title: Ontogenetic Change of Signal Brightness in the Foot-Flagging Frog SpeciesStaurois parvusandStaurois guttatus.
abstract: Adult individuals of several anuran species exhibit conspicuous visual displays during intraspecific communication. While signal properties in adults have been subject to an increasing number of studies, little is known about the variation of visual signals in juveniles and during ontogenetic changes. Foot-flagging signals of the Bornean frogsStaurois guttatusandS. parvuswere observed in juveniles a few days after metamorphosis. We investigated color parameters of foot webbings and body coloration of individuals bred at the Vienna Zoo, and their relation to age and body size using spectrophotometry. Our results indicate that the brightness of foot webbings ofS. guttatusandS. parvusincreased with increasing age. Additionally, we compared the results with measurements of adult individuals from a population in Brunei and discuss possible differences related to diet and age as well as the habitat use of juveniles and adults. We suggest that the ontogenetic increase in foot-webbing brightness enhances visual conspicuousness and the signal-to-noise ratio of the visual signal with sexual maturity and potentially functions as cue to the age of the signaler.
authors.affiliation: Department of Integrative Zoology, University of Vienna, Althanstraße 14, A-1090 Vienna, Austria.
authors.forename: Judith
authors.initials: J
authors.lastname: Stangel
authors.affiliation: Department of Integrative Zoology, University of Vienna, Althanstraße 14, A-1090 Vienna, Austria ; Vienna Zoo, Maxingstraße 13B, A-1130 Vienna, Austria.
authors.forename: Doris
authors.initials: D
authors.lastname: Preininger
authors.affiliation: Department of Integrative Zoology, University of Vienna, Althanstraße 14, A-1090 Vienna, Austria.
authors.forename: Marc
authors.initials: M
authors.lastname: Sztatecsny
authors.affiliation: Department of Integrative Zoology, University of Vienna, Althanstraße 14, A-1090 Vienna, Austria.
authors.forename: Walter
authors.initials: W
authors.lastname: Hödl
keywords: Body coloration; Color change; Color signal; Foot webbing; Ranidae; Visual signals