Wednesday, August 31, 2011

Okinawa Montane Viper Feeds During the Winter

Ovophis okinavensis. Photo Credit: 
Al Coritez.
The Okinawa Montane Viper, Ovophis okinavensis is a short, stout-bodied snake that inhabits forested areas, especially near streams, ponds, and marshes, in the subtropical Okinawa and Amami island groups in the Ryukyu Archipelago of Japan. The species is primarily terrestrial and nocturnal and is considered a typical ambush predator. Its diet consists of frogs, lizards, snakes, birds, and small mammals. Although this viper exhibits a generalized diet; however, the diet of some local populations is almost exclusively frogs. Previous ecological studies of O. okinavensis in the northern mountains of Okinawa Island suggested the species is most active from winter to early spring (December to March). And, those studies suggest that the activity pattern of the snake is closely associated with the breeding activities of frogs. Most snakes are active during the warmer parts of the year because they are ectotherms and rely on external heat  to maintain their body temperatures. Ovophis okinavensis is apparently an exception to this pattern. This unusual activity pattern may reflect the availability of prey, which obliges the snake to engage in feeding activities during periods of low temperatures. To test this hypothesis Kadota (2011) examined seasonal activity patterns of both O. okinavensis and the frogs in the study area. He found snake emergence corresponded with the emergence of frogs. The daily emergence of snakes was strongly correlated with that of frogs. These results suggest that O. okinavensis exhibits a foraging strategy that is adjusted to spatial and temporal fluctuations of the emergence of frogs. It would also be interesting to examine the impact of climate change on the behavior of this snake.

Citation: Kadota, Y. 2011. Is Ovophis okinavensis Active Only in the Cool Season? Temporal Foraging Pattern of a Subtropical Pit Viper in Okinawa, Japan.  Zoological Studies 50:269-275.

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