How does environmental variation influence body mass, body size, and body condition? Roe deer as a case study


  • Carole Toïgo,

  • Jean-Michel Gaillard,

  • Guy Van Laere,

  • Mark Hewison,

  • Nicolas Morellet

C. Toïgo ( and G. Van Laere, Office National de la Chasse et de la Faune Sauvage, 5 Allée de Bethléem, Z.I. Mayencin, F-38610 GIERES, France. – J.-M. Gaillard, UMR CNRS 5558 Biométrie et Biologie Evolutive, Univ. Claude Bernard Lyon 1, 43, boulevard du 11 novembre 1918, F-69622 Villeurbanne Cedex, France. – A. J. M. Hewison and N. Morellet, Comportement et Ecologie de la Faune Sauvage, INRA, BP 52627, F-31326 Castanet-Tolosan Cedex, France.


We tested the influence of population density and of drought intensity (measured as the Gaussen Index in spring and summer of the year of birth) on winter body mass, hind foot length, and body condition of roe deer fawns. Body mass decreased with increasing density and increased with increasing Gaussen Index in summer, in a similar way for both males and females. Hind foot length of males showed the same response. On the other hand, hind foot length of females decreased with increasing density only after dry summers, hence when environmental conditions were very harsh. Body condition was affected neither by density nor by drought intensity. Our results indicate that body mass and size are much better indicators of phenotypic quality than body condition in roe deer. The sex-specific responses of body size to environmental conditions could correspond to a differential allocation in favour of daughters by heavier than average roe deer mothers.