Interactions:
What eats it
Although critical, the Western Fence Lizard’s placement on
the food chain is by no means dominant. Due to their sunbathing
nature, Sceloporus occidentalis often find themselves
easy prey for their numerous predators: snakes,
birds, shrews,
and California Striped Racers are just a few.
Interestingly enough, some lizards may even fall victim to an
incredible turn of events. Black widow spiders have been known
to snack on young lizards that are small enough to be stuck in
their web (Nafis, 2013). Fortunately, many lizards get
the opportunity to escape their hunters.
Western Fence Lizards do not possess many resources or
tricks to
protect themselves from these predators. One thing they do have
is the advantage of camouflage. Their dark, earthy colors and
coarse, spiny skin gives them a slight opportunity to be
disguised from the eyes of their foe. Sceloporus
occidentalis also hold the power of speed. Their powerful
hind legs contribute to their rapid sprint speed and quick
movements. Lizards also have the ability to hop or jump short
distances and are excellent climbers, which could be deemed
useful at a time of an attack (Buckley et al, 2010).
The most fascinating and beneficial interaction shared with
S. occidentalis is that of the common tick.
Ticks are a
known carrier of
Lyme disease which is very dangerous to humans,
other animals, and forests. Amazingly, when ticks feed on the
Western Fence Lizard, a protein in the lizard’s blood kills the
Lyme disease bacteria, hindering any further opportunity of that
tick to spread the disease. This phenomenon is statistically
proven based on rates of infected human’s with Lyme disease. In
regions where Sceloporus occidentalis is very abundant,
such as California, rates of the disease are drastically lower
than regions without the lizard, like Northeastern United States
(Swei et al, 2011a).
Dr. Ostfeld and fellow researchers performed a study to test if
these statistics hold legitimate truth. Researchers attempted
to remove S. occidentalis from certain areas to see
what effect it would have on tick density, but more important
the abundance of the Lyme disease pathogen. They also rid areas
of deer mice, dusky-footed wood rats and Columbian black-tailed
deer which all possess some sort of host relationship with
infected ticks. It was found that the ticks preferred the
lizards’ blood and often had difficulty locating another host
when the lizards were removed. Therefore, an overall lower
productivity of the tick species was found. Not surprisingly,
this made the hypothesis hard to accept or reject. However, the
scientists in this study-as well as many others across the world-can agree that increasing the amount of lizards in a
given location can reduce the Lyme disease pathogen in ticks
(Swei et al, 2011b).
Although it is difficult for S. occidentalis to avoid their
predators, their interactions with disease pathogens present a
very beneficial symbiosis. Not only can they run, jump, and
hide, but they can also eliminate harmful bacteria.