Lighting for a Hog Island boa

Q&A
| QUESTIONS & ANSWERS
Lighting for a
Hog Island boa
&
I have recently been
researching full spectrum
lighting for use in my
yearling boa’s new
vivarium. I am particularly
interested in the benefits
of exposing him to UVA
and UVB, and the associated health benefits.
This snake is a Hog Island boa from the
Cayos Cochinos, off the northern coast of
Honduras. After browsing some weather
websites, it appears that the UV levels in that
area are fairly high on average, having a rating
of 10 when I looked earlier today, but I am not
sure how this will translate to a percentage
from the bulb. The vivarium is an LX24, so it is
fairly small.
You are quite right that in the summer/hotter
period, so an index of 8-10 is quite normal in this
area. Long periods are averaging around 5-8 and
there is a very gradual climb from much lower
index numbers from dawn until mid-morning and
then back down from the late afternoon until
sunset. There is often a dense cloud formation
over large parts of the land for long periods, and
the snakes themselves originate from a densely
forested location.
Behaviour in the wild
All of these factors could/would limit the snake’s
ultra-violet (UV) exposure in the wild. However,
let’s not forget that through its tetrachromatic
ability to see in the UV part of the spectrum, so
the snake would be able to select the power
gradient that it requires. It could simply climb
the trees or even move up the hills to increase
its height above ground, and so be exposed to a
stronger, more intense pattern of light.
This is especially true with so-called “leaf scatter”
illumination, where columns of light travel
through the trees and bounce off the leaves in a
perpetual downwards movement. These columns
can be almost as powerful as direct sun and if the
snake’s body is positioned in one of these tiny
columns, so an almost full index can be
experienced, albeit over a proportionately very
small area of its skin. Leaf scatter is the life force for
many forest animals and plants that are adapted
to use high quantities of light filtering down in
small areas.
Another factor to consider is the snake’s period
of activity. Hog Island boas are thought to be
highly crepuscular, becoming active after dusk
falls, and they are to be found sleeping in trees
and on rocks during the day. This will not prevent
them from benefitting from daytime UV exposure,
and they may move from one location to another
during the day, when they will be exposed to
sunlight. It is highly likely, taking all these factors
into account, that the average Hog Island boa is
exposed to a typical UV background index of 2-4.
Potential benefits
In terms of benefits, we can see that shed snake
skin is very UVB absorbent. This is another pointer
towards thoughts that they can use the D3 cycle
like all other reptiles and birds, in order to top up
any dietary shortfall.
We know that snakes are tetrachromats, so a
balanced UVA provision would open up a more
naturally coloured world to the snake and allow it
both to thermoregulate and photoregulate
adequately. This ability can even help snakes to
source prey. Rattlesnakes for instance can see the
urine markers left by rodents as they travel up and
down their runs. Some reptiles also use the ability
to see the reported 99 million extra colours to
select the strongest and healthiest mate.
Initial illumination
The vivarium that you have will obviously just be a
very short term home for a hatchling snake as it is
quite small. This therefore limits your lamp choice
considerably.
As the enclosure is just 41cm (16in) high and
61cm (24in) long, I would use a FSU14 natural
sunlight 38in (15in) lamp and reflector. This is a 2%
UVB lamp that is nevertheless valuable in a system
of this size. The reflector will double the usable
energy produced from the lamp by harnessing its
full power and focussing it down onto the basking
area.
Fit the lamp as far into the hot end as possible,
and use the media on the floor and rocks and
branches to allow the snake to get safely within
25cm (10in) of the lamp. Be careful to protect the
snake and lamp from each other, as snakes will
wrap around cooling lamps and can break them.
It is advisable to make a box section over the
lamp with aviary Twiweld. This is 0.64cm (0.25in)
cage wire that will not inhibit UVB emission but
will help to protect the snake from any burns or
other accidental injuries.
A long term solution
We also know that UVB from lamps massively
decreases in power the further from the lamp
that the light has to travel. The height of the
vivarium is a prime consideration when selecting
the “solar re-creation” system that is right for your
snake.
As the snake grows, you will need to increase
the size of the vivarium, and the energy available
from the lamp. With an enclosure that is 61cm
(24in) high, then a D3 6% or Euro-range Forest 5%
will be perfect. The same amount of energy is
available to the snake in all cases, but the extra
height will require more power at source.
As a rule of thumb, use a lamp to light around
a half to two-thirds of the living space. This then
provides enough area to give the snake a decent
fall-off into a more shady location. Remember the
animal is the true expert! Provide heat and light,
cool and shade, and the snake will readily adjust
its position to meet its requirements, by moving
around its quarters.
John Courteney-Smith, Arcadia Reptile Product
Manager.
DECEMBER 2012 | 53