No abstract

The Au'au Channel between the islands of Maui and Lanai, Hawaii comprises critical breeding habitat for humpback whales (Megaptera novaeangliae) of the Central North Pacific stock. However, like many regions where marine mega-fauna gather, these waters are also the focus of a flourishing local eco-tourism and whale watching industry. Our aim was to establish current trends in habitat preference in female-calf humpback whale pairs within this region, focusing specifically on the busy, eastern portions of the channel. We used an equally-spaced zigzag transect survey design, compiled our results in a GIS model to identify spatial trends and calculated Neu's Indices to quantify levels of habitat use. Our study revealed that while mysticete female-calf pairs on breeding grounds typically favor shallow, inshore waters, female-calf pairs in the Au'au Channel avoided shallow waters (<20 m) and regions within 2 km of the shoreline. Preferred regions for female-calf pairs comprised water depths between 40–60 m, regions of rugged bottom topography and regions that lay between 4 and 6 km from a small boat harbor (Lahaina Harbor) that fell within the study area. In contrast to other humpback whale breeding grounds, there was only minimal evidence of typical patterns of stratification or segregation according to group composition. A review of habitat use by maternal females across Hawaiian waters indicates that maternal habitat choice varies between localities within the Hawaiian Islands, suggesting that maternal females alter their use of habitat according to locally varying pressures. This ability to respond to varying environments may be the key that allows wildlife species to persist in regions where human activity and critical habitat overlap.

No abstract

The ontogeny of behavior in young offspring is a key component of a species life history, influencing short-term survival and life-long future fitness. In this study, we examine the behavioral ontogeny of humpback whale calves during their natal season on the winter breeding grounds. Behavioral data were collected during focal follows for 69 calves. Their relative age was estimated based on the degree of unfurling of the dorsal fin, and analysis of their time budgets revealed that behavior changed as the calves matured. Among the youngest group of calves (n = 27), persistent travel accounted for median 85% (interquartile range 34%) of the calves' time budget, they spent little time alone at the surface and the breathing regime included frequent intermittent breaths. Within the oldest group of calves (n = 26), time spent traveling dropped to a median 47% (IQR 42%) of the time budget, they spent more time at rest, surfaced alone more frequently, and the breathing regime more closely resembled that of adult humpbacks. We suggest potential functions for these and other components of calf behavior during this period, and review our findings in light of recent discussions on the role of predation pressure as a driving force in mysticete migration.

A bioassay to examine the foraging behaviour of the aphidophagous hoverfly, Episyrphus balteatus was used in which various stimuli purported to influence flower choice were tested using model flowers. In choice experiments, E. balteatus exhibited enhanced behavioural responses to the colour yellow, as previously seen in Eristalis by several workers. Previous suggestions that the generalist forager E. balteatus has no preference for colour are re‐examined in the light of this new evidence. The other advertisement cue tested, size, was also demonstrated to play an important role in determining foraging behaviour, with the smaller artificial flowers seemingly preferred. Of the rewards tested, E. balteatus showed preference for the greatest nectar concentrations, whilst increasing pollen did not affect behaviour. These bioassays provided an opportunity to isolate the individual components of decision‐making by E. balteatus during foraging. The separation of sexes and ages in these experiments permitted analysis of inter‐sexual and inter‐generation differences in behaviour, a factor apparently not investigated in previous work.