Mammal monitoring

Muntjac by Paul Newton

Mammal recording was introduced to the BBS in 1995 with a view to help improve our knowledge of the distribution and population trends of some of our commoner mammals.

Compared with birds, the population trends of mammals are relatively poorly known. Even though mammal recording has always been a voluntary addition to the scheme, 90% of BBS observers now actively look for them during their BBS visits.

Download the instructions for monitoring mammals on BBS

Mammal trends to 2015

BBS count data are used to calculate population trends for nine relatively widespread mammal species, shown below. These trends cover the period 1995–2015.

In 2015, 3,340 of the 3,731 BBS squares surveyed, mammals were actively recorded. In 2,848 squares, live mammals were seen and counted, 366 squares found no evidence of mammals and, on 126 squares, only indirect evidence was seen, such as field signs or via local knowledge.

Of the nine mammals for which trends can be produced from BBS counts, two have increased significantly in the UK as a whole since 1995: Roe Deer (53%) and Reeves Muntjac (95%). Trends for herd mammals, for example, Red and Fallow Deer, should be interpreted with caution. This is becuase the presence or absence of a herb in a given BBS visit could heaily influence the overall trend for that species.

Two mammals have declined significantly: Rabbit (59%) and Red Fox (34%). The drivers behind these declines are unknown.

More information on the mammals recorded during the 2015 BBS surveys can be seen in the latest BBS Report (pages 22-23).

The information on species detected more often by signs of their presence than by sightings (e.g. Hedgehog, Mole and Badger) can also be used to estimate trends, although these require more careful interpretation.

Species
Trend 96-14
Significant
Sample
Brown Hare
-5
696
Mountain/Irish Hare
-32
50
Rabbit
-59
*
1,396
Grey Squirrel
-5
722
Red Fox
-34
*
285
Red Deer
18
63
Roe Deer
53
*
403
Fallow Deer
11
60
Reeves' Muntjac
95
*
92

• This table shows unsmoothed trends (in bold) and sample sizes (normal font). 
• Population changes are shown for mammal species for which the sample size is at least 30 squares.
• Trends are percentage changes, and are marked with an asterisk (*) where significant at the 95% level or more.
• The sample is the mean number of squares on which the species was recorded  

Brown Hare - England

Brown Hare BBS trend in England (1995–2015)
Download image (GIF, 17.89 KB)

Brown Hare - North West England

Brown Hare BBS trend in North West England (1995–2015)
Download image (GIF, 17.61 KB)

Brown Hare - Scotland

Brown Hare BBS trend in Scotland (1995–2015)
Download image (GIF, 17.62 KB)

Brown Hare - South East England

Brown Hare BBS trend in South East England (1995–2015)
Download image (GIF, 17.41 KB)

Brown Hare - South West England

Brown Hare BBS trend in South West England (1995–2015)
Download image (GIF, 18.89 KB)

Brown Hare - East Midlands

Brown Hare BBS trend in the East Midlands (1995–2015)
Download image (GIF, 16.89 KB)

Brown Hare - East England

Brown Hare BBS trend in the East of England (1995–2015)
Download image (GIF, 19.19 KB)

Brown Hare - UK

Brown Hare BBS trend in the UK (1995–2015)
Download image (GIF, 18.21 KB)

Brown Hare - West Midlands

Brown Hare BBS trend in the West Midlands (1995–2015)
Download image (GIF, 17.96 KB)

Brown Hare- Yorkshire and Humber

Brown Hare BBS trend in Yorkshire & Humber (1995–2015)
Download image (GIF, 18.56 KB)

Fallow Deer - England

Fallow Deer BBS trend in England (1995–2015)
Download image (GIF, 18.62 KB)

Fallow Deer - UK

Fallow Deer BBS trend in the UK (1995–2015)
Download image (GIF, 18.21 KB)

Grey Squirrel - England

Grey Squirrel BBS trend in England (1995–2015)
Download image (GIF, 16.46 KB)

Grey Squirrel - London

Grey Squirrel BBS trend in London (1995–2015)
Download image (GIF, 19.15 KB)

Grey Squirrel - North West England

Grey Squirrel BBS trend in North West England (1995–2015)
Download image (GIF, 18.97 KB)

Grey Squirrel - South East England

Grey Squirrel BBS trend in South East England (1995–2015)
Download image (GIF, 16.42 KB)

Grey Squirrel - South West England

Grey Squirrel BBS trend in South West England (1995–2015)
Download image (GIF, 18.21 KB)

Grey Squirrel - East Midlands

Grey Squirrel BBS trend in the East Midlands (1995–2015)
Download image (GIF, 18.84 KB)

Grey Squirrel - East England

Grey Squirrel BBS trend in the East of England (1995–2015)
Download image (GIF, 16.55 KB)

Grey Squirrel - UK

Grey Squirrel BBS trend in the UK (1995–2015)
Download image (GIF, 16.48 KB)

Grey Squirrel - West Midlands

Grey Squirrel BBS trend in the West Midlands (1995–2015)
Download image (GIF, 17.51 KB)

Grey Squirrel - Wales

Grey Squirrel BBS trend in Wales (1995–2015)
Download image (GIF, 18.49 KB)

Grey Squirrel- Yorkshire and Humber

Grey Squirrel BBS trend in Yorkshire & Humber (1995–2015)
Download image (GIF, 18.75 KB)

Mountain / Irish Hare - UK

Download image (GIF, 18.82 KB)

Reeves' Muntjac - England

Download image (GIF, 17.38 KB)

Reeves' Muntjac - South East England

Download image (GIF, 18.26 KB)

Reeves' Muntjac - East England

Download image (GIF, 17.61 KB)

Reeves' Muntjac - UK

Download image (GIF, 17.08 KB)

Rabbit - England

Rabbit BBS trend in England (1995–2015)
Download image (GIF, 17.13 KB)

Rabbit - North East England

Rabbit BBS trend in North East England (1995–2015)
Download image (GIF, 15.95 KB)

Rabbit - North West England

Rabbit BBS trend in North West England (1995–2015)
Download image (GIF, 17.4 KB)

Rabbit - Northern Ireland

Rabbit BBS trend in Nothern Ireland (1995–2015)
Download image (GIF, 17.81 KB)

Rabbit - Scotland

Rabbit BBS trend in Scotland (1995–2015)
Download image (GIF, 16.99 KB)

Rabbit - South East England

Rabbit BBS trend in South East England (1995–2015)
Download image (GIF, 16.95 KB)

Rabbit - South West England

Rabbit BBS trend in South West England (1995–2015)
Download image (GIF, 18.2 KB)

Rabbit - East Midlands

Rabbit BBS trend in the East Midlands (1995–2015)
Download image (GIF, 15.39 KB)

Rabbit - East England

Rabbit BBS trend in the East of England (1995–2015)
Download image (GIF, 19.32 KB)

Rabbit - UK

Rabbit BBS trend in the UK (1995–2015)
Download image (GIF, 16.46 KB)

Rabbit - West Midlands

Rabbit BBS trend in the West Midlands (1995–2015)
Download image (GIF, 17.69 KB)

Rabbit - Wales

Rabbit BBS trend in Wales (1995–2015)
Download image (GIF, 18.48 KB)

Rabbit- Yorkshire and Humber

Rabbit BBS trend in Yorkshire & Humber (1995–2015)
Download image (GIF, 17.89 KB)

Red Deer - Scotland

Red Deer BBS trend in Scotland (1995–2015)
Download image (GIF, 16.41 KB)

Red Deer - UK

Red Deer BBS trend in the UK (1995–2015)
Download image (GIF, 16.52 KB)

Red Fox - England

Red Fox BBS trend in England (1995–2015)
Download image (GIF, 16.08 KB)

Red Fox - South East England

Red Fox BBS trend in South East England (1995–2015)
Download image (GIF, 17.44 KB)

Red Fox - South West England

Red Fox BBS trend in South West England (1995–2015)
Download image (GIF, 17.04 KB)

Red Fox - East England

Red Fox BBS trend in the East of England (1995–2015)
Download image (GIF, 17.84 KB)

Red Fox - UK

Red Fox BBS trend in the UK (1995–2015)
Download image (GIF, 16.06 KB)

Roe Deer - England

Roe Deer BBS trend in England (1995–2015)
Download image (GIF, 17.96 KB)

Roe Deer - Scotland

Roe Deer BBS trend in Scotland (1995–2015)
Download image (GIF, 17.5 KB)

Roe Deer - South East England

Roe Deer BBS trend in South East England (1995–2015)
Download image (GIF, 18.68 KB)

Roe Deer - South West England

Roe Deer BBS trend in South West England (1995–2015)
Download image (GIF, 18.88 KB)

Roe Deer - UK

Roe Deer BBS trend in the UK (1995–2015)
Download image (GIF, 17.01 KB)

Comparison of BBS mammal trends with the National Gamebag Census

In 2011 the JNCC funded work to compare BBS mammal trends between 1995 and 2009 with another annual scheme: the National Gamebag Census (NGC), carried out by the Game and Wildlife Conservation Trust. The NGC is a voluntary scheme that collects bag statistics from shooting estates, on average about 650 per year. The aim of the project was to produce an overview of trends in abundance and distribution. 

Of nine species tested, none differed significantly in their trends between the two schemes. For four species where BBS indicated significant increases between 1995 and 2009, the NCG trend was either not significant (Red Deer, Roe Deer and Reeves’ Muntjac) or alsoshowed a significant increase (Grey Squirrel). Rabbit showed a significant decline on BBS whereas NGC found no significant change.

This work demonstrated the feasibility of producing joint BBS-NGC trends for assessing population change for statutory purposes where a single figure is needed. Results of the spatial mapping were also useful, inshowing areas where species are most often detected and where the most marked changes had occurred. However, due to differences in sampling design and methods, the recommendation is to routinely report temporal and spatial results from the two schemes separately.