Ask A Scientist Zoology Archive

name         Christopher H.
status       other
age          30s

Question -   I have seen a number of snakes in the Waterfall Glen
forest preserve surrounding Argonne National Lab.  I have observed
big(maybe 36") ones in the area immediately below the waterfall and have
seen dozens of smaller snakes across the crushed limestone path west of
the airplane flying field in between the wetland area.  My neighbor
believes that they are Water Moccasins, but this seems to be too far
north from my reading.  We use this preserve often for biking, hiking and
dog walking.
Can someone tell me what kind of snakes they are and if they are poisonous?
----------------------------------------
There are a number of snake species in DuPage county and only one is
venomous, well, not really of any concern. The Massasauga is endangered in
Illinois and may still be found in DuPage County, but is not life
threatening to humans.  I have seen them in wet areas not too far from
Waterfall Glen.  However, the population I saw parished with the
construction of Interstate 355.  What a shame!  Obviously we can not tell
the species you have seen because you have not given any descriptions.
Massasauga is mottled with light and dark brown patches and grows no more
than a meter in length.   Garter snakes are very common in the Glen and many
are very dark.  Garter snakes may approach a meter in length as well.

NO! Water Moccasins (more commonly known as Cottonmouths in many areas) are far, 
far away.
   
Well, I have no clue to what you observed.

Steve Sample
==============================================================
Naturalists usually will not use the name "water moccasin" since it may be
used for different species of snakes in different places - that's why we use
scientific names. In Illinois and much of the US "water moccasin" most
likely refers to the cottonmouth (Agkistrodon piscivorus), a southern
poisonous snake that only ranges into extreme southern Illinois. I am not
familiar with Waterfall Glen, but most snakes in northeastern Illinois that
get called moccasin, are northern water snakes (Natrix sipedon), which are
not poisonous but do sometimes act aggressively.

J. Elliott
==============================================================