THE LONG MYND

                                                                                BREEDING BIRD PROJECT

(Note: Opinions expressed in this report are those of the author and may not reflect the views of the SOS)

DECLINE OF GROUND-NESTING BIRDS ON THE LONG MYND 1995 - 2004

INTRODUCTION

A comprehensive survey of upland breeding birds on the Long Mynd was carried out between 1994 and 1998 ( Smith 2004). The population of some ground-nesting birds (Ring Ouzel, Curlew, Snipe and Teal) has been monitored since then. Known population trends are shown in the Chart on the preceding page.

RING OUZEL

Since the end of the systematic recording of Upland Breeding Birds 1994-98, a systematic study of Ring Ouzel has been made.  This is a Shropshire BAP Target Species, and is on the Red List of Birds of Conservation Concern:  2002-2007.

The population was stable throughout the 1990s, at around a dozen pairs.  This reduced to eight in 2000, three in 2001, two in 2002, and one in 2003.  In 2004 only a single un-paired male returned, and the species is now on the verge of extinction as a breeding bird in Shropshire .

This population crash is almost certainly caused by predation.  An RSPB research project compared the success and failure rates of nests found in eight different study areas around Britain .  The loss due to predation on the Long Mynd was far higher than that found in any of the other study areas (Burfield 2002).  In practice, nest loss locally must be higher than that actually recorded - no evidence of breeding was found, and no nests were located, for several of the pairs, or males holding territory, that were located each year. Their nests must have been predated before they could be found.

Nest loss due to predation 1995 – 99 was nine out of 30 nests monitored (30%). Nest loss due to predation has become much worse since – nine out of 14 nests (64%) in 2000 – 03.

The observed rate of nest loss correlated well with the observed rate of population decline, using a simple population model.  A Feeding Areas Study showed that there was no shortage of food on the Long Mynd, and this situation had not changed over many years.  Colour-ringing of birds, so they could be identified individually, showed that the percentage rate of return of the previous year’s birds was usually sufficient to sustain the population, so other possible causes of the decline – conditions in the wintering areas in southern Spain and Morocco, or on migration – can also be discounted.

These specific studies have therefore discounted all possible causes of decline except predation. They have been described in detail in Report Of The Long Mynd Breeding Project: Ring Ouzel 2003, and Ring Ouzel 2004.

CURLEW, SNIPE AND TEAL

Declines have also been observed in the numbers of other ground-nesting birds (Curlew, Snipe and Teal), and their ranges, since 1998.

Population Decline

A systematic survey to establish the breeding population of Snipe was carried out in 2004. Seven – eight pairs were found.

Specific searches were made for Curlew and Teal during the Snipe survey site visits.  Only two pairs of Curlew, and one pair of Teal, were found.  National Trust staff were made aware of this work at the beginning of the season, and they also reported only the same two pairs of Curlew.  These Curlews were not heard after early June, suggesting that both breeding attempts ended in failure.  Another Curlew nest was suspected near the Glider Station (not on National Trust land), but this too failed.

In relation to Snipe and Curlew, changes in the size and / or quality of wet and damp feeding areas can also be discounted.  The National Trust does a periodic monitoring of conditions in the wet flushes – the survey looks at trampling, plant composition, area, wetness and vegetation height of a sample of flushes. No change was found between two surveys in the late 1990s and those in 2001 and 2004, when the most recent monitoring was carried out (Caroline Uff, pers comm.).

Similarly, there has been no apparent change in the number of ponds, or the quality and water levels in them, which might affect Teal.

Contraction Of Range

No Curlew, Snipe or Teal were found in any of the flushes or pools south of Shooting Box. Several of these flushes and pools were occupied 1994-98.

The 1-km sq SO 4192 has been visited twice a year since 1994 as part of the National BTO BBS Survey.  Two pairs of Curlew were recorded on this survey every year up until 1999, then one pair up until 2003.  In 2004, no Curlews were recorded on the survey, on either of the two visits, for the first time since its inception.

Similarly, the survey route passes through two Snipe territories that were used regularly 1994-98. Snipe were found in both in 1999, but in only one in 2000, and in neither since.

Population

The estimated populations of all four species are shown in Table 1 below.

Table 1. Estimated Population Of Selected Ground-nesting Birds

The decline is shown graphically in the Chart at the top of this page.  For each species, the population each year is shown as a percentage of its 1995 population. The chart paints a depressing picture.

MEADOW PIPIT

Meadow Pipit appear to have declined steadily since 1994 in the 1 km sq SO 4192, which has been monitored since then as part of the national BTO Breeding Bird Survey (BBS).

Although numbers have fluctuated from year-to-year, the average trend has shown a reduction in the number of birds recorded on the early season count from 40 in 1994, down to 10 in 2004.

However, this reduction has not been replicated in separate monitoring of Skylark and Meadow Pipit populations, based on surveying eight 1 km transects three times per year, which started in 1996.  These transects are widely distributed across the moorland plateau, and are more representative of the Long Mynd as a whole.

The population of Meadow Pipit should therefore be carefully monitored in future, to assess whether the observed trend in SO4192 is anomalous, or the initial evidence of a more general decline; and, if it is anomalous, whether it indicates that habitat change or predator pressure in that small area is different from elsewhere on the Long Mynd plateau, or the apparent trend is not real, and arises from other factors such as weather conditions influencing the proportion of the population that was active during the BBS surveys.

PREDATORS

Unfortunately, the Long Mynd is surrounded by farms and estates with agricultural and recreational practices that directly benefit all the main predators of ground-nesting birds. These practices, and their effect, are summarised in Appendix 1.

MANAGEMENT PROPOSALS

Wildmoor is the last refuge of Snipe, Curlew and Teal.   

Action should be taken to protect these species from further predation and local extinction.

Crows are the most likely avian predators.  They need trees for nest sites and lookout posts.  There are three mature trees near Wildmoor Pool that regularly contain a Crow’s nest.  There are a large number of small Rowan saplings now beginning to emerge.

It is recommended that action is taken to remove Crows from Wildmoor – shooting, trapping, and destruction of nests, and removal of the small saplings before they grow any larger, and provide additional nest sites and lookout posts.

Consideration should be given to effective (legal) action to remove foxes and other potential predators from this area as well.

Such action can only be effective as a short term stop-gap, and can only succeed in the long run if there are changes to the agricultural and recreational practices on farms and estates which directly increase the number of predators in the countryside as a whole.

The National Trust should also use its influence, nationally and locally, to lobby and campaign for such changes.

In addition, population monitoring of Meadow Pipits should continue.

Leo Smith       December 2004

APPENDIX 1. AGRICULTURE AND INCREASING PREDATOR NUMBERS

Increase In Predators

The decline in the number of ground-nesting birds on the Long Mynd is attributed to the increasing number of predators, an indirect effect of agricultural intensification on, and drainage of, local farmland.

Unfortunately, there is no local quantification of the increase in the number of any of these predators. However, there is direct evidence of a rapid expansion in the local population of three other species that also eat carrion and utilise similar sources of food, and they have benefited from the same agricultural practices

• Firstly, a study of Buzzard in the South Shropshire Hills found 81 pairs in a 10-km square near the Herefordshire border, just south of the Long Mynd, in the late 1990s.  This is the highest known breeding density of the species anywhere. They were certainly much more scarce 10 years earlier (Sim et al 2001). 
• Secondly, Ravens have increased fivefold in only 14 years - from around 50 breeding pairs in 1990 to an estimated 175 pairs in 1999 and 250 pairs in 2003 (Shropshire Raven Study Group, SBRs).
• Thirdly, the Welsh population of Red Kite grew only slowly, supported by intense conservation effort, and did not reach 100 pairs until 1993. However, by 2004 the population was estimated at 400 – 450 pairs. This rate of growth is almost identical to that of the Shropshire Raven population. The Kite’s stronghold, around Rhayader and Tregaron, is less than 100 kilometres from the Long Mynd, and the Welsh hills are subject to the same intensive sheep farming as the Shropshire hills.  Kites are now seen frequently in the Shropshire hills, and are likely to breed here in the near future.

Although other factors will have contributed to the population growth of these three species, particularly milder winters and a reduction in illegal poisoning, the increase in breeding success and overwinter survival rates is almost certainly due mainly to an increase in food supply throughout the year.

Nationally, the population of Carrion Crow “is known to have increased markedly over the whole of its British range since the First World War, and especially since the early 1940s” The increase is attributed to “reduction in gamekeeping pressures, and also, perhaps more significantly, from much reduced persecution by farmers (Marchant et al 1990).  This growth has continued, and the population has increased by 104% in England , and in the UK as a whole, between 1967-2003 (Crick et al 2004 - BTO Research Report No. 353). In the West Midlands , the population increased by 16% over the period 1994-2003 (BBS 2003). In Shropshire , Carrion Crow was found in every one (100%) of 45 1-km squares surveyed by the BBS in 2002 (SBR), and the average number of birds recorded in each square was 15.9. The Abundance Map in the New Atlas (1993) shows that the breeding density in the Shropshire Hills falls into the highest band nationally. Since the 1960s the breeding success has been highest in sheep country (Marchant et al 1990).

It is almost certain that foxes have increased at the same rate.

Although crows and foxes, and perhaps stoats and weasels, are the most likely predators on the Long Mynd, the number of badgers is also increasing. Local farmers believe that the population is now substantially greater than it was a decade ago, and they are virtually unanimous that badgers are the main predators of ground-nesting birds on farmland.

Impact Of Predators

Predation is known to be the main cause of nest loss for Snipe, and, where the predator is known, Crows are most frequently to blame (Mason and MacDonald 1976).

Studies in Northern Ireland, where Curlews have declined considerably, showed that a high rate of nest predation is the likely cause of the decline, and foxes were found to be the main predators on mainland sites (Hooded Crows were a major predator on island sites where there were no foxes); while on heavily keepered land in the northern Pennines, where foxes were more or less absent, and Crows and Ravens very scarce, predation was still the main cause of breeding failure, in this case by stoats (Grant et al 1999, Murray Grant RSPB pers.comm.).

In the case of Lapwing, nests within 50m of a field boundary (trees for Crows to perch, and cover for foxes) were significantly more likely to be predated than those more than 50m from one (Sheldon 2002).

Ravens themselves may also be part of the problem. They have been seen to actively search for Curlew nests on Orkney and in Northern Ireland , and several cases of actual predation were witnessed on Orkney (New Atlas 1993, Murray Grant RSPB pers.comm.). However, ground nesting birds are abundant there, and Ravens are scarce, so searching out this source of food will be less profitable in the Shropshire Hills. Even so, the effects of casual predation by a large number of Ravens on a small population of Curlew and other ground nesting birds may well be important. Also, Ravens recently started breeding on a moorland in the central Pennines , where the Twite population was being monitored. Ravens were seen to cold search an area, and predate a Twite nest, but it is not known whether this was a casual occurrence, or the Ravens do systematically search for nests. There were numerous dead sheep in the area, which provided food and presumably helped the Ravens to become established in the area (Brian Leecey, pers.comm.).

Although predators and prey have to achieve a natural balance in those instances where the predator has only one main prey species, this does not apply for those predators that have a wide variety of food sources.  If there used to be a balance between the number of predators on the one hand, and Snipe, Curlew and Lapwing on the other, then necessarily that balance must have been affected now that the number of predators has increased substantially as a result of modern agricultural methods, and the number of these breeding waders has decreased because of habitat loss. 

This impact becomes even more pronounced when habitat loss means that the waders have to congregate at a few remaining sites where they can still potentially breed, as they make an easier target in these circumstances.

For example, there are relatively few ploughed fields in the Shropshire Hills and Clun Uplands ESAs, and very few of these are ploughed in Spring. The few that remain provide potential Lapwing nest sites, but they are also particularly attractive as feeding sites to Carrion Crows – the ploughing increases access to invertebrate food. Eighty-one Crows were observed on one such Spring cereal field on 9 May. The whole field was not visible, so there were probably rather more than 81 Crows. At another recently ploughed field on 31 March, two Lapwings were accompanied by more than 20 Crows. Any Lapwings attempting to nest in such fields would have their eggs predated in a very short time.

In the case of all three wader species, habitat loss has largely occurred as a result of land drainage, a necessary pre-requisite of modern farming techniques.  The application of fertiliser reinforces the damaging effect of drainage, by accelerating the speed at which the ground dries out.

There are several modern agricultural practices that provide a much- increased food supply for all these predators of ground-nesting birds, particularly at the times when this will have maximum benefit for the population growth and survival rates of the predators - during the breeding season, and also during the winter. Therefore the numbers of many predators now almost certainly exceed the naturally-sustainable level, probably by a considerable margin.

Intensive Sheep Farming

Most of these practices are an integral part of intensive sheep farming. There are now three times more sheep than people in Shropshire .  Numbers have increased three-fold since 1950, and there are now close to a million.  This has been accompanied by the recent tendency for sheep to have two lambs, rather than one. These changes have lead to a big increase in sheep carrion, coupled with greater use of fertilisers to increase the supply of grass to feed them, and use of supplementary feeds, to enable such large numbers of sheep to inhabit the fields.

• Firstly, normal mortality pressures have significantly increased the number of dead sheep on the hillside, as the number of sheep themselves has increased.

• Secondly, there has been a big increase in the quantity of sheep carrion left out on the hillsides from the early 1990s onwards, when the change in processing regulations to combat BSE removed the financial incentive for carcasses to be taken to the knackers yard for rendering.  Hunts, as well as farmers, used to take carcasses from the hillside to the knackers yard, but research by the Shropshire Raven Study Group has shown that the number of carcasses delivered to the four largest knackers yards in the area at the height of the Raven nesting period reduced from 163-402 per week in 1988-91, to an average of less than seven per week in the same period in 1993-97.

• Thirdly, the increasing number of sheep, and the modern tendency for ewes to have two lambs, has significantly increased the amount of afterbirth – a very rich source of food – on the hillside, mainly in March and April.

• Fourthly, the increase in the number of lambs, and their natural mortality, has increased the number of dead lambs available to carrion-eaters throughout their breeding season.

• Fifthly, supplementary foods are left in open troughs in fields where sheep are grazing.  These supplements are themselves a valuable source of food.  While carrying out the preliminary work for the 2004 Snipe Survey, 61 Carrion Crows were counted in a single field, all perched on a row of troughs with supplementary food.  The sheep were eating the grass, rather than the supplementary food.  There were many more Crows in the same field, attracted by the sheep but eating on the ground. Even when the sheep and troughs are moved to a different field, substantial numbers of Crows still visit the vacated field to feed.

All these factors create an increased food supply at the time of both of the two main “pinch points” in the predators’ life cycles – the rich supply of food from lambing in March, April and May increases the number of fledglings and cubs that can be successfully reared, and the increased supply later on in the year increases winter survival rates.

Impact Of Pheasant Shooting

The other major impact on predator numbers is the indirect effect of the increasing popularity of Pheasant Shoots. 

The number of Pheasant chicks put out by shoots has increased considerably in recent years, and is still increasing, and the shoots estimate that only 40% of these chicks are eventually shot.  Some of the shot birds are left where they land, until they get eaten by predators.  Other birds are wounded rather than killed, and either die elsewhere shortly afterwards, or become easy targets for predators.   

Many of the birds that are not shot are eventually predated, or die naturally and are scavenged. Road kills are an additional supply of food.  

The grain and pellets put out to feed young Pheasants are also eaten by predators. A Gamekeeper recently complained that a flock of Ravens was following his tractor while he was putting out pellets for pheasants, and eating them as he watched.

Conclusion

It is theoretically possible, but extremely unlikely, that the increased food supply for predators has not affected their population levels, and the known Raven population explosion is an exception to the general pattern. However, local hearsay evidence from farmers and gamekeepers suggests this is not the case.  

It is also theoretically possible, but extremely unlikely, that the increasing number of predators are each predating fewer birds nests and chicks than they used to (the necessary consequence of more predators having no discernable effect on the populations of the prey species), but then other explanations must be found for the observed population decline of ground-nesting birds. Research on the Long Mynd has clearly shown that higher levels of predation there have affected Ring Ouzel populations to the level of probable extinction, and other possible causes have been researched and ruled out; while Curlew and Snipe have also declined massively, but monitoring of the quality of the wetlands has shown that no observable change has occurred. On The Stiperstones, Curlews have disappeared although, again, there has been no apparent change in the habitat.

It therefore appears that, if action is not taken to control the number of predators of ground-nesting birds, as an integral part of a conservation programme of land use management to improve their habitat, and reduce the intensity of sheep farming and pheasant release, there is a real danger that these birds will become extinct in the Shropshire Hills.

The Government Department for Environment, Food and Rural Affairs (Defra) has a target to reverse the decline in the population of a number of specified farmland bird species by 2020, as part of its Public Service Agreement with the Treasury.

The Report Breeding Snipe In The South-West Shropshire Hills 2004 therefore includes recommendations to Defra to undertake further research to assess the full impact of the agricultural and recreational practices that provide an increased food supply for the predators of ground-nesting birds, and, based on the results, develop policies, programmes and regulations to minimise their impact on these birds.

CONSERVATION PRIORITIES

A situation has been reached now which would have been considered totally implausible 20 years ago. In Shropshire , there are now more breeding pairs of once-scarce species than there are of once common ones:-

·        More Buzzards than Lapwings or Curlews

·        More Merlin than Ring Ouzel

·        Probably more Peregrines than Snipe

·        Perhaps more Ravens than Curlews

·        Probably more Buzzards than Lapwing, Curlew and Snipe combined

While the success of the birds of prey is welcome, urgent action is needed to reverse the decline of ground-nesting birds in the uplands, and elsewhere.

APPENDIX 2. REFERENCES

Gibbons, D. W., Reid, J. B. & Chapman, R. A., The New Atlas of Breeding Birds in Britain and Ireland: 1988–1991. T & A D Poyser (1993). (Referred to as the New Atlas (1993) throughout).

Breeding Bird Survey Annual Reports (1994–2003), British Trust for Ornithology.  (Referred to as BBS (year) throughout).

The Shropshire Bird Reports, published annually by Shropshire Ornithological Society.  (Referred to as SBR (year) throughout).

Burfield, I.J. (2002) The Breeding Ecology And Conservation Of The Ring Ouzel Turdus torquatus In Britain   Ph.D. Thesis Queen’s College University Of Cambridge January 2002.  

Crick, H.Q.P., Marchant, J.H., Noble, D.G., Baillie, S.R., Balmer, D.E., Beaven, L.P., Coombes, R.H., Downie, I.S., Freeman, S.N., Joys, A.C., Leech, D.I., Raven, M.J., Robinson, R.A. and Thewlis, R.M. (2004) Breeding Birds In The Wider Countryside: Their Conservation Status 2003. BTO Research Report No. 353. BTO, Thetford.

Grant, M.C., Orsman, C., Easton , J., Lodge, C., Smith , M., Thompson, G., Rodwell, S. & Moore, N. (1999). Breeding Success And Causes Of Breeding Failure Of Curlew Numenius Arquata In Northern Ireland . Journal Of Applied Ecology, 36: 59- 74.

Marchant, J.H., Hudson , R., Cater, S.P. and Whittington, P. (1990) Population Trends In British Breeding Birds  BTO.

Sheldon, R.D. (2002) The Breeding Success And Chick Survival Of Lapwing Vanellus Vanellus In Arable Landscapes, With Reference To The Arable Stewardship Pilot Scheme. Unpublished PhD Thesis, Harper Adams University College .

Sim, I.M.W., Cross, A.V., Lamacraft, D.L. & Pain, D.J., Correlates of Common Buzzard Buteo buteo density and breeding success in the West Midlands. Bird Study 48: 317-329 (2001)

Smith , L., Report Of The Long Mynd Breeding Project: Ring Ouzel 2003.

Smith , L., Report Of The Long Mynd Breeding Project: Ring Ouzel 2004.

Smith , L., Upland Birds Of The Long Mynd: Report Of The Long Mynd Breeding Bird Project 1994-98 Report presented to National Trust, English Nature, SOS, RSPB, BTO and Defra 2004.

Smith , L., Lapwing, Curlew and Other Breeding Birds in the Upper Onny Area:  Report of the Upper Onny Wildlife Group Survey 2004.

Smith , L., Breeding Snipe In The South-West Shropshire Hills 2004.