The first fieldwork I ever did in Australia was focused on the silvereye. On my first day in the field, having worked in Europe up to that point, I was so struck by this pair allopreening that I took this photo (on the left). Since that time, one of the questions that I have worked on, has been why pair bonds in Australian birds are so different, and much stronger then those exhibited by similar birds in Europe.
Recently I published a review of empirical work in this area in Frontiers in Ecology and Evolution. The paper is open access, and can be downloaded here. We are continuing to conduct research in this area, with one of our main projects being a collaboration with Marc Naguib from Wageningen, focused on the pair bond and acoustic communication between partners in the zebra finch (pair shown on the right above).