Table 1.
Behavioural events of pilot whales for Tenerife, based on49.
| Behavioural event | Definition |
|---|---|
| Apparent nursing | An infant touched its rostrum to the mammary slit area of an adult female pilot whale (out of view of the UAV). The infant may be lying near-motionless whilst its mother was resting, or may be slowly swimming if the mother was swimming. The infant was parallel and almost under the mother (with both tails facing backwards) |
| Belly aside | Pilot whale swam on its left or right side, with one pectoral fin vertically directed towards the water surface. In some cases, half of the body was exposed out of the water |
| Belly to belly | Two pilot whales swam belly-to-belly without touching each other |
| Belly up | Rolled so that its ventral side was facing the surface of the water. Often the belly was fully exposed out of the water |
| Body contact | Physical contact between two or more pilot whales by several means, e.g., pectoral fin touches or rubbing body parts |
| Bubble display | Emitted bubbles from the blowhole underwater. These can be a single bubble, a whole cloud or bubble trains |
| Diving | Swam straight down vertically to a depth when the edges of the body may be difficult to discern. They may even disappear from the image |
| Encircling | One pilot whale swum circles around another in a small radius and at relatively high speed |
| Horizontal roll | A complete roll (360°) along the longitudinal axis and parallel to the water surface |
| Logging | Remained at the surface motionless (> 5 s) |
| Milling | Moved slowly at the surface without a fixed bearing |
| Mouth to mouth | Two or more pilot whales positioned their rostrums towards each other. Sometimes the rostrums were touching |
| Moving slowly | Swam slowly at the surface or underwater (< 2 knots) |
| Resting underwater | Remained underwater close to surface near-motionless |
| Rough housing | An adult pilot whale striked the side of the calf with its head or body |
| Spyhop | Vertically lifted its head out of the water so that the eyes were completely in the air, with a vertical re-entry |
| Tail slap | A slap with the ventral side of the tail or tailstock on the water surface. This behaviour can be repetitive with short intervals between slaps |
| Vertical roll | A complete roll (360°) along the ventral axis and perpendicular to the water surface |