Like all special Infected, a Howler developed from a Viral whose transformation into a Volatile was derailed by a sudden dose of chemicals. As these chemicals attacked the victim’s larynx and lungs, Howlers were created. It’s because of them that the streets of The City are so dangerous. They won’t attack outright, but if one of them spots a human, the toxic substance in their chest will begin to boil, forcing them to emit an unearthly scream that will call other monsters from the surrounding area. A pulsating yellow growth on the Howler’s torso will let you tell it apart from Volatiles and Virals.
It is possible to interrupt a Howler's attempt to call other infected by repeatedly and swiftly attacking. Attacking from above is recommended, as it gives a better chance of defeating the Howler before it has the opportunity to howl. Upon howling, Aiden will be chased by a few Virals, as a level one chase will be applied to him. If howling inside buildings, they will wake up all sleeping infected and alert Virals by making continuous noise.
In appearance, Howlers seem to be an in-between of a Viral and Volatile, boasting the unique jaw of a Volatile and it's pale skin. Despite these physical similarities, Howlers aren't similar at all to either types of infected - just as Bombers aren't similar to Toads, and Goons aren't similar to Demolishers.