Acoustics
CIWR researches the production of humpback song and cetacean vocalizations by using hydrophones and digital recorders to record and document the vocalizations of individual animals. CIWR gathers this acoustic data to better understand cetacean communication and culture.
Male humpback whales sing long and complex songs in the waters of the Cook Islands and other winter breeding grounds in the tropical oceans. Since male humpbacks usually sing during the breeding season, it is likely that the song relates to reproductive function. The song may serve to attract females, assert dominance among other males, maintain a distance between courting males, report information relating to the migration route and the feeding grounds, or many other possibilities that are unknown to us.
Song structure and form have been compared among the Cook Islands' humpbacks and songs recorded at other breeding grounds across the South Pacific and from around the world. Because humpback song varies geographically, comparative analysis of song and DNA samples from the singers are used to determine the stock identity of Cook Islands' humpbacks. Moreover, analysis of the phrases and singers' behaviour yields insights into the functional significance of the humpback song. Over the past 23 field seasons, we have recorded humpback whale songs every year and observed song exchange in the region. After University of Queensland acousticians analyzed SPWRC's 775 songs collected across Oceania, the data reveals song phrases passing from west to east, indicating horizontal cultural transmission of song. Over the past few years, we have had 2 to 3 distinct songs present over the whale season off Rarotonga, which poses a very interesting question of how song interchange is happening here in the Cook Islands.
Migratory convergence facilitates cultural transmission of humpback whale song
Dynamic horizontal cultural transmission of humpback whale song at the ocean basin scale
Population and Behaviour
CIWR documents the populations of humpback whales and other cetaceans that pass through the Cook Islands and observes the behaviour of individual animals.
Field data are documented using voice recorders, GPS, digital imaging and digital video. These include behaviours, individual whales present, geographic position, date, time, etc.
We observe and film both above and underwater behaviour with underwater cameras, GoPro’s, Osmo Action cameras, drones, 360° cameras and pole-cams.
Abundance of humpback whales in Oceania (South Pacific), 1999-2004
Occurrence & Habitat Use of Humpback Whales in the Cook Islands
Surface and Underwater Footage
Video footage is collected to study the behaviour of whales above and below the surface.
Underwater footage can also be used to obtain photo-identification images if these cannot be obtained at the surface, as is often the case with mother and calf pairs, as new mothers seldom show their flukes when they dive.
Underwater footage is obtained by either filming with an underwater camera from the side of the boat or while snorkeling.
Distribution
Using GPS data, including longitude and latitude coordinates, CIWR documents the distribution of all cetaceans that the team observes. These data are compared seasonally to understand habitat use in and among species and in relation to oceanographic variables and global climate change. We have documented every geographic coordinate for sightings from 1998 to 2020 and mapped these points through Geographic Information Systems (GIS).
Satellite Tagging
CIWR attaches satellite tags onto whales in order to test theoretical frameworks of animal navigation using empirical animal location data. This allows us to observe a predictive model for long-distance animal migration, as the whales migrate from Rarotonga to other areas in the Cook Islands and Oceania, and ultimately to Antarctica.
CIWR uses either a pole or pneumatic deployment device to apply the tags onto the whales, approximately at the base of the dorsal fin. These tags consist of a satellite transmitter attached to a stainless-steel anchoring system. The location of the tagged animal is transmitted to an Argos satellite and can be downloaded in nearly real time.
The knowledge of the humpback whale migration route from Oceania to Antarctica bolsters important efforts to minimize the spatial and temporal overlap between migrating whales and potential fishing gear. Previously 
collected satellite tagging data will soon be used to enforce legislation prohibiting the deployment of long line fishing gear in the path of humpback whales migrating across Oceania and down to the Antarctic feeding grounds.
Straight as an arrow: humpback whales swim constant course tracks during long-distance migration
Route Fidelity during Marine Megafauna Migration
Movements of satellite monitored humpback whales from New Caledonia and the Cook Islands
Movements of satellite monitored humpbacks from the Cook Islands
Migratory destination of a humpback whale satellite tagged in the Cook Islands
Infrared Analysis and Multispectral Imaging
In collaboration with University of Canterbury and Dr. Travis Horton, a study was conducted that observes humpback whales using the infrared spectrum. This was the first infrared analysis conducted on whales in a warm water environment. The hope of the project is to create an innovative method of identifying individual whales based on the signature of scarring patterns visible by infrared and a possible passive detection method for documenting the number of whales. We achieve this by using drones with infra-red cameras attached.
We use drones and multispectral imaging as a tool to measure the humpback whales’ biomedical conditions. Through infrared and multispectral imaging, we are able to take measurements of the whale’s body size, physiological conditions and vital signs (pulse, respiration and body temperature), which will help us monitor the health of these whales.
Through this project, we will achieve: 1) non-invasive monitoring of cetacean biomedical vital signs using drone-deployed thermographic sensors across a variety of behavioural states; 2) creating 3-D models of whale morphology and body condition at the individual level using drone-mounted stereoscopic multispectral (i.e. water-penetrating ‘coastal’ blue wavelength) cameras; 3) quantifying the relationship between the timing of long-distance return migration, whale condition, feeding behaviour and genetic markers.
Thermal Imaging and Biometrical Thermography of Humpback Whales
Resident Pod of Spinner Dolphins
Spinner dolphin sightings have been documented around Rarotonga since 2000; however, it has been only since 2016 that CIWR has observed spinner dolphin pods to be resident to Rarotonga.
Spinner dolphins appear to have come and gone over the years. In the 23 years that CIWR has conducted research around Rarotonga, we have sighted dolphins in 12 of those years. We had no sightings in 1998-1999, 2002-2003, 2006-2007, 2009-2011 and 2014-2015.
In March 2016, we were alerted by the fishermen that there were dolphins spotted off the reef of the southwest side of the island. On observation, we found a pod of spinner dolphins mixing with Fraser's dolphins. After no dolphins sightings in 2014 or 2015, we were very pleased to see the spinners return. We have continued to observe spinner dolphins over the following years. In 2020, we had more spinner dolphin group encounters than ever before, with a total of 32 sightings!
We have photographed and filmed the dolphins as much as possible above water. We hope to enhance our cetacean catalogue by including the ID’s of these dolphins by photographing their dorsal fins at a right angle. In 1998 and 1999, photo ID’s were taken of the resident spinner dolphins off of Palmerston Atoll.
