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.