Bird Reports 2012 next

2012 Report of a long term survey of breeding birds on Magog Down, Stapleford

Bryan Davies and Robin Cox, Cambridgeshire Bird Club

 
In a document dated 29/02/12 we proposed a long term breeding bird survey on Magog Down Stapleford. This report covers the trial year of this survey when the methods described in the proposal were tested and modified where necessary. The changes made are described in the revised fieldwork methods in Appendix 1.
 
Field Visits
During the main breeding season (March to June) six visits were made starting on 23 March and finishing on 13 June. On each visit records were made on the same route which included all the main habitats on both the North and South Downs (Table 1 and Appendix 1); this is described as the ‘Main Survey’. In addition several additional visits were made to the grassland area of North Down specifically to map skylark territories in the different grass cutting regimes that have been established; this is described as the ‘Skylark Study’. 
 
Main Survey
The main aim of the survey is to identify the species, and to estimate the number of each species which are probably breeding on the Magog Trust land. The majority of these species are residents that live most of the year on the Down or in the vicinity. In addition there are a smaller number of species which migrate south from the Down each autumn and return to breed the following year; these species are referred to as summer visitors. We also made a note of winter migrant species and several resident species which are unlikely to be breeding on the Down at present.
 
We identified 29 breeding species overall of which the Wood Pigeon was by far the most common. Four of the species were summer visitors (blackcap, chiffchaff, common whitethroat and willow warbler) and the others were residents. The route taken around the Down included 14 different locations where birds were recorded:
 
Location No. of species*
No. of birds**
Table 1: Breeding species recorded at 14 survey locations on the Down.
Car Park and adjacent Picnic area 13 25
Colin's Wood, Roadside and Garden hedges 11 18
Feoffee's fields and edge of Parish Pit 10 18
Feoffee's coppiced hedge 0 0
Clunch pits on Little Trees Hill 14 36
Shelter belt 6 6
Sheep paddocks 5 13
Memorial Wood 6 12
Arable field 16 2
Vestey wood and adjacent mature wood 13 23
Full length of Western boundary hedge 8 21
Villedomer wood 3 4
Magog Wood 10 16
North Down 4 32
  * Wood pigeons not recorded because of likelihood of double counting 
** Minimum number of birds breeding
 
The lists of species recorded in each of the locations are in Appendix 2. 
 
Table 2. lists the numbers of each breeding species recorded and the number of locations in which they were found.
 
Family Total*
Locations UK Status**
Table 2: Species probably breeding on Magog Down
Thrushes      
   Blackbird 11 6  
   Song Thrush 2 2 red
   Mistle Thrush 1 1 amber
   Robin 13 7  
Tits      
   Blue tit 22 8  
   Great tit 19 9  
   Long-tailed tit 9 5  
Finches      
   Chaffinch 23 10  
   Goldfinch 7 2 amber
   Greenfinch 7 3 red
   Linnet 6 2 red
Buntings
     
   Corn bunting 3 1 red
   Reed bunting - - amber
   Yellowhammer 3 1 red
Warblers      
   Blackcap 11 8  
   Chiffchaff 5 4  
   Common Whitethroat 4 1 amber
   Willow Warbler 2 1 amber
Larks      
   Skylark 31 3 red
Crows      
   Carrion Crow 10 4  
   Magpie 12 6  
   Jay 1 1  
Crests and Wrens
     
   Goldcrest 2 1  
   Wren 7 5  
Accentors      
   Dunnocks 8 6 amber
Pipits and Wagtails      
   Meadow Pipit 2 1 amber
   Pied Wagtail 1 1  
Partridges      
   Grey Partridge 3 2 red
   Red-legged Partridge 2 1  
Woodpeckers
     
   Green Woodpecker 1 1 amber
Pigeons and Doves      
   Wood Pigeon large numbers but not recorded
  * Sum of the largest number of birds recorded on any one visit at each location = the minimum no. of birds breeding.
** Species on the UK red list have shown a severe decline in numbers during last 40 years, species on the UK amber list have declined by 25-49% during the last 40 years.
 
The following species were recorded but thought not to be breeding on the Down at present: 
 
Family Status
Breeding probability*
Table 3: Non breeding speicies recorded on Magog Down
Birds of Prey    
    Buzzard Resident High
    Kestrel Resident High
    Red Kite Resident Low**
    Sparrow hawk Resident High
Thrushes    
    Fieldfare Winter visitor Nil
    Redwing Winter visitor Nil
    Wheatear Summer visitor Nil
Crows    
    Jackdaw Resident Low
    Rook Resident Low
Swifts and Swallows
   
    Swift Summer visitor Nil
    Barn swallow Summer visitor Nil
  * Estimate of likelihood of breeding in the future
  ** More likely to breed in the larger woods at Wandlebury

There are several  species that have been recorded on the Down in recent years by the Stapleford Bird Club, which were not recorded during our survey but which maybe breeding currently:
Coal Tit, Bullfinch, Starling, Collared Dove, Great Spotted Woodpecker, Garden Warbler, Pheasant. 
 
Discussion
At least 29 species were probably breeding on the Down in 2012 of which 25 are UK residents and 4 are summer visitors. Eight species with 10 or more records appear to be well adapted to breeding on the Down: Wood Pigeon, Skylark, Chaffinch, Blue Tit, Great Tit, Robin, Magpie and Blackbird. None of these birds are of conservation concern in the UK, with the notable exception of the Skylark, whose numbers have declined so much that it is now on the Red list of the RSPB. Clearly the current management of the grassland both by cutting (see later Skylark Study) and by grazing provides very suitable habitats for this species.
 
However the other four species on the Red List (Song thrush, Corn Bunting, Yellowhammer and Grey Partridge) are present in very small numbers and would benefit from measures designed to increase their numbers (see section on conservation measures). Some of these measures would also benefit the 8 species on the RSPB Amber list (Table 1) the UK populations of which have also declined substantially.
 
Conservation Measures 
The four factors that are most likely to be limiting the breeding success of birds that are struggling to maintain populations on Magog Down are:
 
Lack of food overwinter
This will affect only the resident species but is likely to seriously reduce the number of birds able to survive during the late winter early spring period. Although Finches and Buntings are likely to be the worst affected, all resident species suffer to some extent. Various types of berry will sustain the Thrushes during the early winter but the influx of wintering fieldfare and redwings exhaust this food source long before the end of winter. Apart from bird-feeders in the few gardens adjacent to the Down, the surrounding cropped landscape, growing mainly autumn sown cereals and oil seed rape, provides negligible quantities of food to sustain wintering birds. During a recent winter visit to the Magog Down on 6 December it was nearly devoid of birds with only 3 blackbirds, 2 Blue Tits and a magpie recorded. 
 
This virtual absence of residents is undoubtedly a consequence of a lack of food and it contrasts strongly with sites where either natural food is available e.g. at Fowlmere RSPB Reserve or where food is provided regularly in gardens.  It may be argued that in the past, before the natural downland was ploughed up to produce arable crops, food availability for resident birds during winter months would have been negligible. However this overlooks that the farmsteads were located in valleys nearby to the Downs where there was a good supply of bird food on cereal stubbles and a plentiful supply of grain at stacks particularly during the threshing period.
 
This food ‘desert’ is reinforced by the absence of any overwinter strips of bird seed producing plants in the surrounding fields. The supply of food during this critical period could easily, but at a cost, be improved by supplementary feeding points and/or by strips of plant species producing seeds for birds sown in the arable area on South Down or in nearby arable fields. The species/varieties of seed provided would need to be indigenous to avoid contamination with non native plants.
 
Shortage of insects for chicks
Chicks of the majority of the bird species breeding on the Down will not
fledge successfully without a good supply of insects. The severe restriction in this supply is one of the major factors responsible for the steep decline in populations of farmland birds in lowland England. The Magog Trust has recognised this limitation and ensured that their grassland areas are managed to ensure that insects can prosper. Furthermore the area of chalk grassland managed by the Trust is being increased by the conversion of some of the former woodland to grass. The profusion of flowering plants on the Downs, coupled with the success of the skylark population, suggest that shortage of insects during the breeding season may not be a major current limitation of breeding success.
 
Shortage of suitable habitats for nesting
Each species has its own preferred nesting habitat(s), so it is not possible to make many general statements on the availability of suitable habitats. It is likely that there is not a shortage of nesting sites for those species breeding in substantial numbers e.g. Woodpigeon, Skylark, Chaffinch, Great and Blue Tit, Blackbird and Blackcap.
Those species only breeding in small numbers, and some species not breeding at present, may have insufficient suitable nesting sites available. Of these species the Corn Bunting, Yellowhammer, Willow Warbler and Kestrel appear the most likely to benefit from additional nesting sites. 
 
Corn buntings nest in cereals but, because it is a late breeder, cereal harvest usually curtails its success. Strips of wild bird seed species which include patches of un-harvested wheat enhance its breeding success. 
 
The Yellowhammer nests in well managed hedgerows with occasional taller singing perches (also essential for corn buntings which in 2012 sang from the electricity pylon). At present the western boundary hedge adjacent to the arable is the only suitable hedge, although it lacks good singing perches. The coppiced southern boundary to Feoffees field will, in future, extend the length of hedge suitable for this species and for common whitethroats nesting in the uncut herbage bordering the hedge. The western boundary hedge next to Villedomer wood is becoming too tall but could, with suitable management, extend the length of suitable habitat for these two species. When hedges are cut, layered or coppiced it is important that only a section of the hedge should be cut in any one year.
 
Willow warblers nest in low ground cover close to trees, a habitat which should be preserved and extended on all the woodland edges.  The nesting of Kestrels and perhaps Tawny Owls would be encouraged by the siting of additional suitable boxes in trees.
 
At present the recently planted woods are poor providers of both nesting habitat and food, apart from berries on some of the shrubs. It will be interesting to discover if the projected thinning management, which where feasible will include some clearings and coppicing, will result in sufficient undergrowth to enhance both insect populations and nesting opportunities. Records taken before and after thinning in Villedomer Wood will provide an estimate of these effects.
 
Predation and Disturbance
There is no information on egg and chick losses caused by predators on Magog Down but the numbers of magpies and grey squirrels suggest that these predators may cause substantial losses. Likewise we have no information on the effects of disturbance caused by dogs and their walkers but it would seem precautionary to replace the wire fences preventing access from the perimeter dog walk into the woodland areas where they have failed. The 2012 poster campaign requiring dogs walking on North Down to be on leads during the skylark season appeared to be effective  particularly during vulnerable period before incubation.
 
Absent birds 
Several species recently recorded on the Down by the Stapleford Bird Club were not recorded during our 2012 Survey. Of these the Great Spotted Woodpecker, Bullfinch, Coal Tit, Starling and Collared Dove are all species that we would expect to be breeding there. Other species for which we consider there are already suitable habitats on the Down are Lesser Whitethroat, Garden Warbler, Spotted Flycatcher, Tawny Owl, Sparrow Hawk and Red Kite.
 
Skylark Study
Apart from wood pigeons, there were more skylarks on Magog Down then any other species. All the grassland areas and the arable area contained skylark territories with the largest number on North Down, where a rotational cutting regime has been practised for several years. The grass is cut in quadrants during August every third year, so that during the breeding season there are quadrants of short grass cut the previous year, quadrants of intermediate length grass cut two years ago and quadrants of longer grass cut three years ago 
 
With the help of Louise Bacon of the Cambridgeshire Bird Club territories were mapped on 1 May after the birds had established their nesting territories. Of the 12 territories identified 11 were in areas of longer grass, 1 in an area of intermediate length grass and none in the short grass areas. Territories were recorded in all the four quadrants of longer grass. It is probable that the greater protection from predation of nests provided by the longer herbage is the reason for the choice of nest sites. 
 
In 2012 a prolonged drought, prior to and during the early breeding period, resulted in very little growth on the most recently cut quadrants. In future years the contrast in grass length may be less extreme which in turn may influence the distribution of territories. This study will be repeated in 2013.
 
 
Appendix 1. Revised Fieldwork Methods.
In the project proposal (29/02/2012) we wrote that territories would be mapped for each of the birds recorded during site visits, but in practice it was found that this was too time consuming and could not be achieved effectively in the old woodlands. Instead we used the methods adopted for the BTO Breeding Bird Survey by which all the birds seen or heard were recorded on a pre-arranged route through 14 locations covering all the main habitats. The early morning visits were completed in about 2 hours on 7 occasions (23/03, 29/03, 19/04, 01/05, 08/05, 29/05, 10/06). For each location, lists of birds recorded were prepared for each visit and the largest number of a species recorded on any one visit was identified. Provided they were recorded in suitable habitats these birds were assumed to be breeding. Sometimes it was possible to identify breeding pairs, but often this was not possible, so that the estimated number of birds is likely to underestimate the actual number breeding. Provided the estimates are reached by the same method every year, comparisons between years will be meaningful. 
 
For the 2013 Survey we will make 6 visits – 2 in March, 2 in April, and two in May. Because substantial changes have been made to the methods, the numbers of birds recorded during 2013 will be standardised at 100, not the numbers recorded in 2012.
 
The route taken will be the same as in 2012, starting in the Picnic area through the Car Park - down the off lead dog field  into Collins Wood along the path alongside the Babraham Road – up the path through Collins Wood next to the boundary fence to the end of the wood – down the steps and along the boundary path overlooking Feoffees field – through the padlocked gate along the closed path past the 3 clunch pits with the two western sheep paddocks to the south – through the second padlocked gate and along the path between Magog Wood and the two eastern sheep paddocks – along the path between Memorial Wood and the arable area to – the path between the new Vestey Wood and the old shelter belt – up the path between the western boundary hedge and arable area - Vildomer Wood- along the southern edge of North Down to end of Magog Wood –along the edge of Youth Wood  down to Car Park.
 
 
Appendix 2. Maximum number of Breeding Birds recorded at each Location
Car park and Picnic area
4 Chaffinch, 3 Goldfinches, 2 Blackbirds, 1Wren, 2 Greenfinches, 2 Great Tits, 1 Blue Tit, 2 Long-tailed Tits, 2 Robins, 2 Dunnocks, 1 Pied Wagtail, 2 Willow Warblers (both singing), 1 Blackcap.
Colin’s Wood- Roadside hedge- Garden hedges
2 Blackbirds, 3 Chaffinches, 3 Great Tits, 2 Blue Tits, 2 Long-tailed Tits, 1 Robin, 1 Wren, 1 Dunnock, 1 Magpie, 1 Chiffchaff, 1 Blackcap.
Feoffees Field and edge of Parish Pit
1 Chaffinch, 2 Linnets, 1 Great Tit, 2 Blue Tits, 1 Dunnock, 2 Magpies, 2 Carrion Crows, 1 Jay, 4 Skylarks, 1 Grey Partridge, 1 Blackcap.
Clunch Pits on Little Tree Hill
2 Blackbirds, 1 Robin, 5 Chaffinches, 1 Greenfinch, 2 Dunnocks, 5 Great Tits, 7 Blue
Tits, 2 Longtailed Tits, 1 Robin, 3 Wrens, 1 Carrion Crow, 2 Magpies, 1 Chiffchaff,
2 Goldcrests
Shelterbelt
1 Mistlethrush, 1 Robin, 1 Chaffinch, 1 Wren, 1 Great Tit, 1 Green Woodpecker
Sheep Paddocks 
1 Blackbird, 4 Carrion Crows, 3 Magpies, 2 Red-legged Partridge. 3 Skylarks
Arable
6 Skylarks
Memorial Wood
1 Chaffinch, 3 Robins, 1 Wren, 2 Great Tits, 4 Blue Tits, 1 Blackcap
Vestey Wood and Mature Wood
3 Blackbirds, 1 Song Thrush, 3 Robins, 4 Chaffinches, 1 Greenfinch, 1 Wren,
2 GreatTits, 1 Blue Tit, 1 Long-tailed Tit, 1 Dunnock, 2 Chiffchaffs, 2 Blackcaps,
1 Magpie  
Full length of Western Hedge
1 Blackbird, 1 Chaffinch, 3 Blue Tits, 4 Goldfinches, 2 Corn Buntings,
3 Yellowhammers, 4 Common Whitethroats, 2 Blackcaps
Villedomer Wood
1 Chaffinch, 1 Robin, 2 Great Tits
Magog Wood
1 Song Thrush, 2 Chaffinches, 1 Great Tit, 2 Blue Tits, 2 Long-tailed Tits, 2 Robins,
3 Magpies 1 Dunnock, 1 Blackcap, 1 Chiffchaff
North Down
24 Skylarks, 2 Meadow Pipits, 4 Linnets
 
 
11 December 2012.