Aloha colleagues: We are pleased to inform you of a new publication using Crittercam to study the underwater behavior and mating system of humpback whales in Hawaiian waters. If you would like a pdf, please contact elia.herman@duke.edu. *Herman, E. Y. K., Herman, L. M., Pack, A. A., Marshall, G., Shepard, C. M., Bakhtiari, M. Winter 2007/2008. When Whales Collide: Crittercam Offers Insight into the Competitive Behavior of Humpback Whales on Their Hawaiian Wintering Grounds. Marine Technology Society Journal, 41(4): 35-43.* ABSTRACT Despite years of study, the humpback whale mating system remains an enigma. Sustained observations of subsurface behavior may help reveal important components of the mating system. In 2005 and 2006, we deployed Crittercam, an animal-borne imaging and data-logging tool, on humpback whales in their winter grounds. We focused our efforts on competitive groups, believed to be the epicenter of mate selection. Over 27 days of fieldwork in Maui waters we deployed 10 front- or rear-facing Crittercams on escorts (males) in competitive groups. This work revealed: (1) Five whales swimming to depths of over 150 m, with one animal diving down 298 m; (2) Instances of competitive behavior (inflated pleats, chasing) occurring along the seafloor; (3) The displacement of a primary escort (the whale closest to the female) by a challenger; (4) A detailed time budget of one principal escort maintaining his position over a 73-min observation window; (5) Threats and body strikes between secondary escorts; (6) Apparent affiliative behavior by females, including possible pectoral fin stroking of a principal escort and drafting in a principal escort's pressure wave; and (7) A secondary escort resting on the bottom while sculling its pectoral fins through the substrate, throwing up clouds of sand. In summary, Crittercam allowed us to observe diving behavior and sustained micro-interactions between animals in competitive groups occurring far below the surface. Such observations can have significant bearing on interpretation of the mating system by assisting in uncovering behaviors that may be involved in mate guarding, dominance hierarchies, and female choice. (c) Winter 2007/2008 Marine Technology Society Journal -- Elia Y. K. Herman Masters of Environmental Management Candidate, 2008 Nicholas School of the Environment and Earth Sciences Duke University