In a paper published today (Griffith & Hooper 2017), we characterise the variation in bill colour across 1800km of the tropical savannah in Australia, clearly identifying the contact zone between the different subspecies (identified by bill colour), and providing evidence for selection against hybrids. This paper is one of the first outcomes from a project that started with fieldwork back in 2009 and required lots of amazing fieldwork on cattle stations across the top end. The full paper can be found here.