INTERSPECIFIC TERRITORIALISM

Abstract

SUMMARY 1. The term “interspecific territorialism” is defined. 2. Examples are given of interspecific territorialism between ( a ) members of the chat genus Oenanthe ( leucopyga, lugens, monacha, oenanthe, and pleschanka ) ; ( b ) oenanthids and a female Monticola solitarius ; and ( c ) the shrikes Lanius collurio and L. nubicus. 3. An encounter between a Robin Erithacus rubecula and a pair of Stonechats. Saxicola torquata is described. 4. It is contended that common outline and mannerisms are more important than common plumage characters in stimulating these interspecific reactions. 5. Interspecific territorialism is apparently one of the means evolved to eliminate the effect of competition between closely allied species with a similar ecology.