WATTLE SIZE IS CORRELATED with MALE TERRITORIAL RANK in JUVENILE RING- NECKED PHEASANTS Anna Papeschi Universita Di Firenze, [email protected]
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University of Nebraska - Lincoln DigitalCommons@University of Nebraska - Lincoln Papers in Natural Resources Natural Resources, School of 2003 WATTLE SIZE IS CORRELATED WITH MALE TERRITORIAL RANK IN JUVENILE RING- NECKED PHEASANTS Anna Papeschi Universita di Firenze, [email protected] John P. Carroll University of Georgia, [email protected] Francesco Dessi-Fulgheri Universita di Firenze Follow this and additional works at: http://digitalcommons.unl.edu/natrespapers Part of the Natural Resources and Conservation Commons, Natural Resources Management and Policy Commons, and the Other Environmental Sciences Commons Papeschi, Anna; Carroll, John P.; and Dessi-Fulgheri, Francesco, "WATTLE IS ZE IS CORRELATED WITH MALE TERRITORIAL RANK IN JUVENILE RING-NECKED PHEASANTS" (2003). Papers in Natural Resources. 657. http://digitalcommons.unl.edu/natrespapers/657 This Article is brought to you for free and open access by the Natural Resources, School of at DigitalCommons@University of Nebraska - Lincoln. It has been accepted for inclusion in Papers in Natural Resources by an authorized administrator of DigitalCommons@University of Nebraska - Lincoln. 362 SHORT COMMUNICATIONS The Condor 105:362±366 q The Cooper Ornithological Society 2003 WATTLE SIZE IS CORRELATED WITH MALE TERRITORIAL RANK IN JUVENILE RING-NECKED PHEASANTS ANNA PAPESCHI1,4,JOHN P. C ARROLL2,5 AND FRANCESCO DESSIÁ-FULGHERI1,3,4 1Dipartimento di Biologia Animale e Genetica, UniversitaÁ di Firenze, Via Romana 17, 50125 Firenze, Italy 2The Game Conservancy Trust, Fordingbridge, Hampshire SP6 1EF, UK 3Centro di Studio per la Faunistica ed Ecologia Tropicali, C.N.R., Firenze, Italy Abstract. We used morphological measurements chos al inicio de la eÂpoca reproductiva, esto sugiere and behavioral observations to investigate the relation- que el tamanÄo de la caruÂncula podrõÂa ser usado como ship between male ornaments and male social rank una senÄal de niveles de agresioÂn y condicioÂn corporal during the breeding season in a free-ranging popula- entre los machos. tion of one-year-old Ring-necked Pheasants (Phasi- anus colchicus). The sample was of birds of the same age class to avoid the confounding effect of age dif- Several studies of the Ring-necked Pheasant (Phasia- ferences. Tail length, used by females in mate choice, nus colchicus; the Common Pheasant in Europe) have and tarsal spur length, used by males as a weapon in demonstrated that the tail, tarsal spur, and head orna- ®ghts, were not correlated with male rank, whereas the ments play a role in intrasexual and intersexual inter- size of the wattle was the most important trait. This actions (von Schantz et al. 1989, Hillgarth 1990, Grahn combined with recent studies showing that wattle size et al. 1993, Mateos and Carranza 1995, 1996, 1997). reliably indicates male testosterone levels at the begin- However, the results of these studies are contradictory ning of the breeding season suggest that, among males, and they do not identify the information contained in wattle size may be used as a signal of aggression level, the male signals, nor how they affect intraspeci®c in- and body condition. teractions in natural conditions. Von Schantz et al. (1989) showed that female Ring- Key words: intrasexual selection, male ornaments, necked Pheasants choose to mate with long-spurred male rank, Phasianus colchicus, Ring-necked Pheas- males and that mating with long-spurred males in- ant, territoriality. creases female reproductive success. However, subse- quent studies by the same authors demonstrated that El TamanÄo de las CaruÂnculas Esta tarsal spur length was not related to male success in Correlacionado con el Rango Territorial de los attracting females, nor with female reproductive suc- Machos en Faisanes Phasianus colchicus cess measured as number of sired chicks and number Juveniles of hatched young, respectively (Grahn et al. 1993). Surprisingly, tarsal spurs, which males use as weapons, Resumen. Utilizamos medidas morfoloÂgicas y did not show any relationship to a male's ability to observaciones de comportamiento para investigar la gain a territory, or, among territorial males, with ter- relacioÂn entre los ornamentos de los machos y el ran- ritory quality (Grahn et al. 1993). Other experimental go social de eÂstos durante la eÂpoca reproductiva en studies have demonstrated that spur length does not una poblacioÂn silvestre de faisanes Phasianus col- affect female mate preference (Hillgarth 1990, Mateos chicus de un anÄo de edad. La muestra consistioÂde and Carranza 1996), whereas some soft ornaments, aves de la misma clase de edad para evitar el efecto such as the periocular wattle and tail, can in¯uence de diferencias entre edades. La longitud de la cola both intersexual and intrasexual interactions (Mateos (utilizada por las hembras en la seleccioÂn de pareja) and Carranza 1995, 1997). These ®ndings are the result y la longitud de la espuela tarsal (utilizada por los of experimental studies conducted in controlled con- machos como un arma en enfrentamientos) no se co- ditions, and little is known about the role of male traits rrelacionaron con el rango de los machos, mientras as signals in nature. Indeed, male-male interactions que el tamanÄo de la caruÂncula fue el caracter maÂs and social hierarchy can be dif®cult to study in an importante. En combinacioÂn con estudios recientes aviary, considering the extent of the male territory in que muestran que el tamanÄo de la caruÂncula indica the wild and unknown effects of con®nement on ter- con®ablemente los niveles de testosterona en los ma- ritorial behavior. Our recent work on both wild and hand-reared pop- ulations of Ring-necked Pheasants documented a link Manuscript received 15 March 2002; accepted 29 between wattle size and testosterone plasma levels: November 2002. wattle size increase is the ®rst signal of seasonal go- 4 E-mail: dessi@uni®.it nadic recrudescence (Papeschi et al. 2000), and the 5 Present address: Warnell School of Forest Resourc- wattle is the only male ornament positively affected by es, University of Georgia, Athens, GA 30602-2152. a testosterone administration (Briganti et al. 1999). SHORT COMMUNICATIONS 363 Secondary male traits depending on testosterone levels sexual interactions, such as red (wattle), dark blue (ear are rare in birds, where plumage dimorphism involves tufts) or blue and brown (tail). an estrogen-based mechanism (Domm 1939, Witschi For each male we measured body mass (to the near- 1961, Owens and Short 1995): estrogen induces female est 10 g), ¯attened wing chord and tail lengths (length plumage patterns, whereas the absence of estrogen re- of the longest feather, to the nearest 1 mm), length of sults in male-like ornamentation (including tarsal vertical wattle axis (to the nearest 0.1 mm), spur length spurs). (to the nearest 0.1 mm) and shaft diameter of the ®rst In birds, head traits are dynamic. They play the (proximal) primary feather (to the nearest 0.1 mm). role of coverable badge (Hansen and Rohwer 1986, AGE CLASSES Rohwer 1982) in that they can change rapidly to notify an opponent (Maynard Smith 1991), rather Males were divided into two age classes (juveniles 5 than simply act as a static badge of status. Dynamic 1 year old; adults 5 2 years or older) based on shaft traits on the face or head are key signals involved diameter of the ®rst proximal primary wing feather in intrasexual contests of several galliforms (Buch- (Greenberg et al. 1972). The age ratio of trapped males holz 1997, Ligon et al. 1990, Mateos and Carranza was skewed due to management of the estate for hunt- 1997). Such ornaments may be favored because they ing: of 193 measured males, we found 161 one-year- provide more accurate and immediate information old males, 23 adults, and 9 indeterminate. In the Ring- regarding male motivation and condition than a stat- necked Pheasant, older males may have more devel- ic badge. oped ornaments and are more likely to hold a territory The periocular wattle's sensitivity to testosterone, (Ridley and Hill 1987; AP, unpubl. data). Thus to and its extremely dynamic nature, make this male or- avoid confounding effects of age, we only considered nament a potential key signal in male-male contests one-year-old males. among Ring-necked Pheasants. It may function as BEHAVIORAL OBSERVATIONS honest advertisement (Kodric-Brown and Brown 1984, Folstad and Karter 1992) of male quality, con- We carried out observations for 18 days in March dition, and motivation. We investigated the roles of and 18 days in April, 6 hr per day for a total of 216 three different male ornaments, the periocular wattle, hr of observation. Each day we drove in the park tail, and tarsal spur, as signals in male-male interac- along three paths so as to cover the entire area every tions throughout the breeding season in natural con- three days. When a tagged male was sighted we turned off the engine, waited about 1 min to allow ditions. We studied the correlation between these the bird to recover from the alert, and then observed male ornaments measured at the end of winter and his behavior for 10 min. We recorded his position the ranks the males subsequently gained during the in the area, his main behavior (e.g., strutting, feed- breeding season. ing, preening, sneaking, vigilance, chasing, etc.), his METHODS wattle score (1 5 closed, 2 5 half erected, 3 5 erected), and the number of crowings (high-intensity STUDY AREA vocalizations). If the tagged bird was interacting We studied the behavior of 193 free-ranging male with another male, we waited to observe the result Ring-necked Pheasants on Clarendon Park Estate of the interaction. (508569N, 18479W), 5 km east of Salisbury, Wiltshire, MALE RANK ASSESSMENT UK, from 11 February until 30 April 1996. The estate 2 We assessed male ranks on the basis of the behavioral covers approximately 20 km and is dominated by in- observations carried out in March and April.