Conservation Biology Group

Threats and solutions

New study on spatial use of Bonelli’s Eagle

The Conservation Biology Group conducted a study published in the journal Ibis, in order to to answer important questions about the biology and ecology of the species: the size of home-ranges, spatial use patterns, and differences in territorial behaviour between males and females and between pairs with and without chicks.

The group radiotracked 18 Bonelli’s Eagles in three geographically different areas (Vallčs, Garraf and Priorat) in the period 2006-2008. The findings suggest that the Bonelli's eagle has a typical pattern of spatial use. Males and females occupy similar areas throughout the year, and outside the breeding season the eagles use larger territories. Non-reproductive pairs have very large home-ranges (like reproductive pairs outside the breeding season).

The study underlines the degree of territorial dependence of Bonelli’s eagles, particularly on breeding areas. Eagles are highly dependent on its breeding area throughout the year. Outside the breeding season, nesting sites retain their importance as the eagles will use them to rest, shelter and sleep. Therefore, regulations on the conservation of breeding areas should not just be observed during the breeding season but throughout the year, which would include controlling leisure activities that disturb the birds.

The classical approach of protecting only the breeding areas is no longer sufficient. We also need to protect areas further from nesting sites but ideal for hunting, as these are key to the survival of territorial individuals. The article, which explains that Bonelli’s eagles often use areas that have great biological value but are generally unprotected, is the fruit of a project supported by the Pronvincial Government of Barcelona and the Spanish Ministry of Education and Science.

For further information:
  • BOSCH, R., REAL, J., TINTÓ, A., ZOZAYA, E. L. & CASTELL, C. 2010. Home-ranges and patterns of spatial use in territorial Bonelli’s Eagles Aquila fasciata. Ibis, 152: 105–117. doi: 10.1111/j.1474-919X.2009.00985.x