New Zealand Journal of Marine and Freshwater Research abstracts
Distribution of seabirds in coastal waters off Otago, New Zealand
RICHARD L. O'DRISCOLL
Department of Marine Science
University of Otago
P. O. Box 56
Dunedin, New Zealand
MARTIN RENNER
Department of Zoology
University of Otago
P. O. Box 56
Dunedin, New Zealand
FRANK J. AUSTIN
8 Dunblane Street
Dunedin, New Zealand
HAMISH G. SPENCER
Department of Zoology
University of Otago
P. O. Box 56
Dunedin, New Zealand
Abstract The occurrence, abundance, and distribution of
seabirds was studied in a physically dynamic region off the coast of Otago, New
Zealand. Eleven line-transect surveys were conducted in late summer and autumn
of 1994-96, when surface swarms of "krill",
Nyctiphanes australis, were
present in the study area. Twenty species of seabird were recorded. The
abundance and occurrence of species varied between sitting and flying counts.
The most numerous species were sooty shearwaters (
Puffinus griseus),
red-billed gulls (
Larus novaehollandiae), black-billed gulls (
L.
bulleri), and black-backed gulls (
L. dominicanus). Most species
were recorded throughout the study area, and different species were commonly
observed together. Spatial similarity matrices revealed strongest association
between red- and black-billed gulls and black-backed gulls. The small
(kilometre) scale distribution of seabirds varied between surveys, between
transects, and between repeated runs of the same transect 1-3 h apart.
Correlations between seabird abundance, salinity gradient, and krill density
were weak. Counts of seabirds were highly positively skewed. This skewness,
together with spatial and temporal variability in the distribution of flocks,
would make abundance estimation at sea difficult.
Keywords seabirds; spatial distribution; seabird foraging;
fronts; Nyctiphanes australis; Otago
M97060
Received 6 October 1997; accepted 6 January 1998
PDF file of entire paper: medium quality (776K); (scanned from paper original: notes about this process)
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