Protecting the Midget Faded Rattlesnake

Historically, the Midget Faded Rattlesnake was known to be a
rare species across their range which includes Utah, Colorado, and Wyoming (see
range map for the Midget Faded Rattlesnake). More recent studies indicate that while they may not be particularly
rare, they do exist at lower population densities and seem to be more vulnerable
to disturbances associated with land use and development especially since their
geographic range is rich in fossil fuels, wind energy, and recreational use.
What makes them so vulnerable are their fundamental differences in habitat use
compared to other rattlesnakes due largely to their habitat specialization. Midget
Faded Rattlesnakes would best be described as a high elevation, canyon species.
As a high elevation species, the climate is more extreme with short activity
periods and long, cold winters. For the midget faded rattlesnake, this means
less time to grow, less time to find food and mates, and less habitat suitable
for hibernation (cracks deep enough to stay below the frost line for 6-8
months).

The Wyoming Game and Fish Department and the Wyoming
regional Bureau of Land Management have had a special interest in the
conservation of Midget Faded Rattlesnakes since the mid-1990s when one of their
concerned biologists questioned the sustainability of a collection permit
application asking for 200 gravid females. Since then, both the Wyoming Game
and Fish Department and BLM have taken the initiative to determine their
population status, to ensure their protection against such collection as well
as protection from the deleterious effects of energy development and
recreation. The species is now permanently protected from collection across
their range in all three states.

In 2009, the Orianne Society began its conservation efforts in
Wyoming for the Midget Faded Rattlesnake with the Wyoming Game and Fish
Department in partnership with Idaho State University, Clayton State University
(Morrow, GA), and the University of Idaho. The goals of this study were to
develop predictive models that could accurately predict the presence of Midget
Faded Rattlesnakes and their denning habitat, as well as use landscape genetics
modeling to better understand their population dynamics and status. We are
pleased to announce the completion of our models last year that will serve as a
powerful tool for conservation and management decisions in Wyoming. The final predictive
model proved to be 85% accurate in predicting the presence of Midget Faded Rattlesnake
denning habitat so that managers can better evaluate land use and development
that could have negative impacts on their populations. Also, the landscape
genetics revealed just how susceptible they are to disturbance in general and
that roads are likely the greatest threat (including small dirt roads that
service energy development facilities). Our next goal was to secure funding to
extend our models down into the Colorado portion of their range. Their range
includes much of the western slope of the Rocky Mountains in CO. Regional BLM
offices in that area teamed up and came forward with their interest and funding
for a 2-year study that will allow us to realize this goal.

The Wyoming models were generated with copious amounts of habitat
use data collected across the range of Midget Faded Rattlesnakes in Wyoming.
There are elevational and latitudinal differences in the CO range that could
mean variation in habitat and habitat use but the Wyoming data will serve as a
good starting point to develop preliminary models based on the similarities in
CO since there have been no formal studies of the species in this part of their
range. Any differences in habitat use, landscape and climate can be accomodated
in the model with the data we will collect in CO over the next 2 years. We will
begin preliminary model development as we did in Wyoming, but applying the
Wyoming habitat use data to the CO range. These preliminary models will provide
us with random points across the CO range with a spectrum of probability scores
that we will then validate in the field. The probability scores represent how
likely it will be that Midget Faded Rattlesnakes are present at the random
points and then we will report back to the model whether we found snakes or
not. We generate the models using GIS layers that represent those features of
the habitat and climate most correlated to the presence of Midget Faded Rattlesnakes.
In all, we will be developing 4 candidate models based on these variables and
so that we can test them all at the same time, we will use these 4 models to create
a single ensemble model with 5 categories. Those 5 categories are based on how
many of the 4 models predict the presence of Midget Faded Rattlesnakes between
0-5 (0 meaning that none of the 4 models predicted presence and 5 meaning that
all 4 models predicted presence). Also, we will be focusing on denning habitat
since this is the most critical habitat for a population.

One of the challenges in this study is the fact that the
range of Midget Faded Rattlesnakes in CO is an order of magnitude greater than
that in Wyoming (see range map for the Midget Faded Rattlesnake). This means much more land to cover, more man
hours, and a longer period for data collection (but who can complain when that
translates to a lot of hiking in the beautiful Rocky Mountains of Colorado all
the while looking for my favorite little rattlesnake!). As a result, we plan to
collect an order of magnitude more data compared to the data we collected for the
Wyoming models. This will ensure that the predictive power of the CO model
rivals that of our Wyoming models. This study will focus entirely on the
development of predictive models so that managers can have a powerful tool to
help protect Midget Faded Rattlesnakes against increasing energy and land
development as in Wyoming. As long as we will be encountering Midget Faded
Rattlesnakes, we will obtain permits to collect morphometric data, and blood or
other non-invasive tissues for genetic analysis at a later time.

We will also be collaborating with Dr. Stephen Mackessey of
the University of Northern Colorado in a venom study. Dr. Mackessey studies the
composition of snake venoms for a variety of reasons from the ecological to its
application in cancer research. Like most of us, Dr. Mackessey has a fondness
for Midget Faded Rattlesnakes and jumps at any opportunity to see them in the
field and extract their venom. We will be using some of their venom for a
population level analysis to determine differences in venom composition across
their range. We collected a good sampling of venom across their range in
Wyoming last year and it will be nice to do the same in CO for a more
comprehensive study.

Our future goals of course will be to extend our predictive models
into the greatest part of the Midget Faded Rattlesnake range, Utah. Over the
next 2 years we will be seeking interest and partners there to complete our
modeling of the entire range of the species! All 3 states are receiving
increasing interest in energy development and our models will help them
minimize any direct and/or indirect threats to Midget Faded Rattlesnake
populations.