Neighbor Recognition

The basic experimental paradigm for testing for such rudimentary cognitive abilities involved in neighbor recognition is to use a playback experiment in birds in which a tape recording of the neighboring male's song is played at the territory boundary (Brooks and Falls, 1975; Wiley 1977, Godard, 1991). The response of the target male to the neighbors song is usually less extreme than the targets response to a strange male's song. Why is this the case? The Dear Enemy Hypothesis maintains that once males have established territory boundaries it is a waste of the male's time to continue in escalated conflicts with the neighbor. The two exist in a status quo in which they are still assessing one another, but presumably neither is likely to act aggressively because the other male has a home field advantage. Each male also has access to females and food and thus the motivation to "cross the line drawn in the sand" is low for both males. We can express these ideas in terms of the marginal value theorem with the added twist of risk involved in conflict. The marginal gains that are derived from increasing territory size are not worth the risks of an all out battle. However, if the bird hears a stranger at the boundary, the male must act to turn away the intruder. A targeted male in a playback experiment is much more agitated when he hears a strange male's song coming out of the speaker than if he hears a neighbor. Birds even have the capability to remember a neighbor's song across reproductive seasons (Godard, 1991).

Such neighbor-stranger experiments have also been performed on lizards, but in this case a challenger (stranger or neighbor) is tethered at some point in the targets territory, and the reaction of the target is videotaped. Stan Fox has found that the target is more agitated in response to strangers than to his dear-enemy neighbor.
Additional references

Falls, B. and Brooks, R.J. 1975. Individual recognition by song in white-throated sparrows. I. Discrimination of songs of neighbors and strangers. Can. J. Zool. 53: 1412-1420.

Falls, B. and Brooks, R.J. 1975. Individual recognition by song in white-throated sparrows. II Effects of location. Can. J. Zool. 53: 1412-1420.

Godard, R. 1991. Long-term memory of individual neighbors in a migratory songbird. Nature 350: 228-229.

Fox, S.F. and Baird, T.A. 1992. The dear enemy phenomenon in the collared lizard Crotaphytus collaris, with a cautionary note on experimental methodology. Anim. Behav. 44 780-782.


Leiser JK, Itzkowitz M (1999) The benefits of dear enemy recognition in three-contender convict cichlid (Cichlasoma nigrofasciatum) contests. Behaviour 136: 983–1003.

30. Fostman P, Sherman PT (2003) Behavioral response to familiar and unfamiliar neighbors in a territorial cichlid, Neolamprologus pulcher. Ichthyol Res 51: 283–285.