Welsh Journals

CHANGES IN THE BADGER POPULATION OF N. E. CLWYD GEOFFREY SPENCER Records have been kept for all the known badger sets in one 10 km square, that is, approximately 25 sq. miles. There was no bias in the selection of this square, for, at a conference organised by the Mammal Society, it was agreed that each County Recorder, if making such a study, might select the square in which he or she lived. I live in SJ 35. The aim was to locate all sets and to estimate any changes in population at two-yearly intervals. In all cases the observations were made in autumn, as nearly as possible between mid-September and mid-October. Results are now available for a 9-year period, 1965-1974, and results are surprising, even disturbing. No fewer than 69 sets were involved, being occupied at some time during the 9 years. It was clearly not possible to count the animals, so a simple way of finding a measure of the population was devised. For each occasion three observations were made. (1) Was the set occupied or not at the time? (2) Was it a large, active set with 3 or more occupied burrows? (3) How many occupied burrows? In all cases, occupation was decided by the signs of fresh bedding being taken to the burrow. Throughout the period new sets were made and others discovered; the recent history in these cases was found by local enquiry and the results were incorporated into the final figures shown in the table: Year 1965 1967 1970 1972 1974 Number of sets 52 48 35 33 26 occupied Large active 24 23 18 15 13 Sets Burrows believed 151 131 145 96 80- occupied Those who are familiar with the habits of this strange animal will see many objections to the method used and to the implied assumptions but the conclusion seems unavoidable. The population has declined by about 50% during the 9 years. Note that 69 different sets were known to be occupied sometime during the 9-year period. The area had been known, without any detailed study, since 1956. During the 9-year period 1956-1965 the number of sets known to have been occupied was 85. The figure speaks for itself. The value of keeping such simple records became very apparent for, without them, had someone asked an opinion as to the changes in badger numbers in N. E. Clwyd the reply would have been "Sets come and go, but the total population is about the same."