Leaf-nosed bat


The New World leaf-nosed bats are bats found from southern North America to South America, specifically from the Southwest United States to northern Argentina. Both the scientific and common names derive from their often large, lance-shaped noses, though this is greatly reduced in some of the nectar- and pollen-feeders. Because these bats echolocate nasally, this "nose-leaf" is thought to serve some role in modifying and directing the echolocation call. Similar nose leaves are found in some other groups of bats, most notably the Old World leaf-nosed bats.
They are the most ecologically diverse bat family; members of this family have evolved to use food groups as varied as fruit, nectar, pollen, insects, frogs, other bats, and small vertebrates, and in the case of the vampire bats, blood. Most species are insectivorous, but the phyllostomid bats also include true predatory species and frugivores. For example, the spectral bat, the largest bat in the Americas, eats vertebrate prey, including small, dove-sized birds.

Evolution

The Phyllostomidae, also known as New World leaf-nosed bats, are among the most ecologically diverse mammal families. This variation is measured by diversity in skull morphology and diet-related characteristics: Phyllostomidae consists of species that have evolved physical modifications for insectivory, frugivory, hematophagy, nectarivory, and omnivory. The nose-leaf—a distinctive characteristic of the family—is thought to have evolved to reflect the dietary and foraging behavior of different species of Phyllostomidae. With an evolutionary history tracing back to the Oligocene, fossil and phylogenetic evidence suggests the family originated about 30 million years ago. Leaf nosed bats evolved from Yangochiroptera and Miniopteridae with sister groups also evolving from this group. The Phyllostomidae consists of 61 genera and about 227 species.

Description

New World leaf-nosed bats are bilaterally symmetrical and endothermic mammals characterized by an elaborate outgrowth of skin on their noses, called a nose-leaf, which is believed to aid in echolocation. The nose-leaf can be adorned with a vertical leaf, a concave upward leaf, or multiple accessory leaves; varying by species. Leaf-nosed bats lack a tail, have triangular-shaped ears that can have pointed or rounded tips, range in body size from, and have a wingspan of up to or more.
New World leaf-nosed bats are usually brown, grey, or black, although five species are white. They range in size from in head-body length, and can weigh from.

Biology and ecology

Like other bats, leaf-nosed bats are nocturnal foragers that use echolocation to locate food sources, though the food sources vary between species. Many bats in the family Phyllostomidae appear to have limited reliance on echolocation, likely because frugivorous bats do not need to quickly identify flying insects like many other bats. Instead, species of leaf-nosed fruit bats appear to use scent to identify their preferred food sources.
When they are not foraging, leaf-nosed bats roost in abandoned buildings, caves, and beneath folded leaves depending on the species. Nearly every roosting option present among bats is represented within this family, including species that prefer to roost alone, as well as species that roost with thousands of other individuals every day within a large colony. They do not hibernate, although some species have been reported to aestivate.

Diet

The Phyllostomidae demonstrate the most diverse dietary habits of any family of bats across the globe. Because of this, general dietary patterns are categorized for each species. Leaf-nosed bats generally specialize in a particular type of diet which leads to classification in one of these groups: frugivore, nectarivore, insectivore, omnivore, or haematophagous. However, categorizations are based only on primary consumption habits, therefore observing species that occasionally consume food items outside of their particular classifications is not uncommon. Usually, when leaf-nosed bats consume outside of their primary dietary categorization, it is to ensure sufficient intake of nutrients that their primary food source may not provide. For example, nectar and ripe fruits provide sufficient amounts of carbohydrates and water, but are lacking in protein and fat. To meet basic nutritional requirements, leaf-nosed bats that primarily feed on fruit and nectar must also consume insects to ensure sufficient protein and fat intake and visit salt licks to acquire sodium and other nutrients.
Most leaf-nosed bats are classified as insectivores and feed on a variety of small insects. Certain species with this classification capture their prey either while in flight or from foliage in trees or on the ground. Carnivorous species feed on a variety of animals ranging from frogs to other bats. The Desmodontinae fall into this general carnivorous category, but are further distinguished by feeding exclusively on blood. In contrast, some species in this family feed on exclusively plants, gaining needed nutrients from fruits and leaves. Glossophaginae and Lonchophyllinae are nectar-feeding subfamilies.

Life cycle

Leaf-nosed bats are gonochoric that partake in sexual copulation. These bats can live for 20–30 years and females become sexually active at two years of age. Female ovulation occurs from October through September, after the female mates, the gestation period ranges from 8–9 months with an initial 3- to 5-month diapause period when the fetus growth is slowed; this diapause period is controlled by hormones. The female gives birth to a single pup, which has open ears, open eyes, and the first set of deciduous teeth, and is fully furred at birth.

Social systems

Among species that roost in groups, some evidence exists for a social hierarchy with higher-ranking individuals gaining access to preferred areas of the site. Solitary roosting bats, though, live alone and maintain a strict fidelity to a single roosting site. In some cases, males live alone or with harems, while females prefer to roost with other individuals and their pups. In nearly every species that has been studied, mothers and pups maintain a social bond that lasts beyond nursing. Apparently, young bats can learn food preferences from their mothers and when they are reluctant to leave the nest, mothers literally nudge the infants out of the roost.

Range

New World leaf-nosed bats range from the United States, in southern Arizona and the West Indies to northern Argentina. The family inhabits a diverse array of environments and habitats ranging from forests to deserts.

Human impact

Species of New World leaf-nosed bats that make their homes in forested areas are greatly affected by agricultural intensification. Specifically, it has been found that increased agricultural activity by humans causes negative conservation effects on these habitats and as a result reduces abundance and diversity of leaf-nosed bats that live there. California leaf-nosed bats in particular are susceptible to human disruption. This species is known to create large roosts in closed mine shafts due to their potential to provide warmth and isolation. When humans enter the shafts or rework old mines, this disrupts the roosts of the leaf-nosed bats and has the potential to be detrimental to the population as a whole.

Classification

FAMILY PHYLLOSTOMIDAE