Lesser Noddies breed on small islands that are free of introduced predators in Seychelles, including Bird Island. They nest in trees, building substantial cup-shaped nests of leaves and seaweed that they cement together with their droppings, and into which they deposit their single egg. Their breeding season thus commences with much activity on the ground as they search for leaves that they consider suitable for their home-building. This usually involves a noisy melee of birds as they pick up and discard leaves that they consider unworthy, before flying into the trees above with their selected trophies.
While they have nested in Seychelles on Cousin, Cousine and Aride Islands since bird enthusiasts first began investigating the archipelago’s avifauna, breeding on Bird, Frégate, Recif and Denis islands has only begun more recently (1984 on Bird, 2016 on Denis). Like Sooty Terns, they have been regarded as breeding birds of the south-east trade wind period, mainly from May to October. On our arrival on Bird Island in the 1990s we saw the initiation of breeding by Lesser Noddies as Sooty Terns begin their egg laying. In recent years, however, we have found that by the time Sooty Terns are ready to lay, any Lesser Noddy nests already have large chicks, indicating that they have begun their breeding much earlier in the year. Their breeding season is now much longer than previously, and at present, even though there are many flying young from earlier breeding this year, day and night we hear the mournful whistling calls of nestlings begging for food.
This year, now that many Sooty Tern juveniles are flying well and beginning to leave the colony, we have begun to see what appears to be a resumption of Lesser Noddy breeding activity, involving pairs undertaking fast aerial chases while flying high (a courtship display called “high flight”, also undertaken by Sooty Terns early in the breeding season). Each morning we are also seeing parties of Lesser Noddies collecting leaves on the woodland floor and carrying them up into trees. However, while the collection of nest material is an essential part of the breeding cycle, it might also be a component of courtship behaviour; both Lesser Noddies, and their larger cousins Brown Noddies, frequently pick up and fly around with leaves that are too large to carry to their nests and eventually drop these leaves on the ground. And despite seeing a lot of leaf collection recently we have not yet noticed any newly constructed nests in the trees. Alternatively, juveniles from this year’s earlier nests might be practicing their skills of leaf selecting and collection for future breeding attempts.
Whatever the explanation, the Lesser Noddy breeding season on Bird Island does seem to be extending. This might reflect changes in their food supply and in the oceanic conditions that govern this, but more precise monitoring of the birds and their marine environment are needed to establish a link.