Kinda hard to say she only has 4. Who know whats out of frame, or in frame that the hen is blocking.
Actually, I know what's out of frame. I mentioned that I cropped the photo and there was plenty of room in the uncropped photos to see more poults, if they were there. And my camera is set to shoot a burst of three photos. None of the three photos showed any more than four chicks, behind her, in front of her, or anywhere. At this age the young instinctively tend to stay right under her to minimize the risks.
It's a reminder that turkey chicks are very vulnerable. Could be a raccoon, possum, skunk, or other predator broke some eggs before they hatched. Could be that snakes swallowed a few eggs. Could be that some of them succumbed to hypothermia from a rainstorm. Could be that a coyote or fox ambushed them and she lost half her brood. Could be that some crows divebombed the brood right after hatching.
We tend to think more turkeys survive than do. That's probably because we see flocks of 20-30 in early fall, but those are usually four, five, or even six mothers with young all traveling together.
Steve.