Boiga

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.

Species and subspecies

The following species and subspecies are recognized as being valid.

Boiga andamanensis – Andaman cat snake
Boiga angulata – Leyte cat snake – Philippines
Boiga barnesii – Barnes' cat snake – Sri Lanka
Boiga beddomei – Beddome's cat snake – Western Ghat mountains and Sri Lanka
Boiga bengkuluensis –
Boiga bourreti – Bourret's cat snake – central Vietnam
Boiga ceylonensis – Sri Lanka cat snake
Boiga cyanea – green cat snake – Mainland Southeast Asia to eastern India
Boiga cynodon – dog-toothed cat snake – Sundaland and Philippines
Boiga dendrophila – gold-ringed cat snake, mangrove snake
*Boiga dendrophila annectens
*Boiga dendrophila dendrophila
*Boiga dendrophila divergens
*Boiga dendrophila gemmicincta
*Boiga dendrophila latifasciata
*Boiga dendrophila levitoni
*Boiga dendrophila multicincta
*Boiga dendrophila occidentalis
Boiga dightoni – Pirmad cat snake – India
* Boiga dightoni whitakeri – Whitaker's cat snake
Boiga drapiezii – white-spotted cat snake
Boiga flaviviridis - yellow-green cat snake - eastern peninsular India
Boiga forsteni – Forsten's cat snake – Indian subcontinent
Boiga gocool – arrowback tree snake – Bengal, Assam
Boiga guangxiensis – southern China, Laos, Vietnam
Boiga hoeseli - Lesser Sundas cat snake
Boiga irregularis – brown tree snake
Boiga jaspidea – jasper cat snake - Sumatra, Java, Malay peninsula, Borneo
Boiga kraepelini – Kelung cat snake – China, Taiwan, Hainan, Vietnam
Boiga melanota
Boiga multifasciata – many-banded cat snake
Boiga multomaculata – many-spotted cat snake – Himalayan foothills
Boiga nigriceps – black-headed cat snake – Sumatra, Malay Peninsula, Borneo
Boiga nuchalis – collared cat snake – southwestern India
Boiga ochracea – tawny cat snake
Boiga philippina – Philippine cat snake
Boiga quincunciata – Assam, Burma
Boiga ranawanei – Ranawana's cat snake – Sri Lanka
Boiga saengsomi – banded cat snake
Boiga schultzei – Schultze's blunt-headed tree snake
Boiga siamensis – gray cat snake
Boiga tanahjampeana
Boiga thackerayi – Thackeray's cat snake – Western Ghats
Boiga trigonata – Indian gamma snake
*Boiga trigonata trigonata
*Boiga trigonata melanocephala
Boiga wallachi – Nicobar cat snake
Boiga westermanni – Indian egg-eating snake

Nota bene: A binomial authority in parentheses indicates that the species was original described in a genus other than Boiga.

Phylogeny

DNA analysis indicates that Boiga is a sister group to Toxicodryas and Dasypeltis.
Three main clades were identified: B. kraepelini; seven species, B. jaspidea, B. barnesii, B. beddomei, B. ceylonensis, B. quincunciata, B. trigonata, maculata–ochracea; remainder of approximately seventeen species. Within Clade C, subclades include: B. bouretti, drapezii group, cynodon group, irregularis group, B. philippina, B. nigriceps, dendrophila group.

Description

Cat snakes are long-bodied snakes with large heads and large eyes. They vary greatly in pattern and color. Many species have banding, but some are spotted and some are solid-colored. Colors are normally black, brown, or green with white or yellow accents.

Behaviour

Snakes of the genus Boiga are primarily arboreal, nocturnal snakes.

Diet

Snakes of the genus Boiga prey on various small species of lizards, snakes, birds, and mammals.

Venom

The toxicity of Boiga venom varies from species to species, but is not generally considered to be life-threatening to humans.
Since their venom does not usually harm humans, they are popular exotic pets.

Reproduction

Boiga species are oviparous.

In captivity

Boiga dendrophila is by far the most common species in captivity, but B. cyanea and B. nigriceps are also found. Nowadays, B. cynodon, B. philippina and a “Katherine morph” of B. irregularis are also circulating in the South-East Asian exotic pet trade. Others are not commonly available. They are hardy and adaptable and tend to do well in captivity after the initial period of stress from the importation process is passed. They are not bred commonly in captivity, so most specimens available are wild caught, and thus are prone to heavy internal parasite load. Adjusting them to a rodent only diet can be difficult for the inexperienced reptile keeper.

Invasive species

Boiga irregularis in particular has been federally banned in the United States because of its effect by accidentally being introduced to the island of Guam. Some time during the 1950s, some B. irregularis of both sexes reached the island, possibly having hidden in imported plant pots. The island of Guam lacks native snakes or predators that can deal with snakes the size and aggressiveness of B. irregularis. As a result, it has bred unchecked as an invasive species, and has begun consuming the island's bird life in extreme numbers. Dozens of bird species have been completely eradicated from the island, many species that were found nowhere else on earth, and the snake has reached astonishing population densities, reported to be as high as 15,000 snakes per square mile. In addition to devouring the native fauna, this species will routinely crawl into power transformers, and this typically results in both an electrocuted snake and substantial blackouts. In addition, there has been many cases in Guam where deaths are recorded due to the venomous bites from the Boiga snakes. Although they are an invasive species, there has been evidence where there is reverse- colonization of South-East Asia from the Philippines, and the Australasia from Wallacea from multiple lineages within Boiga.