Worcestershire Record No. 17 November 2004 p. 40-42

BUTTERFLIES AND BUMBLEBEES BETWEEN BLACKMINSTER AND BRETFORTON

Terry Knight

Worcestershire Transects

In Worcestershire there are currently about 18 transects that are walked once a week through the summer to record numbers of butterflies (Gregory 2003). Few of these are located in areas that are typical of normal Worcestershire countryside. Instead they have been purposely set up at sites where butterfly numbers are expected to be high and/or rarer species exist. One of these transects is at Windmill Hill, Middle Littleton. This is a Site of Special Scientific Interest and a nature reserve which is noted for its invertebrates.

As far as is known, there are no bumblebee transects elsewhere in the county.

Reason For New Transect

As these special butterfly sites make up just a few percent of the area of the county most of the transects cannot give an indication of the numbers of butterflies in the countryside as a whole. At the end of February 2001 the Foot and Mouth outbreak started to close off the countryside and it looked as if no butterfly transect recording would be possible that year. This provided the spur to find an "on-road" transect location that would be as typical as possible of the present Vale of Evesham in order to give some indication of the numbers in the wider countryside.

The Blackminster Site

About two and a half kilometres south of the Windmill Hill transect is a minor road running east from Blackminster to Bretforton. 0.9 kilometres of this has no hedges and only an open fence one side for a distance of 130 metres. The area used to be all market garden but now only a small part remains. However, it still has asparagus beds, herbs and a narrow strip of derelict orchard. Apart from grassland behind the fence which is either grazed or mown, all the remainder is large-field arable. Crops include corn, rape and beans.

This seemed an ideal "on-road" location and so a length was selected to give an out and back distance of 1.53 kilometres which is comparable to the 1.52 kilometre transect length at Windmill Hill. Details are given in the table to the right.

 

     

WEST

     

(OS grid ref SP 0745 4473)

             

Sect.

Length

Description

 

Description

Length

Sect.

No.

(m)

     

(m)

No.

     

Road

     

1

88

Market garden

l l

Asparagus beds

33

11

     

l l

Sheds and scrub

27

11

     

l l

Waste

76

10

     

l l

     

2

116

Market Garden

l l

     

2

18

Derelict orchard

l l

Grassland

130

9

3

139

Arable

l l

Arable

95

8

     

l l

     

4

192

Arable

l l

Arable

192

7

5

210

Arable

l l

Arable

215

6

             

Road verge about 1 m wide bordering all sections apart from 10

(OS grid ref SP 0821 4460)

EAST

Bumblebees

It was expected from the outset that butterfly numbers would be less than at Windmill Hill and so it would be practical to record bumblebees at the same time. No attempt would be made to identify species of either Bombus or Psithyrus but it is likely that these include B. lucorum, B. terrestris, B. pratorum, B. lapidarius, B. hortorum, B. pascuorum and P. vestalis. The narrow strip of road verge has some Meadow Cranesbill, Creeping Thistle, Spear Thistle, Common Mallow and Autumn Hawkbit which attract bumblebees and consequently the number recorded is probably somewhat greater than if the road verge was absent.

Recording

The standard method of butterfly transect recording was used with an adaptation to suit the site. This consisted of recording for a distance of five metres on one side of the walk rather that two and a half metres each side. Consequently, in general the transect covered about one metre of road verge plus four metres of field beyond. On the eastward part of the walk the area south of the road was recorded and on the westward part the area north of the road.

Week 1 is from April 1st to April 6th and week 26 from September 23rd to September 29th.

Results To-date

The impression gained during recording was that the derelict orchard and its immediate surroundings harboured a greater density of butterflies than the rest of the transect. Consequently, as well as comparisons being made using the full transect data, they are also made using data from sections near the orchard (sections 2, 3, 8 and 9) and sections away from the orchard (sections 1, 4, 5, 6, 7, 10 and 11).

It transpired during 2001 that permission was granted to continue the Windmill Hill transect through the Foot and Mouth crisis. This made it possible to use the results from that butterfly transect as a basis for comparisons at Blackminster thus eliminating most of the effects of variations in the weather.

A summary of the Blackminster results is given in Tables 2, 3 and 4. The total number of each species of butterfly recorded over the four years is given in Table 5. The most abundant species are Small White, Meadow Brown, Gatekeeper, Green-veined White, and Small Tortoiseshell. Graphs showing the butterflies and bumblebees over the 26 week period each year as a percentage of the Windmill Hill butterflies are given in Figures 1, 2 and 3. The graph shown in Figure 4 gives the average number of butterflies and bumblebees per walk over the 26 weeks.

The average number of butterflies and bumblebees seen per walk at Blackminster over the 4 year, 26 week period works out as 3.71 per kilometre and 2.85 per kilometre respectively. This compares with 44.83 per kilometre for butterflies at Windmill Hill and gives a ratio for Blackminster butterflies of 8.3 percent and bumblebees of 6.4 percent.

Year     

(Windmill Hill)

Blackminster

Blackminster

(Butterflies)

Butterflies

Bumblebees

NUMBER (26 WEEK TOTAL)

2001

1872

68

51

2002

1666

175

134

2003

2076

203

114

2004

1473

145

154

NUMBER PER KILOMETER (26 WEEK TOTAL)

2001

1232

44.4

33.3

2002

1096

114.4

87.6

2003

1366

132.7

74.5

2004

969

94.8

100.7

AS PERCENT OF WINDMILL HILL BUTTERFLIES

2001

100

3.61

2.71

2002

100

10.44

7.99

2003

100

9.71

5.46

2004

100

9.78

10.39

Table 2 Results From All Sections


Figure 1
Results From All Sections
(As percent of Windmill Hill butterflies
)

   

Year   

Blackminster                          

Blackminster

Butterflies

Bumblebees

NUMBER (26 WEEK TOTAL)

2001

37

34

2002

109

78

2003

127

75

2004

53

106

NUMBER PER KILOMETER (26 WEEK TOTAL)

2001

35.8

32.9

2002

105.5

75.5

2003

122.9

72.6

2004

51.3

102.6

AS PERCENT OF WINDMILL HILL BUTTERFLIES

2001

2.91

2.67

2002

9.63

6.89

2003

9

5.32

2004

5.29

10.59

Table 3 Results Away From Orchard (Length 1.033 km)

 

 


Figure 2
Results Away From Orchard)
(As percent of Windmill Hill butterflies
)

   

Year

Blackminster

Blackminster

Butterflies

Bumblebees

NUMBER (26 WEEK TOTAL)

2001

31

17

2002

66

56

2003

76

39

2004

92

48

NUMBER PER KILOMETER (26 WEEK TOTAL)

2001

62.2

34.1

2002

132.5

112.4

2003

152.6

78.3

2004

184.7

96.4

AS PERCENT OF WINDMILL HILL BUTTERFLIES

2001

5.05

2.77

2002

12.09

10.26

2003

11.17

5.73

2004

19.06

9.95

Table4. Results From Around Orchard (Length 0.498 kilometers)

 

 


Figure 3
Results From Around Orchard)
(As percent of Windmill Hill butterflies
)

Species

No.

Small/Essex Skipper

20

Large Skipper

1

Brimstone

3

Large White

14

Small White

187

Green-veined White

65

Orange Tip

4

Small Copper

1

Common Blue

4

Red Admiral

1

Painted Lady

3

Small Tortoiseshell

41

Peacock

4

Comma

1

Marbled White

2

Gatekeeper

83

Meadow Brown

152

Ringlet

5

Sum

591

Table 5. Total numbers recorded over 4 years

 

Conclusions

It appears that the derelict orchard has little or no effect on the distribution of bumblebee sightings. However, this is not the case with the distribution of butterflies. In each of the four years the density of butterflies near the orchard has been greater than away from it. The reason for this seems to be that about 90 percent of Gatekeepers and 80 percent of Meadow Browns were recorded in sections near the orchard and the grassland opposite it.

As expected, in typical Vale of Evesham countryside the number of butterflies is much less than on nearby natural grassland managed for nature conservation. This short term study appears to show that there may be less than one tenth in typical present day countryside. At Blackminster the number of bumblebees seems to be generally slightly less than butterflies.

References

GREGORY NEIL 2003. VC 37 (Worcestershire) Butterfly Transects Annual Review 2002, Worcestershire Record 14 : 20.

 
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