Goldcrest

The goldcrest breeds in mature lowland and mountain coniferous woodlands, mainly up to 3,000 m (9,800 ft), and occasionally to 4,800 m (15,700 ft). It uses spruce, larch, Scots pine, silver fir and mountain pine, and in man-made landscapes also introduced conifers such as douglas fir. Breeding densities of up to 591 pairs per square km (1,530 pairs per square mile) have been recorded in Norway spruce in Ireland, and goldcrests constituted over 60% of all birds found in Welsh Douglas fir and Norway spruce plantations. Broad-leaved woods are used only when some spruce or firs are also present. Sites such as parks and cemeteries are used only when they offer suitable conifers that are not otherwise locally available. The height and nature of any undergrowth is irrelevant. Unlike more specialised birds such as the Eurasian nuthatch and the Eurasian treecreeper, both of which forage on tree trunks, the kinglets do not need large woodlands, and their population density is independent of forest size. Once breeding is over, this species will readily move into deciduous trees and shrubs, heathland and similar more open habitats. The Tenerife subspecies occurs in the mountain region previously occupied by laurisilva, but now dominated by tree heaths. It is common only in that habitat, becoming rare in pine forest, where it occurs only where tree-heath is also available. The goldcrest has a huge range in Eurasia, breeding from Macaronesia to Japan. It is common in middle and northern temperate and boreal latitudes of Europe, between the 13–24 °C (55–75 °F) July isotherms, and thus predominantly in cooler climates than the firecrest. Further east it occurs discontinuously through southern Siberia to Sakhalin and Japan, in the Tian Shan mountains, northern Iran, and from the Himalayas east to central China. This species has bred in Iceland since about 1999, and was widespread by 2004, although numbers are affected by hard winters. Breeding occurs intermittently in the Faroes. The goldcrest has occurred as a vagrant in Jordan and Morocco. This species is partly migratory, northernmost populations deserting their breeding areas in winter. Birds winter in Europe and Asia south of the breeding range. Birds in northern Fennoscandia and Russia vacate their territories between late August and early November, with most leaving in late September to mid-October as the first cold weather arrives. Adverse conditions may lead to disorientation, large numbers gathering on ships on overcast or wet nights. Large influxes include 15,000 birds on the Isle of May in October 1982, and nearly 21,000 birds through a single site in Latvia during September and October 1983. Spring migration is complete by late March on the Mediterranean islands, but continues to late April or early May in northern Europe. The spring passage is much lighter than in autumn, suggesting high mortality on migration. A study in the Baltic region showed that northern goldcrests were more likely to migrate, and increased their body mass beforehand; non-migratory southern birds did not increase their fat reserves. The travel speed of migrating goldcrests increased for those leaving later in the autumn, and was greater for the northernmost populations. Migration was faster on routes that crossed the Baltic Sea than on coastal routes, and the birds with the largest fat reserves travelled at the highest speeds. The ability to lay down fat is adversely affected in this tiny bird by poor health. In Hungary, goldcrests stopping temporarily on migration were mostly found in scrub, including blackthorn, hawthorn and pear, which provided some protection from sparrowhawks. Females migrated slightly earlier than males, but overall there were more males, with an average sex ratio of 1.6:1. Goldcrests can fly 250–800 km (160–500 mi) in one day, although they keep at a lower level in heavy headwinds. This is a tame and inquisitive bird, and tired migrants will land near or on humans, sometimes searching for food on their clothing. The North Atlantic oscillation is an atmospheric phenomenon affecting the weather in Western Europe. When the atmospheric pressure variations in the North Atlantic are large, the springs in Europe are warmer. This brings forward the northward migration of those bird species (including the goldcrest) that winter mainly within western or southern Europe. A general climatic change resulting in more frequent positive North Atlantic oscillation events has led to earlier spring migration of these short-distance migrants since the 1980s. The warmer spring weather brings on plant growth, thus preparing the habitat for returning migrants. The effect is greatest in western and central Europe.