Invasive species in Guam

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As with a number of other geographically isolated islands, Guam has problems with invasive species negatively affecting the natural biodiversity of the island.

Contents

Brown tree snake

A brown tree snake near a snake trap hanging from a fence on Guam Brown treesnake near trap (9598905893).jpg
A brown tree snake near a snake trap hanging from a fence on Guam

Believed to be a stowaway on a U.S. military transport after the end of World War II, the brown tree snake (Boiga irregularis) was accidentally introduced to Guam, which previously had no native species of snake. It nearly eliminated the native bird population. The problem was exacerbated because the snake has no natural predators on the island. The brown tree snake, known locally as the kulebla, is native to northern and eastern coasts of Australia, Papua New Guinea, and the Solomon Islands. It is slightly venomous, but relatively harmless to human beings; it is nocturnal. Although some studies have suggested a high density of these serpents on Guam, residents rarely see them. The United States Department of Agriculture has trained detector dogs to keep the snakes out of the island's cargo flow. The United States Geological Survey also has dogs that can detect snakes in forested environments around the region's islands. [1] [2]

Threat to native birds

The Guam rail now exists only in captivity Endangered Guam Rail Guam DoA (9601697366).jpg
The Guam rail now exists only in captivity

Before the introduction of the brown tree snake, Guam was home to 14 species of terrestrial birds. Two of these fourteen birds are endemic to Guam at the species level: The Guam flycatcher, also called the Guam broadbill, and the Guam rail are not naturally found anywhere else in the world. The Guam flycatcher, was last seen in 1985 and is now believed to be extinct. The Guam rail (or ko'ko' bird in Chamorro), a flightless bird, extinct in the wild, has been successfully bred in captivity. An experimental population of Guam rails has been released on Rota, an island forty miles north of Guam in the Northern Mariana Islands. The loss of these birds is believed to be largely a result of habitat alteration and the effects of the introduced brown tree snake. The devastation caused by the snake has been significant over the past several decades. As many as twelve bird species are believed to have been driven to extinction. [3] However, some of the birds still thrive and are common on other islands at the subspecies level in the Marianas, including Saipan. According to many elders, ko'ko' birds were common in Guam before World War II. [4]

Other bird species threatened by the brown tree snake include the Mariana crow, the Mariana swiftlet, and the yellow bittern, which are still present on the island, though populations are present on other islands in the Marianas. [3]

Guam is said to have many more insects and 40 times more spiders than neighboring islands, because bird populations are severely diminished, and the forests are almost completely silent due to lack of birdsong. [5] [6]

Coconut rhinoceros beetle

Coconut rhinoceros beetle Oryctes nasicornis Thailand.jpg
Coconut rhinoceros beetle

An infestation of the coconut rhinoceros beetle (CRB), Oryctes rhinoceros , was detected on Guam on September 12, 2007. CRB is not known to occur in the United States except in American Samoa. Delimiting surveys performed September 13–25, 2007, indicated that the infestation was limited to Tumon Bay and Faifai Beach, an area of approximately 900 acres (3.6 km2). Guam Department of Agriculture (GDA) placed quarantine on all properties within the Tumon area on October 5 and later expanded the quarantine to about 2,500 acres (10 km2) on October 25; approximately 0.5 miles (800 m) radius in all directions from all known locations of CRB infestation. CRB is native to Southern Asia and distributed throughout Asia and the Western Pacific including Sri Lanka, Upolu, Samoa, American Samoa, Palau, New Britain, West Irian, New Ireland, Pak Island and Manus Island (New Guinea), Fiji, Cocos (Keeling) Islands, Mauritius, and Reunion.

Other invasive animal species

Adult female carabao and calf 2011 Feb, Puerto Princesa to Nasiduan, 10.jpg
Adult female carabao and calf

From the seventeenth through nineteenth centuries, the Spanish introduced the Philippine deer (Rusa mariannus), black francolins, and carabao (a subspecies of water buffalo), which have cultural significance. Herds of carabao obstruct military base operations and harm native ecosystems. After birth control and adoption efforts were ineffective, the U.S. military began culling the herds in 2002 leading to organized protests from island residents. [7] Other introduced species include the giant African snail (an agricultural pest introduced during World War II by Japanese occupation troops).

Guam has no native amphibian species, but now a total of nine amphibian species has been established in Guam. Litoria fallax (native to the eastern coast of Australia) has been present in Guam since 1968, and Rhinella marina (the cane toad) was brought to the island in 1937. The other 7 amphibian species, namely Sylvirana guentheri (native to mainland Asia), Microhyla pulchra (native to mainland Asia), Polypedates braueri (endemic to Taiwan), Eleutherodactylus planirostris (native to the Caribbean), Fejervarya cancrivora (the Guam variety being most closely related to F. cancrivora found in Taiwan), Fejervarya limnocharis (native to Southeast Asia), have been in Guam since 2003 [8] and the Eleutherodactylus coqui also commonly known as the coquí frog native to Puerto Rico that may have arrived from Hawaii, have led to fears that the noise could threaten Guam's tourism. [9] Many species were likely inadvertently introduced via shipping cargo, especially from Taiwan, mainland China, and Southeast Asia.

Introduced feral animals such as pigs and deer, over-hunting, and habitat loss from human development are also major factors in the decline and loss of Guam's native plants and animals.

Feral chickens ( Gallus gallus domesticus ) are found in the forests [10] although they are not significantly integrated into the food webs in most areas. [11]

Threats to indigenous plants

Invading animal species are not the only threat to Guam's native flora. Tinangaja, a virus affecting coconut palms, was first observed on the island in 1917 when copra production was still a major part of Guam's economy. Though coconut plantations no longer exist on the island, the dead and infected trees that have resulted from the epidemic are seen throughout the forests of Guam. [12]

During the past century, the dense forests of northern Guam have been largely replaced by thick tangan-tangan brush ( Leucaena leucocephala ). Much of Guam's foliage was lost during World War II. In 1947, the U.S. military is thought to have planted tangan-tangan by seeding the island from the air to prevent erosion. Tangan-tangan was present on the island before 1905. [13]

In southern Guam, non-native grass species dominate much of the landscape. Although the colorful and impressive flame tree ( Delonix regia ) is found throughout the Marianas, the tree on Guam has been largely decimated.

The Coconut rhinoceros beetle (CRB) infestation has become an epidemic event of palm tree damage on Guam. The CRB infects palm trees by burrowing into the tips of the palms, effectively killing the plant by destroying the shoot apical meristem during the process. While the grubs and larvae of CRB do no actual harm to palms, they populate and grow within the damaged crowns of the palm trees, which is a specific mating habit of Guam CRBs.

A possible solution to the crisis, which has been ecologically analyzed in Western Samoa, would be the introduction of CRB predators. Centipedes, Scolopendra Morsitans, have been found to seek out and eat the larvae of the beetle in logs and other breeding grounds. [14] Manual insertion of the centipedes, or introduction of volatile attractors within the plant, may cause a significant dent in Guam's CRB mortality. The introduction of terpene, fatty acids, or other nitrogenous compound metabolites may allow palm trees to attract CRB-predators such as the centipede through an indirect defense response, [15] which is triggered by mechanoreceptors activating secondary metabolite transcribers via an action potential pathway.

A secondary solution could be introducing metal hyperaccumulation into the palm population on Guam's beaches. Plants that accumulate extra inorganic minerals, such as iron, nickel, or zinc, indirectly deter herbivory by depositing excess materials in certain sections of the plants. [16] While the excess inorganic materials may not directly affect adult CRBs (as minerals would not be deposited in the meristem sections of the plant), it may create an inhospitable and toxic environment for the immature CRBs that are growing in the trees.

Related Research Articles

<i>Boiga</i> Genus of snakes

Boiga is a large genus of rear-fanged, mildly venomous snakes, known commonly as cat-eyed snakes or simply cat snakes, in the family Colubridae. Species of the genus Boiga are native to southeast Asia, India, and Australia, but due to their extremely hardy nature and adaptability, have spread to many other suitable habitats around the world. There are 38 recognized species in the genus. According to the study done by Jiří Smíd regarding Old World cat snakes, the ancestor of the cat snake originated in Africa, from where it diversified and expanded to other countries. Despite this diversity however, the different species have very similar needs in terms of temperature and precipitation.

<span class="mw-page-title-main">Guam rail</span> Species of bird

The Guam rail, known locally and in Chamorro as ko'ko', is a small, terrestrial bird endemic to Guam in the Rallidae family. They are one of the island's few remaining endemic bird species. The species became extinct in the wild in the early 1980s when biologists captured the remaining wild population to establish a breeding program. They have since been successfully introduced to the nearby Rota and Cocos islands. In 2019, they became the second bird species to be reclassified by the International Union for the Conservation of Nature from Extinct in the Wild to Critically Endangered.

<span class="mw-page-title-main">Brown tree snake</span> Species of reptile

The brown tree snake, also known as the brown catsnake, is an arboreal rear-fanged colubrid snake native to eastern and northern coastal Australia, eastern Indonesia, Papua New Guinea, and many islands in northwestern Melanesia. The snake is slender, in order to facilitate climbing, and can reach up to 2 meters in length. Its coloration may also vary, some being brown, green, or even red. Brown tree snakes prey on many things, ranging from invertebrates to birds, and even some smaller mammals. It is one of the very few colubrids found in Australia, where elapids are more common. Due to an accidental introduction after the events of World War II, this snake is now infamous for being an invasive species responsible for extirpating the majority of the native bird population in Guam. Currently, efforts are being made to reduce and control the population on Guam and prevent the snake from spreading to other locations.

<span class="mw-page-title-main">Ecology of Bermuda</span>

Bermuda's ecology has an abundance of unique flora and fauna due to the island's isolation from the mainland of North America. The wide range of endemic species and the islands form a distinct ecoregion, the Bermuda subtropical conifer forests. The variety of species found both on land and in the waters surrounding Bermuda have varying positive and negative impacts on the ecosystem of the island, depending on the species. There are varying biotic and abiotic factors that have threatened and continue to threaten the island's ecology. There are, however, also means of conservation that can be used to mitigate these threats.

<span class="mw-page-title-main">Mariana fruit dove</span> Species of bird

The Mariana fruit dove or Marianas fruit dove, totot on Guam or Paluman totut in Northern Marianas Islands, also known as mwee’mwe in the Carolinian language, is a small, up to 24 cm (9.4 in) long, green fruit dove native and endemic to Guam and the Northern Marianas Islands in the Pacific. It has a red forehead; greyish head, back and breast; and yellow belly patch and undertail coverts.

<span class="mw-page-title-main">Guam kingfisher</span> Species of bird from the US Territory of Guam

The Guam kingfisher, called sihek in Chamorro, is a species of kingfisher from the United States Territory of Guam. It is restricted to a captive breeding program following its extinction in the wild due primarily to predation by the introduced brown tree snake.

<span class="mw-page-title-main">Fauna of the United States</span>

The fauna of the United States of America is all the animals living in the Continental United States and its surrounding seas and islands, the Hawaiian Archipelago, Alaska in the Arctic, and several island-territories in the Pacific and in the Caribbean. The U.S. has many endemic species found nowhere else on Earth. With most of the North American continent, the U.S. lies in the Nearctic, Neotropic, and Oceanic faunistic realms, and shares a great deal of its flora and fauna with the rest of the American supercontinent.

<span class="mw-page-title-main">Mariana crow</span> Species of bird

The Mariana crow is a species of the crow family from the tropical Western Pacific. It is a glossy black bird about 15 inches (38 cm) long and known only from the islands of Guam and Rota.

The Mariana swiftlet or Guam swiftlet is a species of swiftlet in the family Apodidae.

<span class="mw-page-title-main">Golden white-eye</span> Bird in the white-eye family from the Northern Mariana Islands

The golden white-eye is a species of bird in the white-eye family, Zosteropidae. It is the only species within the genus Cleptornis. The golden white-eye was once considered to be a honeyeater in the family Meliphagidae and although it is now known to be a white-eye, its position within that family is still uncertain. The species is restricted to the islands of Saipan and Aguijan in the Northern Mariana Islands, where it is sympatric and competes with the related bridled white-eye. The golden white-eye has golden plumage and a pale eye-ring. It feeds on insects, fruit, and nectar and forages in pairs or small family groups. The bird is monogamous and lays two eggs in a small cup nest.

<span class="mw-page-title-main">Bridled white-eye</span> Species of bird

The bridled white-eye is a species of white-eye native to the Mariana Islands and formerly Guam. The species' natural habitat is tropical forests, shrublands and urban areas.

Robert E. Beck Jr. was a zoologist and conservationist, who worked to save Guam's indigenous native birds from 1982 to 2003. Beck championed the fight to save Guam's native birds, such as the Mariana crow, rufous fantail, Guam flycatcher, Guam kingfisher and the Guam rail, known locally as ko'ko' in Chamorro, which are under the extreme threat of extinction due to the non-native brown tree snake and habitat loss. The rufous fantail and the Guam flycatcher listed above are now extinct in the wild in their native Guam. However, the captive and wild populations of the Mariana crow, Guam rail and the Micronesian kingfisher have increased, due in large part to conservation efforts by Beck.

As with a number of other geographically isolated islands, Hawaii has problems with invasive species negatively affecting the natural biodiversity of the islands.

<i>Oryctes rhinoceros</i> Pest of coconut/oil palms in Asia/Pacific

Oryctes rhinoceros, also known as coconut rhinoceros beetle, Asiatic rhinoceros beetle, and coconut palm rhinoceros beetle, is a large species of beetle, belonging to the rhinoceros beetles subfamily Dynastinae. Oryctes rhinoceros attacks coconut palms and other palms such as the economically important oil palm. It can cause serious damage to the developing fronds (leaves) up to death of the palm. The beetle breeds in decaying palm trunks or other organic matter like sawdust or compost heaps.

Cadang-cadang is a disease caused by Coconut cadang-cadang viroid, a lethal viroid of several palms including coconut, African oil palm, anahaw, and buri. The name cadang-cadang comes from the word gadang-gadang that means dying in Bicol. It was originally reported on San Miguel Island in the Philippines in 1927/1928. "By 1962, all but 100 of 250,000 palms on this island had died from the disease," indicating an epidemic. Every year one million coconut palms are killed by CCCVd and over 30 million coconut palms have been killed since Cadang-cadang was discovered. CCCVd directly affects the production of copra, a raw material for coconut oil and animal feed. Total losses of about 30 million palms and annual yield losses of about 22,000 metric tons of copra have been attributed to Cadang-cadang disease in the Philippines.

<span class="mw-page-title-main">Philippine collared dove</span> Species of bird

The Philippine collared dove is a species of bird in the family Columbidae. It was formerly considered a subspecies of the island collared dove.

<span class="mw-page-title-main">Marianas tropical dry forests</span> Tropical dry broadleaf forests ecoregion of the Mariana Islands

The Marianas tropical dry forests is a tropical and subtropical dry broadleaf forests ecoregion on the Marianas Islands in the western Pacific Ocean.

<span class="mw-page-title-main">Yap tropical dry forests</span>

The Yap tropical dry forests is a tropical and subtropical dry broadleaf forests ecoregion in Micronesia. It includes the Yap Islands and neighboring atolls in the Federated States of Micronesia.

<span class="mw-page-title-main">Oryctes rhinoceros nudivirus</span> Virus and biocontrol agent of Oryctes rhinoceros

The Oryctes rhinoceros nudivirus (OrNV) is a member of the species Alphanudivirus oryrhinocerotis in the family Nudiviridae. It causes lethal infections in larvae and adults of the coconut rhinoceros beetle, a serious pest of coconut and oil palms in tropical Asia and the Pacific. The virus was discovered by Alois Huger in 1963 while searching for diseases of O. rhinoceros in Malaysia. It has been demonstrated to be an effective biological control agent against this beetle pest.

References

  1. ↑ Fritts, T.H.; D. Leasman-Tanner (2001). "USGS: The Brown Tree Snake on Guam". Archived from the original on July 17, 2007. Retrieved July 28, 2007.
  2. ↑ Vice, Daniel S.; Engeman, Richard M. (2000). "Brown Tree Snake Discoveries During Detector Dog Inspections Following Supertyphoon Paka". Archived from the original on August 9, 2011. Retrieved June 7, 2009.
  3. 1 2 John M. Marzluff; Tony Angell (2007). In the Company of Crows and Ravens. Yale University Press. ISBN   978-0-300-12255-8. Archived from the original on December 30, 2015.
  4. ↑ Rodda, Gordon H.; Fritts, Thomas H. (1992). "The Impact of the Introduction of the Colubrid Snake Boiga irregularis on Guam's Lizards". Journal of Herpetology. 26 (2): 166–174. doi:10.2307/1564858. JSTOR   1564858.
  5. ↑ Rogers, H.; Hille Ris Lambers, J.; Miller, R.; Tewksbury, J. J. (2012). Siepielski, Adam (ed.). "'Natural experiment' Demonstrates Top-Down Control of Spiders by Birds on a Landscape Level". PLOS ONE. 7 (9): e43446. Bibcode:2012PLoSO...743446R. doi: 10.1371/journal.pone.0043446 . PMC   3436874 . PMID   22970126.
  6. ↑ "Spiders infest Guam after native birds disappear". 14 September 2012. Archived from the original on June 3, 2016. Retrieved May 2, 2016.
  7. ↑ "More Than 100 Protest Guam Carabao Cull". AnimalRights.net. October 15, 2003. Archived from the original on April 28, 2005. Retrieved June 15, 2007.
  8. ↑ Wostl, Elijah; Smith, Eric N.; Reed, Robert N. (2016). "Origin and Identity of Fejervarya (Anura: Dicroglossidae) on Guam". Pacific Science. 70 (2): 233–241. doi:10.2984/70.2.9. S2CID   54686596.
  9. ↑ Worth, Katie (February 28, 2004). "Two Male Coqui Frogs Found in Guam". Archived from the original on September 29, 2007. Retrieved July 19, 2007.
  10. ↑ "Nature & Wildlife - Chamorro Culture". Guam Visitors Bureau. Government of Guam. 2018-09-24. Retrieved 2021-04-26.
  11. ↑ Fritts, Thomas H.; Rodda, Gordon H. (1998). "The Role of Introduced Species in the Degradation of Island Ecosystems: A Case History of Guam". Annual Review of Ecology, Evolution, and Systematics . 29 (1). Annual Reviews: 113–140. Bibcode:1998AnRES..29..113F. doi:10.1146/annurev.ecolsys.29.1.113. ISSN   0066-4162. S2CID   59396297.
  12. ↑ Hodgson, R. A. J.; Wall, G. C.; Randles, J. W. (1998). "Specific Identification of Coconut Tinangaja Viroid for Differential Field Diagnosis of Viroids in Coconut Palm" (PDF). Phytopathology. 88 (8): 774–781. doi: 10.1094/PHYTO.1998.88.8.774 . PMID   18944882. Archived from the original (PDF) on June 14, 2007. Retrieved June 16, 2007.
  13. ↑ Stafford, William Edwin (1905) Useful Plants of Guam
  14. ↑ Hinckley, Alden (1967). "Associates of The Coconut Rhinoceros Beetle In Western Samoa" (PDF). Pacific Insects. 9: 505–511. Archived (PDF) from the original on August 30, 2017. Retrieved June 9, 2019.
  15. ↑ "Plant Resistance against Herbivory". Archived from the original on September 14, 2018.
  16. ↑ Poschenrieder (2006). "Can metals defend plants against biotic stress?". Trends in Plant Science. 11 (6): 288–295. Bibcode:2006TPS....11..288P. doi:10.1016/j.tplants.2006.04.007. PMID   16697693.
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