For the first time, a pair of migrating swallows have raised three chicks on the Hebridean island of Hirta. The nest was established in a garage operated by defence contractor, Qinetiq, who agreed to leave the doors open for the duration of the breeding season. Swallows are regular summer visitors to St Kilda, but this is the first time that they have successfully raised young.
Meanwhile, efforts to monitor the breeding success of Leach's Storm Petrels received a boost when two chicks were successfully reared in artificial nest boxes. Last summer saw the first successful breeding in newly designed boxes and the continued growth in the numbers of birds using these boxes bodes well for the eventual possibility of tracking breeding success on a routine basis. The population of this species has been in serious decline on St Kilda since the late 1990s.
The St Kilda archipelago, which has been in the care of the National Trust for Scotland since 1957, is one of the UK’s most important seabird colonies. Home to a huge range of species, it boasts the UK’s largest puffin colony, with around 136,000 at the last full count. These popular and distinctive birds have had ‘moderate breeding success’ this summer.
The Trust’s seabird ranger Gina Prior, who is based on St Kilda, said: “Our monitoring has found that the breeding success for puffins was at a similar level to last year with about 45 per cent of breeding pairs raising chicks. We’d be looking for around 70 per cent of nests to produce a chick ideally. If the current levels continue for the long term, then the population of the colony could start to decline as the number of chicks just won’t replace the adults who are dying off.”
Although the breeding season is almost over, Gina’s work continues as she helps ensure that the young birds make a safe departure from St Kilda.
She continued: “Over the next few weeks, pufflings will leave their breeding burrows and return to sea. Some become disorientated by the lights from buildings and ground themselves on shore where they are unable to take flight again. I patrol the buildings at midnight and again at dusk to collect any stray young birds. Before release, they are measured and weighed and this data is the final piece of the ‘breeding success’ puzzle. The information is used as a measure of body condition which provides information on whether the birds are a healthy weight when they leave the colony.”
St Kilda is the UK’s only natural and cultural World Heritage Site and is the remotest outpost of the British Isles lying 41 miles (66 km) west of Benbecula. Marking the end of thousands of years of human occupation, St Kilda’s remaining population was famously evacuated to the mainland at their own request in 1930.
The archipelago was allocated World Heritage status by UNESCO in 1986 in recognition of its natural heritage, exceptional natural beauty and for the significant natural habitats that it supports. In July 2004 this was extended to include the surrounding marine environment and in 2005, recognition was also given to St Kilda’s unique cultural landscape.