Sample Collection
Individual-linked fecal samples were collected in 2014 from adult female Sable Island horses, during an annual survey of the population. All samples were collected within 5 min of defecation and kept on ice in the field (maximum 6 hrs), before being homogenized, subset into 2.0-ml screw cap cryotubes, and frozen at −20 ºC in the field for up to two months. Samples were stored at −80 ºC for long-term storage, after transport to the mainland. Alongside the collection of fecal samples, data on horse location, social membership, and parental status were recorded. The study system and sampling protocol are described in greater detail elsewhere .