Giant golden-crowned flying fox

The giant golden-crowned flying fox (Acerodon jubatus), also known as the golden-capped fruit bat, is a species of megabat endemic to the Philippines. Since its description in 1831, three subspecies of the giant golden-crowned flying fox have been recognized, one of which is extinct. The extinct subspecies (A. jubatus lucifer) was formerly recognized as a full species, the Panay golden-crowned flying fox. Formerly, this species was placed in the genus Pteropus; while it is no longer within the genus, it has many physical similarities to Pteropus megabats. It is one of the largest bat species in the world, weighing up to 1.4 kg (3.1 lb)—only the Indian and great flying fox can weigh more. It has the longest documented forearm length of any bat species at 21 cm (8.3 in).

It is primarily frugivorous, consuming several kinds of fig and some leaves. It forages at night and sleeps during the day in tree roosts. These roosts can consist of thousands of individuals, often including another species, the large flying fox. Not much is known about its reproduction; it gives birth annually from April through June, with females having one pup at a time. Predators of the giant golden-crowned flying fox include raptors such as eagles, the reticulated python, and humans.

Owing to deforestation and poaching for bushmeat, it is an endangered species. Though national and international law makes hunting and trade of this species illegal, these regulations are inadequately enforced, meaning that the species is frequently hunted nonetheless. Even in roosts that are more stringently protected from poaching, it is still affected by human disturbance via tourists who intentionally disturb them during the day.

An early description of this species may be found in William Dampier's account of his circumnavigation, A New Voyage Round the World.

Taxonomy

The giant golden-crowned flying fox was described as a new species in 1831 by German naturalist Johann Friedrich von Eschscholtz. Eschscholtz placed it in the genus Pteropus with a scientific name of Pteropus jubatus. Its species name "jubatus" is from Latin, meaning "having a mane or crest, crested". The holotype had been collected on the Philippine island of Luzon during an expedition led by Otto von Kotzebue. The genus Acerodon was described six years later in 1837, with A. jubatus as the type species for the new genus. As of 2005, three subspecies of the giant golden-crowned flying fox are recognized:

• A. jubatus jubatus (Eschscholtz, 1831)
• A. jubatus mindanensis (K. Andersen, 1909)
• †A. jubatus lucifer (Elliot, 1896)

A. jubatus lucifer had been described as Pteropus lucifer in 1896 by Daniel Giraud Elliot. A. jubatus lucifer, commonly the Panay golden-crowned flying fox, is still sometimes considered an extinct species of megabat. A 1998 publication noted that there were no morphological differences that distinguish A. jubatus lucifer from A. jubatus. This publication was used by Mammal Species of the World and the IUCN as justification as listing A. jubatus lucifer as a subspecies of A. jubatus rather than as a full species.

Description

Overall, the giant golden-crowned flying fox is similar in appearance to many Pteropus species. It is different in its smaller canine teeth and its larger and more complex molars and premolars. Its upper incisors are slightly longer than Pteropus species, as well as sharper. Its four lower incisors have a greater disparity in length between the inner and outer pair than do Pteropus. Its dental formula is 2.1.3.22.1.3.3 for a total of 34 teeth.

The giant golden-crowned flying fox is one of the largest bat species in the world. It is among the heaviest of all bat species, with individuals weighing up to 1.40 kg (3.1 lb). The only bat species known to weigh more than the giant golden-crowned flying fox are the Indian flying fox (Pteropus medius) and great flying fox (Pteropus neohibernicus), with a maximum weight of 1.6 kg (3.5 lb) and 1.45 kg (3.2 lb) respectively. It has the longest forearm length of any species, measuring up to 215 mm (8.5 in). The great flying fox has a slightly shorter forearm length, and its wingspan is thus presumed to be lesser as well. The wingspan of the Indian flying fox is up to 1.5 m (4.9 ft), while the giant golden-crowned flying fox has a wingspan of 1.5–1.7 m (4.9–5.6 ft). This species is somewhat dimorphic, with males slightly larger than females in many cranial and external measurements.

The giant golden-crowned flying fox gets its common name from its fur coloration. It has golden coloration that begins between its eyes and terminates to a narrow "V" shape at the nape of its neck, though sometimes extending to the upper shoulders. The sides of its face, brows, and throat are black, while the sides of its neck and upper back are maroon; this maroon fur transitions into brownish black, which then grades into reddish brown down the back. On its ventral (belly) side, its fur is generally black, though the front of the neck may have a maroon tinge and its belly may be interspersed with yellow hairs. Its hindlimbs are covered with brownish black fur, and its flight membranes are pale brown.

Biology and ecology

Diet and foraging

The giant golden-crowned flying fox is largely frugivorous, though it also consumes plant leaves (folivorous). One study found that it is particularly dependent on Ficus fruits (figs), with Ficus seeds found in 79% of all fecal pellets. Especially common Ficus seeds were from the Urostigma subgenus (which includes Ficus species commonly referred to as banyan), as well as Ficus variegata.

The results support that the primary food group is composed of fig species, including Ficus subcordata and unidentified leaves. There is a lack of consensus on whether items found frequently in the fecal samples are actually prioritized or found as an alternative food for these bats.

Multiple types of figs can also contribute to different nutrients for the species. Frugivorous bats usually do not consume foods rich in protein. The overconsumption of fruits, paired with leaves may contribute to an adequate amount of protein in their diet. Figs are superior sources of calcium, which may also aid in their growth to adults.

Like nearly all megabats, giant golden-crowned flying foxes cannot echolocate, and thus rely on sight to navigate. This species likely commutes long distances between its roost and foraging grounds. Individuals who roosted on the island of Maripipi, for example, were documented traveling more than 12 km (7.5 mi) to access sites on another island, Biliran.

Roosting and behavior

Giant golden-crowned flying foxes are nocturnal, sleeping for most of the day. They do engage in some social and maintenance behaviors during the day at times, with solitary behaviors such as self-grooming, excreting waste, and wing flapping more prevalent in the afternoon and social behaviors such as fighting and mating in the morning. It forms harmonious mixed species colonies with another megabat, the large flying fox (Pteropus vampyrus). When time to leave the roosts for nightly foraging, the two species will head in the same direction. In the 1920s, colonies of these two species would number as many as 120,000 individuals. As of 1992, the largest of these colonies was 5,000; many comprised only several hundred individuals.

Reproduction

Little is known about mating and reproduction of the giant golden-crowned flying fox. The litter size is one individual, with females likely producing no more than one litter per year. It has also been speculated that females may only give birth every other year. Based on limited observation, it is thought that females may not reach sexual maturity until two years of age. On Negros Island, females gave birth in April or May; based on other observations, females likely give birth during this time across its range. On the island of Maripipi, young were born in late May and June. This species show signs of a Type II survivorship curve. Parents take effort into the survivability of the offspring to ensure maturity and independent growth. This species may live up to 13–30 years in the wild.

Predators, parasites, and disease

Although they typically live a long life in the wild, they are also hunted by humans and other apex predators such as the Philippine eagle. They may also be susceptible to wildlife diseases. The giant golden-crowned flying fox is impacted by ectoparasites (external parasites) including Cyclopodia horsfieldi, which is a species of fly in the family Nycteribiidae ("bat flies"). It is preyed on by several raptors including the Philippine eagle, white-bellied sea eagle, and possibly the Brahminy kite. Non-avian predators include the reticulated python and humans.