Ábrahám Levente (szerk.): Válogatott tanulmányok IV. - Natura Somogyiensis 15. / Miscellanea 4. (Kaposvár, 2009)
Lánszki József - Sárdi Bertalan - Széles Gabriella: Falvakban és külterületi mezőgazdasági környezetben élő nyestek táplálkozási szokásai
234 ATURA SOMOGYIENSIS For the quantitative (percentage biomass or %B) estimation the scats were washed through filters (0.5 mm pore diameter) and dried, after which the remains of each items were separated. All dry prey or plant remains were weighed and multiplied by coefficients of digestibility described by Jedrzejewska and Jedrzejewski (1998) for the marten, such as small rodents, insectivores, bats and weasel x23, medium-sized mammals, e.g. brown hare x50, cervid carcasses xl5; domestic ungulate carcasses хЦ8, birds x35, reptiles and amphibians *18, fish x25, insects x5, and plants xl4. In the rare case of dog or cat food, factor of birds was used. Plant and animal food was evaluated separately because the plant material was unlimited food source for martens in the study localities and period. Distribution of prey body weight was determined in accordance with Clevenger (1993), to create categories such as <15 g, 15-50 g, 51-100 g, 101-300 g and >300 g. Classification of prey on the basis of zonation (characteristic level of occurrence or the physical stratification where a species is most active) was made according to published data from Gittleman (1985) on predators, 1 - terrestrial and terrestrial but sometimes arboreal, 2 - arboreal and arboreal but sometimes terrestrial, and 3 — aquatic or water-linked. Prey species were classified on the basis of their typical environment associations such as 1 - open field species, 2 - forest species or species living in dense shrubby, and 3 - mixed or habitat generalist species which may live both in open field and in forest. Prey species were classified on the basis of their human associations (Lanszki 2003), 1 - wild, 2 - human-linked, and 3- mixed. List and category of each animal food species contains Appendix 1. Statistical analysis The main animal food categories used in the trophic niche and environment dependent calculations were 1 - small mammals, 2 - domestic animals and house-food (plain cooking and pet food), 3 - birds, 4 - other vertebrates (reptiles, amphibians and fish) and 5- invertebrates (arthropods and molluscs). Non-food (originally indigestible) substances ingested and hair fibres swallowed by the stone martens while grooming were not included in the calculation. Trophic niche breadth (B) was calculated in accordance with Levins’ index (Krebs 1989): B= 1/ , where p = the relative biomass consumed of the ith taxon; and standardized across food taxa: В =(B-l)/(n-l), rating from 0 to 1. Diet composition depending on the habitat types was expressed in two ways (Table 1): number of occurrences in each food categories (N), and percentage of biomass consumed (%B). The consumption of main food taxa on the basis of the estimated percentage biomass values was compared with the two habitat types using independent samples t-test. The Chi-square ( ) test was applied for distribution analysis for the diet composition; prey consumption on the basis of weight, zonation and environmental associations of prey of the martens living in the two environments (village and farm). The Chi-square ) test was also applied for distribution analysis of marten scat and owl pellet numbers in each localities, furthermore for distribution analysis for the non-food item in the two habitat types. Small pebbles which probably originated from gizzard of birds were excluded from this calculation. Hierarchical cluster analysis was used to compare data of diet composition (%B) recorded for different study locations. SPSS 10 (1999) statistics program was used for processing data.
