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Humpback Whales (humpback + whale)
Selected AbstractsSWIMMING SPEEDS OF SINGING AND NON-SINGING HUMPBACK WHALES DURING MIGRATIONMARINE MAMMAL SCIENCE, Issue 3 2007Michael J. Noad Abstract Limited data exist on swimming speeds of humpback whales (Megaptera novaeangliae) and none on swimming speeds of singing whales during migration. We tracked humpback whales visually and acoustically during migration from the breeding grounds past our study site on the east coast of Australia (latitude 26°28,S). The mean swimming speed for whales while singing was 2.5 km/h, significantly less than for non-singing whales with a mean of 4.0 km/h but significantly greater than the mean of 1.6 km/h observed for singing whales on the Hawaiian breeding grounds. Between song sessions, there was no significant difference in speeds between whales that had been singing and other whales. Migration speeds were less for whales while singing but increased during the season. Although humpback whales can swim rapidly while singing (maximum observed 15.6 km/h), they generally do not do so, even during migration. Slower migration by singers would delay their return to the polar feeding areas and may be costly, but may be a strategy to provide access to more females. [source] Structure of the cerebral cortex of the humpback whale, Megaptera novaeangliae (Cetacea, Mysticeti, Balaenopteridae)THE ANATOMICAL RECORD : ADVANCES IN INTEGRATIVE ANATOMY AND EVOLUTIONARY BIOLOGY, Issue 1 2007Patrick R. Hof Abstract Cetaceans diverged from terrestrial mammals between 50 and 60 million years ago and acquired, during their adaptation to a fully aquatic milieu, many derived features, including echolocation (in odontocetes), remarkable auditory and communicative abilities, as well as a complex social organization. Whereas brain structure has been documented in detail in some odontocetes, few reports exist on its organization in mysticetes. We studied the cerebral cortex of the humpback whale (Megaptera novaeangliae) in comparison to another balaenopterid, the fin whale, and representative odontocetes. We observed several differences between Megaptera and odontocetes, such as a highly clustered organization of layer II over the occipital and inferotemporal neocortex, whereas such pattern is restricted to the ventral insula in odontocetes. A striking observation in Megaptera was the presence in layer V of the anterior cingulate, anterior insular, and frontopolar cortices of large spindle cells, similar in morphology and distribution to those described in hominids, suggesting a case of parallel evolution. They were also observed in the fin whale and the largest odontocetes, but not in species with smaller brains or body size. The hippocampal formation, unremarkable in odontocetes, is further diminutive in Megaptera, contrasting with terrestrial mammals. As in odontocetes, clear cytoarchitectural patterns exist in the neocortex of Megaptera, making it possible to define many cortical domains. These observations demonstrate that Megaptera differs from Odontoceti in certain aspects of cortical cytoarchitecture and may provide a neuromorphologic basis for functional and behavioral differences between the suborders as well as a reflection of their divergent evolution. Anat Rec, 290:1,31, 2007. © 2006 Wiley-Liss, Inc. [source] Distribution and abundance of West Greenland humpback whales (Megaptera novaeangliae)JOURNAL OF ZOOLOGY, Issue 4 2004Finn Larsen Abstract Photo-identification surveys of humpback whales Megaptera novaeangliae were conducted at West Greenland during 1988,93, the last 2 years of which were part of the internationally coordinated humpback whale research programme YoNAH, with the primary aim of estimating abundance for the West Greenland feeding aggregation. The area studied stretched from the coast out to the offshore margin of the banks, determined approximately by the 200 m depth contours, between c. 61°70,N and c. 66°N. The surveys were conducted between early July and mid-August and 993 h were expended on searching effort. A total of 670 groups of humpback whales was encountered leading to the identification of 348 individual animals. Three areas of concentration were identified: an area off Nuuk; an area at c. 63°30,N; and an area off Frederikshåb. Sequential Petersen capture,recapture estimates of abundance were calculated for five pairs of years at 357 (1988,89), 355 (1989,90), 566 (1990,91), 376 (1991,92), and 348 (1992,93). Excluding the anomalously high estimate in 1990,91, the simple mean is 359 (se= 27.3, CV = 0.076) and the inverse CV-squared weighted mean is 356 animals (se= 24.9, CV = 0.070). These calculations lead us to conclude that between 1988 and 1993 there were 360 humpbacks (CV = 0.07) in the West Greenland feeding aggregation. Using the Cormack,Jolly,Seber model framework non-calf survival rate was estimated at 0.957 (se= 0.028). Our data have low power (P < 0.3) to detect a trend of 3.1%, assuming the probability of a type I error was 0.05. [source] Site fidelity and movements of humpback whales (Megaptera novaeangliae) on the Brazilian breeding ground, southwestern AtlanticMARINE MAMMAL SCIENCE, Issue 4 2010Leonardo L. Wedekin Abstract Site fidelity and movements were studied for humpback whales photo-identified from 1989 to 2006 in the Abrolhos Bank, southwestern Atlantic, Brazil. A total of 2,612 individuals were identified, 374 of which were observed on more than one occasion. The cumulative number of identified whales has increased since 1989. Recapture rate was low and varied among different years. A total of 33 whales was observed using the Abrolhos Bank for longer than 10 yr, up to a maximum of 16 yr. Our data suggest that different whales show distinct movement rates. Some whales used a large extent of the Abrolhos Bank region. Opportunistic photo-identification data (on the scale of the Brazilian coast from 4° to 23°S) revealed important information about stock identity. The longest distance between within-season resightings was over 600 km, while one whale was observed in two locations separated by more than 1,400 km in different years. Long-range movements within and between seasons support the single stock hypothesis for humpback whales wintering off the Brazilian coast. [source] Correlation between body length and fluke width in humpback whales, Megaptera novaeangliaeMARINE MAMMAL SCIENCE, Issue 4 2010Renata S. Sousa-Lima First page of article [source] SWIMMING SPEEDS OF SINGING AND NON-SINGING HUMPBACK WHALES DURING MIGRATIONMARINE MAMMAL SCIENCE, Issue 3 2007Michael J. Noad Abstract Limited data exist on swimming speeds of humpback whales (Megaptera novaeangliae) and none on swimming speeds of singing whales during migration. We tracked humpback whales visually and acoustically during migration from the breeding grounds past our study site on the east coast of Australia (latitude 26°28,S). The mean swimming speed for whales while singing was 2.5 km/h, significantly less than for non-singing whales with a mean of 4.0 km/h but significantly greater than the mean of 1.6 km/h observed for singing whales on the Hawaiian breeding grounds. Between song sessions, there was no significant difference in speeds between whales that had been singing and other whales. Migration speeds were less for whales while singing but increased during the season. Although humpback whales can swim rapidly while singing (maximum observed 15.6 km/h), they generally do not do so, even during migration. Slower migration by singers would delay their return to the polar feeding areas and may be costly, but may be a strategy to provide access to more females. [source] COLLISIONS BETWEEN SHIPS AND WHALESMARINE MAMMAL SCIENCE, Issue 1 2001David W. Laist Abstract Although collisions with motorized ships are a recognized source of whale mortality, little has been done to compile information on the frequency of their occurrence or contributing factors. We searched historical records and computerized stranding databases for evidence of ship strikes involving great whales (i. e., baleen whales and the sperm whale). Historical records suggest that ship strikes fatal to whales first occurred late in the 1800s as ships began to reach speeds of 13-15 kn, remained infrequent until about 1950, and then increased during the 1950s-1970s as the number and speed of ships increased. Of 11 species known to be hit by ships, fin whales (Balaenoptera physalus) are struck most frequently; right whales (Eubalaena glacialis and E. australis), humpback whales (Megaptera novaeangliae), sperm whales (Physeter catodon), and gray whales (Escbricbtius robustus) are hit commonly. In some areas, one-third of all fin whale and right whale strandings appear to involve ship strikes. To assess contributing factors, we compiled descriptions of 58 collisions. They indicate that all sizes and types of vessels can hit whales; most lethal or severe injuries are caused by ships 80 m or longer; whales usually are not seen beforehand or are seen too late to be avoided; and most lethal or severe injuries involve ships travelling 14 kn or faster. Ship strikes can significantly affect small populations of whales, such as northern right whales in the western North Atlantic. In areas where special caution is needed to avoid such events, measures to reduce the vessel speed below 14 kn may be beneficial. [source] | ||||||||||