How would a Reflecting-Oven-Jay Evolve?

Question

This answer to my question about light-as-a-weapon came up with an interesting concept:

The Reflecting-Oven-Jay

This is a small African predatory bird with a perfectly smooth set of wings with an area of ~100 cm², so maybe the size of a pigeon. It hunts in large flocks, around 10,000 birds to a group (there are plenty of real birds that form flocks this size).

Using some basic multiplication, this flock can focus about 130 kW of sunlight. The flock decides to kill and eat an elephant, who has a metabolism of around 3000 Watts and already has to work to keep cool on a warm day (heat sink ears, spraying water on itself, etc). By spreading out and focusing sunlight on the elephant, the birds totally overwhelm the elephant's ability to cool itself, raising its body temperature by about a degree Celsius every 2 minutes (130 kW / 4 tons*specific heat of water), leading to slow heatstroke and death. Divided evenly, there's a lb of meat for every bird in the flock, a huge windfall, sustaining the group though any cloudy days until the next kill.

I thought this was an intriguing idea as it nicely used light as a weapon in a novel and unexpected (and frankly terrifying) way. Imagine having a flock of these things decide you are their next lunch and start the slow cooking process...

The problem though is that while the end result is at least plausible, the evolutionary path is not obvious. How could a bird manage to evolve and become the Reflecting Oven Jay from a relatively normal starting point?

Answer 1

A baby male African jay bird hatches from its egg. In addition to its colorful feathers, one of its tail feathers has a reflective quality. It could be because this family of birds has had a diet with more aluminum in it than normal, and has adapted to it. Regardless of mutation that caused this reflective pigment to appear, some feathers on this new bird do not absorb any light.

Now, this doesn't make the bird live any longer, or get any stonger, in itself. But let me tell you - he is a hit with the ladies. They see the little glimmer coming from the end of this bird, and they all want some tail (pun intended). This little bird has quite an impressive progeny.

Eventually, because of the popularity of the reflective tails, this trait is more likely to be passed on to future generations. And what is more, the reflection itself becomes more and more pronounced.

One day, while hunting, a certain jay learns that he can reflect light off a feather to temporarily stun a very hard to catch, yet singularly tasty little bug. In turn, this jay becomes just a bit stronger, and lives just a bit longer. While teaching his offspring to hunt, he shows them the trick he learned.

This hunting trick soon spreads through the flock. Later, on another hunting expedition, a few birds are practicing the stun trick. They found, however, that when they all focused their feathers on the bug at the same time, they actually killed it, cooking it through. Disappointed (who wants to eat a dead bug?), they try it again on another bug nearby, which in this case, is actually quite larger than the bug they usually stun and eat. A single bird would never be able to do much harm to it, but they found that when they worked together, they were able to stun it and eat it.

This group of cooperating jays soon became the strongest around. As they taught more and more jays, including their offspring, they were able to take down larger and larger prey.

Answer 2

Like any evolution really, the reflective properties of the features show up faintly in a few specimen, maybe even more than a single race. But our particular race had more advanced 'societal' ties.

Credit to Seth : A baby male African jay bird hatches from its egg. In addition to its colorful feathers, one of its tail feathers has a reflective quality. It could be because this family of birds has had a diet with more aluminum in it than normal, and has adapted to it. Regardless of mutation that caused this reflective pigment to appear, some feathers on this new bird do not absorb any light.

Now, this doesn't make the bird live any longer, or get any stonger, in itself. But let me tell you - he is a hit with the ladies. They see the little glimmer coming from the end of this bird, and they all want some tail (pun intended). This little bird has quite an impressive progeny.

The trait is now more pronounced in the bird population, and the reflective qualities of their features starts changing their feeding habits. For one, they have to be more careful feeding off normal seeds and flora as predators spot them easily by the sunlight they reflect. This however becomes a pro rather than a con as some of the birds discover they can blind predators to quickly escape their grasp. They take the habit of always feeding in groups, certain birds ready to blind predators while others feed. The change from individual feeding to group feeding however has impacts. For one, food becomes harder to come by. This forces them to modify their food source becoming more heavily omnivorous forcing them to feed in places where they are in even more danger of being hunted. Group size increases again. With so many birds now acting as 'blinders' they start sometimes killing smaller persistent predators (through the method described by OP). The now omnivorous bird sees this as a potentially infinite new food source and again they change their feeding behavior.

Final result is the scenario described by the OP where they no longer bait predators but simply are predators.

Answer 3

Envision a pigeon-sized scavenging bird that summers in Europe and spends winters in Africa. During migrations, it travels in large flocks, and disperses at either end to look for gross dead things. Also during the migrations, other birds want to snack on them, and so when one jay gets dazzlingly shiny wings it survives the migrations slightly better just by being confusing to look at.

As this mutation spreads in one flock, that flock becomes incredibly frustrating to hunt. Simultaneously, the birds begin to consciously direct their dazzle during migrations and use it to drive off other scavengers when not migrating. It begins to be effective to stay together to scavenge, because being near these flocks is unpleasant at best and increasingly dangerous, at least to eyesight. Eventually the flocks become coordinated, at which point their victims are not merely blinded.