Anim. Behav., 1997, 53, 471–485 Signals in intra-sexual competition between ring-necked pheasant males CONCHA MATEOS & JUAN CARRANZA Biology and Ethology Unit, University of Extremadura ( Received 12 September 1995; initial acceptance 23 November 1995; final acceptance 11 April 1996; M S. number: 5024) Abstract. Many sexual ornaments are signals commonly used in both sexual selection contexts: mate choice and intra-sexual competition. Previous studies show that female choice in ring-necked pheasants, Phasianus colchicus, is influenced by features of some male ornaments. Experiments and correlational data were used in this study to investigate the role of male ornaments in male–male agonistic encounters. Some traits used by females in mate choice, namely tail length and black points in the wattle, had no effect in male–male competition, but the length of ear tufts had a role in both contexts. The most important traits appeared to be the head ornaments, which include ear tufts, but also wattle size. Head ornaments function as coverable signals that are displayed to rival males informing about readiness to fight, fighting ability and resource-holding power; and the total time spent displaying correlated with testosterone level, physical condition and rank. Thus, the costs of displaying head ornaments appear to be both inherent and target-receiver dependent.  1997 The Association for the Study of Animal Behaviour Extravagant secondary sexual characters of males have been widely assumed to evolve and be main- tained by female choice, and to have a limited role in intra-sexual selection, mainly because they are not effective as weapons (Darwin 1871; Fisher 1930; Kirkpatrick 1982; Møller & Pomiankowski 1993). Recently, however, some authors have pointed out that male–male competition may lead to the development of exaggerated ornaments, whose role in agonistic signalling had been largely ignored (Andersson 1982; Kodric-Brown & Brown 1984; Zahavi 1991; Zuk 1991; Krebs & Davies 1993). According to this point of view, extravagant ornaments and displays may be con- sidered as having evolved through sexual signal- ling between members of the same sex, different sex, or both, and should be treated as biological signals. Males of the ring-necked pheasant, Phasianus colchicus, are elaborately ornamented, with bright and coloured plumage, long tail, and red wattle and ear tufts on the head, while the females are cryptic and non-ornamented. They have a polygynous mating system, based on the defence of mating territories by males, which typically provide no parental care. Males compete for territories and only territorial males mate, while others remain as satellites (Lachlan & Bray 1976; Cramp & Simmons 1980; Go ¨ransson 1984; H ill & Ridley 1987; Biadi & Mayot 1990). In agonistic displays, male ring-necked pheasants show and exaggerate most dimorphic traits: they slope the body towards their opponents and spread the tail and plumage, inflate the wattle and raise the ear tufts. The losers in turn stop signalling their status by lowering the wattle and the ear tufts and folding over the plumage. In nature, territory holders maintain their wattles and ear tufts erect while satellite males do not (Cramp & Simmons 1980; Ridley & Hill 1987). The same ornaments are shown before females during courtship, and previous studies indicate that tail length, length of the ear tufts, presence of black points in the wattle, and duration of wattle display, positively influence female choice (Hillgarth 1990a ; Mateos & Carranza 1995; but see Go ¨ransson et al. 1990). Some authors have claimed one should distinguish between the effects of mate choice and intra-sexual competition in the evolution of dimorphic traits in many species (e.g. Andersson 1994). As in other species, pheasants’ weapons and ornaments play an important role in Correspondence: C. Mateos, Ca ´tedra de Biologı ´a y Etologı ´a, Facultad de Veterinaria, Universidad de Extremadura, 10071 Ca ´ceres, Spain (email: carranza@cc. unex.es). 0003–3472/97/030471+ 15 $25.00/0/ar960297  1997 The Association for the Study of Animal Behaviour 471