Threat display in birds

• Published in: Canadian journal of zoology Vol. 79; no. 6; pp. 931 - 942
• Main Authors: Hurd, Peter L, Enquist, Magnus
• Format: Journal Article
• Language: English
• Published: Ottawa, Canada NRC Research Press 01.06.2001; National Research Council of Canada; Canadian Science Publishing NRC Research Press
• Subjects: Aggressiveness; Animal communication; Animal ethology; Aves; Biological and medical sciences; Birds; Fundamental and applied biological sciences. Psychology; Ornithology; Psychology. Psychoanalysis. Psychiatry; Vertebrata; Interspecific competition; Review; Agonistic behavior
• ISSN: 0008-4301; 1480-3283; 1480-3283; 0008-4301
• DOI: 10.1139/z01-062

The study of threat displays has long been an area in which theory and empirical work have each spurred the other forward. Communication is currently the focus of great interest and effort on the part of modellers. A great deal that classical ethologists have accurately described about threat displays still lacks adequate explanation. Here we review the empirical literature on the use of threat displays by birds competing for small valued resources, both to refocus theoretical attention upon the key characteristics of threat and to assess the degree to which current theory explains these characteristics. We aim to demonstrate that threat displays communicate information about aggressive motivation, but are not handicaps. Handicap models predict a single graded display, while the vast majority of studies report repertoires of about four to six discrete threats for any given species. These displays vary with motivational and strategic considerations, and may be demonstrated to rank consistently on a scale of willingness to escalate, thus providing information about aggressive motivation. We conclude by identifying those features of avian threat displays that have not been adequately explained, in the hope that this reexamination of empirical data will help focus theoretical attention on these issues.