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 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. Behaviour Breeding The goldcrest is monogamous. The male sings during the breeding season, usually while foraging rather than from a perch. It has a display involving bowing its head towards another bird and raising the coloured crest. Firecrests will sometimes defend their territories against goldcrests, but the amount of actual competition between the species may not be very great. A Spanish study suggested that territorial conflicts between species, and other phenomena like males singing mixed or alternating songs, were most frequent when one species locally far outnumbered the other; in other circumstances, the two species learned to ignore each other's songs. However, in very small areas of conifers it is rare for the goldcrest and the firecrest to share territories; either one or the other is present, but not both. A male goldcrest will defend his territory against either species, sometimes including some firecrest phrases in his song. The goldcrest's nest