So sorry for your loss - I know what it is like to loose poults. Don't let any one tell you turkeys are stupid. The reason for putting their heads high in the air and standing erect with tail down during a rain storm is "To make their profile smaller (think about it) having less surface area for the rain to beat on and soak into. Poults do not have the natural oils within their feathers to repel water, this will come with molting, age and new plumage. Poults have down which soaks up water like a sponge. I am betting on being cold and wet causing death from exposure "hypothermia". Turkeys carry very innate traits passed on by generations of this prehistoric bird. Knowing how to stand with their heads pointed high in the air is just one of many innate or natural instincts. I truly hope you find a couple replacements so the other isnt lost calling (peep, peep, peep) all the time.