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A home range is the area an individual animal regularly uses during its activities over a specified period, for example finding food, resting and reproducing. It describes space use; a territory adds the behavioural question of which area the animal defends.

Animal radiotelemetry can supply a sequence of locations from a transmitter carried by the animal. A 2011 study combined location tracking and collar activity sensors to compare owned and unowned free-roaming domestic cats. Measuring location and activity together linked the spatial pattern to behaviour rather than treating every recorded point as equivalent.^[ref]

A boundary depends on the observation period and the method used to summarize positions. In an invented example, $95$ of $100$ recorded positions fall in one region and five are distant excursions. That region contains $95\%$ of these observations; this alone does not prove that the animal spends $95\%$ of all future time there. Unequal sampling and serially related locations matter. A utilization distribution instead describes how use varies across space, connecting a range outline with the frequency of use within it.

John Krebs investigated animal behaviour through experiments connecting signals with ecological outcomes. With Ruth Ashcroft and Mike Webber, he examined birdsong and territory maintenance in great tits. Their 1978 paper describes removing resident pairs and occupying the vacated areas with loudspeakers; new pairs settled faster in controls than in song-occupied areas.^[ref]

The experiment makes an invisible social boundary testable: physical space remains after the owners leave, while an acoustic cue can still influence newcomers. It supports a signalling role in territorial exclusion without requiring an observer to witness a fight at every boundary. The same paper tested the effectiveness of varied song repertoires, illustrating the use of controlled signal manipulation to study animal communication.

Institutional profile: www.biology.ox.ac.uk/people/john-krebs .

Mike Webber coauthored a 1978 experimental study with John Krebs and Ruth Ashcroft on birdsong and territory defence in the great tit. The paper compared aspects of song repertoires as signals used in maintaining territories.^[ref]

A central design feature was playback: a loudspeaker can reproduce an acoustic cue while separating it from the presence of a resident animal. This makes a sound signal experimentally manipulable. A difference in settlement after playback is evidence about the signal's effect in the tested situation; it does not by itself show how an arriving bird internally represents the singer. The contribution verified here is the joint experiment rather than a separately documented division of labour among its authors.

Ruth Ashcroft coauthored experimental research with John Krebs and Mike Webber on the role of birdsong in great tit territory defence. Their 1978 paper tested whether variation in a male's song repertoire improves its effectiveness as a territorial display.^[ref]

The methodological question is how to distinguish a song's possible functions. Sound associated with a territory could influence competitors, prospective mates, or both. A test measuring settlement by competitors addresses a different outcome from a test measuring mate attraction. The study's experimental framing therefore links an observable acoustic pattern to a specified behavioural response, rather than treating every elaborate signal as evidence for a single function.

A territory is an area that an animal or group defends against others in a specified context, such as access to food, mates or a nest. A home range instead describes the area normally used. An animal can visit a large home range while defending only one part of it, and repeated use alone does not demonstrate defence.

Defence need not involve continuous fighting. John Krebs and collaborators studied territorial birdsong in the great tit. Their 1978 paper describes experiments that removed resident pairs and occupied their former territories with loudspeakers. New pairs settled more quickly in control areas than in areas occupied by playback, supporting a role for acoustic signals in maintaining exclusion.^[ref] The comparison changes an apparent occupancy cue while removing the original owners, helping separate the effect of song from the mere presence of a resident bird.

For an observational example, a cluster of animal radiotelemetry positions may establish concentrated space use. Calling that cluster a territory additionally requires evidence such as exclusion, boundary displays or a response to an intruder. A location map alone cannot supply that behavioural conclusion.