Zaeschmar J.R.,Massey University |
Visser I.N.,Orca Research Trust |
Fertl D.,Ziphius EcoServices |
Dwyer S.L.,Massey University |
And 5 more authors.
Marine Mammal Science | Year: 2014
On a global scale, false killer whales (Pseudorca crassidens) remain one of the lesser-known delphinids. The occurrence, site fidelity, association patterns, and presence/absence of foraging in waters off northeastern New Zealand are examined from records collected between 1995 and 2012. The species was rarely encountered; however, of the 61 distinctive, photo-identified individuals, 88.5% were resighted, with resightings up to 7 yr after initial identification, and movements as far as 650 km documented. Group sizes ranged from 20 to ca. 150. Results indicate that all individuals are linked in a single social network. Most observations were recorded in shallow (<100 m) nearshore waters. Occurrence in these continental shelf waters is likely seasonal, coinciding with the shoreward flooding of a warm current. During 91.5% of encounters, close interspecific associations with common bottlenose dolphins (Tursiops truncatus) were observed. Photo-identification reveals repeat inter- and intraspecific associations among individuals with 34.2% of common bottlenose dolphins resighted together with false killer whales over 1,832 d. While foraging was observed during 39.5% of mixed-species encounters, results suggest that social and antipredatory factors may also play a role in the formation of these mixed-species groups. © 2013 Society for Marine Mammalogy.
Deakos M.H.,The Hawaii Association for Marine Education and Research Inc. |
Branstetter B.K.,National Marine Mammal Foundation |
Lori M.,Systems Center Pacific |
Fertl D.,Ziphius EcoServices |
Mobley Jr. J.R.,University of Hawaii at Manoa
Aquatic Mammals | Year: 2010
When two species share a common habitat, interspecific interactions can take many forms. Understanding the dynamics of these interactions can provide insight into the behavior and ecology of those species involved. Two separate, unusual interactions are described in which a humpback whale (Megaptera novaeangliae) lifted a bottlenose dolphin (Tursiops truncatus) completely out of the water. Both incidents occurred in Hawaiian waters. Based on reports of object play by humpback whales, and the apparent initiation and cooperation of each dolphin being lifted, object (i.e., the dolphin) play by the whale and social play by the dolphin seem to be the most plausible explanations for the interaction. Aggressive and epimeletic behavior by the humpback were also considered.
Smultea M.A.,Smultea science |
Smultea M.A.,Texas A&M University at Galveston |
Brueggeman J.,Canyon Creek Consulting |
Robertson F.,University of British Columbia |
And 4 more authors.
Arctic | Year: 2016
Increasing interactions of polar bears (Ursus maritimus) with human activity, combined with impacts of climate change, are of critical concern for the conservation of the species. Our study quantifies and describes initial reactions and behaviors of polar bears observed from an icebreaker during summer 1991 at two exploratory drilling sites (near sites drilled in 2015) located in the Chukchi Sea 175 km and 312 km west of Barrow, Alaska. Polar bear behavior was described using continuous sampling of six predetermined focal group behavior states (walking, running, swimming, resting, feeding or foraging, unknown) and six behavioral reaction events (no reaction, walking away, running away, approaching, vigilance [i.e., watching], unknown). Forty-six bears in 34 groups were monitored from the Robert LeMeur (an Arctic Class 3 icebreaker) for periods of five minutes to 16.1 hours. Significantly more bear groups reacted to icebreaker presence (79%) than not (21%), but no relationship was found between their reactions and distance to or activity of the icebreaker. Reactions were generally brief; vigilance was the most commonly observed reaction, followed by walking or running away for short (< 5 minutes) periods and distances (< 500 m). Eleven percent of bear groups approached the vessel. No significant difference was found between reactions when cubs were present and those when cubs were absent. Despite the limited sample sizes, these findings are relevant to assessing potential impacts of resource development and shipping activities on polar bears, especially given the sparsity of such information in the face of growing human activity in the Arctic offshore areas. Overall, climate change is leading to longer and more extensive open-water seasons in the Arctic and therefore to increasing marine traffic—more vessels (including icebreakers) for a longer time each year over a wider area. © The Arctic Institute of North America.