I always thought it was a bit dangerous to shoot up at an iguana perched on a house rooftop- if you miss you never know where that projectile will land
A lead pellet from an airgun has limited distance which is significantly reduced once maximum velocity has been reached from the barrel. Maximum shots at these lizards on the ground are about 30 or 35 yards.
Any shots at the lizards in the trees or on the roofs that miss their targets will fall to the ground with the mass and weight of a typical hail stone. In other words, ain't nothing going to happen.......