A Note on a Green Moa Egg from Chatto Creek, Central Otago

Transactions and Proceedings of the Royal Society of New Zealand, Volume 83, 1955-56, Page 223

A Note on a Green Moa Egg from Chatto Creek, Central Otago L. O. Simpson [Received by the Editor, September 14, 1954.] Abstract On the 5th November, 1953, Mr. Mclean, of the Otago Dental School, brought into the Otago Museum a large number of fragments of a green moa egg. He had received them from Mr. C. I. Irwin, of Black's School, Ophii. The egg had been uncovered by a Rabbit Board employee, while falling a bank to fill in a rabbit warren. Unfortunately, the egg, which had been nearly complete, was shattered by a blow from a pick. Mr. T. R. Beatson, of the Otago Museum staff, has made an exceedingly fine reconstruction of the fragments, piecing together nearly three-fifths of the original. The reconstruction showed the egg to be 16 cms. in length, 10.75 cms. in diameter at its widest part and to have an approximate volume of 976 ccs. This is by no means the first record of green shell from sites in Otago, although there are no reports of green shell outside the province. White (1876) described pieces of egg shell of greenish colour, which appeared to him to be parts of a large egg, probably that of a large duck. When more green shell was recovered from a sand drift in 1886, the same author presumed that the shell lost its colour by bleaching. In the Otago Museum Collection there is a piece of moa eggshell collected by White in 1875 at Mt. Nicholas, Lake Wakatipu, and labelled, “Egg shell of Moa (green)”. To-day these pieces of shell are quite white. Sinclair (1939) in a report on the excavation of a cave at Wickliffe Bay also records green egg shell, but did not think the shell was Moa egg shell (p. 142). In a personal communication (January, 1954) L. Lockerbie states that, as far as he is aware, the only site to produce green Moa egg shell in any quantity is Pounawea. There, the green shell is found in an ash layer lying between an upper loose shell deposit and, a lower black greasy deposit, and associated with refuse material (chiefly bones) and artefacts. On the 29th November a party comprising the honorary archaeological staff of Otago Museum and the author, journeyed to Chatto Creek to investigate the site, for a large number of fragments of white Moa egg shell had been reported in association with the green egg. The site was in an eroded gully in the foothills on the western side of Chatto Creek. Due to the complete lack of vegetation except scattered cushion plants, the eastern face of the foothills is steeply eroded. The main erosion—channels run downhill from west to east, and into these at various angles run a great number of smaller tributary channels. About half way to the top of the foothills, the gully in which the egg was found runs downhill for some 230 feet from south to north. On the 21st December a second party, comprising Miss J. Harding, Exhibition Officer, Otago Museum, Mr. J. B. Mackie, Lecturer in Surveying, Otago School of Mines, and the author, returned to the site to survey the area. The profile and sections of the gully figured in this paper are a tribute to the technical skill of Mr. Mackie, who was wholly responsible for their preparation. On the second

visit no digging was carried out. A number of pieces of green egg shell had been washed out of the debris of the previous dig by heavy rain which had since fallen. Digging on the site revealed over 500 fragments of white Moa egg shell, which is nearly twice as thick as the green shell, and which in Mr. Beatson's opinion, represent at least four different eggs. Late in the afternoon a number of green shell fragments, which fitted in Mr. Beatson's reconstruction, were recovered some five feet higher than the original finding place, as shown in Fig. 1, Plate 1. Several bones recovered from the same region as the egg shell were sent to Dr. W. R. B. Oliver for identification. All of these were referable to the species Euryapteryx gravis. Dr. Oliver remarks of the femur, “the length agrees better with Euryapteryx than it does with Zelornis”. Bones from a skeleton in a neighbouring gully were all identified as Pachyornis elephantopus. Fig. 1.—Profile of the gully in which the Moa egg was found. S1, S2, S3, S4, are the subsidences mentioned in the text. Figs. 2, 3 and 4.—Cross sections at A, B, and C respectively. Discussion It is unlikely that the identity of the eggs from this deposit will be established with absolute certainty. Oliver (1949, p. 44) gives formulae by which the size of the egg may be calculated from the measurements of certain bones. By using the measurements of the egg in reverse, the green eggs would belong to Megalapterous didinus. Oliver suggests this on p. 46 of his book. From a consideration of the numerous finds in this region of material of the above species it is reasonable to accept Oliver's guess as correct. Three main points concerning this provisional identification are:

(1) By the number of specimens preserved, Otago Central appears to have been well populated in the past by Megalapterous didinus. (2) Lockerbie reported green shell from Pounawea and Papatowai. From the latter site the distal end of a right femur of Megalapterous didinus has been collected. (3) Oliver's formula provides measurements which are well within the normal range of individual variation. The fact that the measurements were determined before a whole egg was available for study is noteworthy. The fact that bones of Megalapterous didinus have not been found on the site is possibly a reflection on the relative numbers of this species in the region in comparison with the numbers of Euryapteryx gravis and Pachyornis elephantopus. If, as Oliver suggests, the green egg belongs to Megalapterous didinus, then his suggestion that the eggs of Pachyornis elephantopus were white to creamy is all the more worthy of consideration. The number of bones of Euryapteryx gravis and Pachyornis elephantopus in the region could well be related to the great amount of white egg shell found in the deposit. Should further excavation reveal bones of Megalapterous didinus it would be decisive support for Dr. Oliver's deduction. In an endeavour to record the colour of the Chatto Creek egg against the possibility of future bleaching, the colour was identified as Hue No. 32.5, 5/3, Hue Symbol 2.5 Gy. in Munsell's Book of Colours. Although this shade did not perfectly correspond, it was very close to the natural colour, which may be best described as olive green. Distribution of the shell in the deposit appeared to be completely random, and there was nothing to confirm Duff's (1950) statement, p. 276 that. “Apparently the upper arch of the egg yields first, the pieces often sliding down inside the walls or sides, to he cupped at the bottom. The sides may collapse next after suffering considerable abrasion at their upper margin, the bottom becomes worn and thin from external pressure, and the top pieces which first broke away remain the soundest portions of the egg.” Even though the shell fragments had been water transported, the broken edges were quite sharp, and there was no evidence of unequal wear such as is mentioned by Duff. The lack of abrasion exhibited by the shell was in sharp contrast to the condition of bones from the same deposit, which were badly worn. Two explanations are offered to explain the difference in position of the green egg and the green shell fragments. The first is that the egg had been broken at a higher level, and only the larger part carried down to the low level deposit. On a considerably later date the smaller part was carried down and re-deposited at a higher level, which is represented by the fragments recovered on the 21st December. The second explanation is that the egg was broken and deposited at the level indicated by the shell fragments. A subsidence caused by the collapse of the roof of the subterranean watercourse which undermines the gully, could explain the difference in the deposit levels. The author inclines to the latter view. Reference to Fig. 1 shows that subsidences have occurred in no less than four places, which are indicated in the figures as S1, S2, S3 and S4. Further digging may assist in a better understanding of this gully deposit. No explanation of the presence of the large amount of white shell is advanced in this note. The author is indebted to Dr. H. D. Skinner for the opportunity of reporting this find to Mr. T. R. Beatson, Mr. L. Lockerbie, Mr. R. Law, and Mr. W. Collet,

for their assistance. Special thanks are due to Mr. J. B. Mackie for an accurate survey, which is the basis of the figures, and to Dr. W. R. B. Oliver for identification of the bones. References Duff. R., 1950. The Moa-Hunter Period of Maori Culture. Department of Internal Affairs, Wellington, 405 pp. Oliver, W. R. B., 1949. “The Moas of New Zealand and Australia,” Dominion Museum. Bull. 15. Sinclair, E. D., 1939. “Excavation of a Cave, Okia Flat, Wickliffe Bay.” Jour. Polyn. Soc 49, 137. White, T., 1876. “Moa Caves in Wakatipu District” Trans. N. Z. Inst. 8, 197. L. O. Simpson, M.Sc. Central Medical School Suva, Frji.