The native range of Ctenosaura similis extends from southern Mexico through Panama. From an initial introduction of 3 animals in 1979, the species now numbers in the thousands on Gasparilla Island in southwest F...The native range of Ctenosaura similis extends from southern Mexico through Panama. From an initial introduction of 3 animals in 1979, the species now numbers in the thousands on Gasparilla Island in southwest Florida. In response to complaints of property damage from residents and threats to native species, local officials and the US Department of Agriculture Wildlife Services began a removal program in 2008. Through 2011, trappers removed 9467 ctenosaurs. The number removed declined from 32 iguanas/day in 2008 to 1.9 iguanas/day in 2011 despite no easing of the control effort. We necropsied 2757 ctenosaurs to document aspects of their natural history. Females outnumbered males overall, although the largest size class (>300 mm snout-vent length) included 32 males and just 2 females. Reproduction was seasonal. We found oviducal eggs in females from early Apr to early Jun, approximately 2 months later than C. similis in its native range. We trapped hatchlings from late Jul to early Oct coincident with the summer rainy season. Clutch size increased with female body size, with 62 being the largest clutch size recorded. In general, the biology of the invasive population on Gasparilla Island resembles native C. similis populations in Central America, except for the lack of large individuals. We suggest that shorter day length and colder temperatures create environmental conditions that are suboptimal for individual growth compared to those in the native range.展开更多
Reducing populations of invasive lizards through trapping and shooting is feasible in many cases but effective inte-grated management relies on a variety of tools, including toxicants. In Florida, using wild-caught no...Reducing populations of invasive lizards through trapping and shooting is feasible in many cases but effective inte-grated management relies on a variety of tools, including toxicants. In Florida, using wild-caught non-native black spiny-tailed iguanas Ctenosaura similis, we screened acetaminophen and zinc phosphide to determine their suitability for effective population management of this prolific invasive species. Of the animals that received acetaminophen, none died except at the highest test dose, 240 mg per lizard, which is not practical for field use. Zinc phosphide produced 100% mortality at dose levels as little as 25 mg per lizard, equivalent to about 0.5% in bait which is lower than currently used in commercial baits for commensal rodent con-trol. We conclude that zinc phosphide has potential as a useful tool for reducing populations of invasive lizards such as the black spiny-tailed iguana provided target-selective delivery methods are developed [Current Zoology 57 （5）： 625~529, 2011].展开更多
Florida, along with Hawaii, has among the two worst invasive species problems in the USA, and the state is espe-cially susceptible to establishment by alien reptiles. Besides the large numbers of established non-nativ...Florida, along with Hawaii, has among the two worst invasive species problems in the USA, and the state is espe-cially susceptible to establishment by alien reptiles. Besides the large numbers of established non-native reptile species in Florida, many of these species present novel difficulties for management, or have other characteristics making effective management ex-tremely challenging. Moreover, initiation of management action requires more than recognition by experts that a potentially harmful species has become established. It also requires the political will along with concomitant resources and appropriate per-sonnel to develop effective methods and apply them. We review the situation in Florida, including assessment of risk for estab- lishment, and we use a subset of prominent species to illustrate in more detail the array of invasive reptile species circumstances in Florida, including routes of introduction, impacts, and potential and implemented management actions. These examples not only highlight the severity of the invasive reptile problems in the state, but they also show the diversity in resolve and response towards them and the motivating factors [Current Zoology 57 （5）： 599-612, 2011].展开更多
文摘The native range of Ctenosaura similis extends from southern Mexico through Panama. From an initial introduction of 3 animals in 1979, the species now numbers in the thousands on Gasparilla Island in southwest Florida. In response to complaints of property damage from residents and threats to native species, local officials and the US Department of Agriculture Wildlife Services began a removal program in 2008. Through 2011, trappers removed 9467 ctenosaurs. The number removed declined from 32 iguanas/day in 2008 to 1.9 iguanas/day in 2011 despite no easing of the control effort. We necropsied 2757 ctenosaurs to document aspects of their natural history. Females outnumbered males overall, although the largest size class (>300 mm snout-vent length) included 32 males and just 2 females. Reproduction was seasonal. We found oviducal eggs in females from early Apr to early Jun, approximately 2 months later than C. similis in its native range. We trapped hatchlings from late Jul to early Oct coincident with the summer rainy season. Clutch size increased with female body size, with 62 being the largest clutch size recorded. In general, the biology of the invasive population on Gasparilla Island resembles native C. similis populations in Central America, except for the lack of large individuals. We suggest that shorter day length and colder temperatures create environmental conditions that are suboptimal for individual growth compared to those in the native range.
文摘Reducing populations of invasive lizards through trapping and shooting is feasible in many cases but effective inte-grated management relies on a variety of tools, including toxicants. In Florida, using wild-caught non-native black spiny-tailed iguanas Ctenosaura similis, we screened acetaminophen and zinc phosphide to determine their suitability for effective population management of this prolific invasive species. Of the animals that received acetaminophen, none died except at the highest test dose, 240 mg per lizard, which is not practical for field use. Zinc phosphide produced 100% mortality at dose levels as little as 25 mg per lizard, equivalent to about 0.5% in bait which is lower than currently used in commercial baits for commensal rodent con-trol. We conclude that zinc phosphide has potential as a useful tool for reducing populations of invasive lizards such as the black spiny-tailed iguana provided target-selective delivery methods are developed [Current Zoology 57 （5）： 625~529, 2011].
文摘Florida, along with Hawaii, has among the two worst invasive species problems in the USA, and the state is espe-cially susceptible to establishment by alien reptiles. Besides the large numbers of established non-native reptile species in Florida, many of these species present novel difficulties for management, or have other characteristics making effective management ex-tremely challenging. Moreover, initiation of management action requires more than recognition by experts that a potentially harmful species has become established. It also requires the political will along with concomitant resources and appropriate per-sonnel to develop effective methods and apply them. We review the situation in Florida, including assessment of risk for estab- lishment, and we use a subset of prominent species to illustrate in more detail the array of invasive reptile species circumstances in Florida, including routes of introduction, impacts, and potential and implemented management actions. These examples not only highlight the severity of the invasive reptile problems in the state, but they also show the diversity in resolve and response towards them and the motivating factors [Current Zoology 57 （5）： 599-612, 2011].
