BirdTrends 2011 - BTO - British Trust for Ornithology

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Population changes
Demographic trends
Causes of change

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Starling
Sturnus vulgaris

Key facts

Conservation listings: Europe: SPEC category 3 (declining) (BiE04)
UK: red (species level, race vulgaris); amber (race zetlandicus, >20% of European breeders) (BoCC3)
UK Biodiversity Action Plan: priority species
Long-term trend: England: rapid decline
Population size: 804,000 territories in 2000 (1988-91 Atlas estimate updated using CBC/BBS trend: BiE04, APEP06); 8,500,000 birds in Britain in 1994-2000 (Robinson et al. 2005a)

http://www.bto.org/birdtrends2010/images/starl03CV300w.jpg

Migrant status	Resident	Nesting habitat	Cavity nester
Primary breeding habitat	Farmland	Secondary breeding habitat
Breeding diet	Animal	Winter diet	Vegetation

Status summary

The abundance of breeding Starlings in the UK has fallen rapidly, particularly since the early 1980s, and especially in woodland (Robinson et al. 2002, 2005a) and continues to be strongly downward. The declines have been greatest in the south and west of Britain; recent BBS data suggest that populations are also decreasing in Scotland and Northern Ireland, where the trends were initially upward. The species' UK conservation listing has been upgraded from amber to red as the decline has become more severe. Widespread declines in northern Europe during the 1990s outweighed increases in the south, and the European status of this species is no longer considered 'secure' (BirdLife International 2004). Overall, there has been widespread moderate decrease across Europe since 1980 (PECBMS 2011a).

Population changes in detail

Source	Period (yrs)	Years	Plots (n)	Change (%)	Lower limit	Upper limit	Alert	Comment
CBC/BBS England	42	1967-2009	584	-87	-90	-82	>50
	25	1984-2009	900	-80	-83	-76	>50
	10	1999-2009	1526	-44	-46	-39	>25
	5	2004-2009	1646	-26	-29	-20	>25
BBS UK	14	1995-2009	1734	-45	-48	-41	>25
	10	1999-2009	1841	-41	-44	-37	>25
	5	2004-2009	1988	-27	-31	-21	>25
BBS England	14	1995-2009	1421	-51	-54	-47	>50
	10	1999-2009	1501	-44	-46	-40	>25
	5	2004-2009	1623	-26	-30	-21	>25
BBS Scotland	14	1995-2009	144	-29	-40	-12	>25
	10	1999-2009	152	-35	-46	-22	>25
	5	2004-2009	168	-27	-40	-11	>25
BBS Wales	14	1995-2009	82	-63	-72	-49	>50
	10	1999-2009	87	-48	-57	-36	>25
	5	2004-2009	85	-30	-40	-16	>25
BBS N.Ireland	14	1995-2009	77	26	1	71
	10	1999-2009	90	-31	-44	-16	>25
	5	2004-2009	98	-34	-51	-15	>25

Tables show changes with their 90% confidence limits. Alerts are flagged for significant changes only. See here for more information.

Demographic trends

Causes of change

There is good evidence that changes in first-year overwinter survival rates best account for observed population change. Although direct evidence explaining the ecological drivers behind this is lacking, changes in the management of pastoral farmland are thought to be largely responsible.

Change factor	Primary driver	Secondary driver
Demographic	Decreased juvenile survival
Ecological	Unknown

Further information on causes of change

As the population has dropped, the numbers of fledglings per breeding attempt has increased markedly (see above); clutches are now larger, and rates of nest loss at the egg and chick stage have fallen. These improvements in breeding performance suggest that decreasing survival rates are likely to be responsible for the decline. Evidence for this is provided by Freeman et al. (2007), who conducted a population modelling exercise and found that changes in first-year overwinter survival rates could best account for observed population change, and were sufficient, on their own, to explain the broad pattern of decline. The decline in survival rates nationwide coincided with the major period of population decline. MacLeod et al. (2008) also provide evidence linking Starling declines to the non-breeding-season environmental conditions, suggesting that the species' population status is dependent on interactive or synergistic effects of food availability and predation.

There is little direct evidence from studies analysing the ecological drivers of the declines. However, changes in pastoral farming practices are likely to account for at least some of the decline in the wider countryside, probably related to changes in food resources, though these are largely unquantified (Robinson et al. 2005). Loss of permanent pasture, which is the species' preferred feeding habitat, and general intensification of livestock rearing are likely to be having adverse effects on rural populations, but other causes should be sought in urban areas (Robinson et al. 2002, 2005). Whilst the number of cattle has declined, sheep numbers have increased, producing a different sward structure (Chamberlain et al. 2000, Fuller & Gough 1999) and patterns of stock rearing have changed. These may have reduced foraging opportunities for Starling (Robinson et al. 2002, 2005). Also the use of insecticides on grassland, though low, is targeted partly at tipulids, which may have reduced foraging opportunities further (Vickery et al. 2001). Although there is little published evidence that the density of tipulids has changed over time (Wilson et al. 1999), the area of permanent pasture has declined and the use of insecticides on them has increased. Drainage of grasslands is also thought to have reduced the quality of foraging conditions (Newton 2004).

Further research into urban Starling population dynamics is to be encouraged if we are to understand the causes of decline of this charismatic species more fully.

Species references

BirdLife International (2004) Birds in Europe: population estimates, trends and conservation status. Cambridge.

Chamberlain, D.E., Fuller, R.J., Bunce, R.G.H., Duckworth, J.C. & Shrubb, M. (2000) Changes in the abundance of farmland birds in relation to the timing of agricultural intensification in England and Wales. Journal of Applied Ecology 37: 771-788.

Freeman, S.N., Robinson, R.A., Clark, J.A., Griffin, B.M. & Adams, S.Y. (2007) Changing demography and population decline in the Common Starling Sturnus vulgaris: a multisite approach to integrated population monitoring. Ibis 149: 587-596.

Fuller, R.J. & Gough, S.J. (1999) Changes in sheep numbers in Britain: implications for bird populations. Biological Conservation 91: 73-89.

MacLeod, R., Clark, J. & Cresswell, W. (2008) The starvation-predation risk trade-off, body mass and population status in the Common Starling Sturnus vulgaris. Ibis 150 (suppl 1): 199-208.

Newton, I. (2004) The recent declines of farmland bird populations in Britain: an appraisal of causal factors and conservation actions. Ibis 146: 579-600.

PECBMS (2011a) Population Trends of Common European Breeding Birds 2011. CSO, Prague. Full text

Robinson, R.A., Siriwardena, G.M. & Crick, H.Q.P. (2002) Status and population trends of the Starling Sturnus vulgaris in Great Britain. Pp 11-32. in Crick, H.Q.P., Robinson, R.A., Appleton, G.F. Clark, N.A. & Rickard, A.D. (eds) Investigation into the causes of the decline of Starlings and House Sparrows in Great Britain. Research Report 290. BTO, Thetford.

Robinson, R.A., Siriwardena, G.M. & Crick, H.Q.P. (2005) Status and population trends of Starling Sturnus vulgaris in Great Britain. Bird Study 52: 252-260.

Vickery, J.A., Tallowin, J.T., Feber, R.E., Asteraki, E.A., Atkinson, P.W., Fuller, R.J. & Brown, V.K. (2001) The management of lowland neutral grasslands in Britain: effects of agricultural practices on birds and their food resources. Journal of Applied Ecology 38: 647-664.

Wilson, J.D., Morris, A.J., Arroyo, B.E., Clark, S.C. & Bradbury, R.B. (1999) A review of the abundance and diversity of invertebrate and plant foods of granivorous birds in northern Europe in relation to agricultural change. Agriculture, Ecosystems & Environment 75: 13-30.