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Growth of Tasmanian Muttonbirds

Keywords: Jagged growth curve, storage model


Following the Second World War, D. L. Serventy carried out a detailed study of the lifecycle of the Tasmanian muttonbird (Puffinus tenuirostris, often called the short-tailed shearwater). The data here concerns the growth pattern of fledgling birds of this species.

After the eggs hatch, the parent birds spend much time away from the next, and with increasing time their returns become rarer and rarer. When they return the young bird feed copiously, and there is very rapid weight-gain; whilst they are absent, the offspring loses weight. The result is not a smooth growth curve such as one finds in most measurements in developing animals and birds, but a 'sawtooth' effect. The data were collected in 1954 as weighings each morning of two fledgling chicks on Fisher Island, Bass Strait, and each set terminates on the day the chick left the nest.

Much of the interest in these curves comes not from the description they give of the weight of the chick, but from the information they contain on the feeding patterns of the parents. There are three obvious features of the data; the timing of the feeds and the size of the feeds when they occur, both of which represent aspects of the feeding pattern of the parents; and the loss in weight of the chicks between feeds. Henstridge and Tweedie (1984) proposed a model, similar to those used in storage theory, which describes each of these phenomena separately.


Data file (tab-delimited text)


Henstridge, J. D., and Tweedie, R. L. (1984). A model for the growth pattern of muttonbirds. Biometrics, 40, 917-925.



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