Over the past 25 years, a range change has been observed in the Siamese fireback in Khao
Yai National Park, Thailand. It has moved from lower to higher altitudes and is now found in areas where previously only silver pheasant were reported. To investigate this new phenomenon, thought to have been triggered by a change in the general forest structure within the region, a long-term project was initiated. This paper investigates the breeding behaviour of these two species to establish if similarities exist, which in an extreme case could result in inter-breeding. The data collected are based
on colour-ringed (n = 7) and radio-tagged individuals (n = 2), observed at fifteen minutes intervals in order to examine social interactions between individual males and females and between males themselves. Preliminary analyses undertaken after one breeding season (2007), indicate differences between the two species’ mating strategies. Siamese fireback show a strong skew, with a dominant male largely monopolizing proximity, and therefore access to all the females in a group, while silver pheasant were observed to have a lower skew, with all males in a group sharing almost equal proximity to females. In addition, Siamese fireback males were also sporadically observed joining silver pheasant groups. With the data so far available, some cross-species breeding appears possible as the mating systems of both species do appear to stimulate the formation of mixed-species groups during
the breeding season.