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Thickness of 1967-69 whooping crane eggshells compared to that of pre-1910 specimens

Daniel W. Anderson·J.F. Kreitzer
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Abstract

Table 1 summarizes measurements of pre-1910 Whooping Crane ( Grus americana ) eggshells obtained from 10 North American museums and private egg collections. They include 30 eggs from Iowa, 5 from North Dakota, 13 from Manitoba, and 2 each from Saskatchewan and Alberta; 11 of the eggs were classified as subelliptical and 41 as oval according to the shapes described by Palmer (1962: 13). Mean clutch size of 29 sets averaged 1.83. We found no significant geographical variations (P < 0.20) among eggs from different portions of the former range (Allen, 1952: 19) of the Whooping Crane, although geographical variations in size and weight are known to occur in the eggshells of the Sandhill Cranes ( G. canadensis ), which are more widely distributed and more taxonomically diverse (Walkinshaw, 1949: 68-70). The average thickness and weight of the 52 eggshells were 0.60 mm and 20.1 g, respectively. These measurements are similar to those of Allen (1952: 180), citing M. Schonwetter, who gives the average thickness of Whooping Crane eggshells as 0.58 mm and the average shell weight as 20.75 g (n = 14 weights).

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Daniel W. Anderson, J.F. Kreitzer. 1971. Thickness of 1967-69 whooping crane eggshells compared to that of pre-1910 specimens. https://doi.org/10.2307/4083896

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