Food Supply (Orthoptera, Mantodea, Rodentia and Eulipotyphla)

Slovak Raptor Journal 2017, 11: 1–14. DOI: 10.1515/srj-2017-0005. © Raptor Protection ofSlovakia (RPS)

Food supply (Orthoptera, Mantodea, Rodentia and Eulipotyphla) and food preferences of the red-footed falcon (Falco vespertinus) in Slovakia Potravná ponuka (Orthoptera, Mantodea, Rodentia a Eulipotyphla) a potravné preferencie sokola kobcovitého (Falco vespertinus) na Slovensku

Anton KRIŠTÍN, Filip TULIS, Peter KLIMANT, Kristián BACSA & Michal AMBROS

Abstract: Food supply in the nesting territories of species has a key role to the species diet composition and their breeding success. Red-footed falcon (Falco vespertinus) preys predominantly on larger insect species with a supplementary portion of smaller vertebrates. In the breeding periods 2014 and 2016 their food supply, focusing on Orthoptera, Mantodea, Rodentia and Eulipotyphla, was analysed at five historical nesting sites of the species in Slovakia. Preference for these prey groups in the diet was also studied at the last active nesting site in this country. Overall we recorded 45 Orthoptera species (of which 23 species are known as the food of the red-footed falcon), one species of Mantodea, 10 species of Rodentia (of which 2 species are known as the food of the red-footed falcon) and 5 species of the Eulipotyphla order in the food supply. With regard to the availability of the falcons' preferred food, in both years the most suitable was the Tvrdošovce site, which continuously showed the greatest range and abundance of particular species. In the interannual comparison the insects showed lower variability in abundance than the small mammals. In 2014 the growth of the common vole (Microtus arvalis) population culminated and with the exception of a single site (Bodza) a slump in abundance was recorded in 2016. In comparing the diet composition with the food supply at the last Slovak breeding site Rusovce (Special Protection Area Sysľovské polia), we recorded significant preference for grasshopper Caliptamus italicus (in 2014), common vole (in 2016) and cricket Tettigonia viridissima (in both years) in the falcons' diet. They did not prey on the Apodemus sylvaticus species belonging among the abundant small mammal species in that locality. Conserva- tion measures in the agricultural landscape are discussed in relation to homogeneous red-footed falcon breeding territories. Abstrakt: Potravná ponuka v hniezdnych teritóriách druhov hrá kľúčovú úlohu pre zloženie potravy druhov a ich hniezdny úspech. Sokol kobcovitý (Falco vespertinus) loví prevažne väčšie druhy hmyzu, dopĺňané menšími stavovcami. V hniezdnom ob- dobí rokov 2014 a 2016 bola na piatich historických hniezdiskách druhu na Slovensku sledovaná jeho potravná ponuka so zamer- aním na Orthoptera, Mantodea, Rodentia a Eulipotyphla. Na poslednom aktívnom hniezdisku sa študovalo aj zastúpenie týchto skupín v potrave. Celkovo sme zaznamenali 45 druhov Orthoptera (z toho 23 druhov je známych ako potrava sokola kobcov- itého), jeden druh Mantodea, 10 druhov Rodentia (z toho 2 druhy sú známe ako potrava sokola kobcovitého) a 5 druhov radu Eu- lipotyphla. Z hľadiska potravnej ponuky bola v oboch rokoch najvhodnejšia lokalita Tvrdošovce, ktorá kontinuálne vykazovala najvyššie druhové bohatstvo a abundanciu jednotlivých druhov. V medziročnom porovnaní hmyz vykazoval menšiu variabilitu početnosti ako drobné cicavce. V roku 2014 totiž vrcholila gradácia populácie hraboša poľného (Microtus arvalis), ktorá s výnim- kou jednej lokality (Bodza) zaznamenala v roku 2016 prepad početnosti. Pri porovnaní zloženia potravy s potravnou ponukou na poslednej hniezdnej lokalite na Slovensku – Rusovce (Chránené vtáčie územie Sysľovské polia) – sme zaznamenali preukaznú preferenciu lovu druhov Caliptamus italicus (v roku 2014), Microtus arvalis (v roku 2016) a Tettigonia viridissima (počas oboch rokov). Sokol nepreferoval druh Apodemus sylvaticus, ktorý patril k početným druhom drobných cicavcov na lokalite. V závere diskutujeme o možných opatreniach s cieľom ochrany sokola kobcovitého v homogénnych hniezdnych teritóriách poľnohos- podárskej krajiny.

Key words: foraging ecology, birds of prey, Falco vespertinus, food availability, conservation measures

Anton Krištín (corresponding author), Institute of Forest Ecology, Slovak Academy of Sciences, Štúrova 2, SK- 960 53, Zvolen, Slovakia. E-mail: [email protected]. Filip Tulis, Kristián Bacsa, Department of Ecology and Environmental Sciences, Faculty of Natural Sciences, Constantine the Philosopher University in Nitra, Tr. A. Hlinku 1, 949 74, SK-949 01 Nitra, Slovakia. E-mail: [email protected]. Peter Klimant, Institute of Virology, Biomedical Research Center, Slovak Academy of Sciences, Dúbravská cesta 9, 84505 Brati- slava, Slovakia. E-mail: [email protected]. Michal Ambros, State Nature Conservancy of the Slovak Republic, Protected Landscape Area Ponitrie, Samova 3, 94901 Nitra, Slovakia. E-mail: [email protected].

1 Krištín A, Tulis F, Klimant P, Bacsa K & Ambros M: Food supply (Orthoptera, Mantodea, Rodentia and Eulipotyphla) and food preferences of the red-footed falcon (Falco vespertinus) in Slovakia

Acknowledgment: This research was carried out within the project LIFE 11/NAT/HU/000926 Conservation of Red-footed Fal- con in the Carpathian Basin.

Introduction fining the red-footed falcon friendly habitats for poten- The primary factor determining the individual diet and tial habitat management. Other data on the food supply breeding success of raptors is evidently the range of and its effect on the species diet are insufficient. available prey in the predators' territory (Martin 1987, Based on recent knowledge we have analysed: i) the Ontiveros & Pleguezuelos 2000, Hoi et al. 2004). In food supply (Orthoptera, Mantodea, Rodentia and Euli- fact, the prey animals must be not only present, but potyphla) and its variability at five historically known constantly available and accessible (Holmes & Schultz breeding sites in south-western Slovakia; and ii) how 1979, Mikola 1985). Food availability represents a fun- the food supply is reflected in the species diet composi- damental factor in the raptors’ diet composition, and tion at the last nesting site of the species in Slovakia. fluctuations in availability influence not only their functional or numerical responses (Andersson & Er- Methods linge 1977, Korpimäki & Norrdahl 1991), but also their S t u d y a r e a spatial activity (Village 1982), intra- and interspecific We studied the food supply in five historical breeding competition (Morosinotto et al. 2017) and have a signi- localities of red-footed falcon (RFF) and one current ficant impact on their breeding success, individual fit- breeding site in the southern part of western Slovakia. ness and population dynamics (Korpimäki 1984, Study sites are delimited as plots of circular shape with Korpimäki & Wiehn 1998, Ontiveros & Pleguezuelos a diameter of 3 km and an overall plot area of 2 827 ha. 2000). The plots are situated in an agricultural landscape, and The red-footed falcon (Falco vespertinus), as a form parts of protected bird areas (Fig. 1) as follows: mostly insectivorous and migratory raptor species, can 1. Rusovce, SPA Sysľovské polia, GPS of the centre be found in Central Europe from April until October 48°01' N, 17°07' E; 135 m a.s.l..; the current nesting site (Danko 2008). Its diet is composed mainly of flying in- is characterized by intensively cultivated fields, several sect species (mostly Orthoptera, Coleoptera and windbreaks and field spinneys. Almost 44% of the study Odonata), and to a lesser extent of vertebrates (Mam- plot is located in Austria, characteristic for its mosaic malia, Amphibia) (Balát & Bauer 1955, Keve & Szijj structure of narrow fields. 1957, Purger 1998, Tulis et al. 2017). This raptor is 2. Lehnice, SPA Lehnice, 48°04' N, 17°27' E; 119 m highly opportunistic, making use of local abundances a.s.l.; this former nesting site from before 2004 is situ- and seasonal variations in prey, with orthopterans as ated to the north of the village of Lehnice, within in- its principal food (Cramp 1980, Szövényi 2015). tensively cultivated fields, windbreaks and field However, short-term changes in the diet composition spinneys. may occur even due to the impact of meteorological 3. Zeleneč, SPA Úľanská mokraď, 48°17' N, 17°35' factors (Horváth 1963, Haraszthy et al. 1994). E; 133 m a.s.l.; this former nesting site from before In the past, this species occupied several sites in 2001 is characterized mainly by intensively cultivated Slovakia (Gúgh et al. 2015), but since the 1970s its field biotopes, several windbreaks and spinneys, and population size has decreased sharply (Slobodník et al. strips alongside the motorway in the vicinity of the 2014). Nowadays, the last breeding colony is situated in Zeleneč services area. the Special Protection Area (SPA) Sysľovské polia in 4. Bodza, SPA Ostrovné lúky, 47°51' N, 17°53' E, south-western Slovakia. To date the reason for the fal- 110 m a.s.l.; this former nesting site from before 1993 is cons' disappearance from their former breeding sites is situated SE from the Bodzianske Lúky village and it is unknown, and so we have tried to show the effect of typical for its intensively cultivated fields, old riverbeds location on the food supply for this falcon species. with accompanying tree vegetation, field spinneys and The availability of Orthoptera as food for the red- the Rakytie dispersed settlement. footed falcon was studied in the area of Vásárhelyi 5. Tvrdošovce, SPA Dolné Považie, 48°06' N, 18°01' Plain in Hungary using an extensive collection of ma- E; 110 m a.s.l.; this former nesting site from before terial (Szövényi, 2015). This study also focused on de- 2010 is the most diversified of all five studied sites and

2 Slovak Raptor Journal 2017, 11: 1–14. DOI: 10.1515/srj-2017-0005. © Raptor Protection ofSlovakia (RPS) study plots represent the main previous foraging territ- The line elements of vegetation (avenues, wind- ories of the red-footed falcon, characterized mainly by breaks) were selected for the monitoring of small mam- permanent grasslands with various degrees of saliniza- mals. At the end of summer, when the agrotechnical tion (salt marshes), vineyards with varied intensity of interventions in the agricultural landscape culminate, the cultivation, and bright poplar forest with nesting boxes greenery transects form refuges for small mammals and provided for the falcons. thus they make it possible to capture a wide species When mapping the availability of Orthoptera and spectrum of small mammals available at the studied Mantodea, we excluded extensive areas of arable land sites. and monocultures of annual agrarian cultures (corn, maize, oilseed rape) in which the supply of the studied S a m p l i n g O r t h o p t e r a a n d insects is negligible, even though sometimes the flying M a n t o d e a a s f o o d s u p p l y species pass over them and thus they are accessible to Every site was visited twice a year, first in the early “air-hunting falcons”. In contrast, from the viewpoint of summer period, during the feeding phase of falcons occurrence, species richness and Orthoptera abundance, (June 30, July 31 and August 1, 2014; June 29, July 13 the following are considered attractive: mainly perman- and August 1, 2016) and second during the fledgling ent grasslands, edges of field spinneys, windbreaks and period (August 25 and September 1, 2014; August avenues of trees, wetland areas with dispersed bush and 24–25, 2016) in order to sample the widest species tree vegetation, and edges of such biotopes, in some spectrum possible, occurring in both seasonal aspects. cases their mosaic representation, all with higher The material was sampled mostly by sweeping herb and Orthoptera diversity. shrub vegetation (cca. 1,000 sweeps per site/visit/hab-

Fig. 1. Five study sites of red-footed falcon food supply (A) and their locations in Slovakia (B). Sites: 1 – Rusovce, 2 – Lehnice, 3 – Zeleneč, 4 – Bodza, 5 – Tvrdošovce. Obr. 1. Päť študovaných lokalít potravnej ponuky sokola kobcovitého (A) a ich lokalizácia na Slovensku (B). Lokality: 1 – Rusovce, 2 – Lehnice, 3 – Zeleneč, 4 – Bodza, 5 – Tvrdošovce.

3 Krištín A, Tulis F, Klimant P, Bacsa K & Ambros M: Food supply (Orthoptera, Mantodea, Rodentia and Eulipotyphla) and food preferences of the red-footed falcon (Falco vespertinus) in Slovakia itat). This method was supplemented with acoustic semiquantitative values (1–4) in all the studied plots of identification, beating from the lower parts of trees and the locality was divided by the number of studied plots. shrubs, and individual collection of specimens. We Site effect of the species diet composition of spent at least two hours of collection at each site. Orthoptera, Mantodea and small mammals on the semi- Abundance of individual species at the studied sites was quantitative values, separately during both studied expressed using the following classification scale: 1 – years, was evaluated using a general linear model with very rare (less than 3 adult specimens), 2 – rare (3–10 Poisson distribution. specimens), 3 – abundant (11–100 specimens), 4 – very abundant (more than 100 specimens), when the highest D i e t p r e f e r e n c e a n a l y s i s semiquantitative value is given (Tab. 1). We calculated the diet preference of red-footed falcons Altogether, cca. 8,000 individuals of Orthoptera and at their active breeding site Sysľovské polia during the Mantodea were identified in 2014 and cca. 6,500 indi- years 2014 and 2016. Food supply from this site was viduals in 2016. The material was identified by means compared with the diet of red-footed falcons in the same of identification keys (Harz 1969, 1975). The system years (Tulis et al. 2017) using the Ivlev-index (Ivlev and nomenclature proceed from the work of Kočárek et 1961) using the “selectapref“ package (Richardson al. (2005). 2017), where: Px = (a - b)/(a + b), in which "a" is the proportion of caught animals in the given area, "b" is the S a m p l i n g s m a l l m a m m a l s a s proportion of the given area in relation to the whole. f o o d s u p p l y "Px" is the preference (-1 ≤ Px ≤ 1) or avoidance of each Small mammals were captured in August and Septem- prey species (+1 is absolute preference, -1 is absolute ber by means of the CMR method (capture – mark – re- avoidance). Calculation only using the Ivlev-indexes capture). Live traps (50 per line) were located in a would not be sufficient for demonstrating whether the trapping line at 10 m distance from each other. At each preference values of the habitat types are significant or study site, two trapping lines were exposed. In 2014 the not. Hence we tested significance (P < 0.05) using the traps were exposed for 2 nights (2 × 50 traps × 2 Bonferroni z-test (Neu et al. 1974). nights), while in 2016 the traps were exposed only for 1 All statistical analyses were performed using the R night (2 × 50 traps × 1 night). The captured individuals software v. 3.2.5 (R Core Team 2016). were identified and marked. Only the data from the first capture of individuals were entered into analyses. The Results system and nomenclature proceed from the work of O r t h o p t e r a a n d M a n t o d e a Baláž et al. (2013). As the length of the exposition of s p e c i e s a s t h e f o o d s u p p l y traps in 2014 differed from the year 2016, the data on f o r F a l c o v e s p e r t i n u s capture of small mammals were standardised by correc- Altogether 45 Orthoptera (around 36% of the orthopter- tion to 50 trap-nights. ofauna of Slovakia) and one mantid species were found at five sites (20 plots) in the former and current nesting F o o d s u p p l y e s t i m a t i o n a t territories of the red-footed falcon in south-western s t u d y s i t e s Slovakia in 2014 and 2016. Of them there were 22 The study sites were evaluated based on several factors: katydid and cricket species (Ensifera), 23 grasshopper i) overall number of Orthoptera, Mantodea, Rodentia species (Caelifera) and one mantid species (Mantodea). and Eulipotyphla species; ii) number of species known In 2014 there were found altogether 44 Orthoptera spe- as the food of red-footed falcons and recorded primarily cies (21 Ensifera and 23 Caelifera species) and in 2016 in the territory of Slovakia in the works of Balát & there were two grasshopper species less, i.e. 42 Bauer (1955) and Tulis et al. (2017), and also in the diet Orthoptera species (21 Ensifera and 21 Caelifera spe- of other parts of the Pannonian Lowlands (Fülöp & Sz- cies) (Tab. 1). Mantids were found in both years. livka 1988, Haraszthy et al. 1994, Purger 1998, Comparing the food supply between the two years, Szövényi 2015); and iii) abundance of individual spe- there were three species less (Phaneroptera falcata, cies. For Orthoptera and Mantodea this was expressed Tetrix bipunctata and Tetrix undulata) in 2016, but we with semiquantitative values (see above), while the loc- found one rare bush-cricket Platycleis affinis more in ality score was calculated for each site: the sum of Tvrdošovce. In total we found at least 23 species inter-

4 Slovak Raptor Journal 2017, 11: 1–14. DOI: 10.1515/srj-2017-0005. © Raptor Protection ofSlovakia (RPS) esting as food supply for the studied falcon species and 15 species rare from the viewpoint of zoogeography and faunistics. Altogether 22–33 species were found at the particular sites in 2014 and slightly more, 23–38 Orthoptera species in 2016 (Fig. 2). Mantids were found at all sites. The species abundance at the particular sites was related to the vegetation diversity, mosaic of microhabitats, and the level of preservation or isolation of the locality.

O r t h o p t e r a i n t h e f o o d s u p- p l y o f R F F a t t h e R u s o v c e Fig. 2. Number of Orthoptera and Mantodea species at five s i t e studied red-footed falcon sites in 201 4 and 201 6. Obr. 2. Počet druhov Orthoptera a Mantodea na piatich Altogether 23 Orthoptera species were found there (in študovaných lokalitách sokola kobcovitého v r. 201 4 a 201 6. both 2014 and 2016), mainly in the ecotones of field spinneys and windbreaks. The species considered interesting as food for RFF are mainly Ruspolia nitidula, Platycleis veyseli, Tettigonia viridissima, Gryllus ably due to little-preserved biotopes at the studied site, campestris, Calliptamus italicus, Oedipoda caerules- which appears to be the least suitable for the target fal- cens, Aiolopus thalassinus. Rare species from this site con species nowadays. The species valuable for the food were katydids Phaneroptera nana, R. nitidula and mac- of RFF were P. nana, R. nitidula, T. viridissima, G. ropterous individuals of P. veyseli. The most abundant gryllotalpa, while Platycleis grisea was the species typ- species were tree crickets Oecanthus pellucens and ical for this site. We also found there an allien bush grasshoppers Euchorthippus declivus, Chorthippus cricket Meconema meridionale, which at that time was apricarius and Chorthippus biguttulus (Tab. 1). only the third species record in Slovakia after Bratislava and Zvolen (Vlk et al. 2012). The most abundant were O r t h o p t e r a i n t h e f o o d s u p- tree crickets O. pelluscens, grasshoppers E. declivus, C. p l y o f R F F a t t h e L e h n i c e apricarius, C. biguttulus. s i t e We found there 25 and 26 Orthoptera species in both O r t h o p t e r a i n t h e f o o d s u p- studied years. The species considered most valuable p l y o f R F F a t t h e B o d z a s i t e from the viewpoint of food supply for RFF were mainly Overall, we found 33 and 29 Orthoptera species here bush-crickets R. nitidula, T. viridissima, species of Met- (2014 and 2016 respectively). The most valuable food rioptera genus, crickets Gryllotalpa gryllotalpa and G. supply for RFF consisted of P. nana, Conocephalus fus- campestris. The most abundant species, similarly to the cus, Conocephalus dorsalis, R. nitidula, T. viridissima, other sites, were tree cricket O. pellucens, grasshoppers two species of Metrioptera genus, and G. gryllotalpa, C. E. declivus, C. apricarius, C. biguttulus, though most of italicus. Several of these species occur there mostly be- the studied plots were strongly ruderalized. The rarer cause of the amount of wetland biotopes in the studied species at this site were P. nana, R. nitidula, crickets plots, several of which belong among the most abundant Pteronemobius heydenii, Xya pfaendleri (on the bank of ones. the reservoir 1.5 km north of the village of Lehnice), Mantis religiosa was also rather abundant there. O r t h o p t e r a i n t h e f o o d s u p- p l y o f R F F a t t h e T v r d o š o v c e O r t h o p t e r a i n t h e f o o d s u p- s i t e p l y o f R F F a t t h e Z e l e n e č This site is highly valuable from the viewpoint of the s i t e well-preserved state of halophytic vegetation and fauna, Altogether 23 and 24 Orthopera species (2014 and also regarding orthopterans. The most species of all the 2016) were found there, which is the lowest species studied sites were found here, 34 in 2014 and 38 in number in comparison to the other studied sites, prob- 2016. Bush-crickets P. veyseli, P. affinis, Decticus ver-

5 Krištín A, Tulis F, Klimant P, Bacsa K & Ambros M: Food supply (Orthoptera, Mantodea, Rodentia and Eulipotyphla) and food preferences of the red-footed falcon (Falco vespertinus) in Slovakia ť k a e e a i t s c v a i o o t m n e r n n a e a 2 1 2 1 2 1 2 t w t b d i z d e t d o e ú n č n n h 1 2 2 2 1 1 1 2 1 c w i u o a o v b p w u á o a 1 2 1 1 1 2 1 3 m q G a i i n – š e n a o m m v v v 3 1 1 2 1 1 1 2 2 í G W d e a t o r t a l , s i l a t v t u t 1 1 2 2 2 2 1 1 1 1 3 2 2 3 1 o i s G e n T t k e m h a n r t o u u 2 2 2 1 2 2 1 1 2 3 1 2 a F o s f k f v q i o k e i – 2 1 2 1 1 1 2 3 1 2 3 – L m e a v m e F u z a l r y e s ; d t 1 3 3 2 1 1 1 2 1 t a ( w i s a l o o ( v i 6 a p k B 2 2 2 2 1 2 2 1 1 1 2 1 1 3 2 2 1 6 w d k 1 a 1 e o 0 v v l t 0 2 č o a 1 1 2 2 1 1 1 1 2 l ý l W 2 e e d 6 n S u r n a n 1 a 2 2 2 1 3 1 2 1 3 1 ó G e m e a 0 l n 4 k u d 2 e i e s 1 4 c 2 1 1 1 1 1 1 2 s G Z 0 1 t m ; – 2 0 u a v 2 2 1 2 1 2 1 1 1 3 F o n e o h e r z t c c n c o i i a e n o 3 2 1 1 1 2 1 1 3 i F i c z n k n d d s h o o e h r 1 1 1 1 1 3 n j y W e c t l u o i v L r l a c 0 f l d a 2 3 1 1 1 1 1 1 1 1 1 1 3 2 1 1 F o 0 a c d f h 1 – o l e é 3 3 1 2 2 3 1 1 > t e t W e i ; e o h c i v s t l ý o v d o 2 1 2 1 2 1 1 1 3 f W a n - n a c o t i u d z b s e d 2 2 1 2 1 2 3 1 3 d e o i o W č u r e p v k o i R d e p 1 2 1 3 1 1 F d r a é l h n o t i v i o i c f k 2 1 2 1 1 V s m 0 e o ľ o r ; 0 e e ) s u 1 s 2 1 2 1 1 1 1 1 2 1 V c v s ) t k e > v i h o s t l c o 4 c 1 2 4 1 2 1 4 n G n p e š ô e l , a p o . 0 v p 2 3 1 2 1 1 2 d s G d d 2 o l n r ( 0 n – i u v S 2 2 3 2 2 2 1 1 1 3 3 s G ( b d T e 0 a a t n h i 0 n u 2 1 2 3 1 2 3 1 2 2 1 2 1 3 3 1 2 F c s y 1 r o á t r t a – e l í n 2 1 2 1 2 2 2 3 1 2 3 L l g 1 v a o e k a 1 z r k 4 c k r d o 2 1 3 2 1 1 1 2 1 a W o , u – l s o . c b d B h 2 1 3 4 2 2 2 3 1 2 1 2 1 1 2 3 1 1 1 1 1 ý e W y d n c i v n e n ý t r a č a 0 1 2 1 2 3 2 1 3 n e r W g e t 0 r s 4 č ; . o n 1 e a 1 o a 1 2 1 1 1 3 1 1 3 1 a p e i G – č 0 p l m d k 1 ú 2 r e v a a 1 s o 3 1 2 1 2 1 1 2 Z G s f v - ý a t o o , l e n . n 2 1 2 1 2 1 1 1 3 F h v – a x S i a e c f n e d L c ý n i l i e 3 2 2 1 1 2 1 1 3 F n n , i a n t 0 u ď m v e s h 1 b i a a 1 1 1 1 1 1 3 ý W r e e – a d i n b k 3 L c z 3 o n 2 3 1 1 1 1 1 1 2 1 1 3 2 1 1 h F e a , o c – z p m . i c t l s d 0 2 – e a W h . a y n i t f i a c u n p n w r e v c e 1 2 0 e W , d d a o á h 1 a t o n s z m t – – n 1 1 3 v i u e W n n 3 l a i v t a R t t e m – 2 d s 1 2 1 1 1 1 1 3 1 F e d M á e a s e r o , t r . d l d p r - n x a y a n r o r a e n a G c r u 2 , r M e a e 3 i r , a r . a – a č k e r i s d t i z < L ; e í a e e n s p t n m ) i s l i r , a t i s u o c t l p e u i m s a a s e y t l d ô s t 3 a a h e a a a d r n e u n p u t n i a n t t n n i l r p r s y t p t o e i r a c r o c a s m i l < a r d e i a s o i o l s e s n s e i n t c s o – á v i t e O o c o l l d r s l v h s s h e o e u i a o i t z a t i o i a s e a – f f d u a l r h s r a l r o s l e r t r l d l i i f c s v f n n b l s e i W o c e a a e s w l u a y a a r s s g i e d r n u e r O t e u s o i t t i r i s s , h y i a a h r a i d i o u u b r f r r e e p i t m – r r r c a l l p u s c i a l a r f g u ť m e t y l b l l c l c a y r i m s l i e e l e y r v n a a e s d a a g v a a p m ľ t a a u t t s o l u v n a w e n y r r r i e y v u n e u i h h o n t a f e l o r l d p p u r a b s s s a p , y e e m m v v i n t m i i i – p p p l n e c v p a s t t a g í i o n o o h g u a t d i d k h e e t n e e t e e e o r r e e l a a o u p p c o l l l b b s t u o 1 e i t s F e c n f n p n n a o c c n n e e o c d c c c o o 1 n c t o č d i o u : ; a u b i p i i a o i i x x x x x a o o g i l o o o a l l l n n l p t l y y y i i i i i t r r t i a l l s o a r a b k / t t t c c t t l d t r r r r r e c o / n n s c : s b a a o a p y y n t t t t t t i a e í k e e a a a P o e e e e e o A d r r e i i s o o u e r a h h h l l l t y ; e i e a e e e e e e n s r y r r d r ) . . a i t e v o p L P P M M C C R D M M P P P P T G P G M M O X T T T T T o n / o ó r i f s e 1 1 i o l k f g l g l o e g g g i i e r i i l . . t a t r v e s e e u a y t t b b t l t m – c o r o a n i e l e e a a a a a e o y l b E T G C T T c v G T k s S

6 Slovak Raptor Journal 2017, 11: 1–14. DOI: 10.1515/srj-2017-0005. © Raptor Protection ofSlovakia (RPS) - a n n a P o 1 2 2 1 2 2 2 1 1 w h e e é h t 1 1 1 2 1 2 2 2 1 3 1 1 2 2 t i c w v f v o o o 1 2 2 4 1 2 2 3 3 1 2 2 2 2 G c 4 0 š s b 4 2 o e o t 3 2 4 3 1 2 2 4 1 3 3 1 G d i k r s v 2 4 4 3 2 2 2 2 2 4 1 1 3 3 1 a g G l T n o i t k 1 4 2 4 1 2 2 2 2 4 2 3 2 2 2 F s o e s n 3 3 2 2 3 3 2 1 1 1 L a r e z 7 e . v 7 d 2 2 2 2 2 2 1 1 1 w h 8 a 1 t o r 3 t o B 2 3 2 1 2 3 3 1 1 w o n p i č 3 3 2 2 1 3 1 1 F W v e 6 F 8 n . 1 2 ý 4 3 2 2 2 1 2 1 1 G e R 8 0 l 1 n f 2 2 e a o 3 1 3 1 1 G v Z t o e n i i 3 2 2 2 1 1 1 1 F e d m c i r e 8 3 2 2 2 2 2 2 F . e n 1 h t t 8 1 h e 2 3 2 1 2 1 1 1 1 W n e d i L l d 3 2 2 1 2 2 1 1 2 F o e i b f i t 3 1 2 2 2 2 3 1 W e . n c p e s v 3 1 2 2 2 2 2 3 1 8 d W . i 4 o 0 s 1 s i n 3 3 3 2 2 1 3 2 3 1 1 W u e e l e R c 2 1 1 2 2 2 2 F y b t s a l 2 2 1 2 2 2 1 1 a V P h e . 1 2 2 2 2 1 3 1 1 1 V d c p o v s r o 1 2 4 3 2 2 4 3 1 2 2 4 2 5 G s . š i 8 * * 4 e o 1 , l 3 3 2 4 2 1 2 2 4 1 3 3 1 4 G d c u r y k t v s 3 4 4 3 2 3 2 2 4 1 3 4 2 G a T l n e P 3 4 2 4 1 2 2 2 2 1 4 2 1 4 2 3 F v s o l u 3 3 2 2 3 2 1 1 1 L S n a z e 3 . 6 a g d 3 3 2 2 2 1 1 1 0 W 1 n o * 4 * B 2 3 2 2 3 1 2 1 o W , h a i č é 3 3 2 2 3 3 2 1 1 1 k t W e i 4 a 5 v n . v 1 o 3 3 2 2 2 2 1 1 1 e 5 G 1 o 0 l l c 2 2 e b S 3 1 2 1 1 Z o G n k i 3 2 2 2 1 1 1 2 F F a e l F c 8 o i . 3 2 2 1 2 2 2 1 1 F 2 R k n 8 1 f o 2 h s o 4 2 2 1 1 1 2 W e t L e e i 4 2 2 1 2 2 1 1 1 3 v F ) d a 8 r t e 9 3 2 3 2 1 2 2 1 e W o h 9 t c p 1 v 2 3 3 2 1 2 3 1 n W 4 r i 1 o v 1 2 e s d o 1 3 3 3 1 2 3 1 1 g u W ý e r h i n f R u é i t a t 1 1 4 1 4 3 2 2 2 3 2 1 2 F P i v n ( / v o e y o s n d i i n c e i i b ž m s n í c i r l o e / n e e a k t e ) j s y p d t e b i 8 e u a i s s s s t l s i l d k o 9 l s n s s a s e s l a u a y o s r h 9 s u l e u u r a p u o v n i r l l k e k s i n e i i 1 u c r r o i a h l t c r e t u e s u i s ó o o v s l r t a o b c l e p l . p s n l p s a t v n i u n s e c e i l s e u h y p l i n s a a l i u m e c . . a e i s s r r r i g r c s d p r h t u u l . r o d g e e p r a s P r c p i r o s a i u c b s a n s ó s s a s s u i a t e a b b d m o p n n a n l i s o h k r u u s h o u i r i P a o i a t a t c u s s s s s s s s ( s p p u p y o s b c v r r s a g p r t h a á u u u u u u u i u / p p r p k u i t l o d e h i i u i u a k l o u a p p p p p p p p t t h r e č t n h h h e p s v s m i a a n d p p p p p p p s r p o t t c t i t t i r i i i i i i i a i a o s r r r u a t c o l o e r i b o d s s a t h h h h h h h s h o e o o o p i n t t t t t t t c k t o h p s z y o b o w e t p i c l r r r r r r r r i v h h i h o o y o o e u h n l k / l o d n d i / s l c o o o o o o o r o c c t i . r C e C P o L o a e m n a o h h h h h h h h h F i u u u t o e d r y y . . s h t t d f n p C A O D E E E C C C C C C C C O S M C / t i i i 1 1 u l l a o o h e d . . r i n i t a a . d c č r a n b b e c o c ý o o c i o e o a a g r o o n T T y l b A l N p * n * i

7 Krištín A, Tulis F, Klimant P, Bacsa K & Ambros M: Food supply (Orthoptera, Mantodea, Rodentia and Eulipotyphla) and food preferences of the red-footed falcon (Falco vespertinus) in Slovakia

S m a l l m a m m a l s i n t h e f o o d s u p p l y o f R F F a t t h e R u s o v c e s i t e Altogether 7 species of small mammals were recorded there in 2014 (Tab. 2). The common vole (66.6%) and wood mouse (Apodemus sylvaticus) (9.8%) were the most abundant species there. Common vole is important in the diet of RFF. In 2016 similarly 7 small mammal species were found there, however by then the most abundant species were bank vole (Clethrionomys glare- Fig. 3. Number of small mammal species at five studied red- olus) (39.3%) and M. arvalis (25%), while A. sylvaticus footed falcon sites in 201 4 and 201 6. was represented at 14.3%. Obr. 3. Počet druhov drobných cicavcov na piatich študovaných lokalitách sokola kobcovitého v r. 201 4 a 201 6. S m a l l m a m m a l s i n t h e f o o d s u p p l y o f R F F a t t h e L e h n i c e s i t e Altogether 7 species of small mammals were recorded here in 2014 (Tab. 2). The yellow-necked mouse (Apo- demus flavicollis) (36.5%), A. sylvaticus (22.9%) and rucivorus, crickets Melanogryllus desertus common vole (21.9%) were the most abundant species. and Modicogryllus frontalis, grasshoppers Aiolopus A. sylvaticus and M. arvalis are the species which are thalassinus, Dociostaurus brevicollis, and Stenobothrus significant from the viewpoint of the red-footed falcon crassipes may be mentioned as the most valuable diet. In 2016 we recorded only three small mammal orthopteran species. The most abundant species were species there, the most abundant being A. flavicollis grasshoppers A. thalassinus, Chorthippus dorsatus (54.1%), C. glareolus (29.7%) and A. sylvaticus and C. oschei, thermophilic Ponto-Mediterranean spe- (16.2%). In 2016 the common vole was absent there. cies E. declivus and in the salt marshes of the highest quality also the thermophilic grasshoppers S. crassipes, S m a l l m a m m a l s i n t h e f o o d which were often one of the most abundant. The most s u p p l y o f R F F a t t h e Z e l e n e č abundant overall there were the katydids and crickets C. s i t e fuscus species, O. pellucens on tall herbaceous plants Altogether 6 species of small mammals were recorded and shrubs, and Metrioptera roeselii, grasshoppers Cal- there in 2014 (Tab. 2). The most abundant was M. ar- liptamus italicus and Omocestus haemorrhoidalis on the valis (59.2%). M. arvalis and A. sylvaticus (14.3%) are ruderal vegetation (Tab. 1). species significant from the viewpoint of the diet of RFF. In 2016 we recorded 5 species of small mammals S m a l l m a m m a l s ( R o d e n t i a there. The most abundant was A. flavicollis (65%). In a n d E u l i p o t y p h l a ) a s t h e 2016 the common vole was absent there. f o o d s u p p l y f o r F a l c o v e s- p e r t i n u s S m a l l m a m m a l s i n t h e f o o d Altogether ten rodent species and five Eulipotyphla s u p p l y o f R F F a t t h e B o d z a species were found as food supply at five sites (10 trap- s i t e ping lines), the former and current RFF nesting territor- Altogether 6 small mammal species were recorded here in ies in 2014 and 2016. In 2014, there were 15 species 2014 (Tab. 2). The most abundant species were M. arval- and 13 in 2016 (Tab. 2). Comparing the years 2014 and is (65.5%) and A. sylvaticus (18.4%). Both of these spe- 2016 we did not record fluctuations in the abundance of cies are significant prey of the red-footed falcon. In 2016 small mammals. Only the abundance of common vole we recorded 7 species of small mammals there. The most rapidly dropped in 2016 (with the exception of the abundant species were M. arvalis (55.1%) and striped Bodza site). field mouse (Apodemus agrarius) (28.6%), while A. sylvaticus abundance decreased significantly (2%).

8 Slovak Raptor Journal 2017, 11: 1–14. DOI: 10.1515/srj-2017-0005. © Raptor Protection ofSlovakia (RPS)

Tab. 2. Small mammals (Rodentia and Eulipotyphla) in the food supply in five former and current nesting sites of Falco vespertinus (abundances of species are indicated to 50 trap-nights; black frame = species recorded as red-footed falcon (RFF) prey in Slovakia; L1 – 1 st line, L2 – 2nd line. Sites: Rus – Rusovce, Leh – Lehnice, Zel – Zeleneč, Bod – Bodza, Tvr – Tvrdošovce. Tab. 2. Drobné cicavce (Rodentia a Eulipotyphla) v potravnej ponuke na 5 minulých a súčasných hniezdnych lokalitách Falco vespertinus (početnosť druhov je uvádzaná v prepočte na 50 pasconocí; čierny rám – druh zaznamenaný v potrave sokola kobcov- itého na Slovensku; L1 – 1 . línia, L2 – 2. línia, Lokality: Rus – Rusovce, Leh – Lehnice, Zel – Zeleneč, Bod – Bodza, Tvr – Tvrdošovce. year / rok 2014 2016 locality / lokalita Rus Leh Zel Bod Tvr Rus Leh Zel Bod Tvr biotope / biotop L1 L2 L1 L2 L1 L2 L1 L2 L1 L2 L1 L2 L1 L2 L1 L2 L1 L2 L1 L2 Muridae Arvicolinae Microtus arvalis 7 1 0 3 7.5 1 0 4.5 1 8.5 1 0 4 1 2 9 27 2 1 Clethrionomys glareolus 1 .5 5.5 0.5 3 11 2 9 1 1 3 Microtus subterraneus 0.5 1 Murinae Apodemus agrarius 2 0.5 3 7 7 Apodemus flavicollis 1 .5 0.5 1 0.5 7 4 3 0.5 1 1 0 1 0 1 1 2 1 Apodemus sylvaticus 1 .5 1 2.5 8.5 3 0.5 2 6 4.5 1 3 1 5 9 4 1 8 Apodemus uralensis 1 1 0.5 0.5 2 1 1 2 2 Mus spicilegus 0.5 1 Micromys minutus 2 2 Rattus norvegicus 1 Scoricomorpha Soricidae Crocidura leucodon 0.5 Crocidura suaveolens 1 0.5 2.5 2 Neomys anomalus 0.5 Sorex araneus 1 .5 1 0.5 9 1 1 2 2 7 Sorex minutus 0.5 1 1 locality score / skóre lokality 12.8 24 12.3 21.8 15.5 16 18.5 10 24.5 15.5 No. of RFF prey species / 2 2 2 2 2 2 1 1 2 2 počet druhov koristi sokola kobcovitého *genus Mus sp. was identified in diet of red-footed falcon in Slovakia / *rod Mus sp. bol identifikovaný v potrave sokola kobcovitého na Slovensku

2 S m a l l m a m m a l s i n t h e f o o d Mantodea among the studied sites (n = 245, χ 4 = 8.24, P s u p p l y o f R F F a t t h e = 0.08). In 2016 the site as a factor has even lower im- T v r d o š o v c e s i t e pact on the values of Orthoptera and Mantodea abund- 2 Altogether 12 small mammal species were recorded ance among the studied sites (n = 215, χ 4 = 5.52, P = here in 2014 (Tab. 2). The most abundant were common 0.24). shrew (Sorex araneus) (29%), M. arvalis (16.1%) In small mammals in 2014 we recorded significant and A. sylvaticus (14.5%). Only at this site we also re- site effect on the semiquantitative values of small mam- 2 corded steppe mouse (Mus spicilegus). M. arvalis, A. mal abundance among the studied sites (n = 75, χ 4 = sylvaticus and Mus sp. are significant as prey of the red- 13.05, P < 0.01). However, we did not record any signi- 2 footed falcon. In 2016 we recorded 11 species of small ficant site effect on their abundance in 2016 (n = 90, χ 4 mammals there. The most abundant species were A. = 14.1, P = 0.84). sylvaticus (25.8%) and S. araneus (22.6%). In 2016 the common vole was absent there. D i e t p r e f e r e n c e s o f R F F a t t h e S y s ľ o v s k é p o l i a s i t e d u r- S i t e e f f e c t o n t h e s p e c i e s i n g 2 0 1 4 a n d 2 0 1 6 c o m p o s i t i o n Comparison of the diet and food supply showed that the In 2014 we recorded nonsignificant site effect on the red-footed falcon preferred the great green bush-cricket semiquantitative values of abundance of Orthoptera and (T. viridisima) (in 2014: n = 24 Z = 0.84, CI: 0.12 –

9 Krištín A, Tulis F, Klimant P, Bacsa K & Ambros M: Food supply (Orthoptera, Mantodea, Rodentia and Eulipotyphla) and food preferences of the red-footed falcon (Falco vespertinus) in Slovakia

Fig. 4. Ivlev´s preference index of the red-footed falcon (RFF) diet at the Sysľovské polia site during 201 4 and 201 6 (-1 – total avoidance of food supply; 1 – total preference of food supply; * – significant preference or avoidance; Chorthippus sp. covers all species of this genus found in the RFF diet). Obr. 4. Ivlevov index preferencie potravy sokola kobcovitého na lokalite Sysľovské polia v priebehu rokov 201 4 a 201 6 (-1 – celkové vyhýbanie sa potravnému zdroju; 1 – celková preferencia potravného zdroja; * – štatistický významná preferencia resp. vyhýbanie; v rode Chorthippus sp. sú zahrnuté všetky druhy tohto rodu, zaznamenané v potrave sokola kobcovitého).

0.18, P < 0.05; in 2016: n = 25, Z = 0.84, CI: 0.11–0. food, were described as species which the red-footed 0.17, P < 0.05) as its prey in both studied years. While falcon avoids (Fig. 2). the proportion of T. viridisima in the food supply was 3% in 2014 and 4% in 2016, its proportion in the diet Discussion was 20% in 2014 and 14% in 2016. Even though the C. F o o d s u p p l y italicus was preferred in both years, in comparison with According to the published knowledge from the Panno- its availability in the breeding territory it was preferred nian Lowlands, flying insect species represent a major significantly only in 2014 (N= 24, Z = 0.84, CI: part of the RFF food spectrum, which are supplemented 0.05–0.1, P < 0.05; with 0% proportion in food supply by their hunting of small mammals and other vertebrates vs. 11% in diet). Similar preference was found for the (Fülöp & Szlivka 1988, Haraszthy et al 1994, Purger common vole, but it was preferred significant only in 1998, Szövenyi 2015, Tulis et al. 2017). From the view- 2016 (N = 25, Z = 0.84, CI: 0.22–0.31, P < 0.05; with point of the food supply and availability of the studied 6% in food supply vs. 26% in diet). groups of insects and mammals, we consider Though mice (Mus sp.) were not recorded in the Tvrdošovce to be the most suitable site for RFF. In both food supply at the Rusovce site during the monitoring studied years we recorded there not only high abund- of small mammals, in 2016 the species was recorded ance but also a great variety of species which had just once in the diet spectrum of RFF, which was reflec- already been recorded in the RFF diet in the past. The ted in its high preference. Unexpectedly RFF were seen next most suitable were the Lehnice, Rusovce and to avoid preying on the wood mouse, which belonged Bodza sites. The Zeleneč site showed itself to be less among the abundant small mammal species at this site suitable from the point of view of food availability. In in both studied years (with 9% proportion in food sup- the last seven years, the RFF has been breeding only at ply vs. 1% in diet in 2014 and with 12% in food supply Rusovce, most probably because of links with the pop- vs. 1% in diet in 2016). In the preference analysis any ulations in Hungary and Austria (Palatitz et al. 2015, species occurring at the site but not forming part of the Dvorak et al. 2016, Slobodník et al. 2017). The

Tvrdošovce site as well as the other former nesting sites in the abundance of the common vole. While in 2014 in is probably too isolated from the regular breeding pop- south-western Slovakia the species growth culminated ulation, and that is the reason why despite the quality of and the common vole was the most abundant species of their food supply they stay unoccupied by this falcon, small mammal at all five studied sites, in 2016, with the also despite their suitable breeding habitats and suffi- exception of the Bodza site, there was a sudden slump in ciency of nest boxes. In terms of the comparison of spe- its abundance, when at the Lehnice, Zeleneč and cies composition and abundance it has been found that Tvrdošovce sites the species was not recorded at all. invertebrates, in comparison to small mammals, showed These results suggest that we probably recorded kind of lower variety both in the interannual comparison of the the population decline typical for fluctuations in the same sites and between the sites. Certain differences in common vole population in the environmental condi- the availability of invertebrates among the five sites tions of Central Europe (Jacob & Tkadlec 2010, Jacob et may be explained by the habitat composition effect. Its al. 2013). effect on the species composition in various biotopes It is known (l.c.) that apart from the groups studied has been described for several animal groups, including by us (small mammals, Orthoptera and Mantodea), the invertebrates (Fahrig & Jonsen1998, Söderström et al. diet spectrum of this falcon species is also composed of 2001). All the observed Slovak former and current nest- beetles (Coleoptera), birds and frogs. However, we have ing sites are situated in agricultural countryside. This is not quantified the availability of these last three animal characterized mainly by uniform, large-volume produc- groups. Especially during humid and cold periods and in tion fields strongly affected by intensification, which wet habitats, the toad Pelobates fuscus for example may has a negative impact on the abundance and species become an important part of the red-footed falcon diet variety of invertebrates (Wickramasinghe et al 2004, (Horváth 1963, Haraszthy et al. 1994). It is then neces- Cherrill 2010). In contrast, the species variety of inver- sary to focus also on the importance of other species of tebrates increases with growing heterogeneity of the ag- small vertebrates and invertebrates in the food supply of ricultural landscape (Fahrig et al. 2011), in which case the red-footed falcon at the last breeding sites in Central the area may supply more potential food sources Europe. (Benton 2003). The Rusovce site is composed on the Slovakian side of large-volume production fields (56%), F o o d p r e f e r e n c e s while the rest of the site on the Austrian side consists of Dietary opportunism within the characteristic hunting a heterogeneous agricultural landscape which may have strategies is known in many species of animals and rap- a positive impact on the species breeding (Fig. 1). Alto- tors (Jaksić & Braker 1983, Martin 1987). Based on our gether 63% of the Lehnice site is included in agro-en- results it is evident also in the RFF in Slovakia. The fal- vironmental schemes minimizing the intensification or con preferred the large insect species (T. viridissima, D. pesticide covering of the land, and supporting the pro- verrucivorus, C. italicus) and abundant species of small tection and preservation of natural and semi-natural bi- mammals (M. arvalis) in its food supply. Twenty four otopes. On the other hand, at the Tvrdošovce site only species from the food supply were marked as “not pre- 1.8% of the area is included in an agro-environmental ferred” (i.e. avoided) species. On the other hand, the scheme, and the Bodza and Zeleneč sites are not in- availability of several prey groups (frogs, birds, beetles) cluded in any agro-environmental schemes at all. In was not investigated. For example common spadefoots any case a significant site effect on the abundance of the (Pelobates fucscus) can play an important role in the potential food was recorded only in the case of small RFF diet during colder and rainy periods of breeding in mammals in 2014. Hungary (Horváth 1963, Haraszthy et al. 1994). We are Inter-annual differences in the availability of inver- therefore not able to adopt a complete standpoint on tebrates at the particular sites may also be explained by RFF diet preferences. The species composition of differing natural conditions. Rainfall or low temperat- Orthoptera in the food supply and in the diet was stud- ures for example have a negative impact on the amount ied on the basis of a big sample (5,164 specimens from of insects on various agricultural crops (Beirne 1970, 223 red footed falcon nests) at its nesting sites in south- McClure1989). eastern Hungary in a period of three years (Szövényi Regarding small mammals, we did not record fluc- 2015). This researcher found 26 Orthoptera species in tuations in their abundance among sites, but in the inter- the food supply there, of which 18 species were also annual comparison we recorded the biggest differences found in the diet. Compared with this study, we found

11 Krištín A, Tulis F, Klimant P, Bacsa K & Ambros M: Food supply (Orthoptera, Mantodea, Rodentia and Eulipotyphla) and food preferences of the red-footed falcon (Falco vespertinus) in Slovakia

45 species in the food supply (from cca 14 500 identi- the annual mowing is omitted. Aschwanden et al. (2005) fied specimens), though only six Orthoptera species described a mosaic of different habitat types with grass- featured in the diet, and overall 10 species in 2007 – land mown at different times of the year together with 2016 (Tulis et al. 2017, Fig. 4). This confirms the ex- undisturbed strips to be most likely to provide a year- ceptional variability in the foraging behaviour of the round supply of accessible food for vole hunters such as species and the reflection of the food supply in the diet the Eurasian kestrel. Moreover, perennial covers of composition. Different results may also reflect different broadleaved plants may represent enough habitats for methodological approaches in data collection on the insects (mainly Orthoptera and beetles), the most im- species diet in the studied years. Our food preference portant food for the red-footed falcon. On the other analysis shows avoidance of the wood mouse as prey, as hand, it is important to mention that there are still de- this species' activity does not completely overlap with bates on the clear impact of compensation measures that of the hunting falcon, but it can be trapped also in upon biodiversity (Korňan 2014). open habitats, such as mown alfalfa, maize and oil seed Comparison of the red-footed falcon diet from a rape fields (Zejda 1965, own unpublished results). single Slovak nesting site (Tulis et al. 2017) with the It seems to be that the red-footed falcon does not use food from other parts of the Pannonian Lowlands (Har- general hunting strategies in all habitats. The choice of aszthy et al. 1994) reveals a low number of frogs in the the hunting habitat and its distance from the nest can be red-footed falcon diet in Slovakia. Creation of artificial influenced by sex and colony size in the red-footed fal- but suitable aquatic habitats, representing natural reser- con (Palatitz 2011). However, this researcher identified voirs of rainwater, could lead to increased availability of two particular hunting strategies based on the analysis frogs and aquatic insects (e.g. Odonata) in the breeding of hunting habitats. The first one involved more hunting territories, and they might represent alternative food for over grasslands and alfalfa fields, while the second pri- the red-footed falcon, bearing in mind both the decline oritized grasslands and cereals. We have regularly ob- of the common vole and the lack of terrestrial insects in served the “air hunting strategy”, i.e. the hunting of cold and wet years. flying insects in the raptors' territories, mainly above groups of trees and permanent grasslands, and some- References times above stubble fields which are flown over albeit Aschwanden J, Birrer S & Jenni L 2005: Are ecological rarely, but mainly by flocks of C. italicus. compensation areas attractive hunting sites for common kestrels (Falco tinnunculus) and long-eared C o n s e r v a t i o n i m p l i c a t i o n s owls (Asio otus)? Journal of Ornithology 146(3): With regard to conservation and agricultural practice for 279–286. providing suitable foraging conditions it is necessary to Andersson M & Erlinge S 1977: Influence of predation mention that the species survives in an intensive agri- on rodent populations. Oikos 29: 591–597. cultural landscape, the so-called cultural steppe, so its Beirne BP 1970: Effects of precipitation on crop insects. existence is heavily influenced by human activity. Our The Canadian Entomologist 102(11): 1360–1373. analysis of food supply and diet in the foraging habitats Benton TG, Vickery JA & Wilson JD 2003: Farmland indicates that red-footed falcons use just the open agri- biodiversity: is habitat heterogeneity the key? Trends cultural landscape with enough permanent grasslands in Ecology & Evolution 18(4): 182–188. DOI: and well-preserved woodland and shrubby dispersed 10.1016/S0169-5347(03)00011-9. vegetation with minimal use of insecticides and ro- Cramp S & Simmons KEL 1980: The birds of the denticides. Intensively managed land brings risks con- western Palearctic, vol. 2. Oxford University Press, nected with the homogeneity of agricultural cultures, 728. where a combination of several negative factors Danko Š 2008: Poštolka rudonohá Falco vespertinus, threatens the species diversity. On the other hand, in- 288–289 In: Cepák J, Klvaňa P, Škopek J, Schröpfer creased heterogeneity in the uniform agricultural land- L, Jelínek M, Hořák D, Formánek J & Zárybnický J scape may lead to expanding and stabilising of the food (eds) 2008: Atlas migrace ptáků České republiky a sources in all the studied sites. An interesting alternative Slovenska [Czech and Slovak bird migration atlas]. thus may be ecological compensation areas in the form Aventinum, Praha, 607. [In Czech with English of wild flower strips and herbaceous borders in which summary]

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