Existence of synchronization of reproduction at the level of the social group of the European wild boar ( Sus scrofa )

Reproductive events were recorded in two groups of female wild boars kept in semi natural conditions. The first group had been kept for 2 consecutive years with a male. Most farrowing took place within 4-5 days; 6/7 in the first year and 8/9 for the second. A second group of 5 females was kept for 13 months in the absence of a male, and oestrous cycles were monitored by weekly measurement of plasma progesterone concentrations. All the females experienced summer-autumn anoestrus and resumed cycling in the same week of December. This accurate synchronization of reproduction may result from stimulation amongst females belonging to the same social unit.