From The Urban Dead Wiki
Bellow is a zombie skill which allows the player to notify zombies within a 10 block radius of the presence of 25 or more survivors at that location. Bellow is a child skill of Feeding Groan, and is a narrower varient of its parent skill. Like all zombie skills, Feeding Groan costs players of all character clases 100 Experience Points (XP) to purchase.
If a zombie with Bellow is at a location with 25 or more survivors present, they will have the option to in addition to the standard option. Bellowing, as expected, costs 10 Action Points (AP) at a time, and will return the message You bellow threateningly, your call echoing around the room.
Any zombies within a 10 block radius of this—with examples of the range being shown here and here—will receive the message You heard a loud bellowing X blocks to the east and Y blocks to the north—note that the bolded text is present in-game to draw attention to the notice being a bellow and not a groan. Like groans, bellows can be heard by characters who are currently dead bodies.
Bellowing is affected by the same "muffled" tag as Feeding Groan—any bellows made from behind barricades will give the message You heard a loud but muffled bellowing instead of the usual message. Interesting to note is that bellows from a barricaded building heard by zombies also inside that building will still display as a loud but muffled bellowing from inside the building.
In addition, as for Feeding Groan, if you are a member of the same group as the zombie who bellowed, the bellow will additionally be described as "familiar". You heard a loud and familiar bellowing from somewhere nearby.
When bellowing, if the number of survivors drops below 25 before the bellow is made, the end result will be that a maximum strength Feeding Groan is made instead, with the message recieved being You aren't enraged enough to bellow at this group. You graagh threateningly, your call echoing around the room (or "echoing through the empty streets" if outside).
Bellow appears to have come from the suggestion system, being very close to Suggestion:20090319 Bellow.
Bellows are heard by others as:
- You heard a loud bellowing X blocks to the <direction> (standard bellow, without barricades in the way)
- You heard a loud but muffled bellowing X blocks to the <direction> (standard bellow, with barricades in the way)
- You heard a loud bellowing from very close by (bellow from your location, without barricades in the way)
- You heard a loud but muffled bellowing from inside the building (bellow from your location, with barricades in the way)
- Note 1: Dumbwit of St. George's Hospital, Greentown
- Note 2: Dumbwit of a warehouse, Pegton
- Note 3: Dumbwit of The Usher Building, Heytown