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We used biomass as a way of measuring bird communities. Our results ranged from 9g (a garden in Scotland with a single Coal Tit visiting) to 71,496g (a garden in Norfolk with Mallards). The national average was 3575g, equivalent to 325 Blue Tits, 36 Blackbirds or eight Woodpigeons!

Location

On average, rural gardens (4283g) held greater 'bird biomass' than suburban ones (3195g) which supported more than urban gardens (2679g). On average, larger gardens supported the most 'bird biomass' (4900g). These typically supported larger species such as gambirds, birds of prey and waterfowl. Small gardens, on average, supported the greatest biomass of sparrows/buntings.

On average, gardens in Northern Scotland supported almost twice the biomass of red-listed birds of conservation concern than gardens in the south of England. East Anglian gardens supported the greatest biomass of 'amber-listed' birds. 

Region No. of submissions Av. biomass  Min. biomass  Max. biomass

Channel Islands

 1 7500 g 7500 g 7500 g
East Midlands 354 3437 g 11 g 32,820 g
East of England 609 3926 g 96 g 71,496 g
Ireland 7 4385 g 1014 g 12,294 g
Isle of Man 2 7449 g 1413 g  13,484 g
London 197 3055 g 250 g 20,940 g
North East 171 3943 g 26 g 18,495 g
North Scotland 72 3858 g 222 g 20,122g
North West 432 3434 g 130 g 26,751 g
Northern Ireland 25 3929 g 983 g 12.333 g
South East 814 3747 g 77 g 32,034 g
South Scotland 213 4310 g 9 g 34,474 g
South West 562 3240 g 11 g 29,222 g
Wales 242 3437 g 191 g 22,427 g
West Midlands 378 3351 g 138 g 29,860 g
Yorkshire & the Humber 376 3309 g 22 g  26,878 g

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