What is not covered is the possibility that ropen-like animals cause the lights through a bioluminescence that may not yet be known to modern science.

Nevertheless, I agree with Bunnell regarding many of the mysterious lights near Marfa, Texas: They are not glowing barn owls. But the point is this: Many Marfa Lights show intelligence in their movements, and this is consistent with a living bioluminescent flying creature. This seems to be something Bunnell tries to avoid.

Bunnell makes it clear that owls are common around Marfa. This brings up another possibility: the large bioluminescent predators flying around there may be hunting more than bats: They may also be hunting owls. After all, they only fly around this area a few times each year: just long enough to catch those bats, owls, and other wildlife that are easy pickings. The large predators then fly off to another part of southwest Texas or Mexico; large predators are known to travel.

I’ve not yet made any firm conclusion that Marfa Lights (some of them) are made by ropens, large Rhamphorhynchoid pterosaurs. But many things appear to add up for that hypothesis.

Although there is limited data on what time of year sightings are made, it seems that they are a little less common during winter (supporting this posting). I have found one sighting in which mysterious lights behaved in what could be called a dance-like manner in the winter (which does not support the posting ideas so well).

The intelligent or apparently intelligent movements of some of the lights strongly support the posting hypothesis about ropen-like creatures creating the lights. One light followed a car on a highway; when the car slowed down, so did the light; when the car stopped, so did the light; when the car turned around to approach the light, it went out. [Later, I read about the possibility that this was a mirage; nevertheless, this book mentions other sightings consistent with intelligently directed movements of the lights.]