The other situation is if mom has O type blood. The same thing can happen as with the (-) and (+) blood type difference, but it is not as severe. If mom has O+ or O- blood type, and the baby has A+, A-, B+, B-, AB-, or AB- blood type, an ABO incompatibility can develop.
Why do howler monkeys howl? Howler monkeys live in family groups in the rain forests of South America. They howl so that other monkey groups do not stray into their territories. The sound also helps group members stay in contact with each other. Monkeys are communal animals that live in exclusive groups.
Most monkeys are omnivores. Monkeys love eating ripe fruits and seeds but, they also eat vegetables. Beside bark and leaves, they eat honey and flowers also. The howler monkey is known as the loudest land animal. You can hear their loud calls even when you're 3 miles away from them in jungles.