New rafts for Sussex terns

New tern rafts recently installed at Chichester Harbour, West Sussex, will help support three breeding species.

Chichester Harbour Conservancy has fitted the new tern rafts in Thorney Deep in order to assist with the nesting success of the local tern populations. Three species – Common, Little and Sandwich – breed in the harbour, and while the site has historically been productive for nesting terns, numbers have declined in recent years. Tidal flooding, human disturbance and predators such as foxes are listed as some of the threats the birds face, and emphasise the need for the rafts.

As many as 100 pairs of Common Terns nest in the harbour, with around 80 pairs of Sandwich Terns, while just a handful of Little Terns continue to breed following a recent drop in the number of nesting pairs across the site. The last species has experienced particularly poor breeding success in the harbour in recent years, though both Common and Sandwich have also struggled.

Little Terns have suffered from poor breeding seasons in Chichester Harbour during the last few years (Mike Trew).

Thorney Deeps is a large, semi-tidal lagoon separating Thorney Island from the mainland. The safety of the lagoon makes it an ideal breeding location for terns, and the rafts have been placed on relatively sheltered waters, allowing the birds easy access to feeding sites around both Langstone and Chichester Harbours.

The rafts, which were funded by Sussex Ornithological Society, are anticipated to have a positive effect on the terns' breeding success, with Chichester Harbour Conservancy Ecologist Peter Hughes commenting: "We hope that the terns will nest successfully on rafts in Chichester Harbour in the coming years, giving a major boost to the population in this special area. The rafts should also offer an excellent opportunity for the local community to see these fabulous birds up close."

Chichester Harbour is on the border of Hampshire and West Sussex, with Thorney Island, and indeed most of the harbour, sitting in the latter county. This area, Hayling Island to the west and the wider West Sussex coast east up to Pagham Harbour is particularly attractive to terns, and in the last couple of years has drawn in an excellent cast of rarer species, including Elegant, Roseate, Royal and White-winged.

Breeding Common Tern has declined in Chichester Harbour, but it remains the most numerous of the three species (Peter Garrity).