Diet composition of syntopically breeding falcon species Falco vespertinus and Falco tinnunculus in south-western Slovakia

Abstract

The red-footed falcon and Eurasian falcon represent two syntopical falcon species. While the Eurasian falcon is considered a common and numerous species in Slovakia, the red-footed falcon population has undergone a considerable decline during the past few decades. Nowadays it nests in a single locality in Slovakia, the Sysľovské polia Special Protection Area, which forms the northern and fragmented border of the species distribution area in Europe. By analysing prey remains from 9 nests (from 1998, 2001, 2013, 2014 and 2016), we identified 433 prey items belonging to 35 taxa and 9 orders. Every year, invertebrates made up the major part of the diet spectrum, in which Calosoma auropunctatum, Tettigonia viridissima, Zabrus tenebrioides, Anisoplia aegetum and Rhizotrogus sp. were the most frequent species of prey. Of the vertebrates, Microtus arvalis was the most hunted prey species. By supplementary analysis of 21 photos, we extended our knowledge on the diet by other 6 taxa. The peak of the M. arvalis population growth in 2014 did not manifest itself in the red-footed falcon diet composition. In 1998, 2014 and 2016 we also studied the diet of a syntopical species, the Eurasian kestrel. By analysing prey remains in 22 nests, we identified 1,151 prey items belonging to 37 taxa and 7 orders. In 1998 and 2014 vertebrates predominated, especially the common vole, however in 2016 invertebrates prevailed. This fact could be a reaction to the M. arvalis population peak in 2014 and its decline in 2016. These results suggest that this variability in the foraging behaviour of the Eurasian kestrel, an opportunistic predator, during the hunting of invertebrates increases the diet similarity and overlapping of the food niche of both studied falcon species.Abstrakt: Sokol kobcovitý a sokol myšiar predstavujú dva syntopicky sa vyskytujúce druhy sokolov. Kým sokol myšiar je na Slovensku považovaný za bežný a početný druh, populácia sokola kobcovitého zaznamenala v posledných dekádach značný pokles. V súčasnosti tento druh hniezdi na Slovensku na jedinej lokalite -Chránenom vtáčom území Sysľovské polia, ktorá predstavuje severnú a fragmentovanú hranicu rozšírenia druhu v Európe. Analýzou potravných zvyškov z 9 hniezd (z rokov 1998, 2001, 2013, 2014 a 2016) sme tam determinovali 433 kusov koristi prislúchajúcich 35 taxónom a 9 radom. Bezstavovce tvorili každoročne majoritnú časť potravy, kde najčastejšie zastúpenými druhmi boli Calosoma auropunctatum, Tettigonia viridissima, Zabrus tenebrioides, Anisoplia segetum, Rhizotrogus sp. Zo stavovcov bol najčastejšie lovený druhom hraboš poľný. Doplnkovou analýzou 21 fotografií sme spektrum potravy rozšírili o ďalších 6 taxónov. Vrchol gradácie hraboša poľného v roku 2014 sa na zložení potravy sokola kobcovitého neprejavil. V rokoch 1998, 2014 a 2016 sme tiež sledovali potravu syntopického druhusokola myšiara. Analýzou potravných zvyškov 22 hniezd sme zistili 1151 zvyškov koristi, ktoré patrili 37 taxónom zo siedmych radov. V rokoch 1998 a 2014 v potrave dominovali stavovce, n...

Food supply (Orthoptera, Mantodea, Rodentia and Eulipotyphla) and food preferences of the red-footed falcon (Falco vespertinus) in Slovakia

“…The study sites were evaluated based on several factors: i) overall number of Orthoptera, Mantodea, Rodentia and Eulipotyphla species; ii) number of species known as the food of red-footed falcons and recorded primarily in the territory of Slovakia in the works of Balát & Bauer (1955) and Tulis et al (2017), and also in the diet of other parts of the Pannonian Lowlands (Fülöp & Szlivka 1988, Haraszthy et al 1994, Purger 1998, Szövényi 2015; and iii) abundance of individual species. For Orthoptera and Mantodea this was expressed with semiquantitative values (see above), while the locality score was calculated for each site: the sum of semiquantitative values (1-4) in all the studied plots of the locality was divided by the number of studied plots.…”

Diet of the Red-footed Falcon (Falco vespertinus) in Cyprus during autumn migration

“…Its diet has been studied mainly during the breeding season (e.g. Purger 1998, Szövényi 2015, Tulis et al 2017, while there are no published studies of its diet during the species long distance trans-Saharan migration and during its stay in the winter quarters. In this study, data are presented on the diet of the species in Cyprus, during autumn migration.…”