The BBC is a notoriously liberal biased organisation and even they say it is only humans and domesticated sheep.
BBC - Earth - Are there any homosexual animals?
It would make sense if this were true since it means that a behaviour which would appear to have no evolutionary rationale indeed probably does not have one.
Your speculation about population control is wrong since evolutionary 101 theory recognises that (other than social insects, where the colony is the organism, rather than the individual creature) individuals do not generally behave in ways that 'benefit' groups or the environment at the expense of their own DNA. Genes and DNA are not worried about over-population. They are only worried about reproducing themselves. Over-population is not in evolution's dictionary.
Our resident Einstein Chassamui was coming out with this nonsense a couple of weeks ago on the aboriginal thread but trying argue with him is like trying wrestle with a bowl of jelly so I let it slide