Oct 01, 2026
American mink are capable of delayed implantation. After fertilisation, the embryo can remain in the uterus in a dormant state before implantation occurs. This allows birth to be timed so that the kits arrive during the more favourable conditions of spring.
Source: wikimedia commons
Some armadillos have an even more unusual reproductive strategy. The nine-banded armadillo commonly produces genetically identical quadruplets from a single fertilised egg, rather than simply delaying pregnancy. Delayed implantation is found in some other armadillo species, showing how remarkably flexible reproduction can be among these mammals.
Source: wikimedia commons
Some bear species, including polar bears and black bears, can delay implantation. The female may mate months before giving birth, but the embryo does not immediately begin continuous development. This allows reproduction to be timed around seasonal food availability and the mother's ability to support her cubs.
Source: wikimedia commons
European badgers can delay implantation for several months. Although mating may take place much earlier, the fertilised egg can remain dormant before beginning active development. This ensures that cubs are generally born at a season when food availability is improving.
Source: wikimedia commons
Kangaroos are among the best-known animals capable of delaying pregnancy. A female can give birth while an older joey is still developing in her pouch and another embryo remains in a state of suspended development. When conditions are right, the dormant embryo can resume development, allowing the mother to manage offspring at different stages.
Source: wikimedia commons
Koalas can experience embryonic diapause, although it is less commonly discussed than in kangaroos and wallabies. The ability can help regulate the timing of reproduction and the interval between births, allowing females to respond to reproductive and environmental conditions.
Source: wikimedia commons
Several seal species use delayed implantation as part of their reproductive strategy. After mating, the embryo may remain dormant for a period before implanting in the uterus. This helps synchronise birth with the seasonal conditions that are most suitable for raising pups.
Source: wikimedia commons
Several wallaby species can also use embryonic diapause. After mating, development of the embryo may stop before implantation. The pause allows the mother to delay the arrival of another joey, particularly while she is already nursing a young one.
Source: wikimedia commons
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