Waveney Bird Club helps to halt Tree Sparrow extinctions in the Waveney catchment area
Thirty years ago, the Tree Sparrow was a very familiar sight in the East Anglian countryside and no one would have dreamt that it would ever become threatened. However, at the turn of this Millennium it was on the verge of extinction, both as a breeding and wintering species and local ornithologists feared the worst. They formerly nested in holes in trees, thatched buildings and old orchards and readily took to nest boxes. The Tree Sparrow’s former abundance along with the county’s strategic importance can be seen in the maps depicted in the “1988-1881 Breeding Atlas”. Undoubtedly, the species extinction from Suffolk would have national implications.
Nationally, the Tree Sparrow population crashed between the late 1970s and the early 1990s. There was a decline of 93% on farmland between 1968 and 1999 with the UK range undergoing marked change between the two Atlas periods, with a contraction in the west and south of England. This has continued subsequently with many local extinctions occurring during the 1990s and the current population level is still only about 3% of that of the 1970s. Components of agricultural intensification, such as reductions in winter stubble availability, are likely to be implicated in the decline. Breeding performance has improved substantially as population sizes have decreased, suggesting that decreases in productivity were not responsible for the decline. Following declines across western and northwestern Europe during the 1990s, the European status of this species is no longer considered ‘secure’ and it is now classified as a BAP species Red Listed.
Status in Norfolk and Suffolk
This national decline has been mirrored locally and the Tree Sparrow is now absent from most of East Anglia. Large flocks formerly gathered on stubbles and weedy fields during winter and large movements were logged at coastal watch-points.
Tree Sparrows are fairly sedentary, so the magnitude of wintering flocks can be used as a “health check” for the breeding population. Flocks of 100-150 were regularly recorded up to the mid-1980s and, occasionally, there were four-figure gatherings. Between 1985 and 2005 flocks of 30 or more were very rare indeed, but three-figure flocks have been noted during consecutive winters of 2006-2007 and 2007-2008 perhaps indicating a partial recovery. The current breeding population for both counties is likely to be less than 100 pairs.
Status in the Waveney Catchment
There are only two known colonies in the Waveney Valley catchment, at Thorndon and Flixton both on the Suffolk side of the valley. There have been a few winter records from Mutford, Somerleyton and Burgh St Peter in the past three winters, but otherwise the species is more-or-less absent. No colonies were found in south Norfolk during fieldwork for the Norfolk Atlas during 2002 to 2007.
Overview of the decline
The recent decline of the Tree Sparrow has occurred at the same time as decreases in the numbers and/or range of other farmland birds which share its diet of grass, wildflower seeds and some cereal grains. It is likely that the decline in Tree Sparrow may be due to changes in agricultural practice, both in the UK and in their wintering grounds in south-west Europe. These include the increased use of herbicides and fertilisers, the switch from spring-sown to autumn-sown crops and the consequent loss of winter stubble fields. The general reduction in farmland habitat diversity due to the loss of mixed farming, increased specialisation and habitat fragmentation has also had an effect. Breeding performance has improved substantially as population sizes have decreased, suggesting that decreases in productivity were not responsible for the decline.
Tree sparrows tend to form loose local colonies and, where these are supported with nest boxes and ample seed supplies, local populations can be stable and increasing.
Current actions and advisory work to date
The Suffolk Wildlife Trust has identified key sites as part of their work with Natural England’s Countdown 2010 Project. Landowners have been encouraged to retain the availability of wild birdseed strips (they were often ploughed up in February) to prolong the stay of the Tree Sparrow flocks. Breeding pairs have been located and nest boxes provided and erected in and around the wintering and known breeding areas. Waveney Bird Club volunteers will assist with the project by liaising with landowners, suggesting sites for nest boxes, monitoring nests and ringing chicks. WBC ringers will also target Tree Sparrows as part of their ringing efforts and coordinate work with other ringing groups elsewhere in East Anglia.
Our remaining Tree Sparrow colonies tend to be concentrated in mixed farming areas with access to at least small wetland patches and artificial nest sites or old/pollard trees. However, there are others which thrive in isolated gardens in the middle of arable deserts and survive solely on supplementary feeding. Several of theses sites have been identified and new sites are being sought. Once identified it is important that favourable management is maintained and if possible enhanced using all possible means, both within and beyond the scope of agri-environment schemes. During the breeding season of 2008, significant breeding colonies were identified in the Waveney catchment area and these are to be further enhanced and protected. Current BTO Atlas fieldwork may well locate further colonies, so swift action will be necessary if these are to survive.
Key to success is the plentiful supply of seeds throughout the year and this should include supplementary feeding to ensure overwinter survival and maintain the condition of adults during the breeding season. There should be supplementary provision of nest sites to allow colonies to expand. New boxes should be in place by the end of the breeding season rather than in early spring, as new nest sites are partially established at the end of the breeding season.
The large wintering Tree Sparrow flocks in and around Lackford and Benacre are noteworthy and it is important to support them during the winter and encourage them to stay to breed. The continued provision of wild-bird strips is the mainstay, but supplementary feeding will prolong their stay until the time comes for breeding. Availability of insect food for the young, and a good supply of nesting holes are essential for successful breeding. Nest boxes will provide nest-sites in selected areas. The agreement of the landowners is essential to this proposal.
It is pleasing to note that Tree Sparrows appear to be making a recovery with three-figure flocks being noted in coastal districts and in Breckland in the past two winters. The flocks are attracted to the seed heads of millet and other flowering plants sown by farmers in strips as part of the Government’s Environmental Stewardship Scheme. This is a clear sign that this policy is working which is good news for birds and birdwatchers alike.
If we do nothing, it is likely that the Tree Sparrow will decline further and will soon become extinct as a Suffolk breeding species. Act now or pay the price!