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RTAs - seasonal changes in numbers

The number of badgers killed by R.T.A.s is not spread evenly through the year. Analysis of reports of badger road deaths by national badger experts and by many badger groups has shown that there is marked seasonal variation in the numbers killed, and that there is a regular pattern to this seasonal variation.

Dr Ernest Neal, analysing road casualty reports from Gloucestershire for the years 1973, 1974 and 1976, plotted the monthly totals on a graph. This showed two distinct peaks, the first and by far the biggest in the spring (February to April inclusive), and a second, smaller peak in the autumn (August and September). There was also a distinct dip in the numbers killed during the winter months. Using Neal's figures, and converting them to percentages, I have produced the following graph:

Graph by Steve Jackson, based on information provided by Ernest Neal.

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RTAs - reasons for seasonal variations

The explanation given by Neal for this pattern is that the number of road casualties at a particular time of the year is directly related to the level of badger activity at that time of the year. For example, the period from February to April is, to quote Neal, "a period of great activity, especially among the males, as this is the main mating season, when they spend more time patrolling their territories. It is also the time when young males are reaching maturity and may be seeking out territories of their own. Furthermore, it also coincides with the breeding season and if severe weather occurs, the sows too may have to move further than usual to find enough food."

Then in August-September "feeding is of primary importance, territorial limits are less strictly observed and rather more animals are living rough away from their main setts for varying periods." Because badgers are more active during these periods, and moving about and crossing roads more than they usually would be, it is inevitable that more badgers will be R.T.A. victims during these periods.

Support for this explanation comes from the road casualty figures for 1975, which Neal excluded from the above analysis. This was because the pattern of road deaths in that year was very different from the other years he looked at. In 1975 there was a severe drought in May and June, which greatly reduced the badgers' usual food supplies. This forced them to forage more widely and for longer than usual that summer. Not surprisingly, when Neal drew a graph of road casualties for 1975, it showed a huge peak in the summer which dwarfed those for both the spring and the autumn.

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References

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Additional picture credits

The Eurasian badger photo used at the head of this Article is © Steve Jackson. Credits for the photos used in the right-hand margin of this page for site navigation can be found on the Credits page.

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