European pine martens inhabit and develop on land, outside of bodies of water, and their young develop in nests built on or near the ground, or inside tree cavities and caves/crevices; the female demonstrates parental care within these nests. Embryonic development lasts 4 weeks, and the species reproduces through live birth, with young being born alive on land, not hatching from eggs or larvae. The female mates in summer, and because of delayed development, offspring are born in spring; she gives birth to a litter of 2–5 young in a den and raises them alone until autumn. Sexual reproduction is homogamy, always involving fertilization and without generational change, and the reproductive interval is 1 year. Pine martens reach maturity from 1 to 2 years, and the female has 2–5 litters.