Density-dependent decline of early horn growth in European mouflon


The development of horns in Caprinae can be largely influenced by food-limiting factors such as population density and climate, as well as by negative evolutionary responses to size-selective harvesting. In this study, we investigated the effects of population density, environmental covariates and trophy hunting on horn development in a population of European mouflon Ovis aries musimon introduced to the Mediterranean region of Croatia in the early 1980s. The study population was subject to commercial trophy hunting on males since the mid-1980s. This allowed to analyse the temporal trend in early horn growth in 341 rams legally culled. Cohort-based linear model and analysis of deviance (ANODEV) revealed a significant negative trend in early horn growth, with a decline of ca. 10% over only 15 cohorts (1993-2007). The increase in population density (by ca. 600%) and summer temperature, selected via LASSO regression, explained about 61% and 13% of the decline in early horn growth, as revealed by the ANODEV R2. Our results suggest a prominent role of food-limiting factors in the decline of weapon size. We also found a negative relationship between age at death and early horn growth in our study population, which suggests the occurrence of hunters’ selectivity towards large horns. The effect of trophy hunting on the decline in horn size, however, is difficult to quantify. Our analysis was largely influenced by the rapid increase of mouflon density after introduction, thereby limiting the possibility to detect potential effects of hunting selection, although the large number of rams shot before 5 years of age may possibly lead to undesirable consequences of trophy hunting on mating success. To clarify the consequences of commercial trophy hunting on the mouflon population, the long-term pattern of horn growth and the age-dependent male siring success should be further investigated.

This is a preview of subscription content, log in to check access.

Access options

Buy single article

Instant unlimited access to the full article PDF.

US$ 39.95

Price includes VAT for USA


  1. Ahrestani, F.S., Hebblewhite, M., Post, E., 2013. The importance of observation versus process error in analyses of global ungulate populations. Sci. Rep. 3, 3125.

  2. Anonymous, accessed 15 February 2019. [in Croatian] 2019. Central Hunting Records.

  3. Aublet, J.F., Festa-Bianchet, M., Bergero, D., Bassano, B., 2009. Temperature constraints on foraging behaviour of male Alpine ibex (Capraibex) in summer. Oecologia 159, 237–247.

  4. Bonenfant, C., Pelletier, F., Garel, M., Bergeron, P., 2009. Age dependent relationship between horn growth and survival in wild sheep. J. Anim. Ecol. 78, 161–171.

  5. Bro-Jørgensen, J., 2007. The intensity of sexual selection predicts weapon size in male bovids. Evolution 61, 1316–1326.

  6. Büntgen, U., Liebhold, A., Jenny, H., Mysterud, A., Egli, S., Nievergelt, D., Stenseth, N.C., Bollmann, K., 2014. European springtime temperature synchronises ibex horn growth across the eastern Swiss Alps. Ecol. Lett. 17, 303–313.

  7. Cameron, T.C., O’Sullivan, D., Reynolds, A., Hicks, J.P., Piertney, S.B., Benton, T.G., 2016. Harvested populations are more variable only in more variable environments. Ecol. Evol. 6, 4179–4191.

  8. Carvalho, J., Eizaguirre, O., Pérez, J.M., Mentaberre, G., Lavín, S., Fandos, P., Ruiz Olmo, J., Olivé-Boix, X., Torres, R.T., Fonseca, C., Pettorelli, N., Serrano, E., 2017. Evidence for phenotypic plasticity but not for compensatory horn growth in male Iberian ibex. Mamm. Biol. 87, 101–106.

  9. Chirichella, R., Ciuti, S., Grignolio, S., Rocca, M., Apollonio, M., 2013. The role of geological substrate for horn growth in ungulates: a case study on Alpine chamois. Evol. Ecol. 27, 145–163.

  10. Clutton-Brock, T., 2017. Reproductive competition and sexual selection. Phil. Trans. R. Soc. B 372, 20160310.

  11. Coltman, D.W., Festa-Bianchet, M., Jorgenson, J.T., Strobeck, C., 2002. Age-dependent sexual selection in bighorn rams. Proc. R. Soc. Lond. B. Biol. Sci. 269, 165–172.

  12. Coltman, D.W., O’Donoghue, P., Jorgenson, J.T., Hogg, J.T., Festa-Bianchet, M., 2005. Selection and genetic (co)variance in bighorn sheep. Evolution 59, 1372–1382.

  13. Coltman, D.W., O’Donoghue, P., Jorgenson, J.T., Hogg, J.T., Strobeck, C., Festa-Bianchet, M., 2003. Undesirable evolutionary consequences of trophy hunting. Nature 426, 655–658.

  14. Dennis, B., Ponciano, J.M., Lele, S.R., Taper, M.L., Staples, D.F., 2006. Estimating density dependence, process noise, and observation error. Ecol. Monog. 76, 323–341.

  15. Dormann, C.F., Elith, J., Bacher, S., Buchmann, C., Carl, G., Carré, G., Marquéz, J.R.G., Gruber, B., Lafourcade, B., Leitão, P.J., Münkemüller, T., McClean, C., Osborne, P.E., Reineking, B., Schröder, B., Skidmore, A.K., Zurell, D., Lautenbach, S., 2013. Collinearity: a review of methods to deal with it and a simulation study evaluating their performance. Ecography 36, 27–46.

  16. Douhard, M., Festa-Bianchet, M., Pelletier, F., Gaillard, J.M., Bonenfant, C., 2016. Changes in horn size of Stone’s sheep over four decades correlate with trophy hunting pressure. Ecol. Appl. 26, 309–321.

  17. Douhard, M., Pigeon, G., Festa-Bianchet, M., Coltman, D.W., Guillemette, S., Pelletier, F., 2017. Environmental and evolutionary effects on horn growth of male bighorn sheep. Oikos 126, 1031–1041.

  18. Fenberg, P.B., Roy, K., 2008. Ecological and evolutionary consequences of size-selective harvesting: how much do we know? Mol. Ecol. 17, 209–220.

  19. Festa-Bianchet, M., Coltman, D.W., Turelli, L., Jorgenson, J.T., 2004. Relative allocation to horn and body growth in bighorn rams varies with resource availability. Behav. Ecol. 15, 305–312.

  20. Festa-Bianchet, M., 2017. When does selective hunting select, how can we tell, and what should we do about it? Mam. Rev. 47, 76–81.

  21. Festa-Bianchet, M., Mysterud, A., 2018. Hunting and evolution: theory, evidence, and unknowns. J. Mamm. 99, 1281–1292.

  22. Festa-Bianchet, M., Pelletier, F., Jorgenson, J.T., Feder, C., Hubbs, A., 2014. Decrease in horn size and increase in age of trophy sheep in Alberta over 37 years. J. Wildl. Manage. 78, 133–141.

  23. Garel, M., Cugnasse, J.M., Maillard, D., Gaillard, J.M., Hewison, A.J.M., Dubray, D., 2007. Selective harvesting and habitat loss produce long-term life history changes in a mouflon population. Ecol. Appl. 17, 1607–1618.

  24. Geiger, G., Hofmann, R.R., König, R., 1977. Vergleichend anatomische untersuchungen an den vormägen von damwild (Cervus dama) und muffelwild (Ovis ammon musimon). Säugetierkd. Mitt. 25, 7–21.

  25. Geist, V., 1966. The evolution of horn-like organs. Behaviour 27, 175–214.

  26. Grosbois, V., Gimenez, O., Gaillard, J., Pradel, R., Barbraud, C., Clobert, J., Møller, A.P., Weimerskirch, H., 2008. Assessing the impact of climate variation on survival in vertebrate populations. Biol. Rev. 83, 357–399.

  27. Hadfield, J.D., Wilson, A.J., Garant, D., Sheldon, B.C., Kruuk, L.E., 2010. The misuse of blup in ecology and evolution. Am. Nat. 175, 116–125.

  28. Hengeveld, P.E., Festa-Bianchet, M., 2011. Harvest regulations and artificial selection on horn size in male bighorn sheep. J. Wildl. Manage. 75, 189–197.

  29. Holmes, E.E., Ward, E.J., Wills, K., 2012. MARSS: multivariate autoregressive state-space models for analyzing time-series data. R. J. 4, 11–19.

  30. Jonas, K., Perry, V., 2010. Effects of weather and climate on the dynamics of animal population time series. Proc. R. Soc. B. 278, 1708.

  31. Jorgenson, J.T., Festa-Bianchet, M., Wishart, W.D., 1998. Effects of population density on horn development in Bighorn Rams. J. Wildl. Manage. 62, 1011–1020.

  32. Kusak, J., Krapinec, K., 2010. Ungulates and their management in Croatia. In: Apollonio, M., Andersen, R., Putman, R. (Eds.), European Ungulates and Their Management in the 21st Century. Cambridge University Press, pp. 527–539.

  33. Lincoln, G.A., 1998. Reproductive seasonality and maturation throughout the complete life-cycle in the mouflon ram (Ovis musimon). Anim. Prod. Sci. 53, 87–105.

  34. Mason, T.H.E., Apollonio, M., Chirichella, R., Willis, S.G., Stephens, P.A., 2014. Environmental change and long-term body mass declines in an alpine mammal. Front. Zool. 11, 69.

  35. McDougall, P.T., Réale, D., Sol, D., Reader, S.M., 2006. Wildlife conservation and animal temperament: causes and consequences of evolutionary change for captive, reintroduced, and wild populations. Anim. Conserv. 9, 39–48.

  36. Merchant, P., Hoefs, M., Nette, T., Kale, W., Janssen, M., 1982. Proceedings of the Biennial Symposium of the Northern Wild Sheep and Goat Council, 3., pp. 157–162.

  37. Mysterud, A., Bonenfant, C., Loe, L.E., Langvatn, R., Yoccoz, N.G., Stenseth, N.C., 2008. The timing of male reproductive effort relative to female ovulation in a capital breeder. J. Anim. Ecol. 77, 469–477.

  38. Palazy, L., Bonenfant, C., Gaillard, J.M., Courchamp, F., 2012. Rarity, trophy hunting and ungulates. Anim. Conserv. 15, 4–11.

  39. Pigeon, G., Festa-Bianchet, M., Coltman, D.W., Pelletier, F., 2016. Intense selective hunting leads to artificial evolution in horn size. Evol. Appl. 9, 521–530.

  40. R Core Team, 2016. R: A Language and Environment for Statistical Computing. R Foundation for Statistical Computing, Vienna, Austria

  41. RStudio Team, 2016. RStudio: Integrated Development for R. RStudio, Inc., Boston, MA.

  42. Seletković, Z., Tikvić, I., Vučetić, M., Ugarković, D., 2011. Climatic features and the vegetation of Mediterranean Croatia. In: Matić, S. (Ed.), Forests of the Croatian Mediterranean. — Academy of Forestry Sciences., pp. 142–161 [in Croatian].

  43. Skalski, J.R., Hoffman, A., Smith, S.G., 1993. Testing the significance of individual- and cohort-level covariates in animal survival studies. In: Lebreton, J.D., North, P.M. (Eds.), Marked Individuals in the Study of Bird Populations., pp. 9–28, Birkhäuser.

  44. Tadic, P.M., Marjana, G.P., Ksenija, Z., Ksenija, C., 2014. Drought vulnerability in Croatia. Agric. Conspec. Sci. 79, 31–38.

  45. Tibshirani, R., 1996. Regression shrinkage and selection via the lasso. J. R. Stat. Soc. Ser. B 58, 267–288.

  46. von Hardenberg, A., Bassano, B., Arranz, M.D., Bogliani, G., 2004. Horn growth but not asymmetry heralds the onset of senescence in male Alpine ibex (Capra ibex). J. Zool. 263, 425–432.

Download references

Author information

Correspondence to Luca Corlatti.

Rights and permissions

Reprints and Permissions

About this article

Verify currency and authenticity via CrossMark

Cite this article

Kavčić, K., Corlatti, L., Safner, T. et al. Density-dependent decline of early horn growth in European mouflon. Mamm Biol 99, 37–41 (2019) doi:10.1016/j.mambio.2019.10.001

Download citation


  • Density dependence
  • Horn size
  • Trophy hunting
  • Ungulates
  • Wildlife management