Is my structure best for survival?

[caters]

I am planning to have a mass migration in 1 of my stories and I thought of a few structures for different areas. Each layer around is different people. I have no idea what would be best for crossing a lake or a deep river. But others, I think I have a pretty good idea of what is best. So here they are:

This is my proposed structure for an open area, basically circles within circles. The pink layer is children and moms with babies. The next layer is pregnant women. After that is most people including any women on their period. Adolescents are old enough to be in this layer. Then there are 2 layers of defenders, a primary one the furthest out and the secondary one closest to the majority of people.

If a female defender is on her period at some point, she will go into the middle layer and a person from that layer will take her place. If someone becomes pregnant, that person will go into the second furthest layer in and if it is a defender, another person will take her place. Children when they are adolescents go from the layer furthest in to the middle layer. If 1 of the defenders dies, another person will take its place. For a primary defender having died, a secondary defender will become a primary defender and a person from the middle layer will fill the gap in the secondary defenders.

Going into a forest

Getting out of a forest

In middle of forest.

Are these structures best in terms of number of survivors in the areas I proposed them for? If not what kind of structure would be best? And what kind of structure would be best for crossing a deep and wide body of water?

 

[CupofJoe]

Here are my thoughts...
What threats are they facing?
If it is just the current when crossing a river then you'd want more of an uneven shape with more of the most able downstream to help catch any people that slip or fall, or maybe a fully integrated group with those most able helping those least able directly.
If you are crossing or passing through an environment you usually want a thinner line of people to reduce the track that has to be checked as clear and passable. The Triangles are wide so there would be a lot of clearing away trees and brush for relatively few people.
If there are predators, enemies, or generally aggressive creatures around, then the structure should reflect the way any attack may come.
I'd also have smaller roving groups further out, they will scout the route, look out for potential threats and generally make the way easier and maybe find food en route.

 

[caters]

Well I have thought of threats they would come across and how different predators would attack. If they are crossing a wide river in an area that is hotter for longer in the year, there are likely to be predators that hunt in a similar way to that of crocodiles, by surprise and doing a death roll to both kill their prey and rip it in chunks. These predators could swim underneath all the people if the water is deep enough and grab someone who is either on their period, pregnant, or young. This I think would be the biggest predatory threat overall.

As for forest predators, some hunt in packs like wolves. Others hunt alone like most big cats. Some jump from trees while others run when they get close. And others still, like bears will attack when they feel threatened but don't really hunt people.

Another threat really anywhere is encountering a creature that is venomous or poisonous. The people in the mass migrations have a built in defense against poison and venom but some creatures inject too much venom or too strong of a venom for that defense to be of any use. Similar thing is true for poison absorption. These have an about equal chance of injecting venom or poisoning any 1 person in the group but children are more likely to be severely affected by it.

And like you said currents are a threat as well, especially in narrower rivers which tend to have faster water flow.

 

[CupofJoe]

Most predators look for easy meals, they are not looking for a fight.
Having a "skirmish" force ahead of the main group to flush out predators may work to scare them away.
You might have to look at how real world threats are dealt with. How do people in the Amazon cope with travel?
Why wade across a river? You could make them build rafts and make rope to pull people across away from the crocodile-like attacks.

 

[pmmg]

This strikes me as very organized for a group during migration. I would think the threat of attack would have to be high and for a long period of time to have forced them to organize such. Not sure that it matters, but having been in the military and moving in large groups, we would move into a forest in multiple V shaped waves and not triangles, and when stopping would have roughly a cigar shape.

I find I am asking the same questions as CoJ, unless the threat of attack from any direction is ever present, I don't think such organization is required. In an attack, it really does not take long for the defenders to move through a camp to where the fight is taking place.

If its really a question of have the best formation or survival is at stake, I might argue that breaking up into many small groups increases the chance that some will get by unnoticed, and reduces the chance that all will be killed in a single confrontation. But yes, hard to beat the circle for a defendable position from all sides. If you are going to have women defenders, I am not sure what some of them having their periods have to do with it. That sounds like something from Jewish law about when one can enter a temple. I suppose it might suck more to be on one's period and having to engage in battle, but then being on one's period in general sucks for a lot of activities and people get through it. Why does this even come up?

 

[skip.knox]

I don't know of any historical groups who moved in any of the formations presented. I'm not saying those are wrong or unworkable, only that I can't think of any real-world analogues. The most obvious mitigating factor is pitching camp. These tight formations require everyone to move at the same pace, whereas real-world examples show a variety of groups. There are scouts out front to find a proper place to camp (water; defensible position). There are engineers who prepare the site. There is a van and flanking bodies, armed and mobile. Between them go the people on foot and/or civilians. Wagons normally bring up the rear because putting them into the center creates all sorts of logistical problems. Also, if it's any sort of large body at all, whether military or a civilian migration, there will be herds of animals. There is also the matter of the sick and injured--far more significant an impediment that women, regardless of their condition with children. In all the examples I can think of, there is no special provision that has to be made for the women, save only that they generally do not form combat units. But they keep up just fine.