Although much of this report focuses on declines and their conservation significance, there are many species that are increasing in number as UK breeding birds.
In the current report, there are 22 species for which our most representative long-term trends show a statistically significant doubling in population size over periods of 22–48 years.
These are Mute Swan, Greylag Goose, Canada Goose, Shelduck, Mallard, Goosander, Sparrowhawk, Buzzard, Coot, Stock Dove, Woodpigeon, Collared Dove, Green Woodpecker, Great Spotted Woodpecker, Magpie, Jackdaw, Carrion Crow, Chiffchaff, Blackcap, Nuthatch, Wren and Goldfinch (in taxonomic order). Chiffchaff and Wren have been added to this list in the current report, but Great Tit has been removed as the population increase has dropped just below the threshold for inclusion following five years of negative annual changes.
The steepest long-term increases we have measured have been for Buzzard, Greylag Goose, Great Spotted Woodpecker and Collared Dove, which have all increased by more than 300% since 1967, although Collared Dove numbers have started to decrease more recently.
The 22 species that have doubled over the long term are set against the 28 that have halved in number over similar periods (see Declining species). The gap between these two totals had widened over recent years up to and including the BirdTrends 2015 report, but has since narrowed by four species.
Seven further species, monitored only over a shorter period, have also more than doubled (see Increasing species). These are Mandarin Duck, Gadwall, Little Egret, Red Kite, Barn Owl and Ring-necked Parakeet (all monitored by BBS over 20-years) and Cetti's Warbler (monitored by CES over the period 1990–2015). Two additional species have more than halved over this shorter period.
For thirteen species that are listed as red or amber for a population decline over the long term – Spotted Flycatcher, Wood Warbler, Corn Bunting, Garden Warbler, House Sparrow, Yellowhammer, Song Thrush, Meadow Pipit, Yellow Wagtail, Dipper, Shelduck, Linnet and Sand Martin – the decline has apparently started to level off, or has ceased, during the most recent ten-year period. Signs of recovery noted last year for Tawny Owl and Nightingale, are no longer evident, however. While indications are positive, wide confidence intervals for some of these species allows for the possibility that their severe decline is, in fact, continuing (see Ten-year trends and evidence of species recovery).
Six further formerly declining species – Whitethroat, Dunnock, Tree Sparrow, Bullfinch, Lesser Redpoll and Reed Bunting – have reversed their population trend to show significant increases over the last ten years. Whitethroat has already been moved to the green list (BoCC4). For all these species, however, population levels remain severely depleted, despite the recent increases.