Optimal prey for red fox cubs – an example of dual optimizing foraging strategy in foxes from a dynamic wetland habitat

The red fox (Vulpes vulpes) is the most abundant mesopredator in the Central-European region. Detailed knowledge about their feeding behavior is important both from ecological and wildlife management reasons. Food choices of foxes are poorly predictable in high-biodiversity marshlands. The main aim of our study was to sample parallel the main food-type abundances in the study area and analyze the diet of fox cubs and cohabiting adults across three years during the period of maternal dependence of the cubs. According to the optimal foraging theory, we predicted that the cubs’ diet would show higher energy content, would be more varied, and the individual prey species fed to the young would be larger. We analyzed the composition of adult fox and cub fecal samples collected separately around dens in a marshland of western Hungary, May 2014, 2017 and 2020, when the abundance values of main food sources differed. Rodents and waterfowl dominated the diet, but their relative occurrence in the ..., For the assessment of the diet composition and feeding habits of the red fox, we collected 265 intact scat (fecal) samples in three years (Table 1), Y1 (year 1 – 2014), Y2 (year 2 – 2017), Y3 (year 3 – 2020). Scat samples of cubs and an additional 14 partly consumed prey remains were collected in the surroundings of inhabited dens with actual ongoing cub-rearing, within a distance of 3–5 m from one den with cubs per year.
We prepared and analyzed the fecal samples by means of a standard procedure (Jędrzejewska & Jędrzejewski, 1998). Samples were soaked in water, washed through a sieve (0.5 mm mesh) and dried. All prey remains were separated, and using a microscope, all feather, bone, teeth, hair, fish scales and seed remains were identified to the lowest possible taxonomic level by using key features (detailed by Lanszki et al., 2020) and our vertebrate, invertebrate and plant reference collections. Besides their identification, we also collected prey frequency data from the individ...,