Winter population size and habitat selection of Crested Tits Parus cristatus in Scotland

Abstract

Estimates of the number of winter social groups of Crested Tits in Scotland ranged from 2300 (95% CL 1300–3900) to 3300 (95% CL 2000–5200) during a survey over three winters in ancient native pinewoods and other woodlands. These represent a population of 5600–7900 birds after adjustment for incomplete counts of group sizes. Mean group densities were about ten times higher in ancient native pinewoods (9.0–10.3 km-2) than in other woodlands (0.7–1.3 km-2) which comprised largely planted Scots Pine, Lodgepole Pine and Sitka Spruce. Thus, 35% of the Scottish population of Crested Tits occurred in ancient native pinewood, which comprises only 4.7% of the woodland. Crested Tits were associated mainly with Scots Pine, but were also seen in Lodgepole Pine, Norway Spruce, larch, Rowan, Alder and birch. The group densities within the stands of Scots Pines in ancient native pinewoods were 10.4–12.3 km-2 and 1.2–2.4 km-2 in Scots Pines in other woodlands. Within ancient native pinewoods, they preferred stands with a high proportion of Scots Pines, and particularly those with older trees. In other woodlands, there was again a preference for stands with a high proportion of Scots Pines, and Heather was also selected. Crested Tits will continue to benefit from the planting of Scots Pines, and if the woods develop a Heather field layer. However, they will not benefit from spruce plantations.