Reproduction of the red fox in western France: does staining improve estimation of litter size from placental scar counts?

Sandrine Ruette (1) , Michel Albaret (2)

1 Office National de la Chasse et de la Faune Sauvage, CNERA Prédateurs Animaux déprédateurs
2 Office National de la Chasse et de la Faune Sauvage, CNERA Prédateurs Animaux déprédateurs

We tested a staining method on uteri for counting placental scars on red fox. We estimated reproduction parameters on 358 females collected in three study areas in western France from 1st February 2002 to 31st January 2005. Placental scars ( = 103) were described by macroscopic examinations using the following variables: (1) the width and (2) the aspect of placental scars, (3) the abundance of macrophages or the presence of blood, (4) the presence of swellings, (5) the presence and colour of a central band and (6) the presence and colour of lateral bands. A factorial correspondence analysis showed strong associations between the month when scars were examined and categories of variables. Staining on placental scars made macrophages more visible, facilitating identification of 'active' placental scars, i.e. related to the last pregnancy. However, distinction between placental scars due to earlier pregnancies and resorptions was not possible. The staining method used provides a standard that could be useful for obtaining comparable and repeatable results. The mean number of placental scars was 4.85 ± 1.46 ( = 103) per vixen. The mean number of embryos per vixen was 4.66 ± 1.35 ( = 68) for yearlings and 5.53 ± 1.50 ( = 96) for older females. Including percentages of barren vixens, the total population productivity was significantly smaller for yearlings (3.62 ± 1.86,  = 158) than for older females (4.28 ± 1.75,  = 186). We discuss these results in relation to fox densities, culling and food availability.

Mots clés: Placental scar counts; Litter size; Embryos counts; Productivity; Reproductive performance

Sandrine Ruette, Michel Albaret. Reproduction of the red fox in western France: does staining improve estimation of litter size from placental scar counts?. European Journal of Wildlife Research, 2010, pp.555-564. ⟨10.1007/s10344-010-0465-y⟩. ⟨hal-00640443⟩