To understand biodiversity, it is crucial to have knowledge of different species and their life conditions. Biodiversity learning for children starts with observing plants and animals in the neighbourhood. Therefore, it is important that early childhood (EC) teachers know the local nature. There are few studies on species knowledge among EC student teachers but results from a Norwegian study show that although EC student teachers had poor species knowledge when entering university, their knowledge increased remarkably during their studies. Based on these results, the current study investigates the implementation of species learning in an EC teacher education course in Finland. Our aim was to study the student teachers’ species identification skills, their views on the importance of species knowledge, and their experiences of species learning. The study used a mixed-methods approach and included species identification tests, a questionnaire, learning diaries, and focus group interviews. The results show that the student teachers were eager to learn about species. They found species learning important both for EC teachers and for sustainability, and they appreciated learning about species in a broad sense, from personal, educational, and social perspectives. Our conclusion is that implementing species knowledge in EC teacher education promotes an interest in the natural world and may form a significant contribution to nature and sustainability education for EC teachers.