4 Nov 2022

4 Nov 22 - Indonesia - Banda Sea Cruise Day 9 - Melon-headed Whales Between Leti & Wetar

The previous Blog Post covered the Birds seen on the crossing between Leti & Wetar on the Banda Sea Cruise. My avian highlight was a showy Bulwer's Petrel. But my highlight for the crossing was again taken by a pod of Cetaceans. About 15:15, we saw a distant pod of Cetaceans on the surface. I grabbed some distant photos and had a look at the zoomed up images.
Melon-headed Whale: They were distant small-looking Blackfish and I couldn't see any of the broad dorsal fins that the two Pilot Whale species show
They were clearly Blackfish. Blackfish is the name given for a group of largely black-coloured Dolphins comprising of: Orca (Killer Whale), Long-finned Pilot Whale, Short-finned Pilot Whale, False Killer Whale, Pygmy Killer Whale & Melon-headed Whale. Despite being called Whales, they are all part of the Dolphin family. Their small size and lack of any individuals with high dorsal fins ruled out Orca and I couldn't see any of the individuals showing very broad dorsal fins which males of the two Pilot Whale species show. This eliminated three of the Blackfish, but we would have to wait until they got closer, before we could identify them. I took lots of distant photos, but apart from the above photo, they have all been deleted, as the Blackfish stayed on the surface for closer photos. It's a good job we have moved on from the film cameras I started using many years ago.
Short-finned Pilot Whale: For comparison, these are some of the Short-finned Pilot Whales we saw on the crossing between Babar & Damar Islands. Note, the very broad dorsal fin of the male (2 Nov 22)
Separating False Killer Whale, Pygmy Killer Whale & Melon-headed Whale would need a bit more checking. Fortunately, they stayed on the surface and some of the fifty or so in the pod, passed very close to the Lady Denok. They were small Blackfish about the size of the Indo-Pacific Bottlenose Dolphins & Pantropical Dolphins, and were a lot smaller than the Short-finned Pilot Whales, that we had seen on the crossing from Babar to Damar a couple of days earlier. This allowed us to eliminate False Killer Whales which can grow to a size of 5 - 6 metres: which are a similar size to the 5.5 to 7.2 metres of Short-finned Pilot Whales. In both cases, the males are the larger of the two sexes.
Melon-headed Whale
Separating Pygmy Killer Whale from Melon-headed Whale is trickier as both are about the same size: 2.6 metres for the former & 2.8 metres for the latter species. I've not seen Pygmy Killer Whale, so I have to rely on what I can learn from the excellent Marine Mammals of the World Ed 2 guide and photos online. Useful separation features include the head shape when it is seen from above and the flipper shape. Neither of these features can be seen in any of the photos.
Melon-headed Whale: A dorsal fin profile. The Marine Mammals of the World guide states that Pygmy Killer Whales have a dorsal fin that is tall, slightly falcated & rising at a relatively shallow angle from the back, whereas, Melon-headed Whales have a dorsal fin that is tall, slightly falcated and located near the middle of the back. Comparing photos online, this dorsal fin is fairly steep in angle & the dorsal fin shape suggests this a Melon-headed Whale
Melon-headed Whale: The Marine Mammals of the World guide states that Pygmy Killer Whales have a dark grey to black body with a fairly prominent narrow cape that dips only slightly below the dorsal fin. Whereas, Melon-headed Whales have a rounded cape that dips much lower below the dorsal fin: which would give them a more uniform colouration on the parts of the body I've managed to photograph. Both species have a paler grey broad pale stripe above the eye which extends from the lower body, however, this broad stripe can be difficult to see in either species, unless the lighting is favourable
Melon-headed Whale: Neither species have a beak except some young individuals
Melon-headed Whale
Melon-headed Whale: Looking at photos in the Marine Mammals of the World guide and online, Pygmy Killer Whales have a bulkier body & deeper head shape, compared to the more slender Melon-headed Whales. This photo clearly shows these are a slender more streamline Blackfish
Melon-headed Whale: A close up of the head from the last photo showing the head shape & white lips. Both species can show white lips, with photos and illustrations showing these can be much broader in height in Pygmy Killer Whales (especially older individuals) and narrow in Melon-headed Whales
Melon-headed Whale: Melon-headed Whales occur in all tropical & subtropical deep water oceans from 40 degrees North to 35 degrees South: in the Pacific this is roughly from Southern Japan to halfway down the Australian coast
Based on the photos, these are only my third pod of Melon-headed Whales. The other two pods were both seen between Ascension Island and Cape Verde on 24 Apr 18 while I was on the Atlantic Odyssey.