Study to unlock secrets of west coast seabirds

A contract advertised by the Scottish Government has been awarded to tag and track the Manx shearwater, European storm petrel and Leach's storm petrel species.

The initiative between RSPB Scotland and Marine Scotland has been funded by a grant from the European Maritime and Fisheries Fund.

The British Trust for Ornithology is also involved in the project by providing training on how to tag great black-backed gulls using a special kind of harness.

The total value of the contract is £130,233 covering different remote areas along the west coast.

The breeding of Manx shearwater on Rum will be monitored, with focus on the European storm petrel taking place on the Treshnish Islands and Priest Island to gather data on their distribution and habitat use. St Kilda and North Rona will take centre stage in order to track Leach's storm petrel.

Dr Mark Bolton, principal conservation scientist for RSPB Scotland, said: "This work provides an exciting and important opportunity to discover the locations of the marine feeding areas of Leach's and European storm petrels breeding at the largest colonies in west Scotland, which will inform future management for these priority species."

A Scottish Government spokesman added: "Scotland hosts internationally important populations of seabirds and knowledge on how they use the marine environment is needed to optimise their conservation prospects and ensure the sustainable management of our seas.

"This study will track the at-sea movements of Leach's storm petrel and the European storm petrel for which there is currently very limited data available in Scotland and virtually none on the west coast."

Work on the project began late last year. However, due to Covid-19 restrictions, fieldwork has been delayed until next summer.

Manx shearwaters have a particularly perilous 6000 mile journey from Scotland.
The chicks fledge from the mountains of the Isle of Rum before flying to their wintering grounds in South America.

The birds are incredibly long-lived with the oldest recorded from ringing studies at 50 years, 11 months and 21 days.

However each year some of the young birds can become disorientated by outside lights left on in Kinloch on Rum and surrounding villages, but particularly Mallaig on the mainland.

They often crash land close to the light source and many are then killed by gulls, crows, cats or dogs.

However volunteers rescue scores of them.

A paper published in the Ibis International Journal of Avian Science revealed that the moon and wind play a huge part in the birds' demise. Adverse weather conditions and moonless nights were reported to increase seabird fallout.

"The location of the Manx shearwaters colony in Rum is to the west of Mallaig and the current finding confirms that strong winds blowing towards the source of light pollution causes the largest number of groundings," said the research.

"Our study confirmed that more birds were grounded in nights with less moonlight and in nights with strong westerly winds showing that birds may be blown from their colony in the direction of the light pollution. Low and high visibility conditions also contributed to higher grounding probabilities.

"Thanks to these findings, rescue campaigns could focus their efforts on nights when the risk of groundings is highest or could inform local authorities under which conditions light intensity needs to be reduced."

Usually several hundred are saved in Mallaig, Morar and Arisaig and in 2012 there was a record 709.

More than 60,000 pairs - more than a fifth of the British breeding population of around 295,000 pairs of manxies - breed on Rum.

The Rum colony is unique in that it is in the high mountains of the island as this is not usually the favoured habitat of the species.

Manx shearwaters are clumsy on land so the adult birds only visit the colony at night to avoid predation.

Chicks fledging this year are unlikely to return to the colony next year as they do not return until they are three years old. They first breed at around five years old.

The majority spend the winter months off the coast of South America and adults return to the colony in late March with eggs being laid in May.