The under parts are buff , while the crissum ( the undertail coverts surrounding the cloaca ) , primaries , underwing coverts and flanks are rich rufous - chestnut .
This is mainly visible when it opens its wings .
The under parts are buff , while the crissum ( the undertail coverts surrounding the cloaca ) , primaries , underwing coverts and flanks are rich rufous - chestnut , but this is mainly visible when it opens its wings .