California Leaf Nosed Bat

California Leaf Nosed Bat, Macrotus californicus

The California Leaf Nosed Bat, Macrotus californicus, is known in Mexico as Murciélago Orejón Califoriano de Nariz Foliforme. They are a rather large bat and a member of the Phyllostomidae Family of Bats which are known in Mexico as muerciélagos.  There are 137 different bats known in Mexico at present. The California Leaf Nosed Bat is brown in color and is named for a triangular fleshy growth of skin protruding from the nose. The sexes are similar in size and appearance weighing between 12 and 20 grams; they have wingspans of 30 cm (12 inches), body lengths of 6.2 cm (2.4 inches) and large ears that are in excess of 2.5 cm (1 inch) in length.  They have large eyes and short and broad wings making them one of the most maneuverable bats in flight spreading their uropatagium widely when hovering or flying at low speed, a skill attributed to specialized sensory equipment. Their hearing is so good that they can hear the footsteps of a cricket. They are found in low-land hot desert habitat throughout the Baja and in western Mexico. They are not suited for long distance flying, and are thus non-migratory. They do not hibernate. They roost in the daytime in caves within geothermally heated rocks, deserted mine tunnels and deep grottos which affords escape from summer heat and the drying effects of desert climate, protection from the winter cold, and protection from weather. They hang from sloping parts of the ceiling by one foot or both feet usually swinging gently like a pendulum. The California Leaf Nosed Bat is a “gleaning” insectivore consuming beetles, crickets, grasshoppers, and sphinx moths straight from the ground or from foliage while hovering above while in flight. Prey is detected normally by eye sight but they also have the ability to hunt in total darkness via echolocation. The captured prey is hauled away to an open roost (open buildings, cellars, porches, bridges, rock shelters and mines) where it is dismembered and consumed. They forage between one and four hours after sundown and they retire one to two hours before daylight. In turn they are preyed upon by cats, coyotes, owls, raccoons and snakes. Pups are born from May to June, one or two to a liter, with eyes and ears open and a body that is already furred; they are nursed for about a month. Maternity colonies normally consist of 100 to 200 females. They have an average life-span of 20 to 30 years in the wild. From a conservation perspective the California Leaf Nosed Bat is considered to be Vulnerable due to loss of habitat and human disturbances which are especially detrimental during summer months, when these bats are rearing young.

California Leaf Nosed Bat, Macrotus californicus. Collected from a cave within the Las Cuevas area of Baja California Sur, January 2018. Wing Span: 28 cm (11 inches); body 5.8 cm (2.3 inches). Catch courtesy of Sam Rousseau, Raleigh, NC and Brad Murakami, Surrey, British Columbia, Canada.