Eradication is not the end of it: signs of a mouse on St Agnes show the need for continued biosecurity

Ground bait station sites on St Agnes and connected Gugh Islands during the rodent eradication operation

St Agnes is one five inhabited islands in the United Kingdom’s Isles of Scilly.  Following the eradication of Norway Rats Rattus norvegicus by a ground-baiting campaign a decade ago, both Manx Shearwaters Puffinus puffinus and European Storm Petrels Hydrobates pelagicus have been recorded breeding, signalling a successful operation (click here).  But this is not the end of the story.  It is necessary to put and keep in place best-practice biosecurity measures at points of entry that will greatly reduce the risk of reintroductions – and continue to keep a look out for signs of rodents elsewhere on the island.  A recent report from St Agnes nicely illustrates the problem as repeated here.

Manx Shearwater chick at its burrow entrance on St Agnes, photograph by Jaclyn Pearson

“Conservationists on an island 28 miles off the UK mainland are concerned after signs there may may be a mouse there, potentially putting a colony of seabirds at risk.  Mice and rats have been eradicated from St Agnes in the Isles of Scilly, as part of measures to protect its nationally significant population of storm petrels.  The Isles of Scilly Wildlife Trust said “probable” signs of a mouse including droppings and urine had been spotted, and suspects the creature was brought in within some animal feed.

The trust has been running a successful program with the RSPB and others to get rid of rodents on the islands for the past decade, which has led to the petrel population "bouncing back.  Tony Whitehead, from the RSPB, said it had a "very well worked out response" which involved putting rodent poison in traps across the island and "then keep checking the traps".

He said if "mice do get a hold on the island" they would be likely to eat the eggs of birds like storms petrels and Manx shearwaters, putting populations at risk. Mr Whitehead said a member of the community had spotted the mouse droppings last Thursday.

The residents of the island have been brilliant and hugely supportive.  The wildlife trust said signs had been put up across St Agnes to warn parents of young children and dog owners about traps.”

Read earlier  articles in ACAP Latest News on the rat eradication operation on the Isles of Scilly.

With thanks to Anton Wolfaardt, Mouse-Free Marion Project.

John Cooper, Emeritus Information Officer, Agreement on the Conservation of Albatrosses and Petrels, 11 November 2024