OBSERWATIONS OF BADGERS’ (MELES MELES) BEHAVIOUR NEAR THE SETT IN STOBRAWA LANDSCAPE PARK (SOUTH – WESTERN POLAND)

Joanna Kochan, Wojciech Kruszyński, Grzegorz Kopij
Department of Genetics and Animal Breeding, Wrocław University of Environmental and Life Sciences, Poland

ABSTRACT

From winter 2006 to spring 2008 we studied badgers' behaviour (Meles meles) at the main sett. The study was conducted in the Stobrawa Landscape Park (south – western Poland). Badgers' behaviour could be analyse:  in the sett (underground), near the sett and on foraging grounds. The aim of this study was to recognise this predator behaviour in SLP. We were interested whether badgers behavior depends on the environmental conditions, especially on the population density. Most of this type of research had been conducted in western Europe, where badgers occur in high densities (e.g. 75 individuals/10 km² [10]; 253 ind/10 km² [19]). In central and eastern Europe, badgers' densities seem generally lower, with mean group size of only one to three  [5,13]. The badgers in our study were living at low densities, typically to many populations in continental Europe. We wanted to test hypothesis that differences in population densities across their geographic distribution may result in different behaviour near the sett. Our results have shown that badgers' behaviour changed during the whole year. Various activities near the burrow took, depending on the season, from several minutes to several hours. Some behaviours were season – specific.

Key words: badger, Meles meles, density, foraging behaviour, activity.

INTRODUCTION

The Eurasian badger Meles meles (Linnaeus 1758) is widely distributed throughout the Palaearctic region [17]. This animal occupy underground setts [16]. The badgers setts have been classified into four categories in terms of size and function (main, annexe, subsidiary, outliers) [2,18,22]. The size of social groups varies from 2 to 23 individuals [21,5].

Kowalczyk et al. [13] propose that one of factor determining badger densities is the availability of earthworm to foraging badgers (earthworm size, area of foraging). The diet reflects the badger's characteristic food – searching behaviour. Badger is an opportunistic forager, if a source of food is abundant on particular night, it will concentrate on this [18]. Diet composition depends on the area of occurrence, and this is related to the availability of different kinds of food. There is a significant seasonal variation in diet composition [6]. In central and eastern Europe earthworms are the main component of badger diet [16,6]. Badgers are nocturnal with one long bout of activity. Their rhythms of diet activity differ between spring and autumn, and between adult and subadult individuals [14]. Males has larger activity centres than females [3]. Some of the badger's most characteristic activities near the sett are: bedding collection, digging, scratching and grooming, excited behaviour, mating [18,19]. Originally badgers are described as species exhibiting monogamy [12], indeed some studies from Europe suggest that badgers are not strictly monogamous [20]. The geographic variation in special organisation of badgers throughout the Europe makes them a model species to test the hypothesis that badgers behaviour could be different in low and high density populations. Johnson et al [11] put forward the hypothesis that local ecological conditions dictate animal density and spatial organization and hence determine social behaviour. The results of dispersal behaviour of badgers in different ecological populations (high-density UK, low-density Switzerland) showed a clear and significant difference in the spatial autocorrelation patterns between this two populations [4]. We propose that in the low densities badgers' populations behaviour of these predators could be different comparing to high densities badgers' populations, which means that the badgers' behavior could depend on population density.

MATERIAL AND METHODS

Study area
The study was performed in south-western Poland in the Stobrawa Landscape Park (50°51´ N, 17°44´ E) (Fig. 1), the largest park in Opole Voivodeship (52 636.5 ha). It covers a large part of the Odra valley with a forest complex of Stobrawsko-Turawskie Forests. This is a typical lowland park, mainly with wetlands and pine monocultures covering. There are also preserved fragments of 200-year old matured stands. The climate is the mildest in all of the Opole Province and in Poland at large. The mean annual temperature is 8.5°C. The amplitude of mean temperatures from the hottest and the coldest months  is about 19.5–20°C. This is one of the lowest values in the Opole Province. Mean annual precipitation is about 620 mm in the western part and 680 in the east, as much as 400–420 mm of the average annual rainfall is in the warm period (April-September) while in the cool period (October-March) is about 200–260 mm. The snow cover lasts for 50–60 days [1].

Study on badgers' behaviour
Our study was conducted in three seasons from winter 2006 to spring 2008 at the main sett and on selected feeding grounds.

Badgers living in main sett, which was located in on the edge of fresh coniferous forest with Scots pines (Pinus sylvestris) as the main trees and with some Norway spruces (Piacea abies) and weeping birches (Betula pendula) (Photo 1).

The number of badgers (adults and young) inhabiting a sett was 4, but generally we observed 2 animals near the sett.
Direct observation was aided with binoculars and infra – red glasses ('hot – eye'). These observations were made in the evening and at night from the tree 10 m away from the  main sett. This way badgers were observed in spring and summer from 7 pm to 1 am, and in autumn from 5 pm to 10 pm. Badger's behaviour was quantified since they emerged until they had left the sett, or after having returned to the borrow, did not appear on the surface for about 30 minutes. In addition to direct observation, throughout the years we also visited this sett on two weeks basis to check it is occupied. We regularly inspected the sett, looking for signs of activity around the den (foraging, digging, bedding collection, use of latrines). Study period was divided according to the calendar into the astronomical seasons.

RESULTS

The behaviour observed near the sett includes: area inspection, grooming, digging, bedding collection, foraging near the sett and the use of latrine. It has been showed that there were some behaviour alterations during the whole year (Table 1). Various activities near the sett took, depending on the season, from several minutes to several hours. Some behaviours were season-specific. The fixed element of badgers' behaviour, regardless of the season, was area inspection immediately after leaving the sett (activity time: from 2 to 12 minutes). Another activity which was recorded in all seasons of the year was grooming after leaving the sett, which lasted on average from 5 to 20 minutes. However, this behaviour was not a rule. There was time when badgers, after leaving the sett, would done some other activities rather that grooming.

Bedding collection, cleaning and hole digging were characteristic only for autumn and spring. Before bringing the new material to the sett the animals pulled the old one out. This activity took about 20 to 30 minutes, depending  whether they had a rest during that time or not. The badgers were successively cleaning and enlarging the existing holes, and then digging new ones. Digging holes was very often associated  with bedding collection. Sometimes these two activities could not be separated, because after the badgers swept the ground they were beginning to collect bedding and then again continued to enlarge the hole.

Badgers neither dug nor cleaned their dens in summer. During this period  the area inspection lasted about 3.3 minutes and  grooming  3.75 minutes. Foraging within the sett area was very rare and on average it took 12 minutes but never longer than 17 minutes (Photo 2). The latrine near the sett were not always used but if they were, the time spend on this activity was about 15 minutes and was very often associated with foraging near the latrines.

In autumn badgers spent more time near the shelter area (Fig. 2). It was the season when they started to clean their burrows and enlarge their entrances. In 2006 and 2007, in the first and second sett these activities commenced between October and November, and were finalized at the end of November. Every year in the autumn, new entrances were dug and old ones were enlarged. In this season, in addition to usual activities performed outside the sett, such as area inspection and grooming, badgers also cleaned their burrows, dug new ones, expanded the entrances, and collected bedding. Area check-up took on average 3 minutes in September to around 7 minutes in November, whereas grooming from about 8 minutes in September to around 4 minutes in November. The badgers spent from 30 to 40 minutes on this activity. The longest time when badgers could collected bed without rest was about 45 minutes. Then they had a rest and started another activity. Bedding collection involved an average of 30.5 minutes in September to 35 minutes in November. Also in autumn the foraging time within the sett was longer than in summer and lasted about 28 minutes in September to about 27.5 minutes in November.

In winter badgers were leaving their sett very irregularly and were foraging close by (Photo 2). Pit made by badgers when digging were very close to the holes and they also used latrines which were the nearest (no more that 300 meters away from the burrow). In this period the animals were not seen digging nor cleaning the sett.

In spring badgers once again started to clean and sweep the ground from dens but it was not as intense as in autumn (Fig. 2).  The time devoted to area inspection was from about 5 to 7 minutes in March. Dens digging took about 20 minutes and it was usually associated with bedding collection which was performed about 20 minutes. The foraging within the sett lasted about 15 minutes.

The analysis of the percentage of time devoted to various activities outside setts on the basis of 150 hours of observation (Fig. 3) indicates that the badgers spent most of their time on digging and enlarging entrances. This activity took about 29.9% of the time. The second activity to which  26.4% of the time was devoted was cleaning burrow and bedding collection. These two activities were closely bound and it was difficult to tell them apart. For foraging near the sett approximately 18.7% of the time was devoted, while the use of the latrine near the habitats 13.4% of the time spent within  the sett area. Grooming took about 6.7%, and area examination 5.4% of the time.

DISCUSSION

In our study we observed that badgers usually started grooming after emergence, what has been also recorded by Sumiński [23]. Goszczyński et al. [9] reported that after living sett the first activity of the badger was area inspection. From our own research it turns out that this activity was always performed after leaving the sett. In addition, Goszczyński et al. [7] recorded that the longest time the animals would stay near the sett was in May and June which was linked with the upbringing of their offspring.  Our observations suggest that adult badgers without cubs spent most of their time near sett in autumn, when they were cleaning and digging their burrows. The aforementioned authors observed that in the first half of winter badgers walked very closet to the sett. Kowalczyk et al. [15] have shown that the longest distances was travelled in summer while the shortest in autumn. Our study has also showed that in addition to the winter period the animals moved near their habitats also in early spring (from the beginning of March to April). In autumn badgers expanded their burrows and collect bedding. Depending on the weather, these activities took place from September to November, and sometimes longer if there was no snow [23]  We observed that when there was a lack of snow the animals collected bedding even by the middle of November. Paget and Middleton [19] analyzed badgers behaviour from December to April as follows: digging, gathering of bedding material, scratching and grooming. Neal and Cheeseman [18] indicated that on some nights digging might continued for 2 h or more and huge quantities of sand was removed. Usually one badger dugs but sometimes others join in. According to these authors bedding collection was one of the most characteristic activities of badgers and it was very often associated with digging holes, that can take place during any month of the year although there are peaks of activity. In the south – west England the quietest period for digging and bedding collection were convenient to started with the period June – July and during the August – October period. Our research shows that  the longest time when a badger was seen digging was about 1.5 h and the animal did it itself without any help. Also, bedding collection was the most intense in autumn, from the end of September to November. Badgers almost always foraged alone, it would walk slowly, silently with the nose close to the ground. When worms were available in patches, foraging was restricted to a relatively small. In cold winter, when availability of worm was low, badgers spent little time outside sett and hardly ate anything. During the dry spells in summer when worms were absent badgers continued their activity using other foods [16]. In SLP the badgers in winter were foraging close to the sett, and the emergence was irregular, in a heavy  snowfall they did not leave the sett at all. In addition,  we were very often observing the badgers using alternate sources of food. For example, in autumn we observed the animals on the corn fields, or other cereals. Occasionally they penetrated rotten tree stumps.

Goszczyński et al. [9] found that burrowing and foraging were activities on which badgers spent  most of their time, i.e. 36%. Bedding collection, on the other hand, took 3.9% and throwing the sand away about 7.8% of the time. Our study shows that the badgers spent most of their time on digging and enlarging entrances (29.9% of the time). A badger devoted about 3.2% of the time to area inspection and 11.8% to grooming. In that research, the time spent in burrow was taken into consideration and lasted about 14% of the time, whereas in our study time has not been calculated.

CONCLUSION

In conclusions, we can confirm that our results shows that in the low densities badgers' populations behaviour of these predators is similar to high densities badgers' populations. This means that the badgers' behaviour near the sett does not depend on population density, but is correlated with important events in their lives.

ACKNOWLEDGEMENTS

We thanks all the people involved in the badgers' observation, many thanks to Sławek Kochan. We are also grateful for constructive comments and criticisms from Alain Frantz.

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Accepted for print: 8.04.2011

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