Thermal properties of arctic fox fur and the effect of fur lice infestation.

Abstract

In 2019, a new species of sucking louse was observed in arctic foxes (Vulpes lagopus) on Svalbard and Northern Canada. Abnormal patterns of fur loss, inconsistent with normal moult, were observed across the neck, shoulders and back, raising concerns as to how the animals would cope with damaged fur during the cold Arctic winter. This study investigates the impact of these lice on Svalbard arctic foxes, focussing on louse prevalence, fur condition and thermal properties. A total of 23 fur samples from 17 arctic foxes were used to estimate louse prevalence, abundance and fur damage compared to thermal properties. Louse density was determined by dissolving skin biopsies and counting lice visually. The thermal properties were determined by establishing a steady heat flow through a system of a standard conductor and a fur sample and measuring the temperature at each interface. The prevalence was lower (44%) compared to the prevalence estimated (70%) from the previous trapping season (2021-2022). Conductivity values ranged from 0.0304 – 0.0869 W/m°C and conductance from 0.974 to 2.94 W/m2°C. These values broadly agree with previous studies. No linear relationship was found between louse density and fur state, suggesting an underlying louse population dynamic. While no linear correlation was found between louse density and thermal conductivity of the fur or fur damage and conductivity, a significant (p < 0.05) relationship was found between louse density, fur damage and thermal conductance, implying that infested arctic foxes, as hypothesised, experience excess heat loss compared to non-infested foxes and that this heat loss is due to a loss of fur rather than a change in the internal structure of the coat. A pilot study tested the potential use of thermal imaging in the detection and monitoring of fur loss and lice infestation in wild arctic foxes. The initial results showed promise, but the system requires further refinement before large-scale field trials. An image of an arctic fox was captured with evidence of fur loss.