It's not exactly a warmth trend, but it is warming, and as it does, the Wood Frog Chorale has once again burst into, well, the duck quack songs that the black-masked amphibians are so known for. And as the males croon, the females, their bellies swollen with eggs, listen intently and evaluate the singers. She's picky about song quality, which, apparently, is a proxy for male health, stamina, and desirability as father material, and when she finds a likely candidate for paternity, she swims towards him, somehow signals her desire, and they couple, the male on top. (I'm not making a value judgement about mating positions—male superior, as it were, is just the way frogs do it.) The posture is known as amplexus, and, as is visible in the photograph of the perhaps happy couple, the male is hanging on tightly, his arms locked in what can resemble a death grip. She takes it all in stride as they embrace the situation, which can continue for hours, before swimming off to a proper egg-laying site and laying and fertilizing the next generation.