Researchers monitoring Dublin Port’s tern colonies have reported a series of striking discoveries this year, including the sighting of a bird ringed in Senegal and another Dublin-hatched tern recorded more than 4,500 kilometres away in The Gambia.

The findings are part of the Dublin Bay Birds Project, a long-running study that tracks the breeding success, survival and migration of Common and Arctic Terns nesting in the port. Every chick is ringed to help scientists understand how these seabirds move between Ireland, Europe and Africa.

In August, one fledgling Common Tern ringed in the port in late June was spotted off the coast of Cádiz, Spain, just weeks after taking its first flight. In October, another juvenile from the same colony was recorded at Kartong Bird Observatory in The Gambia. The project team said such sightings show the remarkable connectivity between Ireland and the west coast of Africa and underline the need for international cooperation to protect migratory species.

Closer to home, researchers have gathered ring readings from Dublin Bay sites such as Blackrock and Seapoint, as well as from North Wales and Lancaster. Each record adds to understanding of the key stopover and wintering sites used by terns that hatch in Dublin.

The project also recorded one of its oldest known birds this season. A Common Tern ringed as a chick in 1999 was identified breeding again in the port this summer. The 25-year-old bird has completed annual migrations between Dublin and West Africa, covering almost 15,000 kilometres each year. It is now the oldest known tern in the Dublin colony.

Researchers believe that ongoing conservation work in the port has helped maintain the long-term success of the colony, with some birds returning to the same nesting platforms for more than two decades.

The Dublin Bay Birds Project is supported by Dublin Port Company and the Dublin Bay Biosphere. It provides long-term data to help protect terns as they face increasing pressures from climate change, declining fish stocks and offshore development.

All birds were ringed and handled under licences issued by the National Parks and Wildlife Service and the British Trust for Ornithology.