A new paper just published
on-line:
McSweeney, D.J., R.W. Baird, S.D.
Mahaffy, D.L.Webster and G.S. Schorr. 2008. Site fidelity and association
patterns of a rare species: pygmy killer whales (Feresa attenuata) in the main
Hawaiian Islands. Marine Mammal Science DOI:
10.1111/j.1748-7692.2008.00267.x
Abstract
Most of what we know about cetacean
biology and ecology comes from studies of relatively common species. Despite
their distribution throughout the tropics and sub-tropics, pygmy killer whales
(Feresa attenuata) are rare throughout their range and are one of the most
poorly-known species of odontocetes. During a 22-year study of short-finned
pilot whales (Globicephala macrorhynchus) off the island of Hawai‘i, we
opportunistically photo-identified pygmy killer whales whenever encountered. As
part of a directed multi-species study throughout the main Hawaiian Islands from
2000 through 2007, we also photo-identified individuals and obtained information
on habitat use and behavior. This species was extremely uncommon (representing
only 1.2% of odontocete sightings in directed efforts). Given the low encounter
rates, assessing trends of this population cannot be feasibly done with
line-transect surveys. Despite their rarity, 80% of the distinctive individuals
within groups documented off the island of Hawai‘i were seen on multiple
occasions, individuals were re-sighted over periods of up to 21 yr, and there
was evidence of year-round use of the area. Association analyses indicate stable
long-term associations in mixed-sex groups. High re-sighting rates indicate a
small population of island-associated individuals that may be at risk from
anthropogenic impacts.
Marine Mammal Science subscribers can download a
pdf from the journal web site via the Member Area link at www.marinemammalogy.org, or contact me
for a pdf.
Happy new year
Robin