Abstract
Haematology parameters (N = 24) and serum biochemistry parameters (N = 35) were determined for wild Eurasian beavers (Castor fiber), between 6 months – 12 years old. Of the population tested in this study, N = 18 Eurasian beavers were from Norway and N = 17 originating from Bavaria but now living extensively in a reserve in England. All blood samples were collected from beavers via the ventral tail vein. All beavers were chemically restrained using inhalant isoflurane in 100% oxygen prior to blood sampling. Results were determined for haematological and serum biochemical parameters for the species and were compared between the two different populations with differences in means estimated and significant differences being noted. Standard blood parameters for the Eurasian beaver were determined and their ranges characterised using percentiles. Whilst the majority of blood parameters between the two populations showed no significant variation, haemoglobin, packed cell volume, mean cell haemoglobin and white blood cell counts showed significantly greater values (p<0.01) in the Bavarian origin population than the Norwegian; neutrophil counts, alpha 2 globulins, cholesterol, sodium: potassium ratios and phosphorus levels showed significantly (p<0.05) greater values in Bavarian versus Norwegian; and potassium, bile acids, gamma globulins, urea, creatinine and total calcium values levels showed significantly (p<0.05) greater values in Norwegian versus Bavarian relict populations. No significant differences were noted between male and female beavers or between sexually immature (<3 years old) and sexually mature (≥3 years old) beavers in the animals sampled. With Eurasian beaver reintroduction encouraged by legislation throughout Europe, knowledge of baseline blood values for the species and any variations therein is essential when assessing their health and welfare and the success or failure of any reintroduction program. This is the first study to produce base-line blood values and their variations for the Eurasian beaver.
Highlights
Eurasian beavers (Castor fiber) are large, herbivorous, semi-aquatic, territorial, monogamous rodents that live in small family groups and reach sexual maturity around 3 years of age [1]
Previous genetic studies suggest that the current Eurasian beaver population can be divided into two evolutionary significant units (ESU)—the Eastern European and Western European populations [7]
Bavarian beavers are thought to derive from a mixture of the Eastern and Western European ESU; Norwegian beavers are a relict population from the Western European ESU [8, 9]
Summary
Eurasian beavers (Castor fiber) are large (adults >20 kg), herbivorous, semi-aquatic, territorial, monogamous rodents that live in small family groups and reach sexual maturity around 3 years of age [1]. By the 20th century the species had been reduced to approximately 1,200 individuals in eight isolated populations, largely through hunting [3,4,5]. Over 200 translocations have been recorded, across 25 European countries and current population figures estimate > 1.04 million animals [6]. Previous genetic studies suggest that the current Eurasian beaver population can be divided into two evolutionary significant units (ESU)—the Eastern European and Western European populations [7]. Bavarian beavers are thought to derive from a mixture of the Eastern and Western European ESU; Norwegian beavers are a relict population from the Western European ESU [8, 9]. More recent genetic analysis suggests that such variations represent the two extremes of one species [10]
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