pop_cap
bug report with lot of things:
http://www.bay12games.com/dwarves/mantisbt/view.php?id=2922basically, some points to think of FIRST
1: it's not a hard cap
2: it is periodically checked, not continuously
3: the periodical check can be cancelled, resulting in no status change
1 and 2:
you get 3 migrant waves a year and after that, someone (caravan+liaison) comes to check if there is still space, after which you either get 3 more waves or nothing. If you have 48 dwarves, the cap is at 50, they won't send 2 dwarves, they send 3 waves of many dwarves, dependent in part on your wealth
3: if for some reason the caravan gets destroyed (even partly), or the liaison (possibly) bites the dust, their report isn't finished and migration continues as before. If you get your king before migration has stopped, it will continue too as you get no liaison anymore (or something like it)
To reiterate, the population cap is not a hard limit on the number of dwarves in your fortress; It is a soft cap on immigration that only is checked when a liaison successfully reports back to your home civ. If a player is as little as 1 dwarf under their population cap when the liaison leaves, they will be eligible for a full year of normal immigration. As such, it is recommended that players set their population cap at 20-30 dwarves below the number of dwarves they actually want in their fort.
There is an open bug where it seems that for some people POPULATION_CAP doesn't work at all.VerifyBug:2922
babies should be getting sustenance as long as their mother is near (not sure though, but I never had trouble with having no water). If they're dieing it is most likely because something happened to seperate them from their mother. The mother being dismembered by goblins counts as seperated. Dwarves don't do adoption, if your mother dies you're on your own and you better grow up to child status fast, or die. Babies otherwise don't drink alcohol, but the "hasn't had a drink forever" thought can be ignored