Cooperative Humpies

Today we left our mooring at the southern tip of the island and headed further east, past a seabird colony. We saw a magnificent frigatebird circling over the islet of Curral Velho, where the last pair in the entire Palearctic breeds. These frigatebirds are unusual in that they nest on the ground as opposed to on trees which makes them particularly vulnerable to predation by introduced mammals and humans.

The winds today were light by Cape Verde standards - about 14 knots and forecast to drop to 9or 10 knots in the coming days hopefully making for excellent fieldwork conditions.We took a peak around the corner from Curral Velho at the eastern side of Boa Vista where the wind is normally howling as it faces into the prevailing northeasterly trade winds. We spotted a mother-calf pair both breaching and lob-tailing about 3km offshore. We tracked them slowly inshore until they were in water just 13m deep and we could see them beneath the surface the entire time. We managed to biopsy the mother.

Mother and Calf Pair about 40m from the shore (Darren Craig)

We came across a singing male ("Pat") on our 40km transit along the west coast back to the north of the island. He could be heard singing without and hydrophone through the hull of the boat. We recorded about 25 mins of song as he belted it out right beneath us. He showed us his fluke and even breached as we left him behind us. It was interesting to see this whale surface to breath while singing continuously... normally they stop singing before surfacing to blow.

As we rounded the corner into Baia Sal Rei we encountered a competitive group - the first for us this year. Competitive groups comprise a female (sometimes with a calf) and several males competing for dominance / access to the female. Encounters with competitive groups are very exciting as the males battle it out. Today one of the escorting males had a bleeding gash across his fluke. We saw some streams of bubbles too which can be a sign of aggression. All four whales were approachable so we successfully biopsied each one and Darren photographed two flukes while Pedrin had photographed the other two earlier in the day from the whale-watching boat.

A male escort with fresh grazes on his fluke (Darren Craig)

This is the first time we managed to sample 5 whales in one trip - a fantastic day!

Birds List: Magnificent frigatebird (1), white-faced stormie (>10), Cape Verde shearwater, brown boobie, osprey (1)