ICS discovers first Red-footed Booby breeding event at Alphonse Group |26 April 2021

ALP Attaching a satellite tracking device to a Red-footed Booby

A pair of Red-footed Boobies (Sula sula) were observed breeding recently on St François island of the Alphonse Group, the Island Conservation Society (ICS) has announced.

Despite up to 20,000 individuals roosting overnight throughout the year, a nesting attempt has never been recorded.

First sighted atop a casuarina tree in October 2019, the conservation team were very excited to witness this novel breeding event.

Christopher Narty, conservation ranger of 7 years, had this to say: “After visiting St François so many times, it was just mind-blowing to see the Red-footed Booby has finally started to breed here.”

St François is a thin, crescent moon-shaped island lying at the southernmost point of the Alphonse Group. The outer perimeter is a beach lined with Scaevola (Vouloutye in creole), frequently visited by female sea turtles that emerge from the water to lay their eggs. The inner perimeter is home to other shrubs sitting alongside tall casuarina trees and idyllic mangroves. This assortment of vegetation, in addition to the absence of invasive mammals, makes St François an ideal breeding site for Red-footed Boobies and the Frigatebirds that so often nest in the same vicinity.

In the past, seabirds have suffered at the hands of human civilisation through direct persecution such as consumption of birds and eggs as well as indirect processes including the introduction of invasive predators, habitat destruction, via clearing areas for coconut plantation and guano mining, and extracting nesting trees for timber. In the case of the Red-footed Booby population on Aldabra Atoll, their population has increased substantially since the area received protection in 1967. In an effort to replicate this success across the nation, Seychelles has taken the necessary steps to implement a Marine Spatial Plan (MSP) that has increased its marine protection from just 0.04% to 30% of the surrounding ocean.

ICS conducted a research expedition on St François Island to support the implementation of the MSP by investigating the spatial ecology of non-breeding Red-footed Boobies and Great Frigatebirds (Fregata minor). This was achieved by attaching satellite tracking devices to 6 Red-footed Boobies and 4 Frigatebirds to observe which areas of the vast ocean they are using as foraging grounds. Once the results are published, they will be used to ensure the MSP encompasses areas that are vital to the survival and strengthening of Seychelles seabird populations.

Red-footed Boobies are the only booby species in Seychelles that nest in trees, creating a loose platform from sticks and casuarina needles cemented together by guano. In areas with breeding Frigatebirds they will actually delay building their platforms until their neighbours have finished, to avoid being robbed of nesting material. The entire breeding cycle can last up to 15 months including time taken to build a suitable nest, incubate an egg for over a month and spend five months nurturing the chick while foraging up to 150km from the nest. Following its maiden flight, the chick will continue to be dependent on the parents for a further 6 months.

Despite the elevated vigilance from the Alphonse ICS team, no further nesting was observed until February 2021. Two pairs attempted to build nests but only one made it to the egg laying stage. It is intriguing that the successful nest was built on the same branch of the same tree as seen in 2019. This, coupled with an approximate 15-month interval between eggs being laid, makes it entirely plausible that we are observing the same pair returning to St François to raise their young.

A common technique used to entice seabirds to colonise new breeding grounds is the use of decoys. These are usually custom-made sculptures, of the species in question, in a variety of natural displays that can be placed in the target area in order to entice other birds to attempt nesting. ICS have not deployed any decoys yet, but with any luck, as the seasons go on, the current pair will naturally reassure more prospective parents that St François is the perfect spot to start a family.

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To learn more about ICS visit www.islandconservationseychelles.com

By George Curd

Alphonse Group Assistant Conservation Officer,

Island Conservation Society