Search

Drought is a prominent feature of Hawaii's climate, however, the biological, ecological, cultural, and socioeconomic impacts of drought in Hawaii are not well understood. This paper provides a comp...

The Department of Defense lacks refined capability to assess and predict potential impact of tactical and experimental sound sources in the presence of marine mammals. Although there is sustained concern over the effects on marine mammals of man made sound in the oceans, there is very little direct information about what sound frequency-intensity combinations damage marine mammal hearing. Our broad objective is to transition information about effects of DoD sound types on marine mammal auditory anatomy and acoustic ecology to predictive models and mitigation tools. This effort responds directly to the DoD capability to comply with the National Environmental Policy Act requirements and will contribute directly to answering the National Council's Research Needs related to the effect of low-frequency sound on marine mammals (1994, 2000). This final report summarizes the accomplishments of SERDP Project CS-1082 spanning the lifetime of the project from FY98-FY-00.

More than 20 years have elapsed since the first detailed descriptions of humpback whale song (Payne and McVay, 1971; Winn, Perkins and Poulter, 1971) and despite considerable attention, the function of song remains elusive. In this paper, we review the literature on humpback whale song and describe general methods used to collect data on free-ranging whales. Then, we present the results of three current studies that have used different methods to shed light on the function of whale song.

Steller sea lions (Eumetopias jubatus) breed and rear their young in coastal rookeries dispersed along the northern tier of the North Pacific. Population densities are high and no allomaternal behavior occurs, providing strong selection pressure for mother–pup recognition processes. Mothers and pups establish and maintain contact with individually distinctive vocalizations. Our objective is to understand the acoustic features that serve to identify individual females, and develop a ruggedized computer system to perform acoustic recognition of females in the field. We have cataloged almost 2000 contact calls from 46 females in 1998 and 25 in 1999. Each female is visually identified by marking patterns, which provides the ground truth for acoustic identification. Acoustic properties of the calls were measured and presented to several statistical classifiers. Representations of the calls had to be robust with respect to acoustical variability introduced by motivational changes as the mother and pup regained proximity. The calls, classifiers, and results of generalization tests will be described, and a concept for the field system will be discussed. [Research supported by ONR Research Opportunities for Program Officers award N00014‐00‐1‐0114 to R. H. DeFran, Cetacean Behavior Laboratory, SDSU.]

Many species of baleen whales reside or migrate annually through California waters. During these times some species of vocalizing whales can be detected, identified, and tracked with SOSUS arrays. Historical research by W. Cummings documented strong seasonal changes in narrow‐band ambient sound associated with then unidentified sounds. Contemporary research shows these sounds to be blue and fin whale vocalizations. The current study compares historical and contemporary narrow‐band ambient measurements with respect to mysticete residency and movement through southern California waters. Seasonal peaks in ambient noise agree with earlier reports, but increased anthropogenic sound reduced the magnitude of the effect. Potential sources of changes in ambient noise and their effects on the whales are discussed. [Research supported by the Strategic Environmental Research and Development Program, Project CS‐1082.]

Humpback whales (Megaptera novaeangliae) migrate annually between high‐latitude summer feeding waters and low‐latitude winter mating waters. During migration and in winter waters, adult [male] humpbacks produce long complex songs. Songs gradually change during each singing season, and singers incorporate changes as they occur. Classification of song units using neural networks and cepstral cross correlation reveals that variability in song characteristics within region is lower than variability between regions. These regional differences in song characteristics can be considered to be dialects that are maintained through cultural transmission of regional variants. Thus differences in songs from different regions may be an index of reproductive isolation. Cladistic patterns of geographic and temporal variation in songs support a model of limited migratory exchange among widely separate wintering regions. [Work supported by UARC, SPREP, WDCS, PDCT.]