A retrospective study of mortality in Eurasian lynx (Lynx lynx) in UK zoos

IUCN currently classifies the Eurasian lynx (Lynx lynx) as "Least Concern," however, across its six to nine subspecies, some isolated populations are classified as "Endangered" or "Critically Endangered." Despite this and the species' relative ubiquity in European zoos, a retrospective mortality study of a captive population has not previously been performed. By analyzing necropsy reports, animal records, and the European studbook, we were able to ascertain a cause of death for 38 (73%) of the 52 recorded lynx deaths in UK zoos during the study period (January 1, 2000 to November 1, 2015). "Culling" as part of population management was the most common cause of death (21%) followed by neoplastic (16%), circulatory (11%), neurological (11%), and genitourinary (11%) disease. "Geriatric" individuals accounted for 62% of lynx to die within the study period, 23% were "neonates" and 15% "adults." Neoplasia, circulatory disease, and culling were the leading causes of death in each of these age categories, respectively. Excluding "culls" and "neonates," the mean age at death was 18.81 ± 0.42 years, consistent with existing data. Squamous cell carcinoma was reported in three individuals (8%) and suspected idiopathic epilepsy in four individuals (11%), warranting further investigation. Intraspecific killing (3%) and neonatal mortality, excluding culls, (14%) were reported with lower prevalence than expected based on previous studies of similar species. The lack of data available and high incidence of culling of individuals with a high inbreeding coefficient highlights the need for improved record-keeping and consultation with the studbook coordinator, respectively.