Behavioral Ecology and Sociobiology

, Volume 67, Issue 5, pp 795–804 | Cite as

Gray tree frogs, Hyla versicolor, give lower-frequency aggressive calls in more escalated contests

  • Michael S. ReichertEmail author
  • H. Carl Gerhardt
Original Paper


As animal contests escalate, variation in the performance of aggressive signaling behaviors can give important insights into contest dynamics. In anuran amphibians, males of numerous species utilize distinctive aggressive vocalizations during disputes over calling spaces. Little is known, however, about the causes and consequences of variation in aggressive-call characteristics. We analyzed recordings of calls made during staged aggressive interactions between male gray tree frogs, Hyla versicolor, to determine how variation in a key aggressive-call characteristic, dominant frequency, was affected by increasing contest escalation. We found that dominant frequencies of aggressive calls were lower than those of advertisement calls used to attract females. Furthermore, we found that males lowered their aggressive-call frequencies with increases in escalation. Winners tended to have lower-frequency aggressive calls than losers. We conclude that aggressive calls in H. versicolor are similar to the graded aggressive calls that have been described in several other species. This gradation may allow males to balance the energetic costs of producing lower-frequency calls with the benefits of efficiently repelling rival males. Other processes related to motivation and the physiological effects of participating in contests may also be responsible for the observed variation in aggressive-call frequency with contest escalation. Our results demonstrate that detailed experimental studies of aggressive calling behavior in anurans, which to this point have rarely been performed, are feasible and generate important insights relating to general problems in animal contest behavior and animal communication.


Anuran Aggression Hylid Energetics Contests 



Flavia Barbosa and two anonymous reviewers reviewed earlier versions of this manuscript. Tanya Drew, Nicholas Fowler, Timothy Golden, Daniel Gruhn, Carmen Harjoe, Will Li and Benjamin Nickelson assisted with the staged interactions and call analyses. Thanks to everyone in the Gerhardt lab for advice and assistance with frog collection and testing. Funding is provided by a National Science Foundation Doctoral Dissertation Improvement Grant to HCG and MSR (IOS 1010791), grants from the Chicago Herpetological Society, the Gaige Fund of the American Society for Ichthyologists and Herpetologists, and a Dean E. Metter Memorial Award from the Society for the Study of Amphibians and Reptiles to MSR, and a Graduate Assistance in Areas of National Need fellowship from the University of Missouri and the US Department of Education (P200A070476). This article is part of MSR’s doctoral dissertation from the University of Missouri-Columbia.

Ethical standards

These experiments comply with the current laws of the USA and were approved by the Animal Care and Use Committee of the University of Missouri (protocol nos. 1910 and 6546).

Conflicts of interest

The authors declare that they have no conflict of interest.


  1. Arak A (1983a) Sexual selection by male–male competition in natterjack toad choruses. Nature 306:261–262CrossRefGoogle Scholar
  2. Arak A (1983b) Vocal interactions, call matching and territoriality in a Sri Lankan treefrog, Philautus leucorhinus (Rhacophoridae). Anim Behav 31:292–302CrossRefGoogle Scholar
  3. Arnott G, Elwood RW (2008) Information gathering and decision making about resource value in animal contests. Anim Behav 76:529–542CrossRefGoogle Scholar
  4. Arnott G, Elwood RW (2009) Assessment of fighting ability in animal contests. Anim Behav 77:991–1004CrossRefGoogle Scholar
  5. Backwell PRY (1988) Functional partitioning in the two-part call of the leaf folding frog Afrixalus brachycnemis. Herpetologica 44:1–7Google Scholar
  6. Barlow GW, Rogers W, Fraley N (1986) Do Midas cichlids win through prowess or daring? it depends. Behav Ecol Sociobiol 19:1–8CrossRefGoogle Scholar
  7. Bee MA (2002) Territorial male bullfrogs (Rana catesbeiana) do not assess fighting ability based on size-related variation in acoustic signals. Behav Ecol 13:109–124CrossRefGoogle Scholar
  8. Bee MA, Bowling AC (2002) Socially mediated pitch alteration by territorial male bullfrogs, Rana catesbeiana. J Herpetol 36:140–143Google Scholar
  9. Bee MA, Perrill SA (1996) Responses to conspecific advertisement calls in the green frog (Rana clamitans) and their role in male–male communication. Behaviour 133:283–301CrossRefGoogle Scholar
  10. Bee MA, Perrill SA, Owen PC (1999) Size assessment in simulated territorial encounters between male green frogs (Rana clamitans). Behav Ecol Sociobiol 45:177–184CrossRefGoogle Scholar
  11. Bee MA, Perrill SA, Owen PC (2000) Male green frogs lower the pitch of acoustic signals in defense of territories: a possible dishonest signal of size? Behav Ecol 11:169–177CrossRefGoogle Scholar
  12. Bond AB (1989) Toward a resolution of the paradox of aggressive displays: II. Behavioral efference and the communication of intentions. Ethology 81:235–249CrossRefGoogle Scholar
  13. Brenowitz EA, Rose GJ (1999) Female choice and plasticity of male calling behaviour in the Pacific treefrog. Anim Behav 57:1337–1342PubMedCrossRefGoogle Scholar
  14. Briffa M, Elwood RW (2009) Difficulties remain in distinguishing between mutual and self-assessment in animal contests. Anim Behav 77:759–762CrossRefGoogle Scholar
  15. Briffa M, Elwood RW (2010) Repeated measures analysis of contests and other dyadic interactions: problems of semantics, not statistical validity. Anim Behav 80:583–588CrossRefGoogle Scholar
  16. Burmeister SS, Ophir AG, Ryan MJ, Wilczynski W (2002) Information transfer during cricket frog contests. Anim Behav 64:715–725CrossRefGoogle Scholar
  17. Clutton-Brock TH, Albon SD, Gibson RM, Guinness FE (1979) The logical stag: adaptive aspects of fighting in red deer (Cervus elaphus L.). Anim Behav 27:211–225CrossRefGoogle Scholar
  18. Davies NB, Halliday TR (1978) Deep croaks and fighting assessment in toads Bufo bufo. Nature 274:683–685CrossRefGoogle Scholar
  19. Dyson ML, Reichert MS, Halliday TR (2013) Contests in amphibians. In: Briffa M, Hardy ICW (eds) Animal contests. Cambridge University Press, Cambridge (in press)Google Scholar
  20. Emerson SB (2001) Male advertisement calls: behavioral variation and physiological processes. In: Ryan MJ (ed) Anuran communication. Smithsonian Institution, Washington, pp 36–44Google Scholar
  21. Enquist M (1985) Communication during aggressive interactions with particular reference to variation in choice of behaviour. Anim Behav 33:1152–1161CrossRefGoogle Scholar
  22. Enquist M, Leimar O (1987) Evolution of fighting behaviour: the effect of variation in resource value. J Theor Biol 127:187–205CrossRefGoogle Scholar
  23. Fellers GM (1979) Aggression, territoriality, and mating behaviour in North American treefrogs. Anim Behav 27:107–119CrossRefGoogle Scholar
  24. Gayou DC (1984) Effects of temperature on the mating call of Hyla versicolor. Copeia 1984:733–738CrossRefGoogle Scholar
  25. Gerhardt HC (1991) Female mate choice in treefrogs: static and dynamic acoustic criteria. Anim Behav 42:615–635CrossRefGoogle Scholar
  26. Gerhardt HC (2001) Acoustic communication in two groups of closely related treefrogs. Adv Stud Behav 30:99–167CrossRefGoogle Scholar
  27. Gerhardt HC (2005) Acoustic spectral preferences in two cryptic species of grey treefrogs: implications for mate choice and sensory mechanisms. Anim Behav 70:39–48CrossRefGoogle Scholar
  28. Gerhardt HC, Humfeld SC, Marshall VT (2007) Temporal order and the evolution of complex acoustic signals. Proc R Soc Lond B 274:1789–1794CrossRefGoogle Scholar
  29. Given MF (1987) Vocalizations and acoustic interactions of the carpenter frog, Rana virgatipes. Herpetologica 43:467–481Google Scholar
  30. Given MF (1999) Frequency alteration of the advertisement call in the carpenter frog, Rana virgatipes. Herpetologica 55:304–317Google Scholar
  31. Grafe TU (1995) Graded aggressive calls in the African painted reed frog Hyperolius marmoratus (Hyperoliidae). Ethology 101:67–81CrossRefGoogle Scholar
  32. Howard RD (1978) Evolution of mating strategies in bullfrogs, Rana catesbeiana. Evolution 32:850–871CrossRefGoogle Scholar
  33. Howard RD, Young JR (1998) Individual variation in male vocal traits and female mating preferences in Bufo americanus. Anim Behav 55:1165–1179PubMedCrossRefGoogle Scholar
  34. Kim YG (1995) Status signaling games in animal contests. J Theor Biol 176:221–231PubMedCrossRefGoogle Scholar
  35. Krebs JR, Ashcroft R, Orsdol KV (1981) Song matching in the great tit Parus major L. Anim Behav 29:918–923CrossRefGoogle Scholar
  36. Lange H, Leimar O (2003) The function of threat display in wintering great tits. Anim Behav 65:573–584CrossRefGoogle Scholar
  37. Leary CJ, Harris S (2013) Steroid hormone levels in calling males and males practicing alternative non-calling mating tactics in the green treefrog, Hyla cinerea. Horm Behav 63:20–24PubMedCrossRefGoogle Scholar
  38. Littlejohn MJ (2001) Patterns of differentiation in temporal properties of acoustic signals of anurans. In: Ryan MJ (ed) Anuran communication. Smithsonian Institution, Washington, pp 102–120Google Scholar
  39. Littlejohn MJ, Harrison PA (1985) The functional significance of the diphasic advertisement call of Geocrinia victoriana (Anura: Leptodactylidae). Behav Ecol Sociobiol 16:363–373CrossRefGoogle Scholar
  40. Logue DM, Abiola IO, Rains D, Bailey NW, Zuk M, Cade WH (2010) Does signalling mitigate the cost of agonistic interactions? a test in a cricket that has lost its song. Proc R Soc Lond B 277:2571–2575CrossRefGoogle Scholar
  41. Martin WF (1972) Evolution of vocalization in the genus Bufo. In: Blair WF (ed) Evolution in the genus Bufo. University of Texas Press, Austin, pp 279–309Google Scholar
  42. Maynard Smith J (1974) The theory of games and the evolution of animal conflicts. J Theor Biol 47:209–221CrossRefGoogle Scholar
  43. Maynard Smith J, Parker GA (1976) The logic of asymmetric contests. Anim Behav 24:159–175CrossRefGoogle Scholar
  44. Maynard Smith J, Price GR (1973) The logic of animal conflict. Nature 246:15–18CrossRefGoogle Scholar
  45. Meuche I, Linsenmair K, Pröhl H (2012) Intrasexual competition, territoriality and acoustic communication in male strawberry poison frogs (Oophaga pumilio). Behav Ecol Sociobiol 66:613–621CrossRefGoogle Scholar
  46. Oldham RS, Gerhardt HC (1975) Behavioral isolating mechanisms of the treefrogs Hyla cinerea and Hyla gratiosa. Copeia 1975:223–231CrossRefGoogle Scholar
  47. Parker GA (1974) Assessment strategy and the evolution of fighting behaviour. J Theor Biol 47:223–243PubMedCrossRefGoogle Scholar
  48. Pierce JR, Ralin DB (1972) Vocalizations and behavior of the males of three species in the Hyla versicolor complex. Herpetologica 28:329–337Google Scholar
  49. Reichert MS (2011) Aggressive calls improve leading callers’ attractiveness in the treefrog Dendropsophus ebraccatus. Behav Ecol 22:951–959CrossRefGoogle Scholar
  50. Reichert MS, Gerhardt HC (2011) The role of body size on the outcome, escalation and duration of contests in the grey treefrog, Hyla versicolor. Anim Behav 82:1357–1366CrossRefGoogle Scholar
  51. Reichert MS, Gerhardt HC (2012) Trade-offs and upper limits to signal performance during close-range vocal competition in gray tree frogs Hyla versicolor. Am Nat 180:425–437PubMedCrossRefGoogle Scholar
  52. Reichert MS, Gerhardt HC (2013) Socially mediated plasticity in call timing in the gray tree frog, Hyla versicolor. Behav Ecol 24:393–401Google Scholar
  53. Rillich J, Schildberger K, Stevenson PA (2007) Assessment strategy of fighting crickets revealed by manipulating information exchange. Anim Behav 74:823–836CrossRefGoogle Scholar
  54. Robertson JGM (1986) Male territoriality, fighting and assessment of fighting ability in the Australian frog Uperoleia rugosa. Anim Behav 34:763–772CrossRefGoogle Scholar
  55. Ryan MJ (1986) Factors influencing the evolution of acoustic communication: biological constraints. Brain Behav Evol 28:70–82PubMedCrossRefGoogle Scholar
  56. Ryan MJ (1988) Constraints and patterns in the evolution of anuran acoustic communication. In: Fritzsch B, Hetherington TE, Ryan MJ, Walkowiak W, Wilczynski W (eds) The evolution of the amphibian auditory system. Wiley, New York, pp 637–677Google Scholar
  57. Schwartz JJ (1989) Graded aggressive calls of the spring peeper, Pseudacris crucifer. Herpetologica 45:172–181Google Scholar
  58. Schwartz JJ (1994) Male advertisement and female choice in frogs—recent findings and new approaches to the study of communication in a dynamic acoustic environment. Am Zool 34:616–624Google Scholar
  59. Schwartz JJ, Wells KD (1984) Vocal behavior of the neotropical treefrog Hyla phlebodes. Herpetologica 40:452–463Google Scholar
  60. Schwartz JJ, Wells KD (1985) Intraspecific and interspecific vocal behavior of the neotropical treefrog Hyla microcephala. Copeia 1985:27–38CrossRefGoogle Scholar
  61. Schwartz JJ, Buchanan BW, Gerhardt HC (2001) Female mate choice in the gray treefrog (Hyla versicolor) in three experimental environments. Behav Ecol Sociobiol 49:443–455CrossRefGoogle Scholar
  62. Schwartz JJ, Buchanan B, Gerhardt HC (2002) Acoustic interactions among male gray treefrogs, Hyla versicolor, in a chorus setting. Behav Ecol Sociobiol 53:9–19CrossRefGoogle Scholar
  63. Taylor PW, Elwood RW (2003) The mismeasure of animal contests. Anim Behav 65:1195–1202CrossRefGoogle Scholar
  64. van Staaden MJ, Searcy WA, Hanlon RT (2011) Signaling aggression. In: Huber R, Bannasch DL, Brennan P (eds) Adv Genet 75:23–49. Academic, BurlingtonGoogle Scholar
  65. Wagner WE (1989a) Fighting, assessment, and frequency alteration in Blanchard’s cricket frog. Behav Ecol Sociobiol 25:429–436CrossRefGoogle Scholar
  66. Wagner WE (1989b) Graded aggressive signals in Blanchard’s cricket frog: vocal responses to opponent proximity and size. Anim Behav 38:1025–1038CrossRefGoogle Scholar
  67. Wagner WE (1989c) Social correlates of variation in male calling behavior in Blanchard’s cricket frog, Acris crepitans blanchardi. Ethology 82:27–45CrossRefGoogle Scholar
  68. Wagner WE (1992) Deceptive or honest signaling of fighting ability—a test of alternative hypotheses for the function of changes in call dominant frequency by male cricket frogs. Anim Behav 44:449–462CrossRefGoogle Scholar
  69. Wells KD (1977) The social behaviour of anuran amphibians. Anim Behav 25:666–693CrossRefGoogle Scholar
  70. Wells KD (1978) Territoriality in the green frog (Rana clamitans): vocalizations and agonistic behaviour. Anim Behav 26:1051–1063CrossRefGoogle Scholar
  71. Wells KD (1988) The effect of social interactions on anuran vocal behavior. In: Fritzsch B, Ryan MJ, Wilczynski W, Hetherington TE, Walkowiak W (eds) The evolution of the amphibian auditory system. Wiley, New York, pp 433–454Google Scholar
  72. Wells KD (1989) Vocal communication in a neotropical treefrog, Hyla ebraccata: responses of males to graded aggressive calls. Copeia 1989:461–466CrossRefGoogle Scholar
  73. Wells KD (2001) The energetics of calling in frogs. In: Ryan MJ (ed) Anuran communication. Smithsonian Institution, Washington, pp 45–60Google Scholar
  74. Wells KD (2007) The ecology and behavior of amphibians. The University of Chicago Press, ChicagoCrossRefGoogle Scholar
  75. Wells KD, Bard KM (1987) Vocal communication in a neotropical treefrog, Hyla ebraccata: responses of females to advertisement and aggressive calls. Behaviour 101:199–210CrossRefGoogle Scholar
  76. Wells KD, Schwartz JJ (1984) Vocal communication in a neotropical treefrog, Hyla ebraccata: aggressive calls. Behaviour 91:128–145CrossRefGoogle Scholar

Copyright information

© Springer-Verlag Berlin Heidelberg 2013

Authors and Affiliations

  1. 1.Division of Biological SciencesUniversity of MissouriColumbiaUSA
  2. 2.Abt VerhaltensphysiologieInstitut für Biologie der Humboldt-Universität zu BerlinBerlinGermany

Personalised recommendations