I once watched th bull elephant at Chester do his stuff I think I uploaded some old shots of it in the Chester zoo section.
It wasn't official but it was happening!
White Rhinos
Black Rhinos
Indian Elephants
African Elephants
Cape Buffalo
Forest Buffalo
African Lions
Eland
Blackbucks
Lechwe
Axis Deer
Pere Davids Deer (including males rucking and calling females)
Ostrich (what a clumsy sight that is, a miracle anything is fertilised!)
Rhea
Bactrian Camels
American Bison (including males rucking/fighting for dominance which is impressive)
Olive Baboons
Chimps
Mandrills
My Mediterranean Spur-thighed tortoise 'Fred' and my steel toe capped boots ,, bless him, he tries..
The vast majority of the above is from several years back when I had more
zoo 'opening hours time' on my hands and would spend hours on hours watching a particular species at Knowsley Safari which was only a 10 min drive from my old house. Sadly there are fewer animals their now, although diversity has been maintained, unfortunately the Bison have gone now too... I wish they would do something proactive so I have the opportunity to see Amur Tigers mate too in the near future!!
My small list from my small zoo
(sadly, there's only 1 elephant and she can't mate with anything!)
Miniature horses
Egyptian fruit bats
Yellow mongoose
Cougars
Lion-tailed macaques
Squirrel monkeys
Budgies
Goffin cockatoos
Toco toucans
False water cobras
Leopard tortoises
Russian tortoises
African giant land snails
Walking sticks (various)
Giant cockroaches (various)
Migratory locusts
Atlas moths
Houseflies (they're everywhere )
Asian elephant
Mandrill
Dwarf Mongoose (ever since the females were introduced to the male, I swear he's always been attached to one of them)
Southern ground hornbill
Hadada Ibis
Lion
Amur leopard
Cougar
Green Aracari
Mallards
Gerenuk
Speke's gazelle
Humboldt Penguins
River otter
Amur tiger
Meerkat
African painted dog
Caracal
Kea