Poitou donkeys (a.k.a. Poitevin donkeys) are not a separate species but an ancient breed of donkey widely used in France and abroad in pre-industrial times to sire mules with mares of the Poitevin horse breed. These mules are famously large, strong and tough and remained in high demand for centuries.
That demand declined after WWII due to increased mechanisation, and for a while it seemed the Poitou breed would die out. They’ve since bounced back. I guess the work done at this preserve, to study the genetics of extinct species and recreate them as well as possible fits pretty well with the ongoing work of studying Poitou donkey and mule genetics.