Overview
Beech trees usually flower heavily every three years or so. The profusion of flowers changes the appearance of the trees, and the whole forest, from dark green to scarlet. Clouds of pollen blow down from the trees. The following autumn the trees drop myriads of little seeds (or nutlets). These good years are called ‘mast years’ (‘mast’ is an old word meaning food from the fruits of the forest). In the intervening years, the beech trees produce hardly any flowers or seeds at all.
Many native animals depend on beech trees for their food. In a good flowering year, an army of caterpillars and insects feed on the flowers. Birds, mice, and spiders eat the insects. Mice also eat the seed as it falls. So in bonanza years, beech trees provide so much food that the insect, spider, and bird numbers shoot up, and the mouse population explodes.
Who exploits this superabundance of food? Stoats mainly, for they feed on the mice, birds and the bigger insects. So we have a beech food chain, or web, from beech flowers and seeds – to insects, mice, and birds – to stoats. Every few years, and in step with the beech seeding, mouse and stoat numbers shoot up in a cycle of abundance. And when the food supply runs out, the numbers of the various populations dwindle again. It is New Zealand’s version of the lemming cycles in the northern hemisphere.
Text originally published in Tai Awatea, Te Papa's onfloor multimedia database.