The Dolphin Institute

Honolulu, HI, United States

The Dolphin Institute

Honolulu, HI, United States
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Mizroch S.A.,National Oceanic and Atmospheric Administration | Tillman M.F.,University of California at San Diego | Jurasz S.,SeaSearch and Sea Reach Ltd. | Straley J.M.,University of Alaska Southeast | And 11 more authors.
Marine Mammal Science | Year: 2011

Invasive tags designed to provide information on animal movements through radio or satellite monitoring have tremendous potential for the study of whales and other cetaceans. However, to date there have been no published studies on the survival of tagged animals over periods of years or decades. Researchers from the National Marine Mammal Laboratory and the Woods Hole Oceanographic Institution tracked five humpback whales with implanted radio tags in southeastern Alaska in August 1976 and July 1977, and tracked two humpback whales in Prince William Sound, Alaska, in June 1978. All seven of these individually identified humpback whales were resighted at least 20 yr after first being tagged, and five of the seven have been observed for more than 30 yr; some of them are among the most resighted humpback whales in the North Pacific. Photos of tagging sites taken during and subsequent to tagging operations show persistent but superficial scarring and no indication of infection.These pioneering field studies demonstrated both long-term survival of the whales and the short-term effects of deploying radio tags, which at the time were larger and more invasive than those typically used today. 2010 by the Society for Marine Mammalogy Published 2010. This article is a US Government work and is in the public domain in the USA.

Pack A.A.,University of Hawaii at Hilo | Pack A.A.,The Dolphin Institute | Herman L.M.,The Dolphin Institute | Herman L.M.,University of Hawaii at Manoa | And 10 more authors.
Animal Behaviour | Year: 2012

Assortative pairing, and its relation to mate choice, has rarely been documented in mammals. Using data collected during 1998-2007, we investigated size-assortative pairing as it relates to discrimination amongst potential mates in humpback whale, Megaptera novaeangliae, dyads in the Hawaiian breeding grounds. Across 67 male-female dyads in which both individuals were measured using underwater videogrammetry, male length was positively correlated with female length. Detailed analyses on the assessment of maturity by comparisons with whaling data revealed that mature-sized females associated almost exclusively with mature-sized males and had a significant preference for large mature-sized males. In contrast, mature-sized males were less discriminating in their associations with females and showed no significant preference for mature-sized females. However, mature-sized males that associated with immature-sized females were significantly smaller than males that associated with mature-sized females. Finally, immature-sized males tended to associate with immature-sized females. The sex differences in size preference by mature whales probably reflect the relatively high costs of mature females mating with small or immature males compared to the lower costs of mature males mating with small or immature females. Body size appears to influence the adoption of alternative mating tactics by males such that smaller mature males avoid the costs of competing for the highest-quality females and instead focus their attentions on smaller females that may or may not be mature. Overall, our results provide the first quantitative evidence of size-assortative pairing and female discrimination amongst potential mates in humpback whales and indeed in any cetacean species. © 2012 The Association for the Study of Animal Behaviour.

Herman L.M.,University of Hawaii at Manoa | Herman L.M.,The Dolphin Institute | Pack A.A.,The Dolphin Institute | Pack A.A.,University of Hawaii at Hilo | And 5 more authors.
Behavioral Ecology and Sociobiology | Year: 2013

While on their winter breeding grounds, male humpback whales (Megaptera novaeangliae) produce long sequences of structured vocalizations called song, whose function within the mating system is still unresolved. Here we ask which males sing. Is it only those sexually mature, as typifies songbirds and some lekking ungulates in which vocalizations during the rut are restricted to mature males? Or do immature males join in the chorus? Using an underwater videogrammetric technique, we measured the body lengths of 87 humpback singers in the Hawaiian winter grounds. Applying length and sexual maturity relationships for North Pacific humpbacks as determined by biologists aboard twentieth century Japanese whaling vessels, we found that singer lengths ranged from 10.7 to 13.6 m, with 15 % of lengths indicative of probable sexual immaturity (length < 11.3 m, p [maturity] < 0.5). We interpret this broad participation of males as a lekking aggregation and the asynchronous singing chorus as an instance of by-product mutualism. The participation of many singers yields a heightened signal level that may attract more females to the singing area. Sexually mature males can benefit through access to more females. Immature males may gain deferred benefits through increased opportunities to learn and practice the social, behavioral, and acoustical skills and conventions of the winter grounds that they can apply usefully in later years. © 2013 Springer-Verlag Berlin Heidelberg.

Thorne L.H.,State University of New York at Stony Brook | Thorne L.H.,Duke University | Johnston D.W.,Duke University | Johnston D.W.,Murdoch University | And 16 more authors.
PLoS ONE | Year: 2012

Predictive habitat models can provide critical information that is necessary in many conservation applications. Using Maximum Entropy modeling, we characterized habitat relationships and generated spatial predictions of spinner dolphin (Stenella longirostris) resting habitat in the main Hawaiian Islands. Spinner dolphins in Hawai'i exhibit predictable daily movements, using inshore bays as resting habitat during daylight hours and foraging in offshore waters at night. There are growing concerns regarding the effects of human activities on spinner dolphins resting in coastal areas. However, the environmental factors that define suitable resting habitat remain unclear and must be assessed and quantified in order to properly address interactions between humans and spinner dolphins. We used a series of dolphin sightings from recent surveys in the main Hawaiian Islands and a suite of environmental variables hypothesized as being important to resting habitat to model spinner dolphin resting habitat. The model performed well in predicting resting habitat and indicated that proximity to deep water foraging areas, depth, the proportion of bays with shallow depths, and rugosity were important predictors of spinner dolphin habitat. Predicted locations of suitable spinner dolphin resting habitat provided in this study indicate areas where future survey efforts should be focused and highlight potential areas of conflict with human activities. This study provides an example of a presence-only habitat model used to inform the management of a species for which patterns of habitat availability are poorly understood. © 2012 Thorne et al.

Green S.R.,State University of New York at Buffalo | Mercado E.,State University of New York at Buffalo | Pack A.A.,The Dolphin Institute | Pack A.A.,University of Hawaii at Hilo | And 2 more authors.
Behavioural Processes | Year: 2011

Humpback whales, unlike most mammalian species, learn new songs as adults. Populations of singers progressively and collectively change the sounds and patterns within their songs throughout their lives and across generations. In this study, humpback whale songs recorded in Hawaii from 1985 to 1995 were analyzed using self-organizing maps (SOMs) to classify the sounds within songs, and to identify sound patterns that were present across multiple years. These analyses supported the hypothesis that recurring, persistent patterns exist within whale songs, and that these patterns are defined at least in part by acoustic relationships between adjacent sounds within songs. Sound classification based on acoustic differences between adjacent sounds yielded patterns within songs that were more consistent from year to year than classifications based on the properties of single sounds. Maintenance of fixed ratios of acoustic modulation across sounds, despite large variations in individual sounds, suggests intrinsic constraints on how sounds change within songs. Such acoustically invariant cues may enable whales to recognize and assess variations in songs despite propagation-related distortion of individual sounds and yearly changes in songs. © 2011 Elsevier B.V.

Herman L.M.,The Dolphin Institute | Herman L.M.,University of Hawaii at Manoa | Pack A.A.,The Dolphin Institute | Pack A.A.,University of Hawaii at Hilo | And 5 more authors.
Marine Mammal Science | Year: 2011

From a database of approximately 5,000 Hawaiian humpback whales identified photographically between 1976 and 2010, we extracted 71 males and 39 females having resighting spans of 10 or more years, from first to most recent sighting. Findings included: (1) the male-biased sex ratio was like that found in breeding grounds worldwide; (2) the mean span for males of 20.7 yr (maximum = 32 yr) did not differ significantly from the mean of 19.8 yr (maximum = 29 yr) for females, but males were seen in significantly more years during their spans than were females; (3) the mean number of females seen with and without calf across 11 three-year intervals from 1977 to 2009 did not differ significantly; (4) the calving rate for the 39 females was 0.48 and seven females produced two to eight calves over spans of 22-26 yr; (5) females attracted significantly more escorts in years without calf than in years with calf; (6) individuals showed great diversity in the social units they occupied over their sighting spans, but with the most frequently observed unit for both sexes being the trio of mother, calf, and escort. Males were also observed frequently in competitive groups centered about a female without calf. © 2010 by the Society for Marine Mammalogy.

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