Valentine’s Day is almost upon us, bringing to mind the words of Alfred, Lord Tennyson, “In the spring a young man’s fancy lightly turns to thoughts of love.” If he had written that today instead of 1835, he would probably have mentioned “a young woman’s fancy” as well. And had he been an ecologist rather than poet laureate of Britain, he might have noted that as days grow longer and nights get shorter, courtship and romantic engagement in the Northern Hemisphere become prevalent throughout the animal kingdom. Some performances are already underway.