Abstract
<jats:p>This study examines cranial variation in the red fox (Vulpes vulpes) across three ecological zones of Transcarpathia (lowland, premontane, and montane). We examined 134 skulls, of which 78 were adults and 56 were subadults. All specimens originated from the Zoological Museum of Uzhhorod National University. Only specimens with a recorded locality (district) and sex were included. Twenty-six cranial measurements were taken with 0.1 mm precision, and each skull was assigned to one of the three zones. Morphological differences were detected among the populations. Lowland foxes generally exhibited larger skull measurements than montane individuals, particularly in skull lengths, suggesting that ecological factors may influence cranial development. Among adult individuals, montane foxes had shorter skulls and a narrower neurocranium compared to lowland foxes. The observed pattern supports the notion that the red fox exhibits notable plasticity in response to local ecological pressures. In addition to regional comparisons within Transcarpathia, our dataset was evaluated against published measurements from neighboring countries and other regions of Ukraine. When comparing our data with those from other countries and regions, the premontane males differed only from Romanian individuals in total length and Hungarian individuals in maximum zygomatic width, while females differed only from individuals from the Ukrainian Carpathians. Lowland males differed from most other populations except the Ukrainian Carpathian and Steppe ones, while females differed from all those reported in the literature. Montane males showed differences in total length, maximum zygomatic width, basal length, and neurocranium width compared to the Slovakian, Ukrainian Carpathian, Polissia, Hungarian, Steppe, and Romanian populations, whereas females were less variable and differed only from the Slovakian, Ukrainian Carpathian, Polissia, and Steppe populations. Premontane population showed the least variation compared to published data, whereas lowland and montane populations exhibited greater sex- and population-specific cranial differences across the neighboring fox populations.</jats:p>