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THE BADGER SETT

by
Monica Marassi

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The sett is the underground home of a badger colony. The sett give shelter to badgers during the day and represent a safe place for rearing offspring. Sett dimension may be very different: 1 to 50 entrances (holes); 1 to 50 sleeping chambers and a network of tunnels from 2 to 300 m (Neal, 1986; Roper, 1992b and 1993 in Hayden). The sett dimensions are not correlated to the number of animals of the "clan" (Kruuk, 1978), neither to the number of entrances (Neal, 1986). Dimensions depends better on the sett age (older setts usually are larger than younger), or on the kind of soil (larger setts in easy-to-dig soils)(Neal & Cheeseman, 1996).

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The most common setts have 3 to 10 large entrances. Old entrances are easy to recognize by their huge spoil heaps, which make the difference with other animal's burrows. Most badger holes are between 25 cm and 35 cm (Tavecchia, 1995), and rarely, in very old setts, they are greater than 40 cm. Tunnels usually are larger than height (Neal & Cheeseman, 1996).

Chambers may be very large, between 60 cm and 90 cm , with a height of 45 cm. The chambers are insulated with bedding, periodically renewed by badgers. In the largest "rooms", ventilation holes can be present (Neal & Cheeseman, 1996).

Badger setts have been classified by several authors (Kruuk, 1978 and 1989; Neal, 1986; Thornton, 1988; Smal, 1993 in Hayden):

    Main setts: large setts with several or many entrances and holes. There are usually large mounds of earth called spoil heaps outside and several paths. Main setts are generally used continuously during the year.

    Annexe setts: they are small setts which usually lie within 150 metres from the main sett. Annexe setts are linked to the main sett by a network of well used paths.

    Seasonal or subsidiary setts: small setts usually situated far from the main sett, sometimes near feeding areas. They can be used for brief periods: few weeks or 1-2 months a year.

    Outlier setts: they are very small (1 or 2 entrances), with small spoil heaps. Outlier setts can be used for short periods as refuge and often they can be taken by foxes or rabbits.

However, in Italy badgers have a lower population density than in other parts of north-west Europe, and also social groups and setts can be smaller and less defined. Sometimes there are not big main setts and smaller subsidiaries, but several small setts which can be used by 1 or 2 animals for a variable period.

New setts are usually excaved within the territory of a main sett, and then enlarged. Badgers can dig for several hours during the night. Near an occupied sett there is normally a network of well used paths, which continue into the woods. Badgers probably can recognize their paths from the smell (Neal, 1986).

The badger sett can be used for many generations, even for centuries (Neal, 1986). Main sett is used by the members of a clan as diurnal resting site and as sett for raising offspring. The use of outlier setts may be related with gerarchy within the clan: Roper (1992a) observed that some individuals never used outliers, while others lived there for great part of the year. Subordined badgers lived in outlier setts (Kruuk, 1989), subordined females in particular, in order to raise their cubs.

Bibliografia

  • KRUUK H., 1978 - Spatial organization and territorial behaviour of the European badger (Meles meles) - J. Zool., London, 184, pp. 1-19.

  • KRUUK H., 1989 - The social badger - Oxford University Press, Oxford, p. 156.

  • NEAL E., 1986 - The natural History of badgers - Helm, London, p. 238.

  • NEAL E. & CHEESEMAN C., 1996 - Badgers - T & A D Poyser ltd, London, p. 271.

  • ROPER T. J., 1992a - The structure and function of badger setts - J.Zool., Lond., 227, pp. 691-693.

  • ROPER T. J., 1992b - Badger (Meles meles) setts: architecture, internal environment and function - Mammal Rev., 18, pp. 11-23.

  • ROPER T. J., 1993 - Badger setts as a limiting resource - In The badger, Hayden T.J. ed. Royal Irish Academy, Dublin, pp. 26-34.

  • SMAL C. M., 1993 - Tha National Badger Survey: preliminary results for the Irish Republic - In The badger, Hayden T.J. ed. Royal Irish Academy, Dublin, pp. 9-22.

  • TAVECCHIA G., 1995 - Data on urban badger activity in South Wales: a brief study - Hystrix, 7(1-2), pp. 173-177.

  • THORNTON P. S., 1988 - Density and distribution of badgers in south-west England: a predictive model - Mammal Rev., 18, pp. 11-23.

 

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