There are said to be at least least 1,500 free-roaming deer in Nara Park, Nara, Japan. Taking up residency near Todaiji Temple, home of world's largest bronze Buddha statue and a UNESCO World Heritage Site, the deer often back up the talk of them being messengers of Shinto deities with stunning photogenic abilities.

They've also become a combination of mascot, symbol, and ambassador for Nara, often begging tourists for special deer crackers and wandering about so much they end up using busy crosswalks with commendable etiquette.

As popular as they are in the area, however, not all their behavior is totally understood. The Nara National Museum recently shared a photo of a gathering of deer that seems to only take place during hot summer days--which Japan is seeing plenty of currently--that they call a "deer pool" that has many online quite perplexed.

"We would like to take to take some time to explain to those who may not know the phenomenon of the "deer pool" that has appeared several times here. It's a phenomenon that occurs on hot summer days, when a large number of deer gather on the north side of the museum in the evening, and when the sun goes down, they return to Kasuga Taisha Shrine. The reason is completely unknown. Students, how about making this the theme of your summer independent studies?"

Of course, the simplest and most likely answer is that the deer recognize the spot as the coolest in the area, and gather there unmoving so as not to lose physical strength while they cool down as much as possible. However as the museum states, the behavior is not totally understood, and immediate return to the shrine has some puzzled as well. Others in the comments were wondering how much the deer could be really cooling down when bundled up in such large numbers as well: