A túzok (Otis tarda L.) ízeltlábú táplálékforrás kínálatának vizsgálata alföldi előfordulási területein
Authors: Faragó Sándor 
Published: July 2024

We have carried out the tests in the four lowland regions where the Great Bustards are found: (1) Apajpuszta – Csepeli-plain (1985), (2) Mezőnagymihály – Borsodi Mezőség (1991), (3) Nagyiván – Hortobágy (1988) and Dévaványa – Dévaványai-plain (1985, 1987) (Map 1). We have collected the Arthropods in the study areas with BARBER pitfalls. Each of the annually selected habitats had 5 pitfalls in operation, which we have placed along a line at five meters from each other. The traps were in operation from May to July, sometimes until August. We emptied them in two-week (14-14 day) periods. During laboratory processing, we have determined the number of individuals and measured the total mass of individuals of each taxon per period. The individual and mass data were recorded in tables for each measurement (=every two-week period) and the dominance relationships were calculated, then the basic data were used to calculate the various community-ecological indicators (diversity, evenness, etc.). In addition to the calculated individual and mass ratios, we have also calculated the energy value and dominance of the samples. We have applied cluster analysis to group the animal food sources of each habitat. We have used the BRAY-CURTIS index as a similarity index. Based on the results obtained – regardless of the place and time of the examination – if we want to generalize, then we can say the following facts: (1) The mass and energy ratios that most characterize the food source prove that agricultural habitats are more favourable. (2) The food supply of the habitats changes during the reproduction period, partly for biological (seasonal dynamics of the taxa), partly for reasons of cultivation (mowing, harvesting) and with the maturation of the plants (disappearance of green phytomass), shows fluctuations, decreases or increases. The decrease is typical for cereals and natural grasslands, and the cyclical change is typical for mowed grasslands and alfalfa. We have experienced an increase in spring-sown (e.g. maize) habitats. (3) We cannot generally talk about the goodness of food sources within the same year, we must determine and prioritize the food supply in each period. (4) The extent and quality of the supply of Arthropod food sources is also different in the topographically different places of the Great Hungarian Plain. (5) It can be concluded that, based on the trappings, the decisive role of those taxa in the food supply of Arthropods can be demonstrated, which also play a decisive role in the animal food spectrum of the Great Bustards, so above all the Coleoptera and the Orthoptera. (6) Taking all of this into consideration, we should establish that regardless of the year, place, or period, the more favourable Arthropod food supply of agricultural habitats was one of the motivating factors for the habitat change of Great Bustard, and even today it is one of the explanations for the settlement and nesting of Great Bustards on arable land. (7) The examination of the Arthropod food sources of the Great Bustard showed that the Arthropod resource sets of the agricultural habitats are still suitable for the maintenance of Great Bustard populations. (8) Environmentfriendly farming, the restrained use of chemicals, and the increase in the diversity of food weeds increase the diversity and mass of phytophagous Arthropods and their predators, thus increasing the resources of the habitat.