A team of Spanish and Portuguese scientists led by the University of Granada (UGR) have conducted a study on the ancestral history of the Bonelli’s eagle, a species of bird of prey found in the Mediterranean Basin. The research, published in the journal People and Nature, utilized evidence from fields such as palaeontology, genetics, and ecology to determine when and why this species colonized the region. The study suggests that the Bonelli’s eagle is a recent addition to Europe, establishing itself in the Mediterranean Basin around 50,000 years ago, in contrast to other species like the golden eagle which have a longer history in the area based on fossil records.
Spatial analysis conducted in the study indicated that colder climatic periods were not favorable for the Bonelli’s eagle, unlike the golden eagle which thrived in such conditions. Genetic analysis confirmed that the Mediterranean population of Bonelli’s eagles consisted of only a few individuals around the Last Glacial Maximum, with the population increasing as temperatures rose and human populations grew and became sedentary. However, the study also raised questions about why the Bonelli’s eagle chose to colonize the region during a complex climatic period and not before, which led researchers to investigate the role of early humans in the species distribution.
The study found that human influence played a crucial role in the colonization of the Mediterranean by the Bonelli’s eagle. Through detailed analysis of the competitive interactions between Bonelli’s eagles and golden eagles, researchers determined that golden eagles are dominant and Bonelli’s eagles are subordinate in this relationship. The presence of golden eagles in climatically favorable areas restricts the distribution of Bonelli’s eagles, which are more adaptable to human presence. The authors suggest that the arrival of anatomically modern humans in Europe may have led to the abandonment of golden eagle territories near human settlements, allowing Bonelli’s eagles from the Middle East to occupy these vacant areas.
The study highlighted a mechanism called “human-mediated competitive release” through which human presence indirectly influences the distribution of species, including long-lived species like eagles. The ability of humans to influence species distribution is not new, but the study sheds light on how our ancestors could have impacted the distribution of Bonelli’s eagles in the past. While the proximity to humans once benefited the Bonelli’s eagle, the intensification of human activities in the environment poses a threat to the species today. Factors such as deaths caused by power lines, prey scarcity, and disturbance of nesting sites contribute to the challenges faced by the Bonelli’s eagle in the Mediterranean region.
Overall, the study provides insights into the complex interactions between species, the environment, and human activities that have shaped the distribution of the Bonelli’s eagle in the Mediterranean Basin. By understanding the historical factors that influenced species colonization, researchers can better assess the current threats and challenges faced by iconic birds of prey like the Bonelli’s eagle. The research underscores the importance of considering the past to inform conservation efforts and protect species from the pressures of modern human activities.