Food, Food Availability and Weight of Badgers (Meles meles) in Relation to Agricultural Changes

Abstract

SUMMARY (1) The food of badgers was studied by analysis of faeces collected over 8 years in an area in northern Scotland. The most important food was earthworms, followed by barley. (2) During the study earthworm populations declined, and so did the badgers consumption of worms. Barley was taken when no more oats were available, and consumption rose to a relatively high level. (3) Badger body weights in spring and early summer were positively correlated with earthworm consumption at those times of year. (4) It is postulated that at times of low availability of earthworms in spring badgers lose weight, and they compensate by eating other foods, especially barley, later in the year. This paper describes changes of badger (Meles meles (L.)) food in one study area in north central Scotland over an 8-year period, as well as changes in the body weight of badgers and concurrent changes in agricultural land use which affected food availability, and it discusses a hypothesis to explain the relationships observed. In earlier studies, earthworms (Lumbricus terrestris L.) were found to be by far the most important food of badgers both in our study area and elsewhere in northwest Europe (Skoog 1970; Bradbury 1974; Wiertz 1976; Kruuk & Parish 1981). Not only were they eaten more often and in larger quantities than other foods, but also they remained the most important item in the badger diet despite very wide seasonal fluctuations and large differences between areas in both earthworm availability and earthworm population sizes. Other foods were taken according to availability; it was postulated that badgers changed their foraging strategies to cope with differences in earthworm avail- ability. At the same time, it was found that badger numbers in an area were correlated with earthworm biomass (Kruuk & Parish 1982); this suggested that long-term differences in earthworm availability affect badger population size. The effect of a relatively long term decline in the availability of earthworms on the diet of badgers and the interactions between the consumption of earthworms and other foods are described here. At the same time, the suggestion (Kruuk & Parish 1983) that badger weights in an area are related to the availability of food there is investigated by comparing weights within one area from years with different food availability. The effects of long-term changes in food availability on badger numbers and territory sizes will be discussed elsewhere.