Informal tenancies seem to be state-dependant from what I can find (more concrete in california and florida), though I’d be fascinated to see if this has been legislated or litigated upon more generally. Of course verbal contracts are valid contracts, but that’s the sort of thing that would probably have to be sorted out in court.
In the end as advice for OP, I stand by the opinion that “they can’t kick you out without notice” is not a good idea to base one’s decisions on. You could be kicked out, whether it is legal or not, and the legality of such a no-notice kick out on a verbal and informal contract is certainly not an entirely non-disputed concept in all states.
OP could get kicked out, and maybe they could take their mother to court to try and get that solved eventually, but in the immediate they would end up houseless and in a pretty dire situation.
Honestly (and I see you do recognise this in your comment) but this really seems like a kinda crappy study that I’m surprised made it into plos.
For instance I couldn’t find any evidence of them considering that the dietary choices of the guardian may affect the attitudes of the guardian to vetenarians (and thus the self-reported health of those animals). To take this further, in the scenario that a cat guardian believes their choices make their cat healthier, especially when going against vetinary orthodoxy, the guardian is probably less likely to take the cat to the vet for minor issues. This confounds the analysis of “healthiness” as performed by the authors.
Furthermore any cat that is not an indoor cat is likely also not fed a purely vegan diet (as they do hunt), so they should possibly account for that via a sort of bootstrapped approach. Generally the stats were okay though, and don’t make super strong claims from some pretty weak data. Though GAMs were a pretty odd choice and I’d have preferred some sort of explicit model fit with Bayesian fitting or NLLS.
In the end all of this points to the sort of thing where they should really have been doing perturbational research. I.e. feeding cats different diets in a controlled lab space. This is not the sort of research that lends itself to surveys and that seriously impacts the actual practicality of its findings.
Also as an aside, I really cannot abide anyone who includes a questionably inspirational quote that they said themselves in the fucking French Alps on their own website. That’s just pure wankery. The only people I usually see doing things like that are scientists like Trivers, which is not company one should wish to be in.