Dear Marmamers,

The following paper on resource partitioning in sympatric delphinids was recently published: 

Parra, G., J. 2006. Resource partitioning in sympatric delphinids: Space use and habitat preferences of Australian snubfin and Indo-Pacific humpback dolphins. Journal of Animal Ecology 75:862-874.

 Summary

1.	Many species of delphinids co-occur in space and time. However, little is known of their ecological interactions and the underlying mechanisms that mediate their coexistence.
2.	Snubfin Orcaella heinsohni, and Indo-Pacific humpback dolphins Sousa chinensis, live in sympatry throughout most of their range in Australian waters. I conducted boat-based surveys in Cleveland Bay, north-east Queensland, to collect data on the space and habitat use of both species. Using Geographic Information Systems, kernel methods and Euclidean distances I investigated interspecific differences in their space use patterns, behaviour and habitat preferences.
3.	Core areas of use (50% kernel range) for both species were located close to river mouths and modified habitat such as dredged channels and breakwaters close to the Port of Townsville. Foraging and travelling activities were the dominant behavioural activities of snubfin and humpback dolphins within and outside their core areas.
4.	Their representative ranges (95% kernel range) overlapped considerably, with shared areas showing strong concordance in the space use by both species. Nevertheless, snubfin dolphins preferred slightly shallower (1–2 m) waters than humpback dolphins (2–5 m). Additionally, shallow areas with seagrass ranked high in the habitat preferences of snubfin dolphins, whereas humpback dolphins favoured dredged channels.
5.	Slight differences in habitat preferences appear to be one of the principal factors maintaining the coexistence of snubfin and humpback dolphins. I suggest diet partitioning and interspecific aggression as the major forces determining habitat selection in these sympatric species.

The paper is available through the journal’s website: http://www.blackwell-synergy.com/doi/abs/10.1111/j.1365-2656.2006.01104.x

Those without a subscription to the journal can request a PDF copy from me: g.parra@uq.edu.au

Cheers

Guido

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Guido J. Parra, PhD

Postdoctoral Fellow

School of Veterinary Science
University of Queensland
St Lucia, QLD 4072, Australia

Ph: (07) 3365-3066  Mob: 0437630843
Fax: (07) 3365-1255  Email: g.parra@uq.edu.au

Webpage: http://www.uq.edu.au/vetschool/index.html?page=47564&pid=47559

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