Greater Bulldog Bat
Encyclopedia
The greater bulldog bat or fisherman bat (Noctilio leporinus) is a type of fishing bat native to Latin America
. The bat
uses echolocation
to detect water
ripple
s made by the fish
upon which it preys, then uses the pouch between its legs to scoop the fish up and its sharp claw
s to catch and cling to it. It is not to be confused with the lesser bulldog bat
, which, though belonging to the same genus, merely catches water insects, such as water striders and water beetles.
It emits echolocation sounds through the mouth like Myotis daubentoni, but the sounds are quite different, containing a long constant frequency part around 55 kHz, which is an unusually high frequency for a bat this large.
.
The bulldog bat has a wingspan
of 1 meter (3 feet). The wing of the bat is more than two and a half times the length of the head and body with nearly 65% of its wingspan being its third digit. Its wings are long and narrow and it flies in a stiff-winged fashion. The bat’s wing beat is slow and deliberate. Like most bats, the bulldog bat has a positive allometric relationship for flight musculature and body mass. The bat is a capable swimmer and will use its wings like an oar
. The Greater Bulldog bat also has well-developed cheek pouches are used for storing food when foraging, particularly fish. Its hind legs and feet are particularly large.
) and eastern (Veracruz
) Mexico southward to northern Argentina. It also lives on most Caribbean islands. While vast, it’s range is also discontinuous as the bat is restricted to mostly non-arid lowland and coastal areas and major river basin like the Amazon and Parana. There is geographical variation in the species and are classified as subspecies. In the rim of the Caribbean Basin, bats are large and usually have the pale mid-dorsal stripe, despite being variable in color. These bats are known as N. l. mastivus. In Guianas and the Amazon Basin, the bats are small and dark and often lack the pale mid-dorsal stripe. These bats are known as N. l. leporinus. In eastern Bolivia and the drainage basin of the Río Paraná south of the Brazilian Highlands and north of latitude 30° S, bats tend to be large and pale, more so than the other subspecies. They are known as N. l. rufescens.
. The bats live in hollow tree roosts in other areas as well. They also use deep sea caves for roosting. Like most bats, bulldog bats are nocturnal.
Female bulldog bats stay together in groups while roosting and tend to be accompanied by a resident male. Females associate with the same individuals in the same location for several years unaffected by changes in resident males and movements of the group to different roosts. A male may reside with a female group for two or more reproductive seasons. Bachelor males roost either solitarily or in small groups away from the females. Female bats forage either solitarily or in small groups with their roost mates, with stable female groups returning to the same foraging areas over long time periods. Males forage solitarily and use areas that are larger and different from those used by the females.
s and beetle
s. During the dry season, bat will primarily feed on fish as well as crab
s, scorpion
s and shrimp
to a lesser extent. The bulldog bat mostly forages for fish during high tide and locates them with echolocation. A bulldog bat will perform circular high flight searches. A bat doing a high search flight will make "pointed dips" at the spot where a fish has made a jump. When it descends to the water surface the echolocation signals of the bat decrease in pulse duration and interval which is typical of all bats.
During low search flights, bulldog bats will rapidly snap the feet into the water at a spot where it has found a jumping fish or disturbance. The bat will drop to the water surface, lowering its feet and and then drag its claws through the water in relatively straight lines for up to 10 m. When raking, the bat uses two strategies. In directed random rakes it rakes through patches of water with high activity of fish jumping. With memory-directed random rakes, when there is no jumping fish, it will make very long rakes in areas where it has successfully made a catch before after flying for several minutes without any dips.
and in Belize; the water level has changed and restricted the range. It is also threated by Deforestation
.
Latin America
Latin America is a region of the Americas where Romance languages – particularly Spanish and Portuguese, and variably French – are primarily spoken. Latin America has an area of approximately 21,069,500 km² , almost 3.9% of the Earth's surface or 14.1% of its land surface area...
. The bat
Bat
Bats are mammals of the order Chiroptera "hand" and pteron "wing") whose forelimbs form webbed wings, making them the only mammals naturally capable of true and sustained flight. By contrast, other mammals said to fly, such as flying squirrels, gliding possums, and colugos, glide rather than fly,...
uses echolocation
Animal echolocation
Echolocation, also called biosonar, is the biological sonar used by several kinds of animals.Echolocating animals emit calls out to the environment and listen to the echoes of those calls that return from various objects near them. They use these echoes to locate and identify the objects...
to detect water
Water
Water is a chemical substance with the chemical formula H2O. A water molecule contains one oxygen and two hydrogen atoms connected by covalent bonds. Water is a liquid at ambient conditions, but it often co-exists on Earth with its solid state, ice, and gaseous state . Water also exists in a...
ripple
Ripple
Ripple is the more common name for a capillary wave in fluid dynamics.Ripple can also refer to:* Ripple , a non-profit click-to-donate internet site and search engine* Ripple effect, the socio-educational phenomenon...
s made by the fish
Fish
Fish are a paraphyletic group of organisms that consist of all gill-bearing aquatic vertebrate animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish, as well as various extinct related groups...
upon which it preys, then uses the pouch between its legs to scoop the fish up and its sharp claw
Claw
A claw is a curved, pointed appendage, found at the end of a toe or finger in most mammals, birds, and some reptiles. However, the word "claw" is also often used in reference to an invertebrate. Somewhat similar fine hooked structures are found in arthropods such as beetles and spiders, at the end...
s to catch and cling to it. It is not to be confused with the lesser bulldog bat
Lesser Bulldog Bat
The Lesser Bulldog Bat is an insectivorous and occasionally carnivorous bat of the , ranging through Central America and northern South America....
, which, though belonging to the same genus, merely catches water insects, such as water striders and water beetles.
It emits echolocation sounds through the mouth like Myotis daubentoni, but the sounds are quite different, containing a long constant frequency part around 55 kHz, which is an unusually high frequency for a bat this large.
General description
The greater bulldog bat is a large bat, often with a combined body and head length of 1.9 to 12.7 cm (4.6 to 5 in). It generally weighs from 50–90 grams. Males tend to be larger than females, with the former averaging 67 grams and the latter averaging 56 grams. They also differ in fur color. Males have bright orange fur on the back while females are dull gray. However, both sexes have pale undersides and may have a pale mid-dorsal line. The bulldog bat has tubular nostrils that open forward and down. It has slender, long, pointed ears with a tragus that has a notched outer edge. The bulldog bat has smooth lips but its upper lip is divided by a fold of skin while its bottom lip has a wart, under which are semicircular folds of skin that extend to the chin. It is these features that give the bulldog bat gets name, as it resembles a bulldogBulldog
Bulldog is the name for a breed of dog commonly referred to as the English Bulldog. Other Bulldog breeds include the American Bulldog, Olde English Bulldogge and the French Bulldog. The Bulldog is a muscular heavy dog with a wrinkled face and a distinctive pushed-in nose...
.
The bulldog bat has a wingspan
Wingspan
The wingspan of an airplane or a bird, is the distance from one wingtip to the other wingtip. For example, the Boeing 777 has a wingspan of about ; and a Wandering Albatross caught in 1965 had a wingspan of , the official record for a living bird.The term wingspan, more technically extent, is...
of 1 meter (3 feet). The wing of the bat is more than two and a half times the length of the head and body with nearly 65% of its wingspan being its third digit. Its wings are long and narrow and it flies in a stiff-winged fashion. The bat’s wing beat is slow and deliberate. Like most bats, the bulldog bat has a positive allometric relationship for flight musculature and body mass. The bat is a capable swimmer and will use its wings like an oar
Oar
An oar is an implement used for water-borne propulsion. Oars have a flat blade at one end. Oarsmen grasp the oar at the other end. The difference between oars and paddles are that paddles are held by the paddler, and are not connected with the vessel. Oars generally are connected to the vessel by...
. The Greater Bulldog bat also has well-developed cheek pouches are used for storing food when foraging, particularly fish. Its hind legs and feet are particularly large.
Distribution and variation
The greater bulldog bat ranges from western (SinaloaSinaloa
Sinaloa officially Estado Libre y Soberano de Sinaloa is one of the 31 states which, with the Federal District, comprise the 32 Federal Entities of Mexico. It is divided in 18 municipalities and its capital city is Culiacán Rosales....
) and eastern (Veracruz
Veracruz
Veracruz, formally Veracruz de Ignacio de la Llave officially Estado Libre y Soberano de Veracruz de Ignacio de la Llave , is one of the 31 states that, along with the Federal District, comprise the 32 federative entities of Mexico. It is divided in 212 municipalities and its capital city is...
) Mexico southward to northern Argentina. It also lives on most Caribbean islands. While vast, it’s range is also discontinuous as the bat is restricted to mostly non-arid lowland and coastal areas and major river basin like the Amazon and Parana. There is geographical variation in the species and are classified as subspecies. In the rim of the Caribbean Basin, bats are large and usually have the pale mid-dorsal stripe, despite being variable in color. These bats are known as N. l. mastivus. In Guianas and the Amazon Basin, the bats are small and dark and often lack the pale mid-dorsal stripe. These bats are known as N. l. leporinus. In eastern Bolivia and the drainage basin of the Río Paraná south of the Brazilian Highlands and north of latitude 30° S, bats tend to be large and pale, more so than the other subspecies. They are known as N. l. rufescens.
Ecology and behavior
The greater bulldog bat lives primarily in tropical lowland habitats. The bats are commonly found over ponds and streams. They also found above estuaries of major rivers and bays and lagoons along coastlines. They live in colonies that number in the hundreds. In Trinidad, bulldog bats frequent hollow trees including silk-cotton, red mangrove and balatáBalatá
Manilkara bidentata is a species of Manilkara native to a large area of northern South America, Central America and the Caribbean. Common names include balatá, ausubo, massaranduba, and "cow-tree"....
. The bats live in hollow tree roosts in other areas as well. They also use deep sea caves for roosting. Like most bats, bulldog bats are nocturnal.
Female bulldog bats stay together in groups while roosting and tend to be accompanied by a resident male. Females associate with the same individuals in the same location for several years unaffected by changes in resident males and movements of the group to different roosts. A male may reside with a female group for two or more reproductive seasons. Bachelor males roost either solitarily or in small groups away from the females. Female bats forage either solitarily or in small groups with their roost mates, with stable female groups returning to the same foraging areas over long time periods. Males forage solitarily and use areas that are larger and different from those used by the females.
Food and hunting
The greater bulldog bat is one of the few bat species that has adapted to eating fish. Nevertheless, the bats eat both fish and insects. During the wet season, the bats feed primarily on insects like mothMoth
A moth is an insect closely related to the butterfly, both being of the order Lepidoptera. Moths form the majority of this order; there are thought to be 150,000 to 250,000 different species of moth , with thousands of species yet to be described...
s and beetle
Beetle
Coleoptera is an order of insects commonly called beetles. The word "coleoptera" is from the Greek , koleos, "sheath"; and , pteron, "wing", thus "sheathed wing". Coleoptera contains more species than any other order, constituting almost 25% of all known life-forms...
s. During the dry season, bat will primarily feed on fish as well as crab
Crab
True crabs are decapod crustaceans of the infraorder Brachyura, which typically have a very short projecting "tail" , or where the reduced abdomen is entirely hidden under the thorax...
s, scorpion
Scorpion
Scorpions are predatory arthropod animals of the order Scorpiones within the class Arachnida. They have eight legs and are easily recognized by the pair of grasping claws and the narrow, segmented tail, often carried in a characteristic forward curve over the back, ending with a venomous stinger...
s and shrimp
Shrimp
Shrimp are swimming, decapod crustaceans classified in the infraorder Caridea, found widely around the world in both fresh and salt water. Adult shrimp are filter feeding benthic animals living close to the bottom. They can live in schools and can swim rapidly backwards. Shrimp are an important...
to a lesser extent. The bulldog bat mostly forages for fish during high tide and locates them with echolocation. A bulldog bat will perform circular high flight searches. A bat doing a high search flight will make "pointed dips" at the spot where a fish has made a jump. When it descends to the water surface the echolocation signals of the bat decrease in pulse duration and interval which is typical of all bats.
During low search flights, bulldog bats will rapidly snap the feet into the water at a spot where it has found a jumping fish or disturbance. The bat will drop to the water surface, lowering its feet and and then drag its claws through the water in relatively straight lines for up to 10 m. When raking, the bat uses two strategies. In directed random rakes it rakes through patches of water with high activity of fish jumping. With memory-directed random rakes, when there is no jumping fish, it will make very long rakes in areas where it has successfully made a catch before after flying for several minutes without any dips.
Echolocation
Greater bulldog bats emit echolocation signals that are either at constant frequency (CF), frequency-modulated (FM) or a combination of the two (CF-FM). The longest signals are the pure CF signal which have average duration of 13.3 ms and a maximum of 17 ms. CF-FM signal involve a CF component followed by a FM component. The CF component of the CF-FM signals average 8.9 ms while the FM sweeps 3.9 ms. The CF components have frequencies of 52.8–56.2 kHz with the FM components have average bandwidths of 25.9 kHz. Bulldog bats have two kinds of signal when flying. In one, the CF pulses begin at 60kHz and may drop in frequency but never below 50kHz. The second type involves CF beginning at about 60kHz and drops in frequency by more than one octave.Reproduction cycle
For females, pregnancy occurs from September until January, and lactation starts in November and continues until April. Female bulldog bats give birth to single young each pregnancy. Male bats reproductive pattern with breeding mainly occurring in autumn and winter. Young bats do not leave the roost to attempt to make sustained flight until they reach adult size, which is around one month. There may be a high degree of parental care in this species and both adult males and female stay in the roost with the young during this time.Status
There are no major threats throughout its range. The bat is killed by Guatemala fish farmers. It is also threatened by water pollutionWater pollution
Water pollution is the contamination of water bodies . Water pollution occurs when pollutants are discharged directly or indirectly into water bodies without adequate treatment to remove harmful compounds....
and in Belize; the water level has changed and restricted the range. It is also threated by Deforestation
Deforestation
Deforestation is the removal of a forest or stand of trees where the land is thereafter converted to a nonforest use. Examples of deforestation include conversion of forestland to farms, ranches, or urban use....
.