Policy paper

Annex A1: updating minimum and maximum numbers during 2023 badger control operations

Updated 1 May 2024

Applies to England

Background

In 2023, as in previous years, it became apparent from daily data collected through the course of badger control operations and actual circumstances being observed in the field, that there was a wider variation in badger abundance across the control areas than it had been possible to estimate prior to the control operations. Specifically, some badger control companies were encountering and removing more badgers than expected and some were seeing and removing fewer despite equivalent amounts of effort deployed by similarly trained contractors.

This necessitated updating of the minimum and maximum numbers for 27^{[footnote 1]} control areas following the advice published by Defra in September 2023 (Section D)^{[footnote 2]}.  Area 70 – Somerset’s minimum and maximum numbers at Day 28 were not updated due to a data lag and were uplifted for their continuation beyond 42 days.

Updating numbers in Areas 44 to 53 and 55 to 72

The method used to update the minimum and maximum numbers has not been changed since 2017 but has been improved to take into account further data from effective first year control areas^{[footnote 3]} and effective second, third and fourth year control areas in previous years.

For all areas the minimum and maximum numbers were recalculated using an historical comparator. Taking data from the previous years’ effective control areas, the proportion of the Day 42 cull total that was achieved on each day in each area is calculated, then averaged across areas to generate the historical comparator. This allows the prediction of the expected Day 42 total for any area, from any given day. The minimum and maximum numbers are then set equidistant around the expected cull total. Due to the low numbers removed by the area by Day 28 and the historical comparator providing very close updated minimum and maximum numbers, a bespoke methodology was used for Area 57- Berkshire.

The updated minimum and maximum numbers in 20 areas^{[footnote 4]} were further increased by 1.5% per operational day, to account for their desire to continue beyond 42 days in order to maximise disease control on land parcels where factors such as late maize harvest or poor weather conditions hampered coverage.

The data used to calculate the minimum and maximum numbers is taken from Day 28 of operations and this data and the resulting updated numbers are presented in Table 1.

In the first week of operations, it became apparent that in 2 areas there were considerably more badgers than the initial sett survey population estimate had suggested. The numbers were therefore updated in Area 48- Leicestershire to a minimum of 204 and a maximum of 277 and in Area 55- Shropshire to a minimum of 71 and a maximum of 96 using the methodology explained above. These numbers were updated again based on data from Day 28.

Table 1: Data for updating minimum and maximum numbers in Areas 44 to 72 during 2023 badger control operations.^{[footnote 5]}

Area	Day	Effort	Badgers removed by Day 28	Updated minimum number	Updated maximum number
Area 44 - Avon	28	65	202	214	290
Area 45 - Derbyshire*	28	49	536	742	1006
Area 46 - Gloucestershire*	28	93	81	89	121
Area 47 - Herefordshire*	28	62	390	439	595
Area 48 - Leicestershire	28	63	171	188	255
Area 49 - Oxfordshire	28	56	213	260	353
Area 50 - Shropshire*	28	54	757	936	1270
Area 51 - Somerset*	28	56	386	447	607
Area 52 - Warwickshire*	28	55	409	511	694
Area 53 - Wiltshire	28	67	90	100	136
Area 55 - Shropshire*	28	53	54	68	92
Area 56 - Hampshire	28	59	117	134	182
Area 57 - Berkshire	28	71	15	20	27
Area 58- Staffordshire*	28	79	156	172	234
Area 59 - Worcestershire*	28	88	119	131	178
Area 60 - Shropshire*	28	66	420	460	625
Area 61 - Oxfordshire	28	69	237	268	364
Area 62 - Buckinghamshire*	28	94	507	557	756
Area 63 - Cornwall	28	109	351	384	521
Area 64 - Cornwall*	28	99	123	129	175
Area 65 - Derbyshire*	28	81	486	528	717
Area 66 - Devon*	28	75	61	64	87
Area 67 - Hampshire*	28	97	150	164	223
Area 68 - Northamptonshire*	28	72	580	634	860
Area 69 - Oxfordshire*	28	75	185	201	273
Area 71 - Warwickshire*	28	74	265	287	390
Area 72 - Warwickshire*	28	69	507	550	747

1. Area 54- Lincolnshire did not have minimum and maximum numbers. ↩

2. https://www.gov.uk/government/publications/advice-to-natural-england-on-setting-minimum-and-maximum-numbers-of-badgers-to-be-controlled-in-2023. ↩

3. All second, third and fourth year area calculations are based on all historical yearly area data. ↩

4. For areas listed with ‘*’ the minimum and maximum numbers presented in Table 1 exclude the further increase by 1.5% per operational day. ↩

5. For areas in their second, third and fourth years of control, required effort was relative to the abundance of badgers reported in the area, with a recommended target of 64 units per 100km2 per night over 42 days of operations. As some areas choose to continue beyond 42 days to maximise disease control benefits, all areas expended an appropriate level of targeted effort across their control area. ↩