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Mortality Causes in Free-Ranging Eurasian Brown Bears (Ursus arctos arctos) in Spain 1998-2018.

  • Balseiro, Ana1, 2
  • Royo, Luis J3
  • Gayo, Elena1
  • Balsera, Ramón4
  • Alarcia, Olga5
  • García Marín, Juan F1, 2
  • 1 Departamento de Sanidad Animal, Facultad de Veterinaria, Universidad de León, 24071 León, Spain. , (Spain)
  • 2 Departamento de Sanidad Animal, Instituto de Ganadería de Montaña (CSIC-Universidad de León), Finca Marzanas, Grulleros, 24346 León, Spain. , (Spain)
  • 3 Servicio Regional de Investigación y Desarrollo Agroalimentario del Principado de Asturias (SERIDA), 33300 Villaviciosa, Spain. , (Spain)
  • 4 Consejería de Fomento, Ordenación del Territorio y Medio Ambiente, Oviedo, 33007 Asturias, Spain. , (Spain)
  • 5 Consejería de Fomento y Medio Ambiente de la Junta de Castilla y León, Dirección General de Patrimonio Natural y Política Forestal, 47014 Valladolid, Spain. , (Spain)
Published Article
Animals : an open access journal from MDPI
Publication Date
Aug 31, 2020
DOI: 10.3390/ani10091538
PMID: 32878324


This work summarizes the mortality cases of twenty-five free-ranging Eurasian wild brown bears (Ursus arctos arctos) from the Cantabrian mountain range submitted for necropsy in Asturias and Castilla y León (northwestern Spain) from 1998 to 2018. Mortality cases were classified both caused by (i) "non-human intervention" or "human intervention" causes and based on (ii) "non-infectious" or "infectious" etiology. In four cases (16%) it was not possible to determine the cause of death due to the inadequate preservation of collected specimens or insufficient tissue availability. Based on "non-human intervention" or "human intervention" causes, fourteen of the 21 (66.7%) brown bears died as a consequence of "non-human intervention" due to traumatic lesions (fights, unknown traumas or infanticide), infectious canine hepatitis, neoplasia or mushroom poisoning. In contrast, seven (33.3%) brown bears died by "human intervention" due to illegal hunting (shooting or snare), handling (during transit in an attempt to reintroduce a bear back into the wild) or strychnine poisoning. Based on "non-infectious" or "infectious" etiology, twelve of the 21 (57.1%) brown bears died due to "non-infectious" causes, namely traumatic lesions such as shooting, snare, fighting or infanticide, handling, strychnine poisoning, mushroom poisoning or neoplasia. The remaining nine (42.9%) animals died due to "infectious" diseases which included gangrenous myositis, infectious canine hepatitis or septicemia. In six of those cases traumatic lesions caused by non-human or human activities were complicated with bacterial infection (clostridiosis and septicemia) which finally caused the death of those animals. Additionally, exertional myopathy was observed in the handled animal and in one bear found in a snare. In a free-ranging population of Eurasian brown bear from the Cantabrian mountain range, main causes of death are attributed to non-human related traumatic lesions and infectious diseases (primary developed such as infectious canine hepatitis or secondary developed such as clostridiosis or septicemia) which is in contrast to previously reported data for other bear populations. These data are valuable and may help in the conservation and management of this recovering population.

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