Bird's Survival On Small Islands Dependent On Dark Plumage

New findings published in The Auk: Ornithological Advances reveal that certain animal populations on islands tend to develop weird traits over time. However, one pattern is relatively understudied-otherwise known as a tendency in which certain animal populations develop "melanism," or dark or black coloration.

In this study, researchers visited 13 islands of varying sizes to survey the Chestnut-bellied Monarch populations--birds found in the Solomon Islands. Yet researchers found that a subspecies of the bird coexists with some Chestnut-bellied Monarch populations in the Russell Islands.

As previous studies have shown a link between melanism and aggressive behavior, researchers speculated that the limited space available on smaller islands might make competition for breeding territories more intense, giving an advantage to the most aggressive birds.

Findings revealed that island size could indeed predict the frequency of melanic birds or those with darker skin.

"Patterns of biodiversity on islands have always been important for understanding fundamental principals in ecology and evolution. Using the same archipelago that enchanted Ernst Mayr decades ago, Uy and Vargas-Castro reveal fascinating patterns of melanism and island size," said Rebecca Safran of the University of Colorado, an expert on divergence between bird populations who was not involved in the study, in a news release. "These patterns add to the fundamental importance of islands as natural experiments for studies in biodiversity."

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