Boiga irregularis

Boiga irregularis, Photo: National Park Service

Cladus: Eukaryota
Supergroup: Opisthokonta
Regnum: Animalia
Subregnum: Eumetazoa
Cladus: Bilateria
Cladus: Nephrozoa
Cladus: Deuterostomia
Phylum: Chordata
Subphylum: Vertebrata
Infraphylum: Gnathostomata
Superclassis: Tetrapoda
Classis: Reptilia
Subclassis: Diapsida
Infraclassis: Lepidosauromorpha
Superordo: Lepidosauria
Ordo: Squamata
Subordo: Serpentes
Superfamilia: Colubroidea
Familia: Colubridae
Subfamilia: Colubrinae
Genus: Boiga
Species: Boiga irregularis


Boiga irregularis (Merrem, 1802)

Type locality: Port Essington, N. T. [Dendrophis (Ahetula) fusca].

Holotype: BMNH 1946.1.1.28.


* Coluber irregularis Merrem in Bechstein, 1802: 239
* Hurria pseudoboiga Daudin, 1803: 277 (nomen nov. pro Coluber irregularis)
* Dendrophis (Ahetula) fusca Gray, 1842: 54
* Triglyphodon irregulare — Duméril, Bibron & Duméril, 1854: 1074
* Triglyphodon flavescens Duméril, Bibron & Duméril, 1854: 1080
* Pappophis laticeps Macleay, 1877: 39
* Pappophis flavigastra Macleay, 1877: 40
* Dipsas boydii Macleay ,1884: 548
* Dipsas irregularis — Fischer, 1884: 49
* Dipsas ornata Macleay, 1888: 416
* Dipsadomorphus irregularis — Werner, 1899: 374
* Boiga irregularis - Cogger, 1983: 209
* Boiga irregularis — Cogger, 2000: 618


* Bechstein, J. M. 1802. Herrn de Lacépède's Naturgeschichte der Amphibien oder der eyerlegenden vierfüssigen Thiere und der Schlangen. Eine Fortsetzung von Buffon's Naturgeschichte aus dem Französischen übersetzt und mit Anmerkungen und Zusätzen versehen. Weimar: Industrie Comptoir.
* Cogger, H. G. 2000. Reptiles and Amphibians of Australia, 6th ed. Ralph Curtis Publishing, Sanibel Island, 808 pp.
* Escoriza Boj, D. 2005. Australia. Reptiles and Amphibians, Part 1: Rainforest. Reptilia (GB) (40): 70-75.
* Boiga irregularis at the New Reptile Database. Accessed on 21 August 2008.

Vernacular names
English: Brown catsnake, Brown Tree Snake
日本語: ミナミオオガシラ, ナンヨウオオガシラ


The Brown tree snake (Boiga irregularis) is an arboreal colubrid snake native to eastern and northern coastal Australia, Papua New Guinea, and a large number of islands in northwestern Melanesia.

This snake is infamous for being an invasive species responsible for devastating the majority of the native bird population in Guam.[1]


The Brown tree snake preys upon birds, lizards, bats and small rodents in its native range.[2] It preys on birds and shrews on Guam.[3]

Due to the availability of prey and lack of predators in introduced habitats such as Guam, they have been known to grow to larger sizes than their normal 1 to 2 meters in length.[2] The longest recorded length of this species is one found on Guam measuring three meters.[2]


The reproductive characteristics of the Brown tree snake have not been widely studied.[2] The female is known to produce 4-12 oblong eggs, 42-47 mm long and 18-22 mm wide with a leathery shell.[2] Females may produce up to two clutches per year depending upon seasonal variations in climate and prey abundance.[2] The female deposits the eggs in hollow logs, rock crevices, and other sites where they are likely protected from drying and high temperatures.[2] Populations on Guam may reproduce year round.[4]


The Brown tree snake is a nocturnal snake that can be very aggressive when confronted.[2] It is a rear-fanged colubrid, possessing two small, grooved fangs at the rear of the mouth.[5] Due to the placement of the fangs and grooved rather than hollow fangs, the venom is difficult to convey into a bite on a human, thus is only given in small doses. The venom appears to be weakly neurotoxic and possibly cytotoxic with localized effects, but these effects are trivial for adult humans, and serious medical consequences have been limited to children due to their low mass.[2] This snake is still not considered dangerous to an adult human.[5] The venom seems to be primarily used to subdue lizards, which are more easily positioned in the rear of the mouth for venom delivery.[2]

Invasive species

Shortly after World War II, and before 1952, the Brown tree snake was accidentally transported from its native range in the South Pacific to Guam, probably as a stowaway in ship cargo.[2][5] As a result of abundant prey resources on Guam and the absence of natural predators outside of feral pigs and Mangrove monitors, Brown tree snake populations reached unprecedented numbers.[2] Snakes caused the extirpation of most of the native forest vertebrate species; thousands of power outages affecting private, commercial, and military activities; widespread loss of domestic birds and pets; and considerable emotional trauma to residents and visitors alike when snakes invaded human habitats with the potential for envenomation of small children.[2] Since Guam is a major transportation hub in the Pacific, numerous opportunities exist for the Brown tree snakes on Guam to be introduced accidentally to other Pacific islands as passive stowaways in ship and air traffic from Guam.[2] To minimize this threat, trained dogs are used to search, locate, and remove brown tree snakes prior to the departures of outbound military and commercial cargo and transportation vessels from the island. [6] Numerous sightings of this species have been reported on other islands including Wake Island, Tinian, Rota, Okinawa, Diego Garcia, Hawaii, and even Texas in the continental United States.[7] An incipient population is probably established on Saipan.[2] Paracetamol has been used to help eradicate the snake on Guam. [8][9]


1. ^ Invasive Species: Animals - Brown Tree Snake, National Agricultural Library, United States Department of Agriculture, Retrieved 2010-08-31
2. ^ a b c d e f g h i j k l m n o Fritts, T.H.; D. Leasman-Tanner (2001). "The Brown Treesnake on Guam: How the arrival of one invasive species damaged the ecology, commerce, electrical systems, and human health on Guam: A comprehensive information source". U.S. Department of the Interior. Retrieved 2008-09-11.
3. ^ Pianka, Eric R.; King, Dennis; King, Ruth Allen. (2004). Varanoid Lizards of the World. Indiana University Press, 588 pages ISBN 0253343666
4. ^ Savidge, Julie, Fiona Qualls, and Gordon Rodda. "Reproductive Biology of the Brown Tree Snake, Boiga Irregularis (Reptilia: Colubridae), During Colonization of Guam and Comparison with That in Their Native Range." Pacific Science, 61.2 (2007): 191-199.
5. ^ a b c Mehrtens, John (1987). Living Snakes of the World in Color. New York: Sterling. ISBN 0806964618.
6. ^ Vice, Daniel. "Working Dogs: The Last Line of Defense for Preventing Dispersal of Brown Tree Snakes from Guam".
7. ^ Kraus, Fred (2004). "ALIEN SPECIES". Department of Land and Natural Resources State of Hawaii. Retrieved 2008-09-11.
8. ^ Davis, John (22 September 2007). "Acetaminophen proves effective weapon against brown tree snakes". Guam's News Network. Retrieved 2008-09-11. [dead link]
9. ^ Brad Lendon (2010-09-07). "Tylenol-loaded mice dropped from air to control snakes". Retrieved 2010-09-07.

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