''Macrotus'' is a genus of
bat
Bats are mammals of the order Chiroptera.''cheir'', "hand" and πτερόν''pteron'', "wing". With their forelimbs adapted as wings, they are the only mammals capable of true and sustained flight. Bats are more agile in flight than most bi ...
s in the Neotropical family
Phyllostomidae. This genus contains two species, ''Macrotus californicus'' commonly known as
California leaf-nosed bat
The California leaf-nosed bat (''Macrotus californicus'') is a species of bat in the family Phyllostomidae. It is found in Mexico and the United States. Its natural habitat is hot deserts.
Habitat
California leaf-nosed bats can be found in S ...
and ''Macrotus waterhousii'' commonly known as Mexican or
Waterhouse's leaf-nosed bat
Waterhouse's leaf-nosed bat (''Macrotus waterhousii'') is a species of big-eared bat in the family Phyllostomidae. It is found in the Cayman Islands, Cuba, the Dominican Republic, Guatemala, Haiti, Jamaica, and Mexico, with a range from Sonora ...
. The range of this family includes the warmer parts of the southwestern United States, Mexico, Central and South America, and the Bahama Islands.
Characteristic for the genus are large ears and the name giving triangular skin flap above the nose, the "leaf". The California Leaf-nosed Bat inhabits the arid deserts of the southwestern United States as far north as Nevada, south to Baja California and Sonora, Mexico. The California Leaf-nosed Bat is of medium size, with a total length between 9 and 11 cm Its most distinctive features are the large ears, connected across the forehead. The body is pale grayish brown dorsally with whitish under parts.
The
pelage
Fur is a thick growth of hair that covers the skin of mammals. It consists of a combination of oily #Guard hair, guard hair on top and thick #Down hair, underfur beneath. The guard hair keeps moisture from reaching the skin; the underfur acts as ...
(fur) on the body is silky, the hairs on the back about 8 mm, on the front about 6 mm long. The posterior base of the ears are covered with hair of a woolly texture while the interior surface and most of the anterior border shows scattered long hairs.
[Grinnell, Hilda W. A Synopsis of the Bats of California. 12th ed. Vol. 17. Berkeley: University of California, 1918. Print.] The flight membranes are thin and delicate; the wings are broad and the tail is slightly shorter that the long hind limbs and extends several millimeters beyond the uropatagium (see
Bat
Bats are mammals of the order Chiroptera.''cheir'', "hand" and πτερόν''pteron'', "wing". With their forelimbs adapted as wings, they are the only mammals capable of true and sustained flight. Bats are more agile in flight than most bi ...
).
''Macrotus waterhousii'' is also a big eared
Bat
Bats are mammals of the order Chiroptera.''cheir'', "hand" and πτερόν''pteron'', "wing". With their forelimbs adapted as wings, they are the only mammals capable of true and sustained flight. Bats are more agile in flight than most bi ...
which has ranges from Sonora to Hidalgo
Mexico
Mexico (Spanish: México), officially the United Mexican States, is a country in the southern portion of North America. It is bordered to the north by the United States; to the south and west by the Pacific Ocean; to the southeast by Guatema ...
, south to
Guatemala
Guatemala ( ; ), officially the Republic of Guatemala ( es, República de Guatemala, links=no), is a country in Central America. It is bordered to the north and west by Mexico; to the northeast by Belize and the Caribbean; to the east by H ...
and the Greater
Antilles
The Antilles (; gcf, label=Antillean Creole, Antiy; es, Antillas; french: Antilles; nl, Antillen; ht, Antiy; pap, Antias; Jamaican Patois: ''Antiliiz'') is an archipelago bordered by the Caribbean Sea to the south and west, the Gulf of Mex ...
(excluding
Puerto Rico
Puerto Rico (; abbreviated PR; tnq, Boriken, ''Borinquen''), officially the Commonwealth of Puerto Rico ( es, link=yes, Estado Libre Asociado de Puerto Rico, lit=Free Associated State of Puerto Rico), is a Caribbean island and Unincorporated ...
) and
Bahamas
The Bahamas (), officially the Commonwealth of The Bahamas, is an island country within the Lucayan Archipelago of the West Indies in the Atlantic Ocean, North Atlantic. It takes up 97% of the Lucayan Archipelago's land area and is home to ...
.
This species roosts primarily in caves, but also in mines and buildings. This species is also insectivorous (see
insectivore
A robber fly eating a hoverfly
An insectivore is a carnivorous animal or plant that eats insects. An alternative term is entomophage, which can also refer to the human practice of eating insects.
The first vertebrate insectivores wer ...
), primarily consuming insects of the order
Lepidoptera
Lepidoptera ( ) is an order (biology), order of insects that includes butterfly, butterflies and moths (both are called lepidopterans). About 180,000 species of the Lepidoptera are described, in 126 Family (biology), families and 46 Taxonomic r ...
and
Orthoptera
Orthoptera () is an order of insects that comprises the grasshoppers, locusts, and crickets, including closely related insects, such as the bush crickets or katydids and wētā. The order is subdivided into two suborders: Caelifera – grassho ...
.
[Murray, Kevin L., Theodore H. Fleming, Michael S. Gaines, and Dean A. Williams. "Characterization of Polymorphic Microsatellite Loci for Two Species of Phyllostomid Bats from the Greater Antilles (''Erophylla Sezekorni'' and ''Macrotus Waterhousii'')." Molecular Ecology Resources 8 (2008): 596-98. Print.] The mating and parturition times of M. ''waterhousii'' vary from island to island with 4–5 months
gestation
Gestation is the period of development during the carrying of an embryo, and later fetus, inside viviparous animals (the embryo develops within the parent). It is typical for mammals, but also occurs for some non-mammals. Mammals during pregna ...
.
Macrotus californicus : Roosting Habits and Terrestrial Locomotion
Macrotus has been mainly studied in the field in the Riverside Mountains of California. In the study area Macrotus roosts in the daytime exclusively in caves, deserted mine tunnels and deep grottos.
They are usually within 30 to 80 feet of the entrance of the tunnel, and seemed not to require dark retreats. On many occasions leaf-nosed bats roost in tunnels less than 20 feet deep and fairly brightly lit. In order to be suitable the Macrotus retreat must be mostly enclosed and have overhead pro9tection from the weather.
Roosting chambers are usually large enough to provide considerable ceiling surface and flying space, and thus adequate space allows the animal to find a place to roost while flying. The coolness of the roost also plays a factor in Macrotus selection of roosts, which is why Macrotus would choose to roost in a cool cave in the hot summers. Macrotus prefer to hang from sloping parts of the ceiling and actively grab the rock with ease due to the irregularity of the surface.
the bat seems to rest much of the time while hanging onto the rock with only one foot. The free foot is often used for scratching and for grooming the fur, when the bat is engaged in these activities the body usually swings gently like an erratically disturbed pendulum.
Foraging Habits and Flight of Macrotus Californicus
The flight of the ''Macrotus'' Is remarkable chiefly for its extreme maneuverability. The bat flies fairly rapidly on occasion, but the usual
foraging
Foraging is searching for wild food resources. It affects an animal's Fitness (biology), fitness because it plays an important role in an animal's ability to survive and reproduce. Optimal foraging theory, Foraging theory is a branch of behaviora ...
flight is slow and buoyant, and more nearly silent that of most bats.
In level flight Macrotus wings make a soft fluttering sound that is less sharp and carrying than the sounds made by the wing beats of most other bats. The method of landing is most interesting. The bat flies six to eight inches below the ceiling and upon the wings making a deep down stroke that is directed nearly straight forward the hind limbs and uropatagium.
These movements cause the bat to swoop upward toward the ceiling and as the bat nears the ceiling the wings are pulled back in an upstroke while the bat rolls over 180 degrees so that its back is facing downward and the long legs reach for the ceiling.
Stated briefly, then the alighting maneuver consists of an upward swoop and a half-roll, at the end of which the feet wing rapidly toward the ceiling, seize it, and the wings give a final beat to steady the bat. Often these landings must require remarkably precise judgement of speed and distance, as many landings are made in the midst of a fairly closely spaced group of bats.
Macrotus has two main methods of launching into flight, by dropping form the ceiling and taking flight after a short downward swoop, and by taking flight directly form the roosting place. The bat often hovers, both when foraging and when flying in its daytime retreat. Macrotus seems to hover easily, and it’s able to hover for several seconds at a time. These bats usually forage within three feet of the ground and often drop down closer to the ground nearer the surface where they can occasionally hover for a few seconds.
Even bats released in the daytime flew fairly close to the ground. Leaf-nosed bats seem to be totally
insectivorous
A robber fly eating a hoverfly
An insectivore is a carnivorous animal or plant that eats insects. An alternative term is entomophage, which can also refer to the human practice of eating insects.
The first vertebrate insectivores were ...
, and their food clearly reflects the bats’ foraging habits. Some insects regularly eaten by ''Macrotus'' are almost certainly taken from the ground or from vegetation. The bats’ stomachs often contain
orthopteran
Orthoptera () is an order of insects that comprises the grasshoppers, locusts, and crickets, including closely related insects, such as the bush crickets or katydids and wētā. The order is subdivided into two suborders: Caelifera – grassho ...
insects, noctuid
moths
Moths are a paraphyletic group of insects that includes all members of the order Lepidoptera that are not butterflies, with moths making up the vast majority of the order. There are thought to be approximately 160,000 species of moth, many of w ...
and caterpillars, and beetles of the families
Scarabaeidae
The family Scarabaeidae, as currently defined, consists of over 30,000 species of beetles worldwide; they are often called scarabs or scarab beetles. The classification of this family has undergone significant change in recent years. Several sub ...
and
Carabidae
Ground beetles are a large, cosmopolitan family of beetles, the Carabidae, with more than 40,000 species worldwide, around 2,000 of which are found in North America and 2,700 in Europe. As of 2015, it is one of the 10 most species-rich animal fami ...
, along with unidentified material.
The lists of food items of Macrotus contain a plethora of insects that seldom fly, are flightless, or that fly in the daytime; this constitutes strong evidence that this bat consumes insects that are on the ground or on vegetation. Most leaf-nosed bats forage sometime between one hour after sundown and four hours after sundown, and then retire to a night roosting place. Actually, each bat seems to have a pre-midnight foraging period of roughly one hour.
The greatest activity in the early morning seems to occur between two and one half hours before sunrise and thirty minutes before sunrise. Bats generally begin returning with full stomachs to their daytime roosts about two hours before sunrise, and the last bats usually return approximately twenty minutes before sunrise.
Effect of Diet on Basal Heat production
Insect feeders
Insectivorous
A robber fly eating a hoverfly
An insectivore is a carnivorous animal or plant that eats insects. An alternative term is entomophage, which can also refer to the human practice of eating insects.
The first vertebrate insectivores were ...
more closely resemble temperate zone taxa in their proclivity to relax thermoregulatory control when at rest and in their tendency to have lower basal metabolic rates.
This apparently results form the fact that insectivorous species tend generally to be smaller and gain considerable metabolic savings by reducing body temperature ambient temperature differentials.
[Baker, Robert J., J. Knox. Jones, and Dilford C. Carter. Biology of Bats of the New World Family Phyllostomatidae. Lubbock: Texas Tech, 1976. Print.]
Aerodynamic considerations
Most bats have lower wing loadings than do birds, and he mentioned that this difference may be due to the way bats forage. Most insectivorous birds forage by making repeated, short flights. Bats, on the other hand, remain on the wing for most if not all of the time they are foraging, and insects are captured by virtue of bats' ability to maneuver rapidly.
In birds, the slots formed by the
alula
The alula , or bastard wing, (plural ''alulae'') is a small projection on the anterior edge of the wing of modern birds and a few non-avian dinosaurs. The word is Latin and means "winglet"; it is the diminutive of ''ala'', meaning "wing". The al ...
and primary flight feathers allow these animals to have high wing loadings and fairly low stalling speeds. In the unslotted wings of bats, the wings do not yield such refinements in flight characteristics, but within the size and wing loadings of bats there is little need for increasing lift. In comparison, the flight of bats is much is clearly less efficient than that of birds. The upstroke consumes relatively more power in bats than in birds because the wing surfaces in bats are continuous and do not allow the passage of air as do the spaces between the primaries of a bird.
Lift
Irregular membranes known as the propatagium (the membrane anterior to the humorous and radius) shape the wing. The plagiopatagium (membrane posterior to the humorous)has a greater surface than the chiropatagium (membranes between the digits), particularly the fifth, the position of the hind limb, which anchors the posterior edge of the plagiopatagium, and by the angles that the propatagium and dactylopatagium minus (membrane the second and third digits) make with the posterior parts of the wing membranes. Air pressure against the ventral surfaces of the wing membranes is greater than that against the dorsal surfaces; this helps to maintain a smoother camber.
Macrotus californicus seems to spread its uropatagium widely only when hovering or performing other maneuvers requiring a departure form straight level flight, but the extreme maneuverability observed in Macrotus californicus is probably due to the specializations of its sensory equipment.
Osteology
In Macrotus the position of the hind limbs during level flight differs even more form that in most other mammals. The hind limbs are held behind the bat in a spider-leg- like posture, with the femur extending dorsad and caudad, and with the shank partially flexed and extending caudad and more or less downward.
Vertebral Column
The number of post cervical vertebrae in Macrotus are as follows: twelve thoracic, six lumbar, five sacral, seven caudal.
References
{{Taxonbar, from=Q956183
Bat genera
Taxa named by John Edward Gray
Taxonomy articles created by Polbot