If there is a topic that really excites a Museum evolutionary biologist, it's speciation:
What drives speciation?
What affects rates of speciation?
Why are some groups of organisms more diverse than others?
These are not easy questions at all..
Their hypothesis is higher dispersal abilities on continents will inhibit rates of speciation while higher dispersal abilities on islands will stimulate rates of speciation. Why? Because continents present the opportunity for more continuous, suitable habitat (as opposed to thousands of miles of ocean). Great ability for movement keeps genes a flowing which prevents distant populations from diverging, a step along the path of speciation. Due to the continuity of continental habitats greater ability for movement is not necessary for range expansion, and therefore speciation, whereas on islands it is.
The first step in this process is finding candidate birds (and islands) to test this hypothesis. To avoid an apples to oranges comparison, the team is scouring the literature for candidate bird clades that are well represented on BOTH islands and the mainland. So far, doves, flycatchers, and finches have made the list. Looking forward to an update once you start building those phylogenies and calculating speciation rates!