Does Island Living Influence Plumage Colour?

Island bird populations usually originate from a nearby continental bird population. Although clearly related, mainland and island bird populations differ morphologically. Island bird populations were observed to show less colourful plumage than their mainland counterparts. Reasoning behind these changes are thought to be due to differences in breeding behaviour, climate, or lighting conditions. The importance of colourful plumage in courting behaviour of birds leads us to question why evolution would pressure for duller feathers in island birds. This study acts to identify if island birds typically display less colourful plumage than those living on the mainland. Birds from three different families of songbirds were observed in this study and were categorized as either mainland or island colonists. We will identify the amount of each of three major plumage variants--structural, carotenoid, or melanin--observed on the island and mainland birds. Additionally, by identifying plumage intensity between male and female birds of each species, sexual dichromatism will be identified. This research is very important in understanding what affects the degree of plumage colour observed on birds. The findings of this research will be compared with song analysis, another major courting behaviour, to see if there is a trade off between plumage colouration and song complexity in island life. This data can be applied to many different future studies, furthering our understanding of bird lifestyle based on geographical locations