Rhinella marina (Linnaeus, 1758)
Family: Bufonidae Cane Toad, Giant Marine Toad Status: Established Description: The cane toad is a very large, dry skinned and warty anuran with huge paratoid glands. Females and juveniles are brown with darker mottling and large dark paired blotches and often possess a light cream colored dorsal stripe. Juveniles have a strongly mottled venter. Mature males are a uniform brown to yellowish brown and have at least one spine capping each wart (Pers. Obs.), (Zug and Zug 1979). Individuals can be huge with reports of specimens up to 230 mm SVL. Most adults however range from 100 to 150 mm SVL with females on average larger than males (Zug and Zug 1979). The large size and dry warty skin should distinguish this species from all other anurans in the Marianna Islands. Biology: Zug and Zug (1979) did extensive work on cane toads in their native range and most of the following is taken from there. R. marina can be found in almost any habitat in the Mariana Islands provided that there is a body of semipermanent water nearby. It is most common in open areas heavily impacted by humans and much less commonly encountered in forested environments (pers. obs., Zug and Zug 1979). Cane toads prey upon a wide variety of invertebrates and vertebrates, anything that will fit in its mouth, though ants and beetles made up the largest components of the diet at several sites in Panama. Prey is usually detected visually though there is evidence that auditory and olfactory cues may be used as well. Its large size and catholic diet may combine to make cane toads a significant nocturnal predator. Cane mature at approximately 90 mm SVL and can reach this size within a year of metamorphosis (Zug and Zug 1979). In the Marianas, most breeding takes place with the onset of the wet season, generally in mid-June. Breeding can take place in almost any body of water from roadside puddles to permanent ponds and streams, though breeding sites generally have very little flow (pers. obs). Eggs take between 36 and 96 hours to hatch and metamorphosis takes place in 4 to 8 weeks. The timing of metamorphosis may be influenced by environmental cues (Zug and Zug 1979). Tadpoles and newly metamorphosed individuals can be found throughout the year. It is unknown what kind of ecological impact this frog has had in the Marianna Islands Range: The native range of the cane toad is from southern Texas through Central America to northern South America. It has been introduced throughout the tropics and subtropics as an attempt at controlling pests in sugar cane fields. Extralimital populations occur throughout the Caribbean, Florida, Hawaii, New Guinea, Australia, most major islands in the Philippines, Japan, and China (IUCN Red List 19 Mar 2012). In the Mariana Islands it occurs on Guam, Saipan, Tinian, Rota and Cocos Island. Zug, G. and P. Zug. 1979. The Marine Toad, Bufo marinus, A Natural History Resume of Native Populations. Smithsonian Contributions to Zoology 284. 58 p |