BUTTERFLY EFFECT

As he ages, Norman needs increasing purpose to his rides

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For thirty years, my wife and I have had an interest in butterflies. They're beautiful creatures with a complicated life cycle, and find themselves a marker of global warming. This is seen by the fact that certain species of butterflies, once found only at low heights, are now moving both north and to higher elevations as the earth warms.

My own interest stems from the fact that butterflies are also markers of biological diversity and the health of the environment. Let me give you a couple of examples. There is a strong relationship between ants and butterflies. This relationship is hardly ever discussed when biological diversity and health is mentioned. Who cares about a few tiny ants? There is a butterfly called a Heath Fritillary. This butterfly lays its eggs on common cow-wheat, which thrive when they are near oak trees, deriving mineral nutrients from oak roots. The seeds of these plants are distributed by wood ants and it is the ants that ensure both the survival of the plant and the butterflies.