Yeah, they talk big . . .

Some Real Howlers!

Wikipedia

. . . but can they back it up, or are they just a little nutty:

The howler monkeys whose guttural calls reverberate through Central and South American rainforests possess a secret that the males of the species may prefer to be left unrevealed, . . . [for even though they] make among the loudest, deepest sounds of any land animal, . . . [using] their roars to attract the ladies for mating and [to] intimidate other males, . . . scientists on Thursday said they have discovered a curious paradox: males that make the . . . [deepest] calls[, which are] considered the most alluring to potential mates[,] are endowed with the lowest reproductive potential [and] the littlest testes for sperm production[,] . . . an "evolutionary trade-off" for male howler monkeys between vocal tract and testes size. (Will Dunham, "Howl of a good time: Deep monkey roars come with intimate secret," Reuters, October 23, 2015)

It's all about image, I guess. Or vocaledge . . .