Aepyornis eggs: History, characteristics and market

Transcription

1 Aepyornis eggs: History, characteristics and market Kurt Schläpfer Prof. Dr. K. Schläpfer, St. Gallerstrasse 60, CH-9032 Engelburg, Switzerland May 2015 Summary The aim of this article is to establish a list of all existing Aepyornis eggs. The relevant sources are earlier published egg lists, further articles dealing with Aepyornis eggs, personal inquiries and searches in the Internet. For a reliable inventory of the Aepyornis eggs a distinction has to be made between eggs in institutional possession, i.e. owned by museums, universities etc. and eggs in private possession. While the number of institutional owners is fairly exact to determine, the number of privately owned eggs can only be estimated. A helpful indicator is the information of auction houses about sales of Aepyornis eggs. Based on published purchases, the author estimates that the number of privately owned eggs is more than 30. For the eggs in institutional possession a list is presented showing 78 eggs in 19 countries. The dimensions (length and width) are specified for 63 eggs from which the volumes and the egg weights have been calculated. According to these calculations, the average Aepyornis egg has the following data: Length: 30.6 cm With: 22.5 cm Volume: 8.12 litres Egg weight: 9.34 kg Eggshell weight: 1.64 kg

2 2 A third part of this article is dedicated to the role of Aepyornis eggs as an article of trade. This market does not only include the category of more or less intact eggs, but there are also Aepyornis eggs on sale which are reconstructed from eggshell fragments of different eggs. Another category of growing importance are the replica. Introduction One can safely say that the eggs of the aepyornithids (elephant birds) are more famous than the bird itself. This is due to the fact that considerably more eggs exist than other remains of the bird. In addition, the eggs are the biggest that an animal has ever laid, whereas the elephant bird itself was not the largest bird of all time, but possibly the heaviest.fossil evidence indicates that several species of elephant birds ranging from 90 cm to 3 metres in size had inhabited Madagascar, but most had died out long before our time. The taxonomy of elephant birds is still subject of debate, in particular as to the actual number of species involved. A widely accepted consensus is that seven or eight species once occurred on Madagascar, four in the genus Aepyornis and three or four in Mullerornis. However, for the genus Aepyornis numerous authors tend to assume that there is just one species, the Aepyornis maximus. This species has most probably survived until The species of the genus Mullerornis represent the smaller elephant birds which are known only from subfossil remains and from which no egg has been preserved. A bone belonging to Mullerornis has been radiocarbon dated to about 1260 before our era, suggesting that the bird was still extant 3300 years ago. As all currently existing eggs originate from the genus Aepyornis, and as it is likely that all eggs belong to one species, they are simply called Aepyornis eggs. The purpose of this article is to establish primarily a list of all existing Aepyornis eggs. Between 1901 and 2003 five

3 3 egg lists have been published (see references), but the latest does mainly summarize earlier egg lists and has very few new entries. Almost all eggs listed in these publications are in institutional possession, i.e. owned by museums, universities etc. But there are also Aepyornis eggs in private possession. A further goal is therefore to identify as many of these eggs as possible. From the eggs specified with their dimensions, it is interesting to calculate the egg volumes and egg weights in order to find the average values of an Aepyornis egg. As in recent years many eggs have been offered at auctions, the last part of this article deals with the role of Aepyornis eggs as article of trade. The history of the elephant bird eggs Around 1850 it was unknown in central Europe that a bird species called "elephant bird" has lived 200 years before in Madagascar. Although an article appeared in 1849 about the supposed existence of a giant bird in Madagascar, it was its egg leading to the first contact with the bird, and the bird itself (or what was left of it) was discovered later. In 1850 the captain of a French merchant ship stayed in Madagascar and discovered in the house of a villager a drinking vessel, which on closer inspection turned out to be the shell of a large egg whose upper part was removed. He asked the villagers whether they can also provide intact eggs and, as a result, he obtained three pieces which he brought to Paris. Unfortunately, one of the eggs broke to pieces. The eggs were given to the French zoologist I. Geoffroy Saint-Hilaire who assigned them to a new species, which he called Aepyornis maximus. (The name Aepyornis is derived from the ancient Greek and means as much as "tall bird"). 1851, he presented these eggs to the Academy of Sciences in Paris. Four years later, he was able to show the next two eggs. Museums became soon aware that these eggs are an interesting collector's

4 4 item, with the consequence that the number of eggs coming to Europe was rapidly growing. As early as in 1901, a first list of eggs was published comprising 33 entries, 30 of which were described by their dimensions. The publication was accompanied by a bibliography that only 50 years after the discovery of the eggs and the bird already included some 50 titles. Other egg lists were published in 1931, 1957, 1960 and in Not the most comprehensive but the most detailed list appeared in 1960 in the "Handbuch für Oologie", Vol. 1, by Max Schönwetter (see appendix 2). Apart from the dimensions of the eggs this list includes the eggshell weight and the eggshell thickness. Schönwetter has only listed eggs owned by museums and universities, because he verified all data with own measurements or through personal inquiries. Other lists also contain eggs in private property, however, with sometimes unreliable data. It is not easy to obtain an overview of all currently existing eggs. In particular, the eggs in private possession are difficult to count. The fact that auction houses frequently offer Aepyornis eggs for sale suggests that the number of privately owned eggs may be considerable. In the last 15 years, over 25 of such eggs have been sold at auctions. What is not evident from the existing lists are the eggs outside of Europe. It is clear that soon after the first appearance of the Aepyornis eggs American museums and universities showed interest in these objects. Unfortunately, no list has ever been published about the number of eggs kept in America. A search on the Internet and personal inquiries show that probably 13 institutions (museums, universities etc.) in the USA and in Canada own together 19 Aepyornis eggs. One major owner is the Western Foundation of Vertebrate Zoology in Camarillo, California with six intact eggs and fragments of a seventh egg. Other eggs are in India, Australia and New Zealand. Swit-

5 5 zerland is represented with eight eggs, two located in Zurich and one each in Freiburg, Bern, Solothurn, Basel, Schönenwerd and Geneva. A list of all Aepyornis eggs classified by countries (see table 1) shows a total number of 78. This list only considers the institutional owners and is probably not free from uncertainties, because some information used for this compilation dates back very far. TABLE 1 Aepyornis eggs in museums and in institutional collections (without privately owned eggs and eggs sold at auctions) Country Number Australia 3 Germany 9 United Kingdom 10 Finland 1 France 14 Greece 1 Netherlands 2 India 1 Ireland 1 Italy 1 Canada 1 New Zealand 1 Austria 1 Poland 2 Russia 1 Switzerland 8 Slovakia 1 Hungary 1 USA 19 Total 78

6 6 While some eggs listed in European countries may have changed their owner, it is possible that further eggs are in countries not listed here, as for instance in China or in Japan. What is even more difficult to determine is the number of privately owned eggs. Based on data from auction sales and from existing egg lists, it is likely that more than 30 eggs are in private possession. When estimating the number of existing Aepyornis eggs, it is assumed that all identified eggs are intact. This, however, is only partially correct. Many eggs are partly broken or have missing shell fragments, and some eggs are pieced together from their eggshell fragments. In contrast to this, there are Aepyornis eggs on sale which are reconstructed from eggshell fragments of different eggs. The number of such eggs has increased in the last years and a to list them is beyond the scope of this article. Characteristics of Aepyornis eggs Table 2 shows a listing of 63 eggs whose dimensions are known from publications or from other sources. Using the values for the length and the width, the author has calculated the volume and the weight of the eggs. Weight values are often preferred to compare the eggs of different birds. However, the weight cannot be calculated from the length and width alone. At least one additional value, either the specific weight or the weight of the eggshell, is needed. In the egg list of Max Schönwetter (see appendix 2) the egg weight has been calculated for 23 eggs from the egg volume and the eggshell weight. From these data a specific weight of 1.15 can be derived.

7 7 TABLE List of 63 Aepyornis eggs sorted by volume Measured values Calculated values Length mm Width mm Eggshell weight g Volume ml Mass g Toulouse FRA Bonn GER Perth AUS Heritage Auctions Dublin IRL Solothurn SUI London GBR St. Omer FRA Tring GBR Bern SUI Dresden GER Tring GBR Sens FRA Berlin GER Bonn GER Camarillo USA Private Athen GRE Lyon FRA Camarillo USA Leiden NED Basel SUI Freiburg SUI Bologna ITA Tring GBR Paris FRA Camarillo USA Heritage Auctions Schönenwerd SUI Frankfurt GER Camarillo USA Quebec CAN Paris FRA Private

8 8 Measured values Calculated values Length mm Width mm Eggshell weight g Volume ml Mass g Stuttgart GER Wien AUT Christie's Dresden GER Hildesheim Heritage Auctions Camarillo USA Budapest HUN Private St. Omer FRA Private Paris FRA Paris FRA Warmbrunn POL Perth AUS Private Christie's Tring GBR Private Private Tring GBR Camarillo USA Private Helsinki FIN Paris FRA Bhubaneswar IND Christie's Denver USA London GBR Mean value In contrast to the weight, the volume of Aepyornis eggs can be calculated almost exactly from the length and width, because the eggs have a nearly ideal elliptical form (see appendix 3). The calculation shows that the volume of the present 63 eggs varies between 5.2 litres and 10.7

9 Frequency 9 litres. This variation range appears large, as the largest egg is more than twice as large as the smallest egg. But a comparison with the eggs of other bird species shows that this variation is not abnormal. Ornithologists have repeatedly tried to assign the different egg sizes to other species. This has never led to conclusive results, because the different egg sizes cannot be divided in recognizable groups (see figure 1). Aepyornis eggs '500 Egg volume ml FIGURE 1 Frequency distribution of the volume of Aepyornis eggs As an additional characteristic the eggshell weights are specified for 33 eggs in table 2. The values range between 1116 g and 3346 g what is a variation of a factor of three. An explanation for this large range could be that some eggs are not completely blown out and may contain residual particles leading to a higher eggshell weight. By omitting three conspicuously large values, a mean value of 1643 g is obtained. From this an average eggshell thickness of 3.61 mm is calculated (see appendix 3). The calculated weight values of the present 63 eggs range from 6.0 kg to 12.3 kg.

10 10 To summarize the calculations of the author, an average Aepyornis egg has the following metrics: Length: 30.6 cm With: 22.5 cm Volume: 8.12 litres Egg weight: 9.34 kg Eggshell weight: 1.64 kg Eggshell thickness: 3.30 mm Specific weight (of the full egg): 1.15 Just to remind: An average chicken egg weighs 60 g, and an ostrich egg the biggest egg which is laid by an extant bird 1.6 kg. This permits the following comparison: The weight of an Aepyornis egg corresponds to nearly six ostrich eggs and to about 155 chicken eggs. It is clear that an egg with a capacity of 155 chicken eggs was a welcome food source for the local population of Madagascar, so that the excessive hunt after these eggs might be one of the reasons, why the elephant birds became extinct. The Aepyornis eggs as article of trade There are not only the eggs stored in museums, but there is also a veritable market for collectors or institutions who want to acquire such an egg (or a replica). The eggs offered for sale can be divided into the following categories: Completely intact eggs: These are not blown out or have a blowhole of a few centimetres of diameter. Such eggs are offered by auction houses (e.g. Christie's or Sotheby) where they fetch very high prices (examples see below). Eggs with cracks or missing shell fragments or with inserted fragments, (if they origin from the same egg).

11 11 Eggs which are composed from shell fragments of different eggs: If it is an almost seamless reconstruction, such eggs are also offered at auctions under the term "reconstructed eggs". Eggs with visible adhesive joints are sold by fossil retailers and on Internet platforms for prices of more than 1,000 US$. Replica eggs made from plaster with glued-in eggshell fragments: Eggs of this kind are produced in Madagascar and sold on local markets or abroad. Genuine eggshell fragments can still be found on some beaches in the south of Madagascar. However, the exportation of such fragments is forbidden for tourists. Replica eggs completely made from plastics (polyurethane resin) and hand-finished to simulate the shell structure: Such copies look deceptively real and are for sale for less than 50 US$. FIGURE 2 Immaculuate Aepyornis egg (together with a chicken egg) FIGURE 3 Carefully made reconstruction from shell fragments of different eggs

12 12 It is clear that museums were always anxious to acquire genuine and intact Aepyornis eggs for their collections. However, while the eggs of extant birds have no sales prices, Aepyornis eggs had always to be acquired by purchase. Therefore, it might be of interest to see how the prices in this "market" developed. Before 1900, typical sales prices in Germany were between 500 and Mark. Today this would correspond to about 2,500 to 10,000 US$. Around 1900, Aepyornis eggs were traded in the USA and in Great Britain for 200 to 1,100 US$ (today about 5,000 to 27,000 US$). For the time from 1900 to 2000 only little information on sold eggs is available. In 1971, an egg was sold by Sotheby on an auction for 1,000 (today about 15,000 US$) what was at that time an attractive price. But after 2000, over 25 Aepyornis eggs were offered for sale at auctions. Here some prize examples for immaculate eggs: Year Auction house Price US$ 2004 Binhams 41, Christie's 97, Christie's 134, Christie's 57, Christie's 68, Sotheby 47, Christie's 101, Christie's 205,555 As this small list shows, typical prices for intact eggs are nowadays above 50,000 US$. But the enormous price differences and in particular the maximum price of more than 200,000 US$ are difficult to explain. Clearly, even intact eggs show certain differences in their size and shell structure. But this cannot satisfactory explain the huge price differences. Maybe the most expensive egg was simply at the right time for sale, when several bidders wanted to buy

13 13 this egg at any price. In contrast to intact eggs, reconstructed eggs are offered only seldom at auctions. But if so, they can achieve prices up to 20,000 US$. Reconstructed eggs looking less immaculate are often found on Internet platforms, sometimes for prices less than 5,000 US$. FIGURE 4 Reconstruction with conspicuous adhesive joints FIGURE 5 Replica made from polyurethane resin with hand-finished shell surface

14 14 Appendix 1 Table 1: Specified values for 49 Aepyornis eggs in museums and in institutional possession (Missing values mean that they are not specified by the source.) Place (where the eggs were at the time of publication) Length mm Width mm Eggshell weight g Literature/source Perth AUS Long 1998 Bhubaneswar IND THE HINDU 2008 Helsinki FIN Schönwetter 1986 Quebec CAN Schönwetter 1986 Sens FRA Schönwetter 1986 Perth AUS Long 1998 Dublin IRL National Museum of Ireland Freiburg SUI NZZ 1987 Wien AUT Steindachner 1910 Toulouse FRA Henrici 1957 London GBR Schönwetter 1960 Solothurn SUI Henrici 1957 Bern SUI Mlikovsky 2003, Henrici 1957 Basel SUI Henrici 1957 Schönenwerd SUI Henrici 1957 Paris FRA Eastman 1898 Denver USA Bradbury 1919 Bonn GER Schönwetter 1960 St. Omer FRA Schönwetter 1960 Tring GBR Schönwetter 1960 Dresden GER Schönwetter 1960 Tring GBR Schönwetter 1960 Bonn GER Schönwetter 1960 Berlin GER Schönwetter 1960 Athen GRE Schönwetter 1960 Leiden NED Schönwetter 1960 Tring GRB Schönwetter 1960 Frankfurt GER Schönwetter 1960

15 Place (where the eggs were at the time of publication) Length mm 15 Width mm Eggshell weight g Literature/source Dresden GER Schönwetter 1960 Hildesheim Schönwetter 1960 St. Omer FRA Schönwetter 1960 Paris FRA Schönwetter 1960 Warmbrunn POL Schönwetter 1960 Tring GBR Schönwetter 1960 Tring GER Schönwetter 1960 London GBR Schönwetter 1960 Paris FRA Cauderay 1931 Paris FRA Cauderay 1931 Stuttgart GER Cauderay 1931 Bologna ITA Cauderay 1931 Paris FRA Cauderay 1931 Lyon FRA Cauderay 1931 Budapest HUN Cauderay 1931 Camarillo USA Corado 2015 Camarillo USA Corado 2015 Camarillo USA Corado 2015 Camarillo USA Corado 2015 Camarillo USA Corado 2015 Camarillo USA Corado 2015

16 16 Table 2: Specified values for 14 Aepyornis eggs in private possession and offered at auction Owner or auction Length Width Source mm mm Private Schönwetter 1986 Christie's Christie's Christie's Heritage Auctions Heritage Auctions Heritage Auctions Private Cauderay 1931 Private Cauderay 1931 Private Cauderay 1931 Private Cauderay 1931 Private Cauderay 1931 Private Cauderay 1931 Private Cauderay 1931 Source references Bradbury W. C. 1919: Some notes on the egg of Aepyornis maximus. Condor 21: Cauderey H. 1931: Etude sur l'aepyornis. L'Oiseaux et la Revue Française d'ornithologie 1: Corado R. 2015: Personal communication from the Collections Manager of the Western Foundation of Vertebrate Zoology. Eastman C. R. 1898: On the remains of Struthiolithus chersonensis from northern China with remarks on the distribution of struthious birds. Bulletin of the Museum of Comparative Zoology 32:

17 17 Henrici P. 1957: Aepyornis-Eier. Mitteilungen der Naturforschenden Gesellschaft in Bern 14: Long J. A. et al. 1998: The Cervantes egg: an early Malagasy tourist to Australia. Records of the Western Australian Museum 19: Mlikovsky J. 2003: Eggs of the extinct aepyornithids (Aves: Aepyornithidae) of Madagaskar: size and taxonomic identity. Sylvia 39: NZZ 1987: Neue Zürcher Zeitung, Ei eines ausgestorbenen Riesenvogels für Freiburg. Issue of October 22. Schönwetter M. 1960: Aepyornithiformes. Bd. I: Schönwetter M. 1986: Nachträge zu Band I. Bd. III: 185. Steindachner F. 1910: Jahresbericht für Annalen des k. k. naturhistorischen Hofmuseums, Bd. XXIV: 2. THE HINDU 2008: Rare collections exhibited at museums. Issue of April 8.

18 18 Appendix 2 List of 23 Aepyornis eggs from the Handbuch der Oologie, Vol. 1, page 33, by Max Schönwetter The eggs No. 12 and 21 have been destroyed in the World War II. Gemessene Grössen: measured quantities U: large circumference u: small circumference A: length B: width g: eggshell weight Berechnete Werte: calculated values d: eggshell thickness

19 19 Vol.: egg volume (cbdcm = litre) G: egg weight Rg: eggshell weight in % of the egg weight Schalengewichte hier ohne Schalenhaut: eggshell weights here without membrane Appendix 3: Calculation of the volume and the eggshell thickness An Aepyornis egg is geometrically almost identical with a spheroid which is an ellipsoid with two equal semi-axis. The formula for the volume of a spheroid is: V = 4 3. π. a. b2 (1) If the semi-axis are replaced by the diameters of an egg, the formula reads: V = π 6. A. B2 (2) where A is the egg length and B the egg width. For π 6 the factor can be used. To calculate the eggshell thickness L, the eggshell weight W S, the eggshell surface area S (which is identical with the egg surface area) and the,specific weight γ S of the eggshell must be known. The eggshell thickness is then: L = W s S. γs (3)

20 20 The surface area S can be easily calculated with the following approximate formula: S = B 2 [π (k 1)] (4) where k is the ratio of the two egg diameters: k = A/B (5) Formula (4) can be simplified to S = B 2 ( ,228. k) (5) This formula has been proposed by M. Schönwetter (Handbuch der Oologie, Vol. 4, p.109, 1985). The author has compared this formula with the exact calculation and has found a very good agreement. The following table shows the averaged measured values of the Aepyornis eggs and the therefrom calculated values. Egg length A mm Egg width B mm Ratio of diameters k Eggshell weight W S 1645 ml Specific weight of the eggshell γ S 2.5 Surface area of the egg S 1989 cm 2 Eggshell thickness L mm