Avian eggshell thickness: scaling and maximum body mass in birds

Birchard, G. F. and Deeming, D. C. (2009) Avian eggshell thickness: scaling and maximum body mass in birds. Journal of Zoology, 279 (1). pp. 95-101. ISSN 0952-8369

Full content URL: http://dx.doi.org/10.1111/j.1469-7998.2009.00596.x

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The avian eggshell represents a highly evolved structure adapted to the physiological requirements of the embryo and the potential fracturing forces it is exposed to during incubation. Given its many roles, it is not surprising that the eggshell is also central to the current hypothesis about maximum avian body mass. Eggshell thickness (L) and strength has historically been scaled as a function of initial egg mass (IEM). However, maximum incubator mass (IM) is likely a better indicator of the forces the shell must be selected to withstand during incubation. We
compare the results of analyses of L2 (an indicator of shell strength) as a function of IEM and IM. We conclude from IM scaling that megapode and kiwi eggshells are not thin but rather are thicker than expected and in general birds with a clutch size of 1 have thicker shells, and further, that reversed sexual dimorphism in the large, particularly extinct birds may be a strategy to avoid shell breakage during incubation of the largest eggs without creating a shell so thick as to inhibit hatching.

Keywords:eggshell, scaling, body size, bird, incubation, moa
Subjects:C Biological Sciences > C100 Biology
Divisions:College of Science > School of Life Sciences
ID Code:3900
Deposited On:28 Jan 2011 09:01

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