Newborn gray myotis clustered together in a cave.
Description: The gray myotis is similar to the cave myotis in size, but is dark grayish-brown. Hair is uniformly colored in contrast to the little brown myotis which shows a basal zone of dark hair and lighter, glossy hair tips. Underparts are lighter than the back. This species can be distinguished from other bats in Kansas by; 1) grayish brown fur, 2) the wing membrane which attaches to the ankle rather than farther down along the toes, as in other myotis. The skull has a well-developed crest of bone (sagittal crest) on the top of the skull.
Size: Adults may attain the following dimensions: total length 88-107 mm; tail 32-45 mm; hind foot 9-13 mm; ear 12-16 mm; weight 8-16.6 grams.
Range and Habitat: This bat is known only from the southeastern part of the state. From the few available Kansas records it seems to be confined to storm sewers, but elsewhere is known to occur in limestone caves. It is likely that most gray myotis in Kansas migrate in the autumn to suitable caves in adjacent states, returning in mid-April. A few bats, however, may remain in Kansas the entire year. Interested persons should be aware of the need for information about the distribution and ecology of this endangered species, but it is essential that roosts not be disturbed.
Reproduction: The gray myotis breeds in the autumn before or after entering a hibernation cave. A single egg is fertilized in the spring when it is released from the ovary, sperm being present in the uterus throughout the winter. Females migrate to warmer summer caves in spring where they produce a single young each in May or June. These newborn bats develop in much the same was as young of the little brown myotis. The young remain in the cave while the female forages for food. When the female returns the young are located from among the many others in the cluster, probably by a combination of voice and scent. A young female may breed in the autumn of her first year, and may give birth in the spring of her second year. As is the case of the little brown myotis, the male does not mature sexually until the second year.
| Habits: The gray myotis lives principally in limestone caves throughout the year except for foraging or migration, spending its winger in cool caves with optimal temperatures for hibernation and, during summer, in warmer caves for rearing young. The two sorts of caves may be near each other or may be separated as much as 250 kilometers. In summer caves, adult females congregate in maternity clusters to give birth and rear their young. The males and subadults during this period live in other caves, or at least apart from the maternity group in the same cave. It is at this time of year especially that disturbances of caves causes mortality in young bats. During winter, the gray myotis selects caves that are cool enough to permit hibernation. Interruption of the delicate environmental balance by closing cave entrances, or forming new entrances, may cause death to millions of these bats. | Newborn gray myotis clustered together in a cave. |
Food: The food of the gray myotis is mainly flying insects, especially mayflies, captured over water. Bodies of water suitable for foraging near maternity caves are essential for this species.
Remarks: When numbers of gray myotis congregate considerable guano accumulates on the cave floor, and has a pronounced effect on the ecology of caves. Guano provides a source of food for other organisms such as arthropods and fungi, which live their entire lives within the caves.