Predation on the endangered Hungarian meadow viper ( rakosiensis) by Badger (Meles meles) and Fox (Vulpes vulpes)

Attila Móré1, Edvárd Mizsei2

1Institute for Wildlife Conservation, Szent István University; [email protected] 2Centre for Ecological Research, Hungarian Academy of Sciences; [email protected]

Abstract Hungarian meadow viper (Vipera ursinii rakosiensis) is a globally endangered with a few sub-populations remained after habitat loss and fragmentation. Now all habitats is protected by law in and significant conservation effort have been implemented by habitat reconstruction, development and ex situ breeding and reintroductions, but the abundance is still very low and the impact of conservation interventions are nearly immeasurable according to densities. Hypotheses have been raised, as the predation pressure is the main factor influencing viper abundance. Here we analysed the diet of potential mammalian predators (Badger and Fox) at a Hungarian meadow viper habitat, and found high prevalence of viper remains in the processed faecal samples, and estimated a high number of preyed vipers within half season in a single site. Effective predator control is recommended to support habitat developments and reintroduction.

Keywords: game; predator; predation control; predation pressure; conservation; ; .

Introduction

Meadow vipers (Vipera ursinii complex) are grassland specialist reptiles preying on grasshoppers (Baron 1992, Filippi & Luiselli 2004). Their global distribution of follow the Steppe biom with extensions to other grasslands, in Europe these snakes are present in the Western Alps & Appenines (Vipera ursinii ursinii), Dinarides (Vipera ursinii macrops) and Hellenides (Vipera graeca) mountain ranges; and the Pannonian (Vipera ursinii rakosiensis) and Bessarabian (Vipera ursinii moldavica) lowlands, plains (Mizsei et al. 2018). Lowland populations are threatened by habitat alteration, fragmentation and alteration; majority of the habitats are already gone, populations in Austria and Bulgaria are extinct, only a few populations remained in Hungary and (Krecsák et al. 2003). The Hungarian meadow viper (Vipera ursinii rakosiensis) is one of the most threathened reptiles of Europe, listed as Endangered by the IUCN Red List (European Reptile & Amphibian Specialist Group 1996); furthermore the subspecies is listed in annex II. and IV. of the EU Habitat Directive and strictly protected in Hungary. Despite the huge conservation efforts and significant improvements of habitat size and quality in the last decades, the current abundances of Hungarian meadow viper are still much more lower compared to historical numbers (e.g. Boulenger 1913). Most probably because past abundance of potential predators were very much lower (Reason, Harris & Cresswell 1993, Heltai, Bíró & Szemethy 2001), creating a favourable, low predation pressure epoch. A possible explanation for the low effect of habitat developments on contemporary abundance is that the remained population cannot make a demographic leap up, due to the high predation pressure.

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There are many observations and rumours from biologists, rangers and stakeholders working on the Hungarian meadow viper habitats, but no research have been conducted so far in the topic. However, is additionally known, mortality of radiotagged released vipers by predation is more than 75% within one year, and mark-recapture data of reintroduced viper population showed a low, 42% yearly average apparent survival rate. We designed this pilot study to quantify the effect and importance of predation we collected faecal droppings from potential mammalian predators (Badger, Meles meles and Fox Vulpes vulpes). Our questions were the following: (i) How frequently preyed the Hungarian meadow viper? (ii) What is the difference in the diet of predators (Badger, Fox)? (iii) Is it possible to estimate number of preyed vipers? If so, how many is preyed?

Material and methods We collected Badger and Fox dropping samples between June and December of 2018 biveekly (n = 9 sampling ocassion; n = 3 sampling occasions is missing due to logistical constrains) on the second largest continuous viper habitat at Bócsa-Bugac homokpuszta HUKN20024 SCI in the Kiskunság national Park (fig. 1). Samples were kept in dry (in silicagel) and cold (~5°C) conditions until processing. We have processed the faecal samples following the protocols described by Jędrzejewska & Jędrzejewski (1998): (i.) we sorted food remains, (ii.) meauser weight (0.01±0.005 g precision), (iii.) identified diet components to Order taxonomic level, and Species level in case of Reptilia. Biomass of diet components were corrected using the correction factors described by Jędrzejewska & Jędrzejewski (1998): ×14 plants, ×5 arthropods, ×18 reptiles and ×23 mammals. Monthly frequency and biomass portion of diet components were calculated in the R statistical environment (R Core Team 2018).

Figure 1. Map of sampling sites.

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Results

We found six Badger toilets were sampled across the whole study season; however we found Fox droppings only in two months (June and August). We were able to use 64 Badger and 10 Fox faecal samples for the study (fig. 2). Temporal pattern of food item frequency in Badgers’ diet varied across the study season (fig. 3): arthropods are present in summer end beginning of autumn, and missing in colder months. The main arthropods prey found were Polyphylla fullo (including larvae), Copris lunaris and Orthopterans, and viper remains was found in almost all months, including winter time. We not assessed the temporal pattern of diet of Fox due to the small sample size, however, these Fox samples showed very high prevalence of reptiles. We found scales of Vipera ursinii rakosiensis in all analysed Fox droppings, which possibly originated from three different Fox individual, but please note the limited sample size. Because of the small quantity of Fox samples we were unable to analyse the difference of diet of the two predators. Assuming that every faeces with viper remains are independent case of preying only one viper individual, our result suggest in the study time at the study site at least 46 Hungarian meadow viper was preyed by Badger, and 10 by Fox.

Figure 2. Healed injury on a living Hungarian meadow viper (A), viper preyed and vomited back by Fox (B), viper dorsal and ventral scales in Badger faeces as found in the field (C), viper scales and bones in Badger faeces (D-E), viper and Polyphylla fullo remains in Badger faeces (F).

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Figure 3. Monthly variation of diet composition of Badger.

Figure 4. Balkan wall (Podarcis tauricus) tails and a partial body of Sand lizard (Lacerta agilis) from a single Badger faeces from December.

Discussion

Our results support the hypothesis that common mammalian predators are frequently prey on the Hungarian meadow viper, despite it is a rare and elusive . The Hungarian meadow viper is a frequent prey of Badger and Fox at the study site, as we found high prevalence of vipers in the analysed sample of both predators. The estimated mortality (~60 viper individual) in the study year is a shockingly high number, if we take into account that the current estimation of total population size in the Pannonian basin is 600±100 individual (Annex 11 country report, 2018). We expect similar mortality and predation pressure at other sites, as there is no active predator control at other viper habitats. Mortality caused by avian raports should be measured too; however, the results of our pilot study suggest that predation is the most priority threat currently to the Hungarian meadow viper in Hungary, as habitat loss and degradation has been already inhibited.

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The temporal pattern of dietary habits of Badger on the study site shows vipers used to be prey in winter time, suggesting that this predator dig out hibernating snakes, which could be a further threat as these snakes can overwinter in small groups, furthermore important hibernaculas can be destroyed. Preying on hibernating reptiles was shown also by unexpectedly found remains of 19 Balkan wall lizard (Podarcis tauricus) individuals in a single Badger faeces in December (fig. 4).

Recommendations

To enhance population growth and successfulness reintroduction of Hungarian meadow vipers to reconstructed habitats effective predation control is highly recommended. The herein studied predators are not protected by law and can be legally hunted in all seasons (permission is needed for Badger from 1st of March to 31th of June). Both species can be effectively trapped or excluded by fencing. Prior to complete predation eradication a controlled study with full block design should be carried out to test the effect of predation control on the abundance of Hungarian meadow viper populations.

Acknowledgements. We thank to Csaba Vadász and Márk Lucza rangers of Kiskunság National Park Directorate for their help in the field. We thank to Patrik Katona, Péter Dobra, Dávid Radovics, Zsófia Lanszky, Gergő Rák for help in sampling. We thank to Miklós Heltai and Zsófia Lanszki for methodological suggestions also. This study has been carried out as own research of the Kiskunság National Park Directorate.

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