Multiplicity solution
by Kegler

In eleven answers, creatures are replaced with their appropriate collective nouns.

Multiplicity solution grid

Across
1WE + L + KIN [GANG for ELK]
6NIHIL ("NIGH HILL" hom)
10MIND (hidden)
13P + REP
15OFFER (2 defs)
16WOLF + RAM (rev) [PACK for WOLF]
17L + AMEN + TED
18P + AN(TYRA + I)D [COLONY for ANT]
20DAD + O
23CA(R)PS
25D + EKED
27HYRDA (HARDY anag)
28E + SAU (USA anag)
29E + S + CROWd [MURDER for CROW]
30EDDA (hidden)
32OAFISHLY (AS IF HOLY anag) [SCHOOL for FISH]
34ENDEAR (EARNED anag)
35OBESE (hidden)
36FR(I + SoB)EES [SWARM for BEE]
Down
2GIF + T (rev)
3AND + OVER [FLOCK for DOVE]
4GERMans
5IMP + END
7shIRKER
8CO(WA)RDS [HERD for COW]
9LI(M)ED
10MOTORCADE (DOCTOR MAE anag) [POD for ORCA]
11DEAL (LEAD anag)
12M + ANY
14PA + VILION [PRIDE for LION]
19PlEASANT
20DE(D)UCE + R
21A + DA + R
22OSSEOUS (USE SO-SO anag)
23CHAR (2 defs)
24S(cAVe)AGES
26CLA(M)ORS (CAROL'S anag) [BED for CLAM]
30E + LBA (LAB anag)
31DYER ("DIRE" hom)
32pOsEuR
33LOW (2 defs)