Many species have been found to be induced ovulators and the reasons for this are not always clear. However, one possible reason is that induced ovulation could provide a better reproductive potential for those species that typically have shorter life spans and less encounters resulting in lower mating opportunities throughout their lifetime. Other species may be 'facultatively-induced ovulators' meaning that while they can spontaneously ovulate, the cycle may speed up or slow down depending on the presence of males, females or mating. Some rodents such as squirrels
Cats are another widely-known induced ovulator. After mating, the LH levels in female cats surge, and the time to ovulation can be predicted to occur between 1–2 days later.
Wolverines are other known induced ovulators which require physical mating to cause ovulation. Induced ovulation occurs in various
carnivoran species, including most
felids and several species of
mustelids. Many bear species are able to have induced ovulation including the
grizzly bear, black
bear and
polar bear where both the presence of a male and mating itself are requirements for induced ovulation. However, there are some suggestions that mating is not as strict a requirement for ovulation in bears.
Japanese black bears are induced ovulators. It was observed that most females kept separate from males did not ovulate, whereas females kept in areas with male bears did. Mating between the bears caused elevated progesterone levels, and this was seen by increased progesterone levels measured in the bears in the months that followed the mating seasons. In Japanese black bears, the presence of a male was enough to cause a notable rise in progesterone levels even without mating. This could suggest that
pheromonal/
chemosensory factors could also contribute to induced ovulation in some species. == In cattle ==