* Boars (male pigs) do get vocal during mating season. They make a range of grunts, snorts, and squeals as they compete for females. This is more of an aggressive vocalization than a moan.
* Sows (female pigs) also vocalize during estrus (heat). They may make a series of high-pitched squeals or grunts to attract a boar.
* Pigs are social animals. They use a variety of sounds to communicate with each other, including:
* Grunts: Used for a variety of purposes, including greeting, feeding, and expressing contentment.
* Squeals: Used to express excitement, fear, or pain.
* Snorts: Used to express aggression or annoyance.
* Oinks: Used as a general call, often associated with wanting something.
So, while pigs don't exactly "moan" in the way we think of it, they do become more vocal during mating season and use a wide range of sounds to communicate.