January 2019 has brought very warm weather and plentiful rain to Mahé, the largest and most populated island of Seychelles. Towards the end of the month, low spring tides left vast areas of the foreshore inside the coral reefs free of water, allowing the sand, coral and seaweed to bake in the hot sun within the lagoons. This in turn heated up the incoming sea water as high tide approached. Heavy rain fell directly on to the lagoon and this was augmented by considerable run-off from the land, possibly reducing the salinity of lagoon water and certainly discolouring the water with red silt from the red soils that dominate the land. This combination of physical factors was doubtless responsible for the vast numbers of moribund and dead small sardine-like fish that washed up on the tide line.
Needless to say, this abundance of fish attracted birds. Resident Grey and Green-backed Herons walked leisurely along the strand line, selecting what must have appeared to them to be the best of a huge range of potential prey items, but how they made their selection from the super-abundant supply only they know!
Meanwhile, over the open water migrant Common Terns and Lesser Crested Terns, with an occasional Greater Crested Tern among them, dropped to the surface to pick up floating fish, only rarely using their more usual fishing method of plunge-diving. The abundance and ready availability of prey was such that each individual fed for only a short time before retiring to an exposed rock to digest its meal, often panting in the heat of the day.
Interestingly, Common Terns are much more common in Seychelles now than they were during my residence in the islands in the 1970s, and at that time Lesser Crested Terns were rarely seen. Now, both species are regular visitors to the granitic islands, especially in the northern winter but also increasingly seen in the northern summer. Common Terns clearly originate from breeding populations in the northern hemisphere, but the origin of Seychelles’ Lesser Crested Terns is less certain, for some breed along the north-African Coast and parts of the Middle East, while others breed in the north-eastern Indian Ocean islands and Australasia, the last probably least likely to venture to Seychelles.