Other species were also affected, particularly those nesting under boulders. For instance at the Nunnery colony Razorbill numbers dropped from a peak of 90 pairs to only 1 by 2005, this was followed by rapid declines at other sub-colonies, so that between 1995 and 2004 overall numbers on Canna had dropped by 62%.
The figures below show the percentage change in seabird numbers between 1995 and 2004 on Canna.
| |
% change |
| Fulmar |
-33% |
| Shag |
-50% |
| Herring Gull |
-62% |
| Lesser Black-backed Gull |
-66% |
| Great Black-backed Gull |
-49% |
| Guillemot |
-16% |
| Razorbill |
-62% |
| Kittiwake |
+43% |
Source: HRG data collected under contract to JNCC
These declines on Canna were far greater than those recorded on neighbouring islands. They were also mainly affecting species nesting in burrows or under boulders. Birds nesting on inaccessible cliff ledges, like kittiwakes, were actually increasing in numbers and in 2004 we recorded 1340 pairs of kittiwakes on Canna, the highest total since monitoring first began in 1969.
Brown rats. Research showed that brown rats were to blame. More...
