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Causes and spatio-temporal variations of non-natural mortality in the Vulnerable Spanish imperial eagle Aquila adalberti during a recovery period

Luis Mariano Gonzáleza1, Antoni Margalida c1, Santi Mañosaa2, Roberto Sáncheza1, Javier Oriaa3, José Ignacio Molinaa4, Javier Calderaa5, Antonio Arandaa6 and Luis Pradaa7

a1 Dirección General para la Biodiversidad, Ministerio de Medio Ambiente, Gran Vía San Francisco 4, E-28005 Madrid, Spain.

a2 Universitat de Barcelona, Facultat de Biologia, Avda. Diagonal, 645, E-08028 Barcelona, Spain.

a3 c/San Agustín 22, E-40001 Segovia, Spain.

a4 Dirección General del Medio Natural, c/Rigoberto Cortejoso 14, 47071 Valladolid, Spain.

a5 Dirección General de Medio Ambiente, Apdo. Correos 7, 10181 Sierra de Fuentes, Cáceres, Spain.

a6 Dirección General del Medio Natural, c/ Pintor Matías Moreno, 4, 45071 Toledo, Spain.

a7 Dirección General del Medio Natural, Consejería de Medio Ambiente, c/ Princesa 3, 28008 Madrid, Spain.

Abstract

The analysis of 267 records of non-natural mortality of the Spanish imperial eagle Aquila adalberti over a 16-year period (1989-2004) shows an annual rate of 15.1 individuals found dead per year and that electrocution (47.7%) and poisoning (30.7%) were the most frequent causes of mortality. Most cases (91.7%) were of human origin, and of those 92.3% were accidental. Just over half (50.2%) were related to the transmission of electricity and human activity (collisions and electrocution), and 40.7% related to game practices and livestock protection (control of predators). No differences between sexes were found but subadults were electrocuted more frequently than expected whilst adults were poisoned more frequently. In breeding areas poison was the most frequent cause of mortality, whereas electrocution was the most common cause of death in dispersal areas. Poisoning occurred more frequently than expected in the Northern and Southern regions compared to the West-Central region. Electrocution was significantly more frequent in the West-Central region, and less common in the Southern region. The increase in electrocutions over the last few years is associated with previous non-permanent corrections on electricity power lines, whilst the increase in the cases of poisoning appears to be associated with the use of illegal poison in predator control by small game practices and for livestock protection. Permanent corrections in power lines and more research and awareness effort in the small game sector are recommended to reduce human-induced mortality in this Vulnerable species.

(Received February 14 2006)

(Reviewed August 01 2006)

(Accepted October 10 2006)

Correspondence:

c1 Bearded Vulture Study and Protection Group, Apdo. 43, E-25520 El Pont de Suert Lleida, Spain. E-mail margalida@inf.entorno.es

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