sesamoid is just appearing The tarsals are un changed. The ankle joint sesamoid is well developed No change The tarsals are start ing to fuse with ad jacent long bones Fusion is almost complete with the tarsal bones no longer definable. The ankle joint has almost a mature fo"rm Knee No patella is visible The patella is just appearing as a bony spot The patella is well defined as a triangular shaped bone Little change The patella is starting to fuse with upper tibia Fusion is complete and the knee joint has a mature form Skull The cranial sutures are open and are readily visible No change No change No change The sutures are still visible but are not so easily seen No change EVOLUTIONARY CHANGES IN THE NECK AND THORAX Cervical Vertebrae Cervical vertebrae are defined as those between the occiput and the first rib-bearing vertebrae of the thorax. In the kiwi there are fifteen (Reid and Williams, 1975). Costal processes are present on all but the first cervical vertebra, and they create the canal of the vertebral artery by theirdouble articulation to the vertebral body and the transverse process (Fig. 8); the sutures of these articulations fuse in adulthood. Romer (1977) states that the costal processes are fused in birds, and this is true in adult kiwis, Beale-Radiological study of the kiwi 193 Fig. 8-An axial view of the twelfth cervical vertebra. On one side the costal process can be seen articulating with the transverse process and the vertebral body, creating the canal of the vertebral artery. On the other side the costal" process has been rea<jiYy Fig. 9A - A magnified frontal removed because suture closure view of the kiwi lower cervic;,al has not yet occurred. The and first thoracic vertebrae. ventrally placed hypapophyseal The transverse process of the ridge of vary ing sizes is first thoracic vertebra have the common to the last four same form as the adjacent cervica l vertebra and the fifteenth cervical vertebra. This thoracic vertebrae. c-costal pattern is reflected as process, g- gap created by the proximally as the tw elfth removal of the costal process, cervical vertebra where the h - hypapophyseal ridge, s - patte rn starts to cha nge . spinous process, t - transverse C 15 - 15th cervical vertebra, process, v - canal of the Tl-l st thoracic vertebra, vertebral artery tp - a transverse process Fig. 9B-A magnified frontal view of the cervico-dorsal junction . Vestigial ribs can be seen at the tips of the transverse processes. r-vestigial ribs , C 15 - 15th cervical vertebra, Tl-1st thoracic vertebra, tp - transverse process but not in juvenile kiwis. Studies of other birds may show that they also have sutures which close in adulthood. Examination of the last four cervical vertebrae shows that each has two features absent in other cervical vertebrae but common to the thoracic vetebrae. Each has a ventral midline hypapophyseal ridge (Fig. 8), and in each the transverse processes point rostrally (Fig. 9a). Although the domestic fowl has hypapophyseal ridges on the last cervical vertebrae, their transverse processes point caudally. (The transverse processes of the last vertebrae of the domestic fowl are very similar to the eleventh cervical vertebra of the kiwi). This suggests that in the kiwi ancestor, the four cervical vertebrae were rib-carrying thoracic vertebrae. Two minor details of the anatomy of the modern kiwi support this idea. The sternum has superolateral processes (anterolateral in the older literature) which could represent the attachment sites of the now-missing ribs (see below): and in the radiograph of one bird small bilateral cervical ribs are visible, attached to the C15 vertebra (Fig. 9b). Sternum At the superolateral angles of the sternum there are bony spurs. They are not part of the sterno coracoid (sternoclavicular) articulations, and are separated from the joints by small but distinct grooves. The spurs are in the plane of rib articulations, though the presently existing ribs articulate more caudally along the lateral margin of the sternum (Fig. 10). I believe that these processes are the vestigial remains of previous rib attachments, and that in the kiwi ancestor the thoracic cage was more proximally placed than at present. Lindsay (1885) expresses a similar view for other birds. SEXUAL DIMORPHISM IN THE SKELETON Part of the reason for undertaking the radiological study of both live and dead birds 194- Journal of the Royal Society of New Zealand, Volume 15, 1985 Fig. 10 - A frontal view of the kiwi sternum. There is a distinct groove between the clavicle and the superolateral process . The superolateral process is in the plane of the rib articulation, while the clavicular articulation is not. c - clavicular articulation, g groove between the superolateral process and the clavicular a rticulation, i-inferolateral process, r-rib articulation, s body of the sternum, sp - superolateral process was to determine whether there was any clearly sex-linked variation in the form of the skeleton. None was found . Because male and female kiwis are identical in appearance, physical means such as weighing and measuring have been used to distinguish them. Caithness (1971) found that the mean length of the female kiwi's beak was 126.9 mm with a range of 109 mm to 145 mm. The beak of the adult male measured between 87 mm and 116 mm with a mean of 97.2 mm. The kiwi chick studied here had a beak length of 111 mm at one year old-a value falling between male maximum limit of 116 mm and the female minimum limit of 109 mm. The chick is believed to be a male (a penis was seen when it was aged 1 month, and at puberty it started to call as a male.) Measurements of long bones do not always distinguish the sexes correctly, even though adult females are usually 20% larger than adult males (Reid and Williams, 1975). This is especially so if measurements are taken from radiographs, because of inherent errors in the technique. These errors include the problem of establishing end points; an unknown fore shortening factor which occurs when the projected bone is not parallel to the film cassette; and an unknown magnification factor when the bird is not in contact with the film cassette. PHYSIOLOGY Pulse, Respiration and Temperature Some pulse, respiration and temperature readings were obtained, and examples of these are recorded in Table 2. Pulse and respiration rates were counted using a stethescope. Temperature readings were taken rectally with glass thermometers , or oesophageally using an endo-oesophageal rapid-recording thermocouple thermometer. The thermometers were cross-calibrated, and the difference across the five glass thermometers and the thermocouple was 0.2°C. The comparison between endo-oesophagael readings and rectal readings showed that the rectal temperature recordings were accurate. With the endo-oesophageal readings there were marginal temperature variations according to whether the probe tip was in the thorax or in the abdomen. This was thought to be due to the slight cooling effect due to the respired air as it flowed in and out of the lungs, and the effects of this cooling on the oesophageal wall. The temperatures ranged between 38 °C and 39°C for most recordings from any of the locations. The extremes were 36.9°C and 4-0 oC, and the total number of readings was twenty-five on eight birds . There was one set of recordings (rectal and endo-oesophageal) at 36.9°C. The cause for this low temperature was not evident and the bird was quite normal and healthy. Farner et al (1959) record the temperatures of active kiwis at between 38.2°C and 39.9 °C, dropping to 36.4-°C and 37.2°C at rest. My recordings agree fairly closely with these; the differences are probably due to differences in instrument calibration or the relatively small total numbers of birds that have been examined. Calder (1978) comments that the kiwi's normal temperature is lower than that of most birds, in fact more in the mammalian range (37°-4-0 oC in most domestic mammals). Farner's records of other avian temperatures average 4-1°C and above. The pulse nites recorded for my kiwis were very variable and greatly influenced by their state of mind. The average was about 140 beats/minute, with surges to over 200 when the bird struggled or showed fright. The rapidity with which the pulse rate could increase was most impressive. Beale - Radiological study of the kiwi 195 Table 2 - Physiological Recordings Chick Aged Three Weeks (moments after waking) Chick (after temperature readings) Chick's Father (moments after waking) Pulse 140 140 200-140 odd ectopic beats heard Adult Female (a: active and awake, removed 200-140 from the Tourist display area) variable over 1 minute (b: resting.) Adult (under ketalamine anaesthetic) 200+ Adult (under halothane anaesthetic) 200 Respiration Temperature 40 35 40 38.4°C (two rectal readings-glass thermometer) 39.0 0 C (two rectalreadings-glass thermometer) 39.0 0 C (rectal-glass thermometer) 37.6°C (rectal-glass thermometer) 40-50 39.2°C (rectal-glass and upwards thermometer) 40-50 39.0 oC (rectal thermocouple probe) 39.0 oC (oesophageal thermocouple probe) 40.0oC (rectal-glass thermometer) 40.0oC (oeso phageal-thermocouple probe) Respiration rates were much more constant, averaging 30-40 breaths/minute but higher during anaesthesia. The birds resisted when a soft halothane-dampened pad was placed over their nostrils, and tended to become more agitated as the anaesthetic vapour took effect. However, as the birds were kept under anaesthesia for usually 20-30 seconds, they were already recovering before their pulse and respiration rates had been slowed by the anaesthetic agent. ASPECTS OF THE ALIMENTARY TRACT Introduction Barium studies were performed on two adult birds. Video x-ray recordings of oesophageal, gastric and duodeno-jejunal activity were made on one bird. It was lightly anaesthetised with halothane, and oesophago-gastric filling was done via an oral oesophageal tube. The barium suspension was a commercial barium sulphate powder mixed with water in the ratio of 1:2 by volume. Gut transit time was studied in a second bird by conventional radiographs and by waiting until barium appeared in the droppings. The Oesophagus - Anatomy The cervical oesophagus becomes the thoracic oesophagus at the thoracic inlet. The combined length is approximately 16 cm. (Figs 11a, llb). After passing through the diaphragm it becomes the abdominal oesophagus. This segment is approximately 5 cm long, and terminates in the stomach at the cardio-oesophageal junction. Throughout its complete length the oesophagus behaves as a single organ modified only slightly by its cervical, thoracic or abdominal location and the two junctional boundaries that it traverses. It is a simple muscular tube. Its calibre is constant in the empty position, with the segments 196 Journal of the Royal Society of New Zealand, Volume 15, 1985 Fig. 11A - A frontal view of an anaesthetised kiwi with an orogastric tube in position. The stomach has been filled with a barium and water solution, and the barium has already entered the small gut. The loop of the duo denum swings across the mid line then returns so that the loops of jejunum lie side by side in the right abdomen. d - duodenal, j -jejunum, s-stomach, t-tube in the stomach Fig. 11 B - A lateral view of the kiwi after the stomach has been filled with a barium and water suspension and the filling tube has been withdrawn from the oesophagus. Barium has also started to leave the stomach and is being caqied by peristalsis through the small gut. The bird's legs and wings are visible and partly conceal some of the detail of the gut. ao subdiaphragmatic oesophagus, d-diaphragm (seen moving during fluoroscopy), f-forearm bones, h - humerus, r - ribs streaming down from the sternum to curve up to their appropriate thoracic vertebra distending slightly to accommodate the barium suspensions as they accumulate or pass. There is no unusual pouch that could be called a "crop". The oesophagus is mid-line throughout except at the cardio-oesophageal junction where it is to the left of the mid-line. The Oesophagus - Physiology Barium was introduced by an oral-oesophageal tube into the thoracic oesophagus. Occasional waves of peristalsis (fast stripping action type) moved the barium through the junctional boundary of the diaphragm into the abdominal oesophagus. The oesophagus showed a slight narrowing at the diaphragm, which acted as a pseudo-sphincter as the barium paused above if. Similar pausing or ponding occurred in the abdominal oesophagus, and the same stripping waves emptied this oesophagus into the stomach. All peristaltic waves started above the thoracic inlet. Although the introduced barium tended to remain in the thoracic oesophagus, there was some retrograde flow of barium back into the cervical oesophagus. The Stomach and Duodenum - Anatomy The adult kiwi stomach is a globular, muscular bag with the cardio-oesophagealjunction and the gastro-duodenal openings close together at the top of the globe (Fig. 11). There is a normal triangular duodenal cap to the right of the mid line. The dudodenal loop is simple, without redundancies, and the duodenal loop sweeps round in a smooth curve to the duodeno-jejenual flexure to the left of the mid line and below the mid abdomen. Beale - Radiological study of the kiwi 197 The jejunum then sweeps back across to the right of the mid line and becomes indeterminant loops of small gut. Both the duodenum and the jejunum show intense pallisades of "glands" rather than plicae-circulares. The examination was not carried out long enough to see the ileum. The embryological studies of Parker (1891) were not directed to the gut, but I gained the impression, during the videotaping of the gastric movements, that the stomach may have been a simple tube which developed into a muscular sac by the apposition of adjacent aspects of the lesser curves and their subsequent fusion and obliteration. The Stomach and Duodenum - Physiology The stomach was impassive through most of the observed time as it was passively filled via an oro gastric tube. One convulsive episode of peristaltic activity then occurred lasting several seconds. A coarse, fast, large complex peristalic wave spread around the outer border of the stomach from the cardio-oesophageal junction towards the duodenal opening. As part of the complex wave, there seemed to be also a band of activity as though the stomach was being squeezed circumferentially from the most inferior aspect upwards. Intragastric pressure was obviously raised as the stomach volume decreased. The barium solution was ejected through the duodenal cap and rushed as far as the second loop of the jejunum. Minor amounts of barium solution escaped into the abdominal oesophagus as gastro-oesophageal reflux. The amount of reflux was small, indicating good cardio oesophageal sphincter control. After the first few seconds of violent activity, nothing further was observed over the next thirty seconds. During the activity the grinding affects of the resident gastric grit was obvious. The violent stomach activity induced duodenal peristaltic activity with coarse, fairly slow, to and from stripping-type waves occurring in the second and third parts of the duodenum. No jejunal activity was observed. Gut Transit Time An unanaesthetised bird had an oesophageal tube inserted and 30 ml of barium was introduced into the stomach. At three and a half hours the suspension was in the lower gut and by four hours the suspension was being excreted. The bird was an injured one being cared for in a small enclosure. The procedure was carried out in the early afternoon and the bird had been in the resting state for several hours before this test. Summary The kiwi's oesophagus is an uncomplicated narrow tube of homogeneous form throughout its length. Its peristaltic activity is a stripping wave that moves down the oesophagus at about 1 cm/second. The wave commences in the neck and travels to the cardio-oesophageal junction. The diaphragm produces a minor pseudo-sphincter action with the cardio-oesophageal junction being a major sphincter area. The stomach is a muscular sac. Peristaltic activity seems to be infrequent but violent when it occurs, and the grinding action of the grit is apparent as the stomach contracts. Contraction reduces the stomach volume and ejects gastric contents into the duodenum and beyond. Duodenal peristaltic activities are to and fro coarse, fairly slow (less than 1 cm/second stripping-type waves of peristalsis. OTHER OBSERVATIONS Anaesthesia for kiwis The kiwi is a nocturnal bird and dislikes being disturbed in daytime. Moreover the handling procedures (extraction from its sleeping burrow, placement in a carryingbox, the noises of a car ride and removal from the box into the light of a radiographic room) are probably traumatic, as they would be for any wild bird. On the other hand, individual birds, used to being handled in captivity, become more placid than their wild relatives. The degree of distress suffered during handling modifies the bird's response to the anaesthetic agent. 198 Journal of the Royal Society of New Zealand, Volume 15, 1985 Ketalamine Intramuscular ketalamine was evaluated at 20 mgm/kg with birds weighing 1.8-2.2 kg. Induction time was about two minutes, but this was variable and the response was quite dependent on whether the bird was calm or agitated. Intramuscular supplements were also variable in their action. No deaths or anaesthetic frights were recorded, but ketalamine is a barely satisfactory anaesthetic for kiwis. The distraction of having to give supplementary injections and wait for a response prolonged observation procedures unnecessarily. Halothane Halothane is more effective. A gauze pad soaked in halothane and placed over the bird's nostrils gives rapid anaesthesia, and the removal of the pad gives an equally rapid recovery. Longer anaesthesia by the same technique produced an increasing post anaesthetic effect. No deaths or anaesthetic frights occurred. Air Sacs In two dead adult birds the airways (including the air sacs) were filled with a solution of dental casting material made radio-opaque by the addition of barium sulphate powder, and the amount of filling was controlled by x-ray fluoroscopy. In each case the volume of the airways including the trachea was approximately 170 ml. During filling, no dental mix penetrated below the diaphragm or into any bone. This observation confirms that of Huxley (1882) on the respiratory anatomy of the kiwi. Diaphragm Huxley (1882) has shown, by dissection, that the kiwi possesses a diaphragm but that it is different to the diaphragm of mammals. He also says that there is no phrenic nerve and that innervation is via intercostal nerves. Whatever the anatomical form may be, diaphragm movements, when viewed fluoroscopically, are as one would expect to see in man. Respiration involves both radial movements of the chest wall with associated rib movements, and rostral caudal movements of the domes of the diaphragm. Respiratory movements are a combination of chest wall and diaphragm movements, and in man this requires both phrenic and intercostal nerves. Blood Analysis The only fresh blood obtained was recovered during the dispatch of a bird with leg injury. The bird had been damaged approximateely 24 hours earlier in a gin trap, and since then it had had no food or fluid. Almost clear leg feathers indicated a fairly small blood loss. Despite the presence of an anticlotting agent in a collecting tube intended for sampling human blood, the kiwi blood clotted very rapidly and full blood analysis was impractical. The following serum analysis, including electrophoresis, is valid, with the proviso that the glucose level may have been raised by stress and the potassium concentration may have been raised by any slight haemolysis that could have occurred during collection. The blood was collected from a severed artery rather than by a venepuncture. alpha 1 globulin 1 gil 1% sodium 148 mmol/l alpha 2 globulin 22g/l 42% potassium 5.7 mmolll beta globulin 4g/l 8% glucose 10.6 mmol/l gamma globulin 7g/l 13% urea 5.1 mmol/l total globulin 33g/l 63% albumin 199/l 37% Kiwi Eggs Two eggs became available from the same infertile captive female. She was a large (2.8 kgm) bird in a fairly small run. A mate was introduced in early autumn, and over the next few days she attacked him several times and ultimately killed him. The infertile Beale - Radiological study of the kiwi 199 eggs were laid in early spring (in early August and on October 1st), and at least one more egg was laid during the same spring. The first egg was almost cylindrical and its volume was 342 ml, its length 127 mm and its maximum diameter 73 mm. The second egg was more normally shaped and its volume was 370 ml, its length 127 mm and its maximum diameter 76 mm. The recorded weights were 413 grams and 403 grams, but it seems likely that the 413 grams is not correct-the expected weight based on the egg's volume should be 380-385 grams. Radiographs of the eggs showed that the shells had a uniform thickness throughout and in both the air bubbles were at the blunt end (Fig. 12). Fig. 12-A radiograph of one of the two kiwi eggs recovered during an early stage of the study. A hen egg has been included for comparison and a 28 mm diameter coin makes up the picture. The shells of both eggs are of uniform thickness. Each has an air sac and a brief study of fresh hen's eggs showed that the air sacs develop after delivery while the eggs are undergoing their initial cooling. One assumes that the same process occurs in .the kiwi's egg. E-kiwi egg, e-hen's egg, c-28 mm diameter COIn Although these two eggs were laid by a captive bird, they correspond more closely to the eggs of wild than of captive kiwis, as recorded by Reid (1981). The average wild egg was 125 mm x 80 mm and weighed 430 grams. The average captive egg was 115 mm x 72 mm and weighed 345 grams. The variations in the shapes of the two eggs examined were within the normal range. ACKNOWLEDGEMENTS I am grateful for the help of many people during this study, particularly my partner Dr Peter Durward, the staff of our Practice and the Radiology Department of the Rotorua Public Hospital and Mr Rick Buchanan; the administration and the wildlife staff of the Rainbow and Fairy Springs Tourist Park; the Rotorua office of the Wildlife Branch of the Internal Affairs Department and their Wellington Research and Library Sections; Mr D. P. S. Williamson of the National Radiation Laboratory; and the Editor and the Referee of the Journal of the Royal Society. The opportunity to study kiwis as I have done is a very rare one indeed. REFERENCES Calder, William A., 1978. The kiwi. Scientific American 239: 132-142. Caithness, T. A., 1971. Sexing kiwis. Zoological Society of London Zoology YearBook 11: 206-208. Farner, D. S., Chivers, N., and Riney, T., 1956. The body temperature of the North Island kiwi. Emu 56: 199-206. Huxley Thomas H., 1882. On the respiratory organs of Apteryx. Transactions of the Zoological Society of London 38: 560-569. Lindsay, B., 1885. On the avian sternum. Proceedings of the Zoological Society: 684-716. Owen, Richard, 1841. On the anatomy of the Southern Apteryx (A. australis). Transactions of the Zoological Society of London :L: 257-296. 1849. On the anatomy of the Southern Apteryx (A. australis) Part II. Transactions of the Zoological Society of London 3: 277-300. 200 Journal of the Royal Society of New Zealand, Volume 15, 1985 Owen, Richard, 1871. On Dinornis (Part XVI). Transactions of the Zoological Society of London 7: 381-394. Parker, T. J., 1888a. Preliminary note on the development of the skeleton of the Apteryx. Proceedings of the Royal Society of London 43: 391-397. 1888b. Second preliminary note on the development of the skeleton of the Apteryx. Proceedings of the Royal Society of London 43: 482-487. 1891. Observations on the anatomy and development of the Apteryx. Philosophical Transactions of the Royal Society of London 182 (B): 25-134. ___ 1892. Additional observations on the development of Apteryx. Philosophical Transactions of the Royal Society of London 183 (B): 73-84. Reid, B., and Williams, G. R., 1975. The Kiwi. In G. Kuschel (Ed): Biogeography and Ecology in New Zealand, pp. 301-330. W. Junk, The Hague. Reid, B., 1981. Estimating the fresh weight of the eggs of the brown kiwi. Notornis 28: 288-291. Romer, A. S., 1977. In T. S. Parsons (Ed): The Vertebrate Body, p. 172. W. B. Saunders Co., Philadelphia. APPENDIX Radiographic procedures and aspects ofradiation In four and a half years, between 12 November 1979 and 9 May 1984, 22 examinations were made averaging two radiographs per examination of the whole bird. The film used was Du Pont or Fuji medical x-ray film; the intensifying screens were Du Pont hi-plus; the radiographic factors were in the range of 70 Kvp, 200 rnA, 0.02 sec; and the film anode distance was 150 cm. (Some of the initial examinations were done in the bird's pen using a 15 rnA portable x-ray unit). Nine examinations were performed in the first six months, at weekly intervals to begin with, progressively extending to six weekly intervals. During the next four years the intervals were further extended to six monthly. Williamson (pers. comm. 1984) made a tissue phantom of the bird using National Radiation Laboratory calibration details of our equipment. The estimated mid body dose per exposure for the adult bird was 13 p,Gy. In Rotorua the level of outdoor natural terrestrial gamma is about 170 p,Gy year-1 with a variability of ± 10%. The amount of x-radiation per film received by the bird is in the same order as the variation in natural gamma radiation. In the four and a half years of the study the total dose would be commensurate with that from the natural gamma radiation. By further comparisons the annual dose equivalent limit for occupationally exposed persons is 50 mGy; and in radiotherapy, dosages are measured in tens of grays. Much more important than the inherent safety of the study is the range and type of information that radiology can obtain. Newer organ imaging techniques including ultrasound, nuclear medicine, computerised tomography and others are expanding the specialty very significantly and radiology promises much for other branches of Science. Received 17 September 1984; accepted 16 January 1985.
