Why do bats fly at dawn?

 Why do bats fly at dawn? 

Bats, ounce for ounce are the longest lived of all mammals. A two year old mouse is already a geriatric whereas it takes ten years for a tiny Pipistrel to start to conk out with age and outrageously, it takes 40 years for a 7 gramme Brand's bat to do the same.

We have a good idea why bats live so long; it's the same reason as do pidgeons and parrots ... they have very good mitochondria. In both (very diverse) genera the mitochondria are smaller, more prolific, energy efficient and produce fewer damaging free radicals than do their counterparts in mice and indeed humans.

In recent time mitochondrial well-being has become the focus of a multitude of anti-aging strategies and increasingly photo-therapy using near infra-red radiation (NIR) has gained in popularity.

This is because NIR can penetrate through the skin ( and clothes or fur) and stimulate mitochondrial proliferation. The mechanism is proposed to involve cytochrome c oxidise acting as the NIR photo-receptor  absorbing it at around 800-850nm and from there a path of retrograde signalling informs the cell about what to do for the best.

In effect, new mitochondria potentially 'rejuvenate' an old cell which will have a significant population of damaged mitochondria. As a result of this knowledge and availability of cheap LEDs there is a good, even an over-supply, of NIR lamps for sale for personal as well as professional use.

If NIR, is truly beneficial to mitochondria ( as seems it is)  then the source of NIR and the mechanism of action must be rather more ancient than NIR LED lamps! Fortunately 54% of incident light on the earth is NIR ( 34% is our 'visible' light th erest UV). This gives animals every chance to soak NIR up. 

The whole NIR is good for you edifice however looked like falling becasue our long-lived super mitochobdrial bats are, as everyone knows, nocturnal. Worse, they like dark caves and belfries during the day.

A quick bit of on-line research turned up two facts One I should have known, the other was new to me. The latter is that the most ( by far) NIR during the day occurs at dawn. The former is that bats swarm or just fly about a lot at dawn. 

Phew!