Data from: Stable isotopes reveal diet shift from pre-extinction to reintroduced Przewalski’s horses

The Przewalski’s horse (Equus ferus przewalskii), the only remaining wild
horse within the equid family, is one of only a handful of species
worldwide that went extinct in the wild, was saved by captive breeding,
and has been successfully returned to the wild. However, concerns remain
that after multiple generations in captivity the ecology of the
Przewalski’s horse and / or the ecological conditions in its former range
have changed in a way compromising the species' long term survival.
We analyzed stable isotope chronologies from tail hair of pre-extinction
and reintroduced Przewalski’s horses from the Dzungarian Gobi and detected
a clear difference in the isotopic dietary composition. The direction of
the dietary shift from being a mixed feeder in winter and a grazer in
summer in the past, to a year-round grazer nowadays, is best explained by
a release from human hunting pressure. A changed, positive societal
attitude towards the species allows reintroduced Przewalski’s horses to
utilize the scarce, grass-dominated pastures of the Gobi alongside local
people and their livestock whereas their historic conspecifics were forced
into less productive habitats dominated by browse.