Why should most living pterosaurs be nocturnal? Consider details from sightings in areas where sightings are more common.
When I interviewed natives on Umboi Island, Papua New Guinea, in 2004, the great majority of eyewitnesses had seen only a distant flying light. On the other hand, the dramatic sightings in which details of appearance gave convincing evidence for living pterosaurs there—those sightings were few. That brings up two reasons for nocturnal behavior being probable on Umboi.
The apparent bioluminescence, with extreme brightness, means this flying creature has a major biological committment for night flying. Some of the sightings, albeit few, have shown us that the flying light is indeed the glow from one or more of the pterosaurs or pterosaur-like creatures (separate sightings by Jonathan Ragu and Jonah Jim). In other words, there are not two extraordinary flying objects (a giant flying light and a giant flying pterosaur): There is only one extraordinary flying phenomenon on Umboi, with details observed depending on distant from observer to the ropen. But the point is this: Bioluminescence is useful in the dark.
The Lake Pung sighting, around 1994, by seven “boys” (maybe young teenagers or pre-teens) has allowed us to learn a number of details about the giant ropen. Three of the seven eyewitnesses I interviewed in person, in 2004: Gideon Koro, his brother Wesley, and Mesa Agustin. But aside from details like a long tail, “mouth like a crocodile,” and lack of feathers, we learn something else, something less obvious: Few islanders on Umboi have seen a ropen in daylight. Think about it: With thousands of natives living in many villages scattered across Umboi Island, if a giant flying creature were diurnal, would not many natives have seen it in daylight during their lifetimes? Less than one percent of those natives have ever had a clear view of a ropen in daylight because it rarely comes out in the day.
We might review the two daylight sightings in Georgia a few years ago. The eyewitness saw two apparent pterosaurs flying early in the morning, but after sunrise, the first sighting being very soon after a major storm passed through that part of the United States. It seems likely that the storm had disturbed two nocturnal pterosaurs enough that they made themselves known in daylight, by flying over a highway.
“I can hardly put this book down. It is quite astonishing to read of creatures so large that they can lift a human up into the air or rob a corpse from a new grave. They even glow at night with bioluminescence.. . . This book is so refreshing. Jonathan Whitcomb is to be congratulated for giving us a glimpse of our world denied us by the wildlife ‘experts’ from western countries.”