Leaping lizards and bending boughs: How perch flexibility
affects the way arboreal lizards interact with their habitat
Casey A. Gilman and Duncan J. Irschick
Animals in the wild often navigate
through habitats with highly variable
structural characteristics. For animals that
live in trees, such as many primates,
squirrels, frogs, lizards, and other
arboreal animals, this can mean having to
move back and forth from trunks to small
branches and leaves, which vary not only
in their size, but also their angle, the
amount of space between them, and their
flexibility. While the size of a branch and
whether is it horizontal or vertical (or
somewhere in between) may affect how
quickly an animal is able to move along it,
the flexibility of that branch is also
important, particularly for animals that
depend on jumping to move from place to
place. When an animal jumps from a
flexible perch, if it can stay on the perch
while the perch recoils it can take
advantage of the recoil of the perch and
use that recoil to propel itself, like a
human on a diving board. If the animal
does not stay on the perch during recoil,
the energy the animal has put into the
jump can be lost to the perch itself,
leaving less energy for the jump, and
leaving the perch vibrating. Because
structural flexibility is common and
variable in arboreal habitats, we were
interested in finding out how small
animals, in our case the green anole
lizard, relate to perch flexibility when they
jump and when they are conducting other
aspects of their lizard business.
In a previous lab study we conducted, we
found that green anoles did not stay on the
perch during recoil, and that the more
flexible a jump perch was, the shorter the
A male green anole peeking out from the
other side of a palm petiole
distance the lizards were able to jump. We
wondered, what does this mean for green
anoles in the wild, where they frequently
encounter highly flexible perches? Do they
jump and perch on all types of structures,
regardless of flexibility? We found that these
lizards generally jumped shorter distances
from more flexible perches, and that they
actively avoided using very flexible perches
for jumping, even if they used those same
perches for basking, foraging, or crawling. It
appears that for these lizards, when it comes
to jumping, stiffer perches are the way to
go.