Ophiotropics.com
© 2004-2018 Thomas Jäkel
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Medan   ,   the   provincial   capital   of   Northern   Sumatra,   is   a   bustling   city   of   over   2   million   inhabitants and   a   booming   commercial   centre   for   the   region's   huge   oil   and   agribusiness.   Oil   palm   plantations, rubber,   cocoa,   rice   and   other   crops   dominate   the   landscape.   There   is   little   natural   forest   left,   and the area around the famous lake Toba has been denuded by paper factories.
Given   these   circumstances,   I   was   not   expecting   any   exciting   location   to   observe   Wagler's   vipers   in the   wild.   However,   fortunately,   my   view   proved   to   be   completely   wrong.   Thanks   to   local   friends   and farmers   I   was   able   to   witness   one   of   the   most   dense   populations   of   T.   wagleri    I   have   ever   seen.   I   will not   mention   the   exact   location   here.   However,   similar   habitats   are   still   abundant   in   the   vicinity   of Medan, in particular, in the forests that form the edge of the Karo plateau southwest of the city. I   had   already   spent   numerous   frustrating   hours   of   roaming   around   in   potential   habitats,   e.g.   in Sibolangit   Botanical   Garden,   around   Lake   Toba,   and   even   in   Gunung   Leuser   National   Park.   The forests   around   Berastagi   are   also   beautiful,   but   probably   too   high   above   sea   level,   over   1000   m,   to host temple pit vipers. As   it   often   comes   with   Wagler’s   viper   in   the   wild   (see   my   notes   on   Templer   Park),   you   have   to   look   in the   backyard   of   a   house,   or   a   parking   area   of   a   highway   bordering   forest   to   observe   them.   I exaggerate, but there is some truth in it. The   location   I   would   like   to   show   you   here   is   a   river   valley   that   is   used   by   smallholder   farmers   to grow   cocoa,   rice   and   various   fruits   of   the   region,   like   guava,   pineapple,   sugar   palm   etc.   The   slopes   of the   valley   show   dense   primary   and   secondary   growth   lowland   jungle.   The   climate   is   extremely moist,   as   indicated   by   abundant   mosses   and   lichens   on   trees   and   on   the   ground.   Because   T.   wagleri is so abundant in this place, I think the name 'valley of the temple pit viper' would be a suitable one.
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Although   the   above   habitat   looked   really   inviting   to   check   for   Waglers,   I   did   not   have   to   venture   too far   from   the   road   as   the   animals   flocked   the   cocoa   plantations   and   gardens   of   the   local   farmers.   In fact, this snake is so abundant here that farmers observe it on a daily basis. And they often kill it.
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Farmers' houses are surrounded by numerous trees, often fruit trees. The tree seen in the foreground was inhabitated  by temple pit vipers.
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In    a    period    of    a    five    days,    I    observed    eight    vipers,    and    many    more    were    reported    by    locals. Unfortunately,   the   snakes   had   disappeared   once   I   arrived   at   those   reported   locations.   Because   it was   raining   heavily   every   day   (in   the   late   afternoon)   during   this   trip   in   April   2006,   the   snakes changed   positions   frequently.   Farmers   told   me   that   they   may   stay   at   the   same   place   for   many weeks. So   why   is   T.   wagleri   so   abundant   here?   Well,   for   sure   it   is   the   high   humidity   found   in   this   place,   the close   vicinity   of   the   natural   forest,   and   the   abundance   of   food,   probably   increased   by   humans through agriculture. Birds   and   squirrels   were   abundant   in   the   trees,   as   well   as   house   geckos   and   the   Tockay   ( Gekko gecko ), the call of which is easy to recognize.
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Do you see the viper? It shows a subadult female. Move over the image to enlarge! This image was taken in a garden of a farmer's house.
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Locals   reported   that   also   brown-colored   tree   vipers   can   be   found   in   cocoa   plantations.   They   usually can   be   seen   there   only   in   the   morning.   Afterwards,   they   disappear   (probably   into   the   leaf   litter, which   forms   a   thick   layer   under   cocoa   trees).   Based   on   these   reports,   I   guess,   it   is   Trimeresurus borneensis ,   but   this   has   to   be   confirmed.   Additionally,   I   observed   a   large   specimen   of   Trimeresurus hageni (now Parias hageni ).
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Above: Three  adult females from the 'valley of temple pit vipers'. All animals were photographed under daylight conditions.
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All    adult    females    that    I    saw    were    gravid,    at    a    time    (February-April)    that    is    consistent    with observations   in   Thailand   or   Western   Malaysia.   The   juvenile   male   seen   below   was   captured   mid   of April, thus, it was probaly born recently.
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Juvenile male, about 20 cm long. Note the basically blue coloration of the scales.
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Adult, entirely green male. This snake was collected from a sugar palm tree, several meters above the ground.
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Two   vipers   (adult   male   and   subadult   female),   which   were   observed   in   the   trees   high   above   the ground,   were   in   an   ambush   position   with   the   head   and   forebody   pointing   upwards   (see   image below).   This   was   probably   because   they   were   waiting   for   birds   or   squirrels   to   pass   by.   In   contrast,   on occasions   when   I   saw   these   vipers   on   plants   a   few   centimeter   above   the   forest   floor,   they   usually rested   their   body   on   a   twig   or   leaf   with   the   tail   upwards   and   the   head   pointing   downwards   (see   male viper   in   Sarawak   section).   Of   course,   this   all   makes   perfectly   sense,   yet,   I   had   not   seen   the   ambush position   in   trees   so   clearly   before.   It   also   appeared   to   me   that   they   preferred   broad-leafed   trees,   but this based on very few observations.
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Subadult female, in transition to adulthood, resting in a tree about four meters above the ground, waiting in ambush for prey.
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It   is   the   combination   of   smallholder   agriculture   in   relative   harmony   with   nature   that   makes   this place   special.   The   forests   in   this   valley   are   protected,   mainly   because   they   are   part   of   a   watershed area that provides  water so vital for the constantly growing city of Medan. It   is   also   encouraging   that   local   farmers   try   to   adopt   environmentally   friendly   ways   of   agriculture   by practising   organic   farming   for   instance   (it   was   my   professional   interest   in   agriculture   that   brought me   here   in   the   first   place).   In   view   of   that,   I   hope   that   they   will   succeed   to   preserve   this   beautiful spot, and with it all the Wagler’s vipers and other magnificent wildlife living here.
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Special Feature 2006:
A trip to a temple pit viper population in the vicinity of Medan, North Sumatra
© 2004-2018 Thomas Jäkel
Ophiotropics.com
© 2004-2018 Thomas Jäkel
.
.
Medan   ,   the   provincial   capital   of   Northern   Sumatra,   is   a   bustling   city of   over   2   million   inhabitants   and   a   booming   commercial   centre   for   the region's    huge    oil    and    agribusiness.    Oil    palm    plantations,    rubber, cocoa,   rice   and   other   crops   dominate   the   landscape.   There   is   little natural   forest   left,   and   the   area   around   the   famous   lake   Toba   has been denuded by paper factories.
Given   these   circumstances,   I   was   not   expecting   any   exciting   location   to observe   Wagler's   vipers   in   the   wild.   However,   fortunately,   my   view proved   to   be   completely   wrong.   Thanks   to   local   friends   and   farmers   I was   able   to   witness   one   of   the   most   dense   populations   of   T.   wagleri    I have   ever   seen.   I   will   not   mention   the   exact   location   here.   However, similar    habitats    are    still    abundant    in    the    vicinity    of    Medan,    in particular,    in    the    forests    that    form    the    edge    of    the    Karo    plateau southwest of the city. I   had   already   spent   numerous   frustrating   hours   of   roaming   around   in potential   habitats,   e.g.   in   Sibolangit   Botanical   Garden,   around   Lake Toba,   and   even   in   Gunung   Leuser   National   Park.   The   forests   around Berastagi   are   also   beautiful,   but   probably   too   high   above   sea   level, over 1000 m, to host temple pit vipers. As   it   often   comes   with   Wagler’s   viper   in   the   wild   (see   my   notes   on Templer   Park),   you   have   to   look   in   the   backyard   of   a   house,   or   a parking    area    of    a    highway    bordering    forest    to    observe    them.    I exaggerate, but there is some truth in it. The   location   I   would   like   to   show   you   here   is   a   river   valley   that   is   used by   smallholder   farmers   to   grow   cocoa,   rice   and   various   fruits   of   the region,   like   guava,   pineapple,   sugar   palm   etc.   The   slopes   of   the   valley show    dense    primary    and    secondary    growth    lowland    jungle.    The climate    is    extremely    moist,    as    indicated    by    abundant    mosses    and lichens   on   trees   and   on   the   ground.   Because   T.   wagleri   is   so   abundant in   this   place,   I   think   the   name   'valley   of   the   temple   pit   viper'   would   be a suitable one.
.
.
Although    the    habitat    on    the    right looked    really    inviting    to    check    for Waglers,   I   did   not   have   to   venture too   far   from   the   road   as   the   animals flocked    the    cocoa    plantations    and gardens   of   the   local   farmers.   In   fact, this   snake   is   so   abundant   here   that farmers   observe   it   on   a   daily   basis. And they often kill it.
.
Farmers' houses are surrounded by numerous trees, often fruit trees. The tree seen in the foreground was inhabitated  by temple pit vipers.
.
In   a   period   of   a   five   days,   I   observed   eight   vipers,   and   many   more were   reported   by   locals.   Unfortunately,   the   snakes   had   disappeared once   I   arrived   at   those   reported   locations.   Because   it   was   raining heavily   every   day   (in   the   late   afternoon)   during   this   trip   in   April   2006, the   snakes   changed   positions   frequently.   Farmers   told   me   that   they may stay at the same place for many weeks. So   why   is   T.   wagleri   so   abundant   here?   Well,   for   sure   it   is   the   high humidity   found   in   this   place,   the   close   vicinity   of   the   natural   forest, and   the   abundance   of   food,   probably   increased   by   humans   through agriculture. Birds   and   squirrels   were   abundant   in   the   trees,   as   well   as   house geckos    and    the    Tockay    ( Gekko    gecko ),    the    call    of    which    is    easy    to recognize.
.
.
Do you see the viper? It shows a subadult female. Move over the image to enlarge! This image was taken in a garden of a farmer's house.
.
Locals   reported   that   also   brown-colored   tree   vipers   can   be   found   in cocoa   plantations.   They   usually   can   be   seen   there   only   in   the   morning. Afterwards,   they   disappear   (probably   into   the   leaf   litter,   which   forms   a thick   layer   under   cocoa   trees).   Based   on   these   reports,   I   guess,   it   is Trimeresurus   borneensis ,   but   this   has   to   be   confirmed.   Additionally,   I observed a large specimen of Trimeresurus hageni (now Parias hageni ).
.
Above: Three  adult females from the 'valley of temple pit vipers'. All animals were photographed under daylight conditions.
.
All    adult    females    that    I    saw    were    gravid,    at    a    time    (February-April)    that    is consistent   with   observations   in   Thailand   or   Western   Malaysia.   The   juvenile   male seen below was captured mid of April, thus, it was probaly born recently.
.
Juvenile male, about 20 cm long. Note the basically blue coloration of the scales.
.
Adult, entirely green male. This snake was collected from a sugar palm tree, several meters above the ground.
.
Two   vipers   (adult   male   and   subadult   female),   which   were   observed   in   the   trees high   above   the   ground,   were   in   an   ambush   position   with   the   head   and   forebody pointing   upwards   (see   image   below).   This   was   probably   because   they   were   waiting for   birds   or   squirrels   to   pass   by.   In   contrast,   on   occasions   when   I   saw   these   vipers on   plants   a   few   centimeter   above   the   forest   floor,   they   usually   rested   their   body   on a   twig   or   leaf   with   the   tail   upwards   and   the   head   pointing   downwards   (see   male viper   in   Sarawak   section).   Of   course,   this   all   makes   perfectly   sense,   yet,   I   had   not seen   the   ambush   position   in   trees   so   clearly   before.   It   also   appeared   to   me   that they preferred broad-leafed trees, but this based on very few observations.
.
Subadult female, in transition to adulthood, resting in a tree about four meters above the ground, waiting in ambush for prey.
.
It    is    the    combination    of    smallholder    agriculture    in    relative    harmony    with nature   that   makes   this   place   special.   The   forests   in   this   valley   are   protected, mainly   because   they   are   part   of   a   watershed   area   that   provides      water   so vital for the constantly growing city of Medan.
.
.
Special Feature 2006:
A trip to a temple pit viper population in the vicinity of Medan, North Sumatra