Rooks are widely distributed across the temperate and boreal middle latitudes of Europe across to Asia. It is associated with agricultural land and nests colonially in the crowns of tall coniferous or broadleaved trees. It was a common resident during the second half of the nineteenth century in Guernsey but became extinct as a breeding species sometime between 1920 and 1946. In some cases persecution led to the extinction of colonies and the wide scale clearance of trees during the First and Second World Wars reduced the availability of suitable breeding habitat.
Rooks were a relatively recent colonist to Guernsey. Prior to the second half of the 1800s, Rooks seem to have been a scarce migrant. In the late part of the nineteenth century, flocks were seen in several winters and various attempts were made at colonisation. Rookeries were established in 1880 at Les Vauxbelets and there were about 37 birds using the colony in 1884. These were driven away in 1903 and they established three separate colonies at Les Bordages near St Saviours church, one at Le Vallon near Moulin Huet and one at Le Vauqui�dor, with outliers at Belmont and Melrose. In 1905 the Le Vallon colony alone numbered 150 birds.
The demise of Rooks from the island is difficult to chart. Dobson is certain that they were nesting as late as 1919 as a rookery was recorded in St Andrews but exactly when they disappeared is unknown. Dobson failed to see Rooks in 1946.
The Rook is now a rare spring and autumn migrant with an average of less than one record per year. In spring, birds are recorded from the end of February to the end of May with a peak in the first half of May. In autumn, there are fewer recorded than in spring although the number of birds involved is approximately similar. The first birds are found in Guernsey in mid-September and numbers peak during October and the beginning of November. The last birds are found at the beginning of December. Since the extinction of Rooks as a breeding species there were not any overwintering records until 1-3 birds were found at Beaucamps on 28 December 1996. These remained throughout January and were last seen in 2 February 1997. These or other birds were also seen in the Talbot valley during this period.
There have been several records of larger flocks. In Guernsey, up to 80 and 40 were recorded between 1-15 March 1977 in the Fauxquets and Talbot Valley . In Alderney, 34 were recorded between 1-11 March 1974 and flocks of up to 80 were recorded in the autumn of 1977 (Condor).