Weighing only around five grams, the goldcrest is the smallest bird in Europe and, as a "tiny bird", has few enemies: pygmy owls and sparrowhawks look for larger prey. However, being so small also has its disadvantages, as a goldcrest has to search for food almost non-stop to keep its energy levels up. Especially during the long, cold winter nights, the goldcrest "burns" up to a quarter of its body weight! On cold nights, the otherwise so incompatible goldcrest sometimes huddle together. They cuddle up and thus save energy! The formation of an egg is also an exceptionally energetic feat for a goldcrest. An egg weighs almost one gram, around a fifth of its body weight! The weight of the female can be recognised by the fact that she hardly flies at all on the evening before laying her eggs and only hops around on the branches. As a clutch can have 8 - 12 eggs, the female lays a good double her own weight - a true titanic achievement by this bird dwarf!