學名: Chamaeleo jacksonii Boulenger, 1896
同種異名: Chamaeleo (Trioceros) jacksonii Necas 1999: 165, Chamaeleo jacksonii jacksonii Boulenger 1896, Chamaeleo jacksonii jacksonii Werner 1911: 26, Chamaeleo jacksonii merumontanum Van Hoof et al. 2006, Chamaeleo jacksonii merumontanus Rand 1958, Chamaeleo jacksonii xantholophus Eason, Ferguson & Hebrard 1988, Chamaeleo jacksonii xantholophus Van Hoof et al. 2006, Chamaeleo jacksonii Bonetti 2002: 63, Chamaeleon jacksonii Boulenger 1896: 376, Chamaeleon jacksonii var. vauerescecae Tornier 1904, Trioceros jacksonii Tilbury & Tolley 2009
俗名: Dreihorn-Chamäleon (German), Jackson’s chameleon (English)
Chameleo jacksonii or Jackson's chameleon, is a generalist predator native to Kenya and Tanzania. It has been exported to various countries as a pet species. Jackson's chameleons were accidentally released on the island of Oahu in the 1970’s, and have since established populations on all of the main Hawaiian Islands; a recent study has determined that predation on various endemic invertebrate species is occurring, including a 'Critically Endangered (CR)' Oahu tree snail (Achatinella mustelina). The Jackson’s chameleon prefers wet tropical, high elevation habitat, also favored by native Hawaiian plants and animals.
Three subspecies are recognised, Chamaeleo jacksonii jacksonii Boulenger 1896 (Mt. Kenya); C. jacksonii merumontanus Rand 1958 (Mt. Meru, Tanzania) and C. jacksonii xantholophus Eason, Ferguson & Hebrard 1988.
C. jacksonii xantholophus adult males are light emerald green with vaguely defined yellow along the throat, shoulders, flanks, and crest scales; the head is darker green or turquoise (Waring, 1997), and adults of the species have the ability to rapidly and dramatically change color in response to other chameleons and/or the presence of perceived threat from predators. Males have three brownish annulated horns, consisting of two preocular horns and one rostral (the latter being longest) (Waring, 1997). Adult females of the Mt. Kenya subspecies typically have no horns; their body color (and that of immature males) varies, ranging from gray to reddish-brown to dark olive, often having light blotches on the darker background color (Eason et al. 1988; in Waring, 1997), but again under stress can alter color pattern and brightness. Males normally attain a length of 25-30 cm (SVL = ~15 cm), females are commonly 5 cm shorter (Fergeson et al. 1991; in Waring, 1997). The tail accounts for about half of the animal's length; it is prehensile and often curled in a laterally-flattened coil as the chameleon is perched motionless, in an ambush posture. The limbs are long and adroit (Waring, 1997). Sets of toes are fused medially such that there are two claw-tipped, opposable paddle-like toes on each foot; these grip the arboreal substrate steadfastly (Waring, 1997).
A solitary lifestyle was typical of C. jacksonii at all ages at Makawao, on the Hawaiian island of Maui (Waring, 1997) with smaller individuals generally avoiding larger ones. McKeown (1995) noted that adult males will challenge one another to horn-to-horn pushing duels in territorial attempts to drive away competitors, with the weaker, or more submissive male ultimately retreating. Waring (1997) noted that individuals were often found in the same tree or shrub day after day, nevertheless, they remained apart. Immature and adults coexisted in the same plant, but rarely did they get within 0.5 m of each other (Waring, 1997). As with other species of chameleons, juveniles tend to occupy forest understory and grassy habitat, in what is possibly an ontogenetic habitat shift and an adaptive behaviour to avoid cannibalism by adults (Rotem et al. 2006).
Chameleo jacksonii in the Hawaiian Islands are most abundant in wet, shady habitat between 100 m and 1000 m elevation (Holland et al. 2010) and where daytime temperatures range from 21-32 C° (70-90 F°), night time temperatures range from 10-20 C° (50-68 F°), and rainfall is moderate (McKeown 1995). On the Hawaiian island of Maui, C. jacksonii appeared to mainly utilize suburban and adjacent locations that have luxuriant conditions, usually occupying plants having a network of multiple branches. Nevertheless, they were sometimes found on isolated sparsely-foliated shrubs or trees as well (Waring, 1997). They have been observed on a variety of plants in the Makawao area of Maui, including avocado trees, silk oak, banana, Christmas berry, bottlebrush, guava, and papaya (Waring, 1997). They commonly positioned themselves >2 m above the ground; yet individuals in well-branched shrubs were seen 0.5 m above the ground (Waring, 1997). In their native habitat on Mt. Kenya, C. jacksonii inhabit moist, well-vegetated forests, not only in native arboreal canopies but also in fruit and coffee orchards as well as hedgerows (Ferguson et al. 1991; in Waring, 1997). The same pattern of habitat preference has been observed in the Hawaiian Islands (Holland, personal observation).
Holland et al. (2010) have recently provided the first conclusive evidence of ecological impact using stomach content analysis, recovering the remains of various endemic and native Hawaiian invertebrate species including the 'Critically Endangered (CR)' Oahu tree snail (Achatinella mustelina in IUCN Red List of Threatened Species).
Chameleo spp. including C. jacksonii are popular in the global pet trade with 15, 148 C. jacksonii individuals transferred internationally between 1991 and 1996 (Carpenter et al. 2004). As of the date of publication of this profile, it is legal to buy and sell Jackson’s chameleons in the state of Hawaii.
While once claimed to be the sole supply source of Chameleo jacksonii to the USA market, the export of feral C. jacksonii from Hawaii to mainland America is now illegal (Carpenter et al. 2004). The USA is also the largest market for Chameleo spp. accounting for 69 % of all imports with additional supply from captive breeding and extraction from feral populations further supplying the internal market and not being recorded (Carpenter et al. 2004).
Native range: Kenya (Kikuyu near Nairobi, highlands of central Kenya except of eastern slopes of Mt. Kenya), Tanzania (Mt. Meru), Kenya (eastern slopes of Mt. Kenya) (The Reptiles Database 2010)
Known introduced range: Subspecies Chamaeleo jacksonii xantholophus Hawaiian Islands, Florida, USA
Preventative measures: Chameleo jacksonii is classified by the State of Hawaii Department of Land and Natural Resources, Division of Forestry and Wildlife as ‘‘injurious wildlife’’, and export as well as inter-island transport has been prohibited since 1997 (Hawaii Administrative Rule Section 13-124-3; in Holland et al. 2010). Prior to the recent documentation of predation on native Hawaiian invertebrates, there had been a widespread notion that chameleons have not caused any deleterious environmental impacts (McKeown, 1996).
Chameleo jacksonii has a highly varied diet, and optimal foraging strategy seems to involve feeding on as many different types of prey as are available. Chameleons feed mainly on small invertebrates (e.g. insects, spiders, and snails) captured mainly with their rapidly extensible tongue, which can extend up to 1.5 body lengths (Waring, 1997). However they will also feed on vertebrates smaller than themselves, where prey size is evidently limited by gape size. When presented with large insects or snails, chameleons will tend to not use the tongue strike feeding strategy, but will instead directly approach and grab the prey with the mouth. The sticky tip of the tongue can reach the prey in 0.06 sec (Martin, 1992; in Waring, 1997). The foraging behaviour of C. jacksonii has been described as substantially different from the standard lizard foraging behavior, being somewhere between active predation and ambush or sit-and-wait predation (Hagey et al. 2010). The term "cruise forager" has been used to describe this behavior as follows: the chameleon is "…a species that moves, stops, and merely scans the environment, then moves, stops, and scans, and so on’’ (Regal, 1983; in Hagey et al. 2010). In captivity (and presumably also in the wild), daily water must be available in a way that resembles rain or dew drops on leaves (Waring, 1997). Chameleons will ingest the shiny droplets dangling from the leaf tips though they will rarely drink from a pool of water (Waring, 1997).
The species is ovoviviparous, after mating, the female internally retains the eggs and subsequently gives live birth after approximately three months, to 12-40 precocial, predatory young (Waring, 1997). Melrose (pers. comm.; in Waring, 1997) observed the birth of 13 young, each encased individually in a flexible sac; the infants freed themselves from the membranes. Postpartum parental care does not to occur (Waring, 1997; Holland, personal observation). Being a seasonal breeder in its native habitat, a female may produce broods every six months (Lin & Nelson 1981; in Waring, 1997), though in the tropical climate of Hawaii there does not appear to be any seasonality to their reproductive cycle (Holland, personal observation). At birth, the young are 52-55 mm long, with the tail accounting for 23-25 mm of the length, and the color is black, white and grey; they utilize their tongue to capture live prey from the day of birth (Waring, 1997). At the age of five months, juveniles reach a length of 8-10 cm (Schifter, 1975; in Waring, 1997). Juveniles attain sexual maturity at approximately two years (de Vosjoli, 1990; in Waring, 1997).
校訂者：: Dr. Brenden Holland, Assistant Researcher, Center for Conservation Research and Training, Pacific Biosciences Research Center at the University of Hawaii at Manoa. USA
編輯者: IUCN/SSC Invasive Species Specialist Group (ISSG)
最後修改: Thursday, 27 May 2010