The utility of Argos satellite tagging in monitoring a long-lived raptor: White-tailed Sea Eagle reintroduction to Ireland

Allan Mee, of the Golden Eagle Trust, Norwegian Institute for Nature Research, presents his work reintroducing white-tailed sea eagles, at the European User Conference for Argos Wildlife (EUCAW). As he explains, white-tailed Sea Eagle (WTSE) Haliaeetus albicilla became extinct in Ireland in the early 20th century. The species also disappeared from Britain at this time, in both cases largely as a result of human persecution. Reintroductions in Scotland (1975-85, 1992-96, 2007-11) have now re-established a viable and expanding population there. Reintroduction began in Ireland in 2007-2011 with the release of 100 chicks taken from nests in the wild in Norway under a joint project with Irish and Norwegian counterparts. Prior to release in Killarney National Park birds were fitted with Argos solar GPS PTTs (n=11) or VHF radio transmitters (n=89) for post-release monitoring. While VHF tags have been valuable for the relocation of individuals (alive or dead) within the release area (<50km) their usefulness declined as birds disperse.

Tracking dispersed birds

WTSEs dispersed throughout the island of Ireland, mainly north along the west coast and inland lakes. At least seven birds dispersed to Scotland, most returning to breed in SW Ireland. WTSEs began breeding in the wild in 2012 and to date 25 chicks have been fledged by pairs from 75 nesting attempts. Eight wild chicks have been fitted with satellite tags to date and there have been invaluable in determining timing of dispersal, post-fledging movements and dispersal distances, roost and nest site location.

Argos, a key tool for studying mortality in birds

Argos satellite tags have also allowed the rapid recovery of dead birds and determination of the cause of mortality. Major sources of mortality to date have been illegal poisoning and, to a lesser extent, wind turbine collisions and most recently Avian Influenza. Although cost is a serious issue for small scale conservation projects, satellite tags have proved invaluable in both applied and research elements of the Irish WTSE reintroduction project.

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