Various seabird species can thrive together on small, remote islands even when their diets consist of the same fish. A researcher from Uppsala University has played a key role in creating a mathematical model that aids in comprehending the dynamics of this ecosystem.
“Our model demonstrates that different species can naturally coexist if they vary in their fishing skills and their ability to travel efficiently over long distances to reach fishing grounds,” explains Claus Rüffler, Associate Professor of Animal Ecology at Uppsala University.
Seabirds often nest in huge colonies, sometimes comprising hundreds of thousands of pairs. Ecologists studying these birds have been curious about the factors that govern the size of these colonies. Researchers from Uppsala University and the University of Lausanne have devised a mathematical model to explore how the fishing behaviors of seabirds affect fish availability around a breeding colony, how this influences the growth of bird populations, and how various bird species can coexist in the same breeding grounds while consuming the same resource.
Basic ecological principles suggest that two separate species cannot inhabit the same limited resource; typically, the stronger competitor is anticipated to eliminate the other. This research aims to uncover the reasons that allow seabird species to occupy the same isolated island.
“For all species, the most advantageous fishing spot would be near the island to minimize energy expenditure. However, bird species possess different characteristics, such as wing length and diving depth. Our model indicates that as different species aim to optimize their energy intake, they inherently choose different fishing distances from the colony,” states Rüffler.
The model forecasts that seabirds will segregate the waters surrounding a colony into distinct circular zones, with each species fishing within its designated area.
“Our model fundamentally addresses coexistence and biodiversity. Understanding this aspect is valuable in its own right, as humans seek to grasp the workings of nature. Moreover, such insights are essential for any conservation strategies aimed at protecting vulnerable ecosystems. We also believe that the mechanisms for coexistence outlined in our model could have broader applicability beyond seabirds,” concludes Rüffler.
