During my recent visit to the park, I took several photos of this falcon, but I found it challenging to identify the species myself. Wanting assistance, I uploaded the photos and sought help from a falconry group on Facebook. The consensus among the members was that it appeared to be a hybrid falcon.
After some time, someone commented the following: "Just talked to friends in the bird park, because I worked there over ten years ago.
It is an Altai Saker…
In Germany black Gyr Sakers are sold as pure Altai Sakers"
So, it seems that the staff at the park identifies it as an Altai Saker falcon (Falco cherrug altaicus?/Falco altaicus?), whereas it appears to actually be a hybrid falcon?