List of animals in which homosexuality was observed. Kinda puts a hole through "reproduction is the only natural function of sex," and anything related to that.


Pandora Box
This is a complete list of animals that homosexuality is seen in. Taken from Biological Exuberance: Animal Homosexuality and Natural Diversity by Bruce Bagemihl, Ph.D.

PRIMATES
Bonobo/Pygmy chimpanzee
Common chimpanzee
Gorilla
Orangutan
White-headed gibbon
Siamang
Hanuman langur
Nilgiri langur
Proboscis monkey
Golden monkey
Japanese macaque
Rhesus macaque
Stumptail macaque
Bonnet macaque
Crab-eating macaque
Pig-tailed macaque
Crested black macaque
Savanna baboon
Hamadryas baboon
Gelada baboon
Squirrel monkey
Rufous-naped tamarin
Verreaux's Sifaka
Lesser bushbaby

MARINE MAMMALS
Boto/Amazon River dolphin
Bottlenose dolphin
Spinner dolphin
Orca/Killer whale
Gray whale
Bowhead whale
Right whale
Gray seal
Northorn elephant seal
Harbor seal
Australian sea lion
New Zealand sea lion
Northern fur seal
Walrus
West Indian manatee

HOOFED MAMMALS
White-tailed deer
Black-tailed deer
Elk/Red deer
Swamp deer
Caribou
Moose
Giraffe
Pronghorn
Kob
Waterbuck
Blackbuck
Thomson's gazelle
Grant's gazelle
Bighorn sheep
Thinhorn/Dall's sheep
Asiaticc mouflon
Musk-ox
Mountain goat
American bison
European bison
African buffalo
Moutanin zebra
Plains zebra
Takhi/Przewalski's horse
Warthog
Javelina
Vicuna
African elephant
Asiatic elephant

OTHER MAMMALS
Lion
Cheetah
Red fox
Gray wolf
Bush dog
Grizzly bear
American black bear
Spotted hyena
Eastern gray kangaroo
Red-necked wallaby
Whiptail/Pretty-faced wallaby
Rat kangaroo
Doria's tree kangaroo
Matschie's tree kangaroo
Koala
Fat-tailed dunnart
Northern quoll
American red squirrel
Gray squirrel
Chipmunk
Olympic marmot
Hoary marmot
Dwarf cavy
Yellow-toothed cavy
Aperea/Wild cavy
Long-eared hedgehog
Gray-headed flying fox
Fruit bat
Vampire bat

WATERFOWL & OTHER AQUATIC BIRDS
Grelag goose
Canada goose
Snow goose
Black swan
Mute swan
Mallard duck
Blue-winged teal
Lesser Scaup duck
Australian shelduck
Musk duck
Common murre/guillemot
Laysan albatross
Great cormorant
European shag
Black-crowned night heron
Cattle egret
Little egret
Little blue heron
Gray heron
Purple swamphen
Tasmanian native hen
Dusky moorhen
Hammerhead
Flamingo

SHORE BIRDS
Ruff-breasted sandpiper
Greenshank
Redshank
Black-winged stilt
Black stilt
Oystercatcher
Golden plover
Ring-billed gull
Common gull
Western gull
Kittiwake
Silver gull
Herring gull
Black-headed gull
Laughing gull
Caspian tern
Roseate tern

PERCHING BIRDS
Guianan c**k-ofthe-rock
Calfbird
Swallow-tailed manakin
Blue-backed manakin
Bicolored antbird
Ocellated antbird
Ocher-bellied flycatcher
Tree swallow
Cliff swallow
Bank swallow/Sand martin
Hooded warbler
Chaffinch
Scottish crossbill
Red-backed shrike
Blue tit
Eastern bluebird
Gray-capped social weaver
Sociable weaver
Red bishop bird
Orange bishop bird
House sparrow
Brown-headed cowbird
Wattled starling
Black-billed magpie
Jackdaw
Raven
Raggiana's bird of paradise
Victoria's riflebird
Regent bowerbird
Superb lyrebird

OTHER BIRDS
Ostrich
Emu
Greater rhea
Humboldt penguin
King penguin
Gentoo penguin
Kestrel
Griffon vulture
Sage grouse
Ruffed grouse
Long-tailed hermit hummingbird
Anna's hummingbird
Black-rumped flameback
Acorn woodpecker
Pied kingfisher
Blue-bellied roller
Roseate cockatoo
Peace-faced lovebird
Orange-fronted parakeet

REPTILES AND AMPHIBIANS
Common ameiva
Jamaican giant anole
Green anole
Brown anole
Larehead anole
Checkered whiptail lizard
Desert grassland whiptail lizard
Plateau striped whiptail lizard
Broad-backed skink
Five-lined skink
Red-tailed skink
Inagua curly-tailed lizard
Mourning gecko
Western banded gecko
Fence lizard
Wood turtle
Desert tortoise
Tengger desert toad
Black-spotted frog
Moutain dusky salamander
Garter snake
Water moccasin
Red diamond rattlesnake
Specked rattlesnake
Western rattlesnake

FISH
Blackstripe topminnow
Green swordtail
Southern platyfish
Gluegill sunfish
Guiana leaffish
Least darter
Jewel fish
Mouthbreeding fish
Char
Houting whitefish
Grayling

INSECTS
Clubtail dragonfly
Broadwinged damselfly
Spreadwinged damselfly
Narrow-winged damselfly
Common skimmer dragonfly
Field cricket
Migratory locust
Cockroach
Large milkweed bug
Southern green stink bug
Water strider bug
Bedbug
Green lacewing
Queen butterfly
Monarch butterfly
Checkerspot butterfly
Large white
Glasswing butterfly
Mazarine Blue
Larch bud moth
Grape berry moth
Silkworm moth
Blister beetle
Rove beetle
Stag beetle
Red flour beetle
Alfalfa weevil
Bean weevil
Southern one-year canegrub
Japanese scarab beetle
Souther masked chafter
House fly
Tsetse fly
Stable fly
Blowfly
Long-legged fly
Mediterranean fruit fly
Other fruit fly
Hen flea
Digger bee
Southeastern blueberry bee
Ichneuman wasp
Australian parasitic wasp
Red ant

SPIDERS & OTHER INVERTEBRATES
Hawaiin orb-weaver
Jumping spider
Harvest spider
Box crab
Mite
Acanthocephalan worms
Incirrate octopus

DOMESTICATED ANIMALS
Sheep
Goat
Cattle
Horse
Donkey
Pig
Cat
Dog
Guinea Pig
Rabbit
Rat
Mouse
Hamster
Bengalese Finch
Zebra Finch
Trukey
Chicken
Pigeon
Budgerigar