Trioceros jacksonii (Jackson’s chameleon)
- Summary of Invasiveness
- Taxonomic Tree
- Notes on Taxonomy and Nomenclature
- Distribution Table
- History of Introduction and Spread
- Risk of Introduction
- Habitat List
- Biology and Ecology
- Latitude/Altitude Ranges
- Air Temperature
- Means of Movement and Dispersal
- Pathway Causes
- Pathway Vectors
- Impact Summary
- Environmental Impact
- Threatened Species
- Risk and Impact Factors
- Uses List
- Detection and Inspection
- Similarities to Other Species/Conditions
- Prevention and Control
- Gaps in Knowledge/Research Needs
- Links to Websites
- Principal Source
- Distribution Maps
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PicturesTop of page
IdentityTop of page
Preferred Scientific Name
- Trioceros jacksonii Boulenger, 1896
Preferred Common Name
- Jackson’s chameleon
Other Scientific Names
- Chamaeleo (Trioceros) jacksonii Klaver and Böhme 1986
- Chamaeleo jacksoni jacksoni Werner 1911
- Chamaeleo jacksoni merumontana Rand 1958
- Chamaeleo jacksonii merumontanus Eason, Ferguson and Hebrard 1988
- Chamaeleo jacksonii xantholophus Eason et al. 1988
- Chamaeleo jacksonii xantholophus Eason, Ferguson and Hebrard 1988
- Chamaeleon jacksoni Tornier 1899
- Chamaeleon jacksoni vauerescecae Tornier 1903
- Chamaeleon jacksonii Boulenger 1896
- Trioceros jacksonii Tilbury and Tolley 2009
- Trioceros jacksonii jacksonii Tilbury and Tolley 2009
- Trioceros jacksonii merumontanus Tilbury 2010
- Trioceros jacksonii xantholophus Tilbury and Tolley 2009
Local Common Names
- Germany: Dreihorn-Chamäleon
- USA: yellow-crested Jackson’s chameleon
Summary of InvasivenessTop of page
T. jacksonii is an arboreal lizard native to Kenya and Tanzania that has been introduced via the pet trade to the US states of California (McKeown, 1997), Hawaii (McKeown, 1991; 1996; Goldberg et al., 2004; Kraus, 2006; 2009) and Florida (K.L. Krysko, pers. obs.). It is established only in California and Hawaii. T. jacksonii depends on its slow movements and cryptic colouration to blend into the surrounding environment. It attains a size of up to 160 mm snout-vent length and is sexually dimorphic (Eason et al., 1988; Kraus and Preston, 2011; 2012). The main ecological impacts of T. jacksonii are currently on native animals in Hawaii that may be consumed as prey, including insects (Kraus et al., 2012) and snails (Holland et al., 2010).
Taxonomic TreeTop of page
- Domain: Eukaryota
- Kingdom: Metazoa
- Phylum: Chordata
- Subphylum: Vertebrata
- Class: Reptilia
- Order: Squamata
- Species: Trioceros jacksonii
Notes on Taxonomy and NomenclatureTop of page
Chamaeleonidae is diverse family of lizards, with over 200 currently recognized species distributed throughout Africa, southern Europe and Asia (Tilbury and Tolley, 2009). Many taxonomic descriptions are based on coloration and anatomy, and more recently phylogenetics (Rand, 1958; Klaver and Böhme, 1986; Tilbury and Tolley, 2009; Tilbury, 2010). Based on both anatomical and phylogenetic data, Tilbury and Tolley (2009) elevated the subgenus Trioceros to generic level status, hence the currently recognized name Trioceros jacksonii.
DescriptionTop of page
Trioceros is confined to Africa and is the only genus with the development of cylindrical annulated bony horns, although not all taxa or individuals in the genus have this character (Klaver and Böhme, 1986; Tilbury and Tolley, 2009).
T. jacksonii is a small to medium sized lizard, up to 160 mm snout-vent length (SVL) and sexually dimorphic (Eason et al., 1988; Kraus and Preston, 2011; 2012). Adult males are emerald green, with a darker green or turquoise head with three annulated horns on their head (one rostral and two preocular). A yellow lateral stripe and vertical bars may be present (Eason et al., 1988; Tilbury and Tolley, 2009). Adult females are green to grey with darker blotches, usually with two or more light stripes extending from the eye to the angle of the jaw, and may have either zero, one, or three horns, but if present they are considerably reduced in length compared to males (Eason et al., 1988). This species has a distinct yellowish dorsal crest made up of cone-shaped scales (Eason et al., 1988). Vestiges of gular and ventral crests may be present (Eason et al., 1988). T. jacksonii has eyes that move independently, an extendable tongue, zygodactylous feet, a long prehensile tail that is slightly shorter than SVL (Eason et al., 1988), and the ability to change colour depending on mood (McKeown, 1996; Schmidt, 2001).
DistributionTop of page
T. jacksonii is native to Kenya and Tanzania (Mertens, 1966; Eason et al., 1988; Tilbury and Tolley, 2009). It has been introduced to the USA (Kraus 2009) in California (McKeown, 1997), Hawaii (McKeown, 1991; 1996; Goldberg et al., 2004; Kraus, 2006), and Florida (K.L. Krysko, pers. obs.); however, it is established only in California and Hawaii.
Distribution TableTop of page
The distribution in this summary table is based on all the information available. When several references are cited, they may give conflicting information on the status. Further details may be available for individual references in the Distribution Table Details section which can be selected by going to Generate Report.
|Continent/Country/Region||Distribution||Last Reported||Origin||First Reported||Invasive||Reference||Notes|
|Kenya||Widespread||Native||Not invasive||Mertens, 1966; Eason et al., 1988; Tilbury and Tolley, 2009|
|Tanzania||Widespread||Native||Not invasive||Mertens, 1966; Eason et al., 1988; Tilbury and Tolley, 2009|
|USA||Present||Present based on regional distribution.|
|-California||Widespread||Introduced||1981||Invasive||Vosjoli and Ferguson, 1995; McKeown, 1997||Introduced and established in Morro Bay, San Luis Obispo County; Redondo Beach, Los Angeles County; and San Diego, San Diego County|
|-Florida||Absent, reported but not confirmed||Introduced||2014||Not invasive||Krysko et al., 2004||K.L. Krysko, pers. obs. Introduced to Miami, Miami-Dade County|
|-Hawaii||Widespread||Introduced||1972||Invasive||McKeown, 1991; McKeown, 1996; Kraus, 2009; Hagey et al., 2010; Holland et al., 2010; Kraus et al., 2012||Introduced and established on Oahu, Maui, Hawaii and Lanai|
History of Introduction and SpreadTop of page
In Hawaii, T. jacksonii was introduced via the pet trade from Kenya to Oahu in 1972. By 1980 there were at least five different populations on Oahu; by the mid-1990s T. jacksonii was established on Maui and the eastern side of the Big Island, and in 1995 it was also established on Lanai (McKeown, 1996). In 2010, the first known specimens were collected on the western side of the Big Island (K.L. Krysko, pers. obs.; F. Kraus, pers. comm.). It has not been found on Kauai (KISC, 2015).
In California, T. jacksonii was first introduced via the pet trade in 1981 and has since established populations along the Pacific Coast in Morro Bay, San Luis Obispo County; Redondo Beach, Los Angeles County; and San Diego, San Diego County (de Vosjoli and Ferguson, 1995; McKeown, 1997).
IntroductionsTop of page
|Introduced to||Introduced from||Year||Reason||Introduced by||Established in wild through||References||Notes|
|Natural reproduction||Continuous restocking|
|California||California||1981||Yes||McKeown (1997)||Accidental and Intentional|
|Florida||2014||No||Krysko et al. (2004)||Single animal introduced|
|Hawaii||California||1972||Yes||Kraus et al. (2012); McKeown (1991)||Accidental and Intentional|
Risk of IntroductionTop of page
T. jacksonii is an arboreal lizard which depends on its slow movements and cryptic coloration to blend into the surrounding environment. With its zygodactylous feet and prehensile tail, it grasps firmly onto vegetation when disturbed, and can thus be transported on vegetation to nonindigenous areas without being detected. Additionally, this species is commonly kept in captivity by pet fanciers and intentionally released to establish new populations (Kraus et al., 2012; Kraus and Preston, 2012).
HabitatTop of page
T. jacksonii is found in wet montane and evergreen forests and their peripheries, in gardens and in coffee plantations up to 2800 m elevation (Tilbury and Tolley, 2009; Kraus et al., 2012).
Habitat ListTop of page
|Cultivated / agricultural land||Principal habitat||Natural|
|Disturbed areas||Principal habitat||Natural|
|Managed forests, plantations and orchards||Principal habitat||Natural|
|Rail / roadsides||Principal habitat||Natural|
|Urban / peri-urban areas||Principal habitat||Natural|
|Natural forests||Principal habitat||Natural|
Biology and EcologyTop of page
T. jacksonii is reported to be mature at 9 months of age (Necas, 1999). Females are ovoviviparous and there is a 6–7 month gestation period before giving live birth to up to 51 young (Necas, 1999). Females can mate again as soon as 20 days after giving birth (Necas, 1999), and so this species has the potential for a high intrinsic population growth rate (Kraus et al., 2012).
Physiology and phenology
T. jacksonii can tolerate temperature extremes from 30°C during the day time to 5°C during the night time (Necas, 1999).
T. jacksonii can live up to 10 years in captivity (Necas, 1999).
T. jacksonii is diurnal and exhibits a cruise foraging behaviour, with a moderate amount of time moving, few moves per minute, and a very slow locomotion speed (Hagey et al., 2010).
ClimateTop of page
|Af - Tropical rainforest climate||Preferred||> 60mm precipitation per month|
|BW - Desert climate||Tolerated||< 430mm annual precipitation|
|Cf - Warm temperate climate, wet all year||Preferred||Warm average temp. > 10°C, Cold average temp. > 0°C, wet all year|
|Cs - Warm temperate climate with dry summer||Preferred||Warm average temp. > 10°C, Cold average temp. > 0°C, dry summers|
Latitude/Altitude RangesTop of page
|Latitude North (°N)||Latitude South (°S)||Altitude Lower (m)||Altitude Upper (m)|
Air TemperatureTop of page
|Parameter||Lower limit||Upper limit|
|Mean maximum temperature of hottest month (ºC)||30|
|Mean minimum temperature of coldest month (ºC)||5|
Means of Movement and DispersalTop of page
According to McKeown (1996), T. jacksonii was introduced in 1972 on Oahu, Hawaii, when a pet store owner released several dozen sick imported individuals into his yard in the hope that they would recover. However, Kraus et al. (2012) reported that McKeown admitted that hundreds of chameleons born in western USA pet shops were imported to Hawaii during the 1970s and released in multiple locations to establish additional populations (Kraus et al., 2012). Populations spread quickly as chameleons were translocated to other locations and islands (Kraus et al., 2012).
Pathway CausesTop of page
|Escape from confinement or garden escape||Accidentally released in Morro Bay, San Luis Obispo County, California||Yes||McKeown, 1997|
|Intentional release||Intentionally released in Morro Bay, San Luis Obispo County; Redondo Beach, Los Angeles County; and||Yes||McKeown, 1997; Vosjoli and Ferguson, 1995|
|Pet trade||Intentionally released on Oahu, Maui, Hawaii and Lanai, Hawaii; in Morro Bay, San Luis Obisp||Yes||Kraus et al., 2012; McKeown, 1996; McKeown, 1997; Vosjoli and Ferguson, 1995|
Pathway VectorsTop of page
Impact SummaryTop of page
Environmental ImpactTop of page
Impact on biodiversity
The main ecological impacts of T. jacksonii are currently on native animals in Hawaii that may be consumed as prey, such as insects (Kraus et al., 2012) and snails (Holland et al., 2010). KISC (2015) describes it as a threat to the native birds, insects, spiders and snails found on Kauai, Hawaii, as well as being a potential prey base for brown tree snakes and other snakes.
Threatened SpeciesTop of page
|Threatened Species||Conservation Status||Where Threatened||Mechanism||References||Notes|
|Achatinella mustelina||CR (IUCN red list: Critically endangered) CR (IUCN red list: Critically endangered)||Hawaii||Predation||Holland et al., 2010; Kraus et al., 2012|
|Auriculella||No details No details||Hawaii||Predation||Holland et al., 2010; Kraus et al., 2012|
|Megalagrion blackburni||No details No details||Hawaii||Predation||Kraus et al., 2012|
Risk and Impact FactorsTop of page Invasiveness
- Proved invasive outside its native range
- Has a broad native range
- Abundant in its native range
- Highly adaptable to different environments
- Tolerates, or benefits from, cultivation, browsing pressure, mutilation, fire etc
- Pioneering in disturbed areas
- Tolerant of shade
- Capable of securing and ingesting a wide range of food
- Highly mobile locally
- Long lived
- Fast growing
- Has high reproductive potential
- Negatively impacts animal health
- Reduced native biodiversity
- Threat to/ loss of endangered species
- Threat to/ loss of native species
- Rapid growth
- Highly likely to be transported internationally accidentally
- Highly likely to be transported internationally deliberately
- Highly likely to be transported internationally illegally
- Difficult to identify/detect as a commodity contaminant
- Difficult to identify/detect in the field
- Difficult/costly to control
UsesTop of page
T. jacksonii is viewed by many as an interesting exotic species because of its horns, long tongue and remarkable feeding behaviour (Kraus et al., 2012). Thus, many people have moved it to their property and try to protect it from being removed from the wild.
Uses ListTop of page
- Botanical garden/zoo
- Laboratory use
- Pet/aquarium trade
- Research model
Detection and InspectionTop of page
T. jacksonii can be found during the day and at night. During the day time, intensive visual inspections of vegetation can reveal slowly moving chameleons (Hagey et al., 2010), whereas during night time chameleons are easily found by using flash lights (Krysko et al., 2004; Gillette et al., 2010).
Similarities to Other Species/ConditionsTop of page
The subspecies T. jacksonii xantholophis (Eason et al., 1988) is believed to be introduced to Hawaii and California (McKeown, 1991; 1996). This taxon is distinguished from the other two subspecies (T. jacksonii jacksonii and T. jacksonii merumontanus) by having a greater snout-vent length (SVL; mean 123.7 mm vs. 104.6 mm and 78.4 mm, respectively), more convex postocular and occipital scales, light parietal and dorsal crest scale pigmentation, a greater number of interorbital scales (mean = 7.7) and a smaller crest interval relative to crest scale cluster size (mean = 0.4 vs. 0.6) (Eason et al., 1988).
Prevention and ControlTop of page
In 1973, the Hawaii Board of Agriculture prohibited the importation, sale and possession of T. jacksonii (Kraus et al., 2012). In 1991, legislation enactment of Hawaii Administrative Rules (HAR) Chapter 4-71 incorporated an official List of Prohibited Animals, and in 1992 T. jacksonii was included in this list as a restricted species (Kraus et al., 2012). This allowed for possession and sale of locally obtained animals, but still prohibited importation and inter-island transfer (Kraus et al., 2012). In 1998, HAR Chapter 13-124 made it illegal to export T. jacksonii to the US mainland (Kraus et al., 2012). T. jacksonii is currently listed as CITES Appendix II, which includes species not necessarily threatened with extinction, but in which trade must be controlled in order to avoid utilization incompatible with their survival.
Gaps in Knowledge/Research NeedsTop of page
Although many aspects of the natural history of T. jacksonii have been reported, data are needed on population density, movement patterns, reproduction and other aspects of its biology. A phylogeographic analysis using specimens from introduced populations could be conducted to test invasion pathway and native range hypotheses.
ReferencesTop of page
Boulenger GA, 1896. Description of a new chameleon from Uganda. Annals and Magazine of Natural History, 17:376.
Eason PK; Ferguson GW; Hebrard J, 1988. Variation in Chamaeleo jacksonii (Sauria, Chamaeleonidae): Description of a New Subspecies. Copeia, 1988:580-590.
Gillette CR; Krysko KL; Wasilewski JA; Kieckhefer IIIGN; Metzger IIIEF; Rochford MR; Cueva D, 2010. Oustalet's Chameleon, Furcifer oustaleti (Mocquard 1894) (Chamaeleonidae), a Non-indigenous Species Newly Established in Florida. Amphibians & Reptiles: Conservation and Natural History, 17:248-249.
Goldberg SR; Bursey CR; Kraus F, 2004. Natural history notes: Chamaeleo jacksoni: endoparasites. Herpetological Review, 35:387-388.
Hagey TJ; Losos JB; Harmon LJ, 2010. Cruise foraging of invasive chameleon (Chamaeleo jacksonii xantholophus) in Hawaii. Breviora, 519:1-7.
Holland BS; Montgomery SL; Costello V, 2010. A reptilian smoking gun: first record of invasive Jackson's chameleon (Chamaeleo jacksonii) predation on native Hawaiian species. Biodiversity and Conservation, 19(5):1437-1441. http://www.springerlink.com/content/t8848p5q03319146/fulltext.html
KISC, 2015. Jackson's Chameleon. Kauai Invasive Species Committee. http://www.kauaiisc.org/jacksons-chameleon/ Accessed 02/10/15
Klaver CJJ; Böhme W, 1986. Phylogeny and classification of the Chamaeleonidae (Sauria) with special reference to hemipenis morphology. Bonner Zoologische Monographien, 22:1-64.
Kraus F, 2006. New records of alien lizards from Maui County. Bishop Museum Occasional Papers, 88:61-62.
Kraus F; Medeiros A; Preston D; Jarnevich CS; Rodda GH, 2012. Diet and conservation implications of an invasive chameleon, Chamaeleo jacksonii (Squamata: Chamaeleonidae) in Hawaii. Biological Invasions, 14(3):579-593. http://www.springerlink.com/content/32721672x18186qk/
Kraus F; Preston D, 2011. Diet analysis of the invasive Lizard Chamaeleo jacksonii from a wet forest habitat in Hawaii. Final Report, Contribution No. 2011-011. Honolulu, Hawaii, USA: Hawaii Invasive Species Council, 10 pp.
Kraus F; Preston D, 2012. Diet of the invasive lizard Chamaeleo jacksonii (Squamata: Chamaeleonidae) at a wet-forest site in Hawai'i. Pacific Science, 66(3):397-404. http://www.uhpress.hawaii.edu/journals
Krysko KL; Enge KM; King FW, 2004. The Veiled Chameleon, Chamaeleo calyptratus: a new exotic species in Florida. Florida Scientist, 67:249-253.
McKeown S, 1991. Jackson's chameleons in Hawaii are the recently described Mt. Kenya subspecies, Chamaeleo jacksonii xantholophus. Bulletin of the Chicago Herpetological Society, 26:49.
McKeown S, 1996. A field guide to reptiles and amphibians in the Hawaiian Islands. Los Osos, California, USA: Diamond Head Publishing, 173 pp.
McKeown S, 1997. Notes on an established population of Jackson's chameleons (Chamaeleo jacksonii xantholophus) in California. Bulletin of the Chicago Herpetological Society, 32:101.
Mertens R, 1966. List of novel amphibians and reptiles: Chamaeleonidae. (Liste der rezenten Amphibien und Reptilien: Chamaeleonidae.) Das Tierreich, 83:1-37.
Necas P, 1999. Chameleons - Nature's Hidden Jewels. Frankfurt, Germany: Edition Chimaira, 348 pp.
Rand AS, 1958. A new subspecies of Chamaeleo jacksoni Boulenger and a key to the species of three-horned chameleons. Breviora, 99:1-8.
Schmidt W, 2001. Chamaeleo calyptratus, the Yemen Chameleon. Berlin, USA: Matthias Schmidt Publ., Natur und Tier-Verlag, 79 pp.
Tilbury CR, 2010. Chameleons of Africa: An Atlas, Including the Chameleons of Europe, the Middle East and Asia. Frankfurt, USA: Edition Chimaira, 831 pp.
Tilbury CR; Tolley KA, 2009. A re-appraisal of the systematics of the African genus Chamaeleo (Reptilia: Chamaeleonidae). Zootaxa, 2079:57-68.
Tornier G, 1899. New chameleons. (Neues über Chamaeleons.) Zoologischer Anzeiger, 22:408-414.
Tornier G, 1904. Three new reptiles of East Africa. (Drei neue Reptilien aus Ost-Afrika. Zoologische Jahrbucher.) Abteilung für Systematik, Geographie und Biologie der Tiere [Zoological Yearbook, Department of Systematics, Geography and Biology of Animals], 19:173-178.
Vosjoli Pde; Ferguson G, 1995. Care And Breeding of Panther, Jackson's, Veiled and Parson's Chameleons. Santee, California, USA: The Herpetological Library, Advanced Vivarium Systems, 128 pp.
Werner F, 1911. Chamaeleontidae. Das Tierreich, 27:1-52.
OrganizationsTop of page
USA: Bishop Museum (BM), 1525 Bernice Street,, Honolulu, Hawaii, http://www.bishopmuseum.org/
Principal SourceTop of page
Draft datasheet under review
ContributorsTop of page
15/04/15 Original text by:
Kenneth Krysko, University of Florida, USA
Distribution MapsTop of page
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