Ecology of the Occult Myotis (<i>Myotis occultus</i>): Investigating Diet, Ectoparasites, Distribution, and Morphological Variation

Research Project: 


Project Manager: 

Ernest Valdez

The Arizona myotis or occult myotis (Myotis occultus) is a southwestern U.S. endemic bat that possesses unique morphological variation throughout its distribution. Recent morphological analyses of crania, jaw, and dental features of M. occultus from Colorado and New Mexico have shown that there are three sizes related to geography. In general, individuals located in southern Colorado were overall the smallest in size compared to individuals from New Mexico. However, within New Mexico, individuals located in the lowlands of the Rio Grande Valley were smaller than the largest individuals occurring at higher elevations (e.g., mixed coniferous forests) throughout the state. Analyses of guano revealed that M. occultus from Colorado consumed mostly soft-bodied prey items (e.g., midges and wasps), whereas individuals from New Mexico consumed hard-bodied prey items (e.g., beetles) and differences in diet are likely one reason for geographic variation in morphology. Temperatures and time between first and last frosts also appear to be indirect contributing factors for morphological variation across the range of M. occultus. Additional key findings for diet of M. occultus include the presence of economic pests (i.e., bark beetle and click beetle). In addition to the analyses of morphological differences and diet of M. occultus, ectoparasites were also collected and identified. Prior to this study, only two ectoparasites were known to occur on M. occultus. After close examination of 202 specimens of M. occultus, over 2000 ectoparasites belonging to 9 families and 13 genera were documented. This represents the first extensive study of ectoparasites occurring on M. occultus. Additional highlights include the discovery of three new species of mites belonging to the genera Alabidocarpus, Pteracarus, and Chiroptonyssus.