A Three years satellite tracking study on the juvenile dispersal of the Crowned Eagle

SARASOLA, J.H

Puerto Iguazú

Workshop; Telemetry Workshop: Birds in Argentina and other areas of South America; 2011

The crowned eagle (Harpyhaliaetus coronatus) is one of thelargest and most severely treated birds of prey ranging in SouthAmerica that inhabits open woodlands and savana-like habitats ofArgentina, Paraguay, Bolivia, and southeastern Brazil. Despite its widerange and critical conservation few studies exist on wild populationsof the species and many aspects of its biology are still unknown.Some of them include patterns of habitat use, habitat selection, andmovement. The latest is of special concern because crowned eaglesare suspected to be a migratory species, and assertion that is partiallysupported by information gathered from local people in some areasof the species’ range. Results from interviews conducted to localfarmers in western La Pampa province of Argentina also support thefact that both adult and young eagles leave nesting areas after thebreeding season. In this work we present new data on the dispersal movements of a juvenile crownedeagle in semiarid landscapes of Argentina. Our aim was to determine the pattern and timing of dispersaldisplacements as well as the extent of such dispersion movements using satellite telemetry. We aimed toprovide basic and essential information of this unknown aspect of eagle’s biology that would be valuable inthe design, planning, and execution of future conservation programs for the species.A Platform Transmitter Terminal (PTTs; North Start Scienceand Technology, LLC, King George, VA) was attached to a youngcrowned eagle in January 19 of 2007 when it was still at nest inwestern La Pampa province, Argentina. We gathered informationon movements of the juvenile crowned eagle from the moment ofradio tagging up to 21 January 2010 when the transmitter ceasedworking. The device was set to collect locations every three days andfor a period of six hours. We collected 3561 localization for all theseven Location Classes (LC3 to LCZ) during 1099 transmission days.Accurate localizations (LC3 to LC1) comprised 62% of total: 8% (302localizations) for Class 3, 21% (738) for Class 2 and 33% (1169) forclass 1.Dispersion movements started on October 2007, eight monthafter the young eagle abandoned its nest. We observed consistentuse of riparian habitats by the juvenile crowned eagles through thethree years of dispersal movements. Total distance traveled by thejuvenile eagle during the three years period was 7000 km with amaximum distance from the nest of 400 km. During the study periodwe identified four zones, including its natal area, in which the birdremained for periods > 50 days. Our results of three year individualsatellite monitoring highlight two relevant aspects on the biologyof this endangered species: 1) the crowned eagle seems not to bemigratory species with individuals making regular return movementsin the same direction at about the same time each year and 2) thespecies is able to perform large dispersal movements that extend toseveral hundred of kilometers.