Most of Leon’s research focused on two groups of organisms: mosquitoes and salamanders. He approached his studies on these animals in a multi-disciplinary fashion. Leon studied behavior, population and community ecology, population genetics, and transcriptomics. He executed both laboratory and field experiments. He particularly excelled at experimental design, both in the lab and in the field. Field trips with Leon were always a delight. He had an excellent naturalist’s eye, and delighted in sharing his discoveries with everyone. He was curious about everything he saw, and his knowledge of natural history was broad and deep and not at all limited to the organisms he studied. (The one exception was birds, as he classified all birds as “pigeons”.) This broad knowledge did deepen his research as he noted subtle aspects of the environment that could impact his focal species. These experiments and field studies produced insight and major contributions to amphibian ecology and evolution, mosquito population regulation, compassionate conservation, biodiversity conservation, and – late in his career – green roof ecology.