63 Territories and Home Ranges

Key Idea: Territories are defended regions, whereas home ranges are generally larger areas that are not defended. A territory is the area occupied by an animal and defended against intruders. Territories may be large and multi-purpose for feeding, mating, and rearing young, or they may be small and for a single purpose, e.g. mating grounds called leks. Home ranges are usually much larger that territories. They are not defended and may overlap with the home ranges of other members of the species. This means that even solitary animals can remain in contact with others.

The home range is the area where an animal may roam but does not defend. It may overlap with several other home ranges. Overlap Nest

The area where the animal spends most of its time is called the core area and usually contains the best resources.

Territory size depends on a many factors including resource availability, the social behaviour of the animal, and the energy expended to defend it. Gannet territories consist of the nest and the area immediately around the nest. The home range consists of the ocean covered when searching for food. Territories are actively defended and, once established, provide relatively undisputed access to the resources within. (e.g. food, shelter, water, nest or den site). Territories may be established by fighting and are marked by calling or using scent marks.

Lekking in greater sage grouse

A lek is an aggregation of males engaging in competitive displays. Males defend their lek territories, which are usually established seasonally. Females select mates based on their display or position in the lek. Highly ranked males occupy the middle of the group with lower ranked individuals on the periphery.

Graham Collins

Ownership of a territory is usually continually proclaimed. Male skylarks (above) may sing for twenty minutes at a time while flying high above their territory. Maintaining a territory benefits an animal by maintaining access to a resource, e.g. a nesting site or food source.

1. (a) Distinguish between a territory and a home range:

(b) Describe how the core area is similar to the territory:

(c) What aspects might determine the size of the home range in any given area?

2. Establishing and maintaining a territory takes time and energy. Describe its adaptive value to the organism: