Starling photographed at My garden on 22/8/2018 Photo: © Sue De Mouilpied (visit site)

Despite now being one of the most familiar species in the islands, numbers of Starlings have fluctuated over the past two centuries. Smith thought them to be a rare breeder in Guernsey but wrote that large numbers of migrants passed through in autumn and, in some years, large flocks stayed into winter. By 1903, they were reported as breeding commonly (Dobson) and Dobson found them abundant in his visits in 1946, 'occupying every available nesting site'. Numbers have also fluctuated on Alderney (Dobson, Conder) but, in Sark, records of breeding Starlings have been restricted to certain areas such as La Seigneurie woods, Le Manoir, La Forge and other wooded areas (Rountree).

Over the past 30 years, Starlings have probably declined as a breeding and wintering species, at least in Guernsey, although there is no formal census data to support this. Starlings are still a common breeding species in all the major islands and in the 1989-91 GBBS, Starlings were recorded breeding in every square. However, the widespread improvements to houses and agricultural buildings will have reduced the number of available nesting holes and agricultural improvement and conversion from a mixed farming system to one dominated by intensive grass production will have also reduced the suitability of farmland as a feeding area. Intensive silage production, addition of large amounts of inorganic fertilisers and regular mowing have reduced the botanical and also invertebrate diversity in the Bailiwick's agricultural grasslands such that species rich low-intensity grassland managed as hay fields are restricted to only a few fields. Guernsey, especially, has undergone large-scale improvements to grassland but this has occurred to a lesser degree on other islands.

After breeding, large numbers of Starlings congregate in flocks which contain a high proportion of juveniles. The largest flocks tend to occur in coastal areas where birds feed on piles of rotting vraic washed up on the islands' beaches. The large flocks start to build up on beaches during June and July while smaller flocks inhabit gardens and other areas of non-agricultural grassland.

In autumn, large numbers of migrant Starlings pass through the islands and a proportion of these stay to winter. Throughout October and November parties of birds, sometimes up to several hundred birds, are seen passing over coastal headlands. Throughout the autumn and winter flocks of up to 1,000 birds are seen throughout the island, generally on beaches or in areas with large amounts of open grass such as the L'Erée aerodrome, the airport, Mare de Carteret or La Grande Mare. In the 1970s and 1980s feeding flocks of 2,000+ birds were recorded but these kinds of numbers have not been recorded in the last decade.

Birds roost communally, and the roosts, sometimes several thousand birds strong, have been found in reedbeds or in areas with tall trees. One notable roost was a roost which was used in the early and mid-1980s in Saint's Valley. Starlings and large numbers of thrushes used the roost during the winter from October onwards. Between 1993 and roosts have been located at La Claire Mare and an area at Longcamps but in past years many different areas have been used, including all of the island's major reedbeds. In the winters of 1982/83 and the following winter, several hundred birds roosted at the Bus Terminus in Town. These birds were branded a public nuisance and were the subject of frequent media attention.