Mariana Fruitbat by Cassie Isaacson
Mariana Fruitbat
aka ‘Fanihi’
aka ‘Pteropous Mariannus Mariannus’
by Cassie Isaacson
Species Description & Ecology
The Mariana Fruitbat is a midsize bat and a member of the pteropodidae which is characterized by large eyes, strong nocturnal vision, a large humerus, and the absence of the ability to echolocate. The wingspan of Mariana Fruitbats is typically 5-6 inches. Their bodies are covered in brown and black fur and they are often likened to domestic dogs because of their very large eyes and ears and canine-like snout; this may explain their success in viral youtube videos of adorable baby bats which may have caused me to choose them as the subject of my project.
The Biology of Bats by Gerard Neuweller
Geographic and Population Changes
The Mariana Fruitbat is endemic to the Mariana Islands, which are part of the territory of Guam. As its name suggests, the Mariana Fruitbat consumes a diet comprised largely of fruit, supplemented with nectar, pollen, and leaves. Therefore, it relies heavily upon the existence of a forest habitat which supplies its sustenance. However, in recent years, that habitat has become increasingly threatened. This region has faced habitat destruction due to agriculture, economic development, introduction of non-native species, and war. Surveys conducted in 1983 and 2000 indicate a 40% decrease in population size, with most of that decrease happening on the two islands which previously hosted the highest populations of Mariana Fruitbats: Anahatan and Pagan.
Map of Mariana Islands
http://www.sscnet.ucla.edu/geog/tdfpacific/marianas_islands.html
Listing Date and Type of Listing
The Mariana fruitbat is listed as a level 9 endangered species, on a scale from 1-18, indicating that it is endangered and at risk of extinction, but it is not an extremely high priority case. The original recovery plan for the Mariana Fruitbat was released in 1998, but has since been updated in 2009 to reflect more current data and strategies for recovery.
Cause of Listing and Main Threat to its Continued Existence
According to the U.S. Fish and Wildlife Service, there are five factors that contribute to a species’ status as endangered, which are as follows:
- Present or threatened destruction of habitat.
- Overutilization for commercial, recreational, scientific, or educational purposes.
- Disease or predation.
- Inadequacy of existing regulatory mechanisms.
- Other threats, manmade or natural.
The Mariana Fruitbat meets these criteria in the following ways:
- Its habitat is undergoing degradation as a result of ungulate damage (i.e. hooved mammals trampling foliage at ground level), threat of alien plant species introduced on these islands, and worsening conditions (air and land quality) of local environment due to increased development in 20th century.
- The Mariana fruitbat is overutilized as a food source for local settlements; overhunting is part of a local tradition, and though hunting Mariana fruitbats became illegal in the 1970’s, the problem persists because enforcement of these laws is lacking, and it opportunistic hunting is still common. So far it has been difficult to stop illegal hunting because Fruitbat has been part of traditional meals for indigenous people.
- The Mariana Fruitbat is a victim of predation by the brown tree snake, which tends to target young fruitbats, precluding population growth as the young are not able to reach reproductive age.
- Regulatory mechanisms are inadequate in the case of the Mariana fruitbat because, as previously addressed, the laws intended to protect this species are not sufficiently enforced.
- Other threats to the Mariana fruitbat include the unlikelihood of recolonization as population continues to drop, growing air traffic at the nearby Andersen air force base, as well as natural threats, such as typhoons and volcanic eruptions.
Brown Tree Snake, Predator of Mariana Fruitbat
https://commons.wikimedia.org/wiki/File:Brown_tree_snake_Boiga_irregularis_2_USGS_Photograph.jpg
Description of Recovery Plan
Steps for Recovery:
- Sustain existing Mariana Fruitbat population by limiting risk factors
- Direct action to prevent illegal hunting, which will provide Fanihi population the opportunity to grow
- Measures to preserve existing habitat and improve upon other potentially viable habitats
- Control, and in some cases, removal, of Brown Tree Snake
- Research to further understand the history of Fanihi and ecology in order to better understand its sensitivity to threats, develop improved management solutions, and predict future sensibility.
What Can You Do?
It may seem like conservation of Mariana Fruitbat is far too distant and removed of an issue for you to be able to have any major impact, but that’s not true. After all, the publicity gained in the 1980s through 1990s, as well as the use of a petition, helped the Mariana Fruitbat gain enough visibility to become listed as an endangered species. One direct action you can take is donate to “Bat Conservation International,” an organization whose mission is to protect and conserve many bat species. Donations go towards funding research efforts, education on bats, and protection of bats’ natural habitats. On a smaller scale, you can spread the word in your own community simply by talking about the issue of endangered species including the Mariana Fruitbat.
Other Resources
If you would like to learn more here is a website to check out that can provide more information, including the current endangerment status, the ecological role of this species, and more.
Additionally, here is a link to a video that provides insight to the local perspective on the endangered Mariana Fruitbat, and why hunting remains a problem:
Sources
(The Biology of Bats by Gerard Neuweller)
After class, I had that that fruit bats were only being affected by the brown tree snake, and I didn't even realize then that the brown tree snake targets the young bats. The animal I researched, the Gulf Coast Jaguarundi is also greatly affected by habitat degradation, really makes us think about our affect on the Earth. Thank you for showing how even though the bat lives far away, we can still make an impact.
ReplyDeleteIt seems that so many different animals and plants are being negatively affected by the introduction of the brown tree snake. It's amazing how one species can almost wipe out so many others. This is a case where you can really understand how being on an island (especially one so small) can make it extremely easy for a species to go extinct, or at least be in danger of it. Great post!
ReplyDeleteI am almost surprised that the Mariana Fruit Bat is only listed at a level nine because like you said it is endemic to an area of very small islands which, as we learned in class, makes it very easy to go extinct. On the other hand, it doesn't surprise me that the Brown Tree Snake is its main predator. It seems like those snakes destroy/eat everything!
ReplyDelete-Michelle Henderson
Since this species lives on such a small island, I'm not surprised it is on the endangered list. It also seems that the brown tree snake is a predator to many different species which isn't that surprising either. -Rachel Kenison
ReplyDelete