Barn Owl Blackbird Blackcap Blue Tit Bullfinch Buzzard Canada Goose Carrion Crow Cetti's Warbler Chaffinch Chiffchaff Coal Tit Collared Dove Common Crossbill Common Sandpiper Coot Cormorant Corn Bunting Cuckoo Curlew Dipper Dunnock Feral Pigeon Garden Warbler Goldcrest Golden Plover Goldfinch Goosander Grasshopper Warbler Great Crested Grebe Great Spotted Woodpecker Great Tit Green Woodpecker Greenfinch Grey Heron Grey Partridge Grey Wagtail Greylag Goose Hen Harrier Hobby Hooded Crow House Martin House Sparrow Jackdaw Jay Kestrel Kingfisher Lapwing Lesser Redpoll Lesser Spotted Woodpecker Lesser Whitethroat Linnet Little Grebe Little Owl Long-tailed Tit Magpie Mallard Marsh Tit Meadow Pipit Merlin Mistle Thrush Moorhen Mute Swan Nightingale Nightjar Nuthatch Oystercatcher Peregrine Pheasant Pied Flycatcher Pied/White Wagtail Raven Red Grouse Red Kite Red-legged Partridge Red-throated Diver Redshank Redstart Reed Bunting Reed Warbler Ring Ouzel Ring-necked Parakeet Ringed Plover Robin Rook Sand Martin Sedge Warbler Shelduck Siskin Skylark Snipe Song Thrush Sparrowhawk Spotted Flycatcher Starling Stock Dove Stonechat Swallow Swift Tawny Owl Tree Pipit Tree Sparrow Treecreeper Tufted Duck Turtle Dove Wheatear Whinchat Whitethroat Willow Tit Willow Warbler Wood Warbler Woodcock Woodlark Woodpigeon Wren Yellow Wagtail Yellowhammer

Mute Swan Greylag Goose Canada Goose Shelduck Mallard Tufted Duck Goosander Red Grouse Red-legged Partridge Grey Partridge Pheasant Red-throated Diver Cormorant Grey Heron Little Grebe Great Crested Grebe Red Kite Hen Harrier Sparrowhawk Buzzard Kestrel Merlin Hobby Peregrine Moorhen Coot Oystercatcher Ringed Plover Golden Plover Lapwing Snipe Woodcock Curlew Common Sandpiper Redshank Feral Pigeon Stock Dove Woodpigeon Collared Dove Turtle Dove Ring-necked Parakeet Cuckoo Barn Owl Little Owl Tawny Owl Nightjar Swift Kingfisher Green Woodpecker Great Spotted Woodpecker Lesser Spotted Woodpecker Magpie Jay Jackdaw Rook Carrion Crow Hooded Crow Raven Goldcrest Blue Tit Great Tit Coal Tit Willow Tit Marsh Tit Woodlark Skylark Sand Martin Swallow House Martin Cetti's Warbler Long-tailed Tit Wood Warbler Chiffchaff Willow Warbler Blackcap Garden Warbler Lesser Whitethroat Whitethroat Grasshopper Warbler Sedge Warbler Reed Warbler Nuthatch Treecreeper Wren Starling Dipper Ring Ouzel Blackbird Song Thrush Mistle Thrush Spotted Flycatcher Robin Nightingale Pied Flycatcher Redstart Whinchat Stonechat Wheatear Dunnock House Sparrow Tree Sparrow Yellow Wagtail Grey Wagtail Pied/White Wagtail Tree Pipit Meadow Pipit Chaffinch Greenfinch Goldfinch Siskin Linnet Lesser Redpoll Common Crossbill Bullfinch Yellowhammer Reed Bunting Corn Bunting

• Key to species texts
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• Population changes
• Demographic trends
• Causes of change

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• BirdFacts page on species biology
• BirdTrack results

Source	Period (yrs)	Years	Plots (n)	Change (%)	Lower limit	Upper limit	Alert	Comment
CBC/BBS England	42	1967-2009	281	-73	-80	-62	>50
	25	1984-2009	405	-73	-77	-67	>50
	10	1999-2009	569	-51	-54	-47	>50
	5	2004-2009	570	-35	-39	-31	>25
BBS UK	14	1995-2009	731	-48	-52	-43	>25
	10	1999-2009	714	-35	-40	-30	>25
	5	2004-2009	739	-24	-29	-19
BBS England	14	1995-2009	572	-63	-66	-60	>50
	10	1999-2009	548	-49	-52	-45	>25
	5	2004-2009	553	-33	-36	-28	>25
BBS Scotland	14	1995-2009	74	-2	-19	16
	10	1999-2009	75	-9	-22	7
	5	2004-2009	87	-12	-24	0
BBS Wales	14	1995-2009	56	-34	-50	-16	>25
	10	1999-2009	59	-27	-39	-11	>25
	5	2004-2009	58	-10	-25	9

Cuckoo abundance may be related to their breeding success, which might in turn be determined by the abundance of breeding success of host species. Evidence from BBS data show strong variation in Cuckoo population trends between habitats, which may reflect regional differences in the main hosts and differing trends in Cuckoo breeding success among those host species (Newson et al. 2009). Douglas et al. (2010) found a strong positive correlation between change in Cuckoo numbers and numbers of Meadow Pipit in the previous year, also based on BBS data, but this only accounted for 1% of the decline in Cuckoo populations so this is unlikely to be a primary driver. A study from the 1980s using Nest Record Scheme data also found changes in usage of some key host species (Brooke & Davies 1987) but the authors also thought that this was unlikely to be the main cause of population decline. There has perhaps been a disproportionate emphasis on the role of brood parasitism aspects in Cuckoo decline.

Another hypothesis for the decline of Cuckoos relates to phenological mismatch in the timing of host and Cuckoo breeding. There is evidence relating to climate-induced changes in phenology, although the extent to which this may be driving population declines is unclear. Douglas et al. (2010) used BBS data and found that in recent decades, earlier breeding Dunnock nests have become less available to Cuckoos, whilst those of Reed Warblers more so. However, they suggested that changes in host phenology are likely to have had only a minimal impact on Cuckoo population trend (Douglas et al. 2010). In Europe, other recent studies have suggested that climate change might disrupt the association between the life cycles of the Cuckoo and its short-distance migrant hosts and they state that this mismatch may contribute to the decline in Cuckoo (Saino et al. 2009, Moller et al. 2011). Thus, evidence at European scale at least is equivocal.

Given that the Cuckoo is a migrant, and the fact that many long-distance migrants have been found to be declining (Sanderson et al. 2006; Hewson & Noble 2009), factors operating on wintering grounds have been suggested as a possible primary driver of Cuckoo declines (Glue 2006, Payevsky 2006, Newson et al. 2009). However, little work has focused on this area to date. Decreased food supplies on the breeding grounds has also been suggested as a possible cause (Glue 2006), following the rapid declines of many British moth species (Conrad et al. 2006), important prey items in Cuckoo diet, but detailed research on this is lacking.

Brooke, M. de L. & Davies, N. (1987) Recent changes in host usage by Cuckoos Cuculus canorus in Britain. Journal of Animal Ecology 56: 873-883.

Conrad, K.F., Warren, M.S., Fox, R., Parsons, M.S. & Woiwod, I.P. (2006) Rapid declines of common, widespread British moths provide evidence of an insect biodiversity crisis. Biological Conservation 132: 279-291.

Douglas, D., Newson, S., Leech, D., Noble, D. & Robinson, R. (2010) How important are climate-induced changes in host availability for population processes in an obligate brood parasite, the European Cuckoo? Oikos 119: 1834-1840.

Glue, D. (2006) Cuckoos in crisis? BTO News 263: 22-23.

Hewson, C. & Noble, D. (2009) Population trends of breeding birds in British woodlands over a 32-year period: Relationships with food, habitat use and migratory behaviour. Ibis 151: 464-486.

Marchant, J.H., Hudson, R., Carter, S.P. & Whittington, P.A. (1990) Population Trends in British Breeding Birds. BTO, Tring.

Møller, A.P., Saino, N., Adamík, P., Ambrosini, R., Antonov, A., Campobello, D., Stokke, B.G., Fossøy, F., Lehikoinen, E., Martin-Vivaldi, M., Moksnes, A., Moskat, C., Røskaft, E., Rubolini, D., Schulze-Hagen, K., Soler, M. & Shykoff, J.A. (2011) Rapid change in host use of the Common Cuckoo Cuculus canorus linked to climate change. Proceedings of the Royal Society B Biological Sciences 278: 733 -738.

Newson, S., Ockendon, N., Joys, A., Noble, D. & Baillie, S. (2009) Comparison of habitat-specific trends in the abundance of breeding birds in the UK. Bird Study 56: 233-243.

Payevsky, V. 2006 Mechanisms of population dynamics in trans-Saharan bird migrants: a review. Zoologichesky Zhurnal 85: 368-381.

Saino, N., Rubolini, D., Lehikoinen, E., Sokolov, L., Bonisoli-Alquati, A., Ambrosini, R., Boncoraglio, G. & Moller, A. (2009) Climate change effects on migration phenology may mismatch brood parasitic cuckoos and their hosts. Biology Letters 5: 539-541.

Sanderson, F., Donald, P., Pain, D., Burfield, I. & van Bommel, F. (2006) Long-term population declines in Afro-Palearctic migrant birds. Biological Conservation 131: 93-105.