Sexual Activities for Pleasure in Animal Kingdom
It is a winner takes all system. Only 4% of males of elephant seals manage to have sex in their lifetime, as males fight bloody battles on females, the winner then takes all the harem to enjoy by himself. While losers has no warm nights at all. It is a male dominating society, that feminists will never like to live within. Though it is funny and similar to man's vanity. But we can never consider it a proof on sex-for-sex behavior. It is more likely a way of natural selection common in all primates and other species too.
Yes, female owls practice sex at a price. Surly not money. Yet, the male owl must get his female some food and offer it to here, once she starts eating, this means she accepts his offering, after dinner, the game starts. Nature manifested sacred sex much earlier before pagans do I can say. Still this one too we cannot consider as a support for sexual pleasure concept.
Autoerotica & Homosexuality in Animals
Autoerotism is quite common among male horses and kangaroos. Most amazing is the behavior of female porcupine employing a stick in masturbation. It is also common among lions, bats, and all pirates, employing limbs and tails to induce genital and nipple stimulation. Among all, higher apes are well know to be the most simulating species in their masturbation activities. Autism in this way, is no doubt a proof on pleasure being an objective. Also homosexual behaviors are very common in the animal kingdom, from goats to lions, we do have homosexual practices between same sex males and females. Sometimes also bisexuality is reported in species for long was thought to be exclusively heterosexual
Who Needs Sex to Procreate?
Many species in nature, and upon isolation of its female individuals, will procreate independently, it is a well known story in invertebrates. Yet, recent studies proved it does exist in some species of fish and birds. Wherein the ova autonomously transform into a matured zygote, undergoes the whole steps of embryonic life, to produce a progeny carrying 100% of his mother's chromosomes and gene map.
So, if God wanted us to have sex only to procreate, he had other mechanisms that he could apply to us too. Yet, it was His will we do have such a recreational activity, that will support the ego feeling of humans and accordingly support the development of planet Earth. i.e. Supports man mission as a viceroy on land