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Research Area 10 - Dietary preferences and behavioral differences of the endemic Hainan Keelback and the widespread Red-necked Keelback on Hainan Island, China

The genus of keelbacks (Rhabdophis) is a very unique and unusual group of snakes. Most members of this genus possess unique glands called nuchal glands in the nape of the neck. Very little is known about these glands, but some members of the genus sequester poisons from their toxic prey, which, so far, is only known to come from toads. The genus has evolved some unique defensive behaviors associated with these glands.

Work will be conducted within the Shennongjia (pronounced as three separate words: Shen Nong Jia) National Nature Reserve in western Hubei Province. Shennongjia is an 800,000 acre reserve that was established in 1982. The reserve is in a temperate latitude and consists of extension mountains, ranging from 1,200 ft at the lowest to over 10,000 ft at the summit.

Since 2006 I have been conducting herpetological inventories at this reserve and have found 48 species of reptiles and amphibians. Two species which live sympatrically within the reserve but differentiate themselves through habitat and elevation are the keelback snakes of the genus Rhabdophis. Shennongjia is home to one of the more common keelbacks, the tiger keelback (R. tigrinus) and the less widespread Groove-necked keelback (R. nuchalis).

We are interested in examining the dietary preferences of these species as well as their defensive behaviors. The genus Rhabdophis is one of the few genera in the world that is classified as both poisonous and venomous (rear-fanged). The genus obtains poisons from toxic prey it eats (to date this is only known to be in the form of toads). These poisons are stored in nuchal glands along the neck. The glands are unique among vertebrates in many ways and their full function and use among the 21 species is poorly known.

Within this elite group of snakes, the groove-necked keelback is part of a smaller group that possess additional glands along the dorso-lateral body. How these additional glands come into play into this species’ evolutionary history is still unknown.

The presence of these glands has been shown to be associated with certain behaviors called nuchal gland related behaviors. The three prominent behaviors are: 1) raising the forebody, 2) arching the neck, and 3) neck butting, where the animal swings the arched neck into the stimulus.

The groove-necked keelback seems to lack two of these three behaviors. It also tends to prefer on earthworms instead of toads. We plan to examine whether or not this species does in fact prefer non-toxic earthworms to toxic toads, and to examine its defensive behavior suite compared to other members of Rhabdophis. Perhaps this species is diverging from the rest of the genus and is now just a relict member, showing residual behaviors that are no longer necessary for the species’ survival.

The chosen REU student will assist in the sampling for specimens of both groove-necked keelbacks and tiger keelbacks, though the primary focus will be on groove-necked keelbacks, which are more common at the study site. Upon capture, animals will be sexed, measured, and weighed. Under the supervision of the advisor/ mentor, the student will assist in conducting laboratory experiments testing the defensive behaviors and dietary preferences of these snakes.​

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