The Highland Ringing Group Canna seabird team, consisting of Bob Swann, David Aiton, Andrew Call, Simon Foster, Alan Graham, Kenny Graham, Andrew Ramsay and Ally Young arrived on Canna on 30^th June to conduct intensive rat and bird monitoring work on the island. We were to be ably assisted by Shona Quinn (Clyde RG), Chris Rodger (SNH) and Kathryn Mackinnon.

 

On 1^st July Roy Dennis and a BBC Natural History Unit camera crew came over in order to gather information and footage for a forthcoming Natural World programme on the problems facing the UK’s seabirds. Most of the filming was done on the Sunday and right on time the clouds parted to reveal the island at its best. Roy interviewed the project administrator about the trends in seabird numbers on Canna and about the rat eradication project. The crew left on the 3^rd.

 

As they left Edwin Blake and his associate from the RZSS arrived bringing the first contingent of mice to be released back onto the island. Testing had shown that all animals were free of disease and parasites, so safe to release. They were left in their cages in one of the sheds at the square to settle down, after their long journey up from Edinburgh. Later Fraser Dodds from the Highland Wildlife Park and three Napier University students arrived to help Edwin release the mice. The mice were released on the 11^th July and the students will remain on the island to monitor their progress up till the 17^th July.

 

Meanwhile the HRG team were busy checking bait stations along the monitoring grid. 778 stations on the grid were checked plus 109 extra ones. There was no sign of rats, although some blocks had been nibbled by shrews and one had been nibbled by a baby rabbit that had squeezed into one of the bait stations. This is excellent news as this was the first time the bait stations in the seabird colonies at Geugasgor and Lamasgor had been checked, since the WMIL team had left Canna in March. The 16 permanent stations round the pier were also checked and showed no signs of rat activity.

 

A full census of breeding seabird numbers was also undertaken by the HRG team. Details of numbers over the last 3 years are given in the table below. It should be remembered that 2005 was a particularly bad year, with, for the first time in recent years, severe food shortages affecting most seabird colonies in north west Scotland.

 

Following the period of cold weather in March, it was obvious that that most of Canna’s seabirds had laid far later than normal. It also appeared that many had not got in good enough condition to breed at all. This was particularly evident for Kittiwake and probably Guillemot and some Shags. For all three species lots of non-breeding adults were noted in the colonies. The continued decline in gull numbers and possibly also Fulmar is probably related to the recent sharp decline in fishing activity around Canna. Formerly a large fishery for prawns resulted in a lot of discards being available to these birds. This probably supported an unnaturally high population of these species.

 

So was there any sign of seabird numbers recovering following the removal of the rats? For some species there certainly was. Despite many shags not breeding, the recent long term decline had halted and overall a small increase occurred. At the Lamasgor colony (formerly heavily affected by rats) numbers increased from 48 nests in 2005 (many of which contained the remains of predated eggs) to 72 in 2006 most of which contained eggs or small chicks. The biggest change was with Razorbills. Nesting in amongst small boulders they were particularly prone to predation by rats. In 2006 numbers showed a very welcome sharp increase back to the sort of numbers recorded in 2000. We also had further evidence of the continued presence of Manx Shearwater, with the remains of 4 plucked ones being found below a Peregrine eyrie at the west end of the island. This suggests that some birds are at least attempting to re-colonise old colonies in the absence of rats.

 

The HRG team left Canna on the 8^th, although David Aiton, Helen Chisholm and boys remained for a further week to complete the rat monitoring work. It is still too early in the season to determine, just how successful, the overall breeding season will be. This will be reported on in the next progress report in mid August.

 

Meanwhile back at NTS HQ in Edinburgh the Canna environmental orientation and interpretation leaflet has finally been produced. As well as giving general information to visitors about Canna it highlights the importance of the EU Life backed rat eradication programme. Visitors are asked to be vigilant in preventing the accidental re-introduction of rats and to follow the guidlines on discarding rubbish. Copies of the leaflet are available at NTS HQ in Edinburgh and on Canna.

 

Bob Swann, Project Administrator