Biology session

Many population genetic studies are based on non-invasive sampling since it is beneficial in many aspects (no disturbance, harm or contact with the organism is needed). This method therefore provides a valuable opportunity to study rare and endangered species. The eastern imperial eagle (Aquila heliaca) is considered as vulnerable on the IUCN red list and highly protected in Hungary. Individual-based population genetic studies revealing survival rates, natal dispersal and annual turnover, are important to learn more extensively about the eagle population.

The eastern imperial eagle is socially monogamous and highly territorial. Naturally shed feathers collected under a given nest site should therefore represent the breeding birds occupying the given territory. However, in various raptors, observations of intruder individuals were recorded, making the accuracy of the shed feather-based identification questionable. Numerous laboratory methods were tested to improve the feasibility of non-invasive samples in DNA-based procedures, but the reliability of this kind of sampling was not yet tested.

Our primary aim was to check the realiability of the routinely used non-invasive feather sampling in a breeding population of eastern imperial eagles in Hungary. Thirty nests were chosen between 2013 and 2015, with collecting five shed feathers and one plucked feather from the nestlings. Additionally, in all known imperial eagle territories (2000-2015; n=175) we looked up for intruder individuals that were recorded on more than one nest site in the same breeding season. Individual identification was made via genotyping on nine microsatellite markers. Resident birds on a given nest site were confirmed by the DNA-profile of the nestlings.

In two nest sites (out of the 30), shed feathers were found that did not belong to the resident pair. Three other intrusion events were found when checking all known territories in the given period. Out of the five intruders (three females, two males), four individual’s original territory was discovered.