October 15, 2010
During the cold winter months, many birds simply can’t find enough food to survive in northern habitats. Insect-eating birds, and some that rely on certain berries or seeds, will head to warmer climates where food is always plentiful. So why don’t birds that live in the warmer climates just stay there all year? In summer, […]
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October 4, 2010
The amount of daylight (photoperiodism) prompts the color changes in leaves, not cooler temperatures. As days get shorter, trees use less chlorophyll. All that green pigment starts to degrade, revealing the other leaf pigments. Trees with leaves that always turn yellow include tulip poplar, birch, hickory, and redbud. Some trees have leaves with high amounts […]
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