Study Findings

Social Sounds

We have been able to record social sounds while in the water with various humpback whale pods; pods that vary by gender, behavior, and size (number of animals). Animals in several different behavioral states have been found to make social sounds (i.e. resting pods, traveling pods, surface active pods, competitive groups, and so on) and pods of different sizes have produced social sounds (where the minimum number of individuals is at least two). We have documented calls in mother/calf pod configurations as well. For a typical view of mothers and calves while resting, see the photo to the right; you will see the part of the calf’s body sticking out from below the mother. You can also watch typical mother/calf/escort resting behavior in a video clip. You can hear some of the various social sounds collected by going to the Gallery page.

Calf Behavior

In addition to being able to catalogue numerous circumstances in which social sound production occurs, we are working on calf underwater behavioral activity budgets. We are investigating the roles of sex, seasonal period, and sea state on Hawaiian humpback whale calf behavioral development. We used underwater video recordings to document when calves were (1) at the surface without their mothers, (2) in physical contact with or in close proximity to (within 5 m) of their mothers, (3) playing, (4) milling, (5) interacting with divers, or (6) vocalizing (social sounds). See study findings in our publication Effects of Sex, Seasonal Period, and Sea State on Calf Behavior in Hawaiian Humpback Whales (Megaptera novaeangliae). 

Calf Vulnerability to Vessel Collisions

One of the results we are seeing is that humpback whale calves spend a large percentage of their time (more than half when the mother is resting) a few feet under the water surface. In other words, at a location where they not visible to boaters. This can have devastating results, as you can see from the photograph (left) showing the back and tail of an injured calf. This calf was photographed in 2005 both above and below the water.

See our publication Humpback whale calf vulnerability to small-vessel collisions; assessment from underwater videography in Hawaiian waters. 

Calf Nursing

Nursing in large baleen whales and specifically the humpback whale is not well documented and difficult to capture in real time. Using underwater video documentation techniques, we collected digital video footage of humpback whale nursing events. From this, we provide an enhanced descriptive account of humpback whale suckling and recorded milk in the water near (see photo below) a nursing mother and calf column for the first time (see photo right). As part of our investigation into nursing behaviors, we assessed if humpback calves demonstrated any patterns of laterality during nursing events. A pattern of laterality was noted in that all suckling events had a right side bias. Nursing bouts were short and intermittent, which coincides with what is known of larger terrestrial mammals such as the African elephant and other baleen whales. These shorter nursing periods are likely are due to the energetics of baleen whale milk coupled with the calf′s short respiration cycle before it has to return to the surface to breathe. Our study shows that underwater observations in marine mammal science provide valuable insight into real time events not easily accessible from vessel or aerial platforms.

 

In the most recent issue of Aquatic Mammals, Ann M. Zoidis, Kate S. Lomac-MacNair, Maren E. Anderson, Andrew J. Day, and M. Esther Jimenez share their innovation of a location tag that was adapted from a fitness tracker watch, and tested on humpback whales .

Humpback Whale Tagging Study

Tagging humpback whales provides valuable insights into their behavior, but it can be prohibitively expensive for small research groups. To address this, our team at Cetos developed a cost-effective tag using the Garmin Forerunner10 (GF10) fitness watch. We hypothesized the watch could be able to track whale movements and dives and set out to test a custom-made, inexpensive, archival, geo-location capable prototype tag, and see if it could collect data of sub-surface humpback whale behavior or on social calls. We tested and validated their prototypes on whales off Hawaii, attaching the GF10 watch to custom floats and a few tag designs including one with an acoustic probe. The tag effectively detected the whale’s location at depths exceeding 50 meters which was greater than the manufacturer depth rating and withstood up to 5-hour deployments, even after high-pressure dives. By identifying key improvements, such as enhanced memory and battery life of the watch, and the addition of a pressure-resistance casing, this study is paving the way for more affordable marine mammal tagging.

Learn more about results from our study in our publication Location Tag Adapted from Fitness Tracker Watch, Tested on Humpback Whales (Megaptera novaeangliae)