Here are the answers.
ACROSS
1 Photo specialist from Ohio (he likes a vignette) (8) MOEBELLE
3 Mobula or Satanoperca? (9) DEVILFISH
6 see 10 Across
8 see 15 Across
10 & 6 Across Related to the elephant (6,3) DASSIE RAT
12 & 21 Across Tall bird (5,5) SARUS CRANE
13 & 18 Across Song and dance ape (5,6) FUNKY GIBBON
15 & 8 Across South African speedster (5,7) KAROO CHEETAH
16 & 7 Down Dark diver (5,6) BLACK DUIKER
18 see 13 Across
19 He knows more than he can tell (3,7) ZOOGIRAFFE
21 see 12 Across
25 Island hopper (3) HIX
26 & 40 Down Dry country guide (7,6) ARIZONA DOCENT
28 Named after a parasite (8) LINTWORM
29 Well travelled photographer (5) TOMEK
31 The animal's head gardener (3,5,3) ZOOPLANTMAN
33 see 30 Down
35 More Experiences than Jimi Hendrix (6) MIGDOG
37 Summer plumage for 43 Down (6) SHORTS
39 see 14 Down
40 see 42 Down
41 L'homme au Camellia sinensis (1,1,1) TLD
45 A useful card (3) SIM
46 & 17 Down Soldier bird (5,8) VOGELCOMMANDO
47 Cool 'cat' or hot drink? (5) TODDY
49 Funny toes (10) ZYGODACTYL
51 & 4 Down Scarily rare (5,5) JAVAN RHINO
52 In the heart of Africa (5) ITURI
53 Fairy blue? (1,1,4) FBBIRD
54 Mr M's first location (10,3) SHAVINGTON ZOO
DOWN
2 CA lady (5) BETSY
3 & 44 Down Oriental image maker (4,6) DEER FOREST
4 see 51 Across
5 ZSL bear cub (7) PIPALUK
7 see 16 Across
9 & 32 Down Striped survivor? (9,5) THYLACINE ALIVE
11 see 33 Down
14 & 39 Across From the shore of Lake Michigan (9,3) MILWAUKEE MAN
17 see 46 Across
20 In memory of a mother orang (5) GIGIT
22 Tiny lad (7) NANOBOY
23 A flying kiwi? (10) CHLIDONIAS
24 see 42 Down
27 His zoo? (6) ZOOISH
30 & 33 Across Might support Holland or Blackpool (6,6) ORANGE PERSON
31 Almost maize (3) ZIA
32 see 9 Down
33 & 11 Down The champion the 'old school' (7,6) PARROTS ANDREW
34 Short Midlander (4) BRUM
36 & 24 Down Mr Aston Martin? (5,5) DAVID BROWN
38 Rather wet and boggy (6) SWAMPY
40 see 26 Across
42 & 40 Across Coo! Found from Africa to India! He-he! (8,4) LAUGHING DOVE
43 Drummer man? (5,3) BONGOROB
44 see 3 Down
48 Sounds like a boat, to some people (5) BATTO
50 What a big pigeon! (5) GOURA
I hope no-one is too frustrated by seeing these answers. I was pleased that so many people had a go. I will post a pdf version in the Resources area as well.