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
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
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.