Mortality Causes in Captive Cantabrian capercaillie (Tetrao urogallus cantabricus) in Spain

19 páginas, 8 figuras, 2 tablas.

The Cantabrian capercaillie (Tetrao urogallus cantabricus) is one of the most severely threatened subspecies of capercaillie. Its current population range is restricted to a small area of the Cantabrian Mountains (northwestern Spain), with only around 200 individuals remaining. As part of the national strategy for the conservation of the subspecies, the Cantabrian capercaillie Captive Breeding Center of Sobrescobio opened in 2009. Here, we use the information provided by the necropsies performed in this facility on 29 individuals (11 males, 13 females and 5 undetermined; 16 chicks and 13 adults) in order to describe the main mortality causes of captive-bred Cantabrian capercaillies. After necropsy, tissue samples were taken for evaluation using standard methods in histology and microbiology. The majority of the captive animals (18/29, 62.07%) died due to infectious diseases, mainly due to Escherichia coli, Clostridium perfringens, or Aspergillus fumigatus infection. The remaining 11 animals died due to stress-related processes (i.e., rupture of the heart apex and cardiomyopathy or neurogenic shock) (8/29, 27.59%), duodenal obstruction and coelomitis (1/29, 3.45%), perforation of the proventriculus and heart with a briar branch (1/29, 3.45%) or euthanasia due to a valgus leg deformity that prevented proper animal welfare (1/29, 3.45%). Young animals (i.e., younger than 2 months) died mainly due to infectious diseases (14/16, 87.5%), while stress-related causes were responsible for most adult deaths (7/13, 53.85%). We additionally report that two free-ranging adult males died due to exertional myopathy. This study provides relevant information for reducing mortality in captive capercaillies and improving both living conditions in captivity and the adaptation of these animals to the wild.

The authors would like to thank colleagues from the University of León and Consejería de Fomento, Ordenación del Territorio y Medio Ambiente of the Government of the Principality of Asturias for their kind support. The authors also thank J. Naves and J. F. García Marín for critically reviewing the manuscript.

This work was partially funded by the Principality of Asturias (PCTI 2021–2023, GRUPIN: IDI-2021-000102) and European Regional Development Fund. Alberto García-Rodríguez was supported by the EU-NextGenerationEU funds through the 2021-2023 Margarita Salas call for the requalification of the Spanish university system, convened by the Universidad de León. Gloria Herrero-García was supported by Junta de Castilla y León and FSE (LE036-20).

Peer reviewed