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.
Howler monkeys are widely considered to be the loudest land animal. According to Guinness Book of World Records, their vocalizations can be heard clearly for 3 mi (4.8 km). The function of howling is thought to relate to intergroup spacing and territory protection, as well as possibly to mate-guarding.