We examine previously-published TSPY sequence data to identify synapomorphies useful for tracking Y-chromosomal gene flow between hybridizing guenon species.We then describe a set of PCR primers and protocols that amplify many of these variable sites from feces. Such Y-chromosomal markers are potentially very useful to conservation studies because they may offer an early sign of introgression as a threat to the genetic integrity of a rare species. Moreover, the ability to survey these markers from feces greatly expands the utility of noninvasive studies.