Journal of the Royal Society of New Zealand abstracts
Maximum possible age of a petrel breeding colony near Punakaiki (South
Island, New Zealand) from radiocarbon and stable isotope analysis of soil
David J. Hawke
School of Applied Science, Christchurch Polytechnic Institute of Technology,
P.O. Box 540, Christchurch 8015, New Zealand.
Email: hawked@cpit.ac.nz
Abstract The lifetime of individual petrel colonies
is poorly known. This study used radiocarbon, 13C, and 15N
analysis of soil to determine the maximum possible age of a colony presently
occupied by Westland petrels. A sample of Ap horizon soil in lithic contact
was selected for analysis, as soil least likely to have been redistributed
by petrel burrowing. Chemical removal of mobile organic matter decreased
δ15N from 14.0‰ (typical of breeding colony soils) to 6.1‰ (within
the range of temperate forest soils without sea-bird breeding). δ13C
values changed little, from -27.1‰ (untreated soil) to -28.4‰ (treated soil),
and were typical of forest soil with C3 vegetation and no incorporation
of marine C. Duplicate AMS radiocarbon analysis of treated sample yielded
a combined conventional radiocarbon age of 864 ± 32 BP, indicating
that sea-bird breeding could not have occurred at the site for more than
740-960 calendar years. Initial colony occupation may have occurred much
later than this, and not been continuous. Sea bird species other than Westland
petrels may also have used the site.
Keywords carbon-13; New Zealand; nitrogen-15; Procellariid;
radiocarbon; Westland petrel
R03006; Online publication date 11 March 2004; Received 12 May 2003; accepted
15 September 2003;
© Journal of the Royal Society of New Zealand, Volume 34, Number
1, March 2004, pp 1-7
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