Pigeonhouse Stream and the Malago (2010)
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Wildlife Survey of PIGEONHOUSE STREAM AND THE MALAGO May / August 2010 For South Bristol Riverscapes Partnership Phil Quinn (Ecology and land use) MIEEM Flat 4, 15 Osborne Road, Clifton, Bristol, BS8 2HB. Tel. 0117 9747012; mob. 0796 2062917; email: [email protected] Wildlife Survey of Pigeonhouse Stream and the Malago (2010) CONTENTS Page 1. Summary 3-4 2. Remit 5 3. Site description 5-6 4. Methodology 7-8 5. Caveat 8 6. Results 8-40 6.1 The Malago 8-25 6.1.1 Dundry Slopes 9-13 M1 East of Strawberry Lane 9 M2 West of Strawberry Lane 10 M3 Ditch in a hedge 10 M4: A Malago is Born 10-11 M5: Teenage Malago 11-12 M6: Pretender to the Throne 12 M7: Claypiece Road isolate 12 6.1.2 Hengrove Plain and Bedminster 14-25 M8: The Stream Invisible 14 M9: Suburban Streamside 14-15 M10: Malago Valley SNCI 15-16 M10a Small tributary ditch 17 M11: A Whimper of a Watercourse 17-18 M12: Up the Junction 18 M13: Fire, Fire, Pour on Water 18-19 M14: Malago Incognito 20 M15: Parson Street to Marksbury Road 20-21 M16: Malago Vale 21-22 M17: The Bedminster Triangle 22-23 M18: Cotswold Road Canyon 23-24 M19: Water Rail 24 M20: Clarke Street dog-leg 24-25 1 Wildlife Survey of Pigeonhouse Stream and the Malago (2010) 6.2 Pigeonhouse Stream 25-40 6.2.1 Dundry Slopes 26-33 P1: Lower slopes tributary stream 26-27 P2a: Pigeonhouse Stream (headwaters) 27 P2b: Pigeonhouse Stream (tufa stream) 28 P2c: Pigeonhouse Stream (ancient woodland) 28-29 P2d: Pigeonhouse Stream (middle slopes) 29 P2e: Pigeonhouse Stream (south of pipeline crossing) 30 P2f: Pigeonhouse Stream (pipeline crossing) 30 P2g: Pigeonhouse Stream (pipeline crossing to culvert) 31 P3: Main tributary 32 P3a: Minor stream 32 P4: Upper tributary stream 33 6.2.2 Hengrove Plain 34-40 P5: Resurgence 34 P6: Hareclive Road to Fulford Road 34-35 P7: Whitchurch Lane or Bust 35-36 P8: The Hengrove Lake District 37 P9: Crox Bottom 37-38 P10: Hartcliffe Way / Pigeonhouse Stream 39-40 7. Discussion 41 7.1 General 41 7.2 Variation between May and August surveys 41 8. Recommendations 42-45 9. Conclusions 46 10. Appendices: Species records 47-61 10.1 Plant species 47-57 10.2 Fish species 58 10.3 Bird species 59-60 10.4 Mammal species 60 10.5 Invertebrate species 61 Survey maps 2 Wildlife Survey of Pigeonhouse Stream and the Malago (2010) 1. Summary Twenty kilometres of the Malago and Pigeonhouse Stream and their tributaries were surveyed over the 20th, 21st and 23rd May 2010 with a follow-up survey on 12th August 2010. Physical access was gained to over 85% of the watercourses where they flowed in an open channel. Slightly more than 3 kilometres of watercourse were found to be culverted. The timing of the survey not only offered an excellent opportunity to record and assess the riparian and emergent vegetation associated with the streams, it was also particularly good with regard to assessing the vegetation of the more wooded sections of stream as many species of herbaceous woodland plants are spring flowering. The main discoveries of this survey are: The headwater streams (on Dundry Hill) are markedly different from the main streams running across urban south Bristol and have great value in terms of nature conservation value. The main streams also have nature conservation value but have been heavily modified by human actions; their flora comprises less rare species but the range of habitat they offer is considerably more diverse than that on the headwaters. The headwater streams are often bordered by exceptionally rich arrays of woodland floor plants, many of which are commonly known as “ancient woodland indicators”. Species of note include tutsan Hypericum androsaemum, wood vetch Vicia sylvatica, hairy wood-rush Luzula pilosa and wood spurge Euphorbia amygdaloides. Other woodland species of note include sanicle Sanicula europaea, wood millet Millium effusum, goldilocks buttercup Ranunculus auricomus, wood anemone Anemone nemorosa and sweet woodruff Galium odoratum. The silt trap ponds on both the Malago and Pigeonhouse Stream have a good diversity of wetland plant and invertebrate species. Imperforate St John’s-wort Hypericum maculatum, technically not an ancient woodland indicator, but found here in a woodland situation, is perhaps the rarest plant species to be recorded during the survey. It has a very restricted distribution in the Bristol region with very few records south of the River Avon. Large fish –possibly roach Rutilus rutilus or rudd Scardinius erythrophthalamus are present in the deeper sections of Pigeonhouse Stream in Crox Bottom; bullhead Cottus gobio are relatively common under stones in the lower reaches of the Malago. Three-spined stickleback 3 Wildlife Survey of Pigeonhouse Stream and the Malago (2010) Gasterosteus aculeatus were frequent and occasionally abundant throughout often forming small shoals. A large population of the attractive damselfly beautiful demoiselle Calopteryx virgo are present on the middle sections of the Malago and Pigeonhouse Stream, particularly in the area around their confluence. By late summer much of the botanical interest along the streams has peaked, with only trifid bur-marigold Bidens tripartita – a late flowering locally Uncommon plant – of note. This species is present mainly in Malago Valley SNCI. Parts of this stream system are very attractive and naturalistic –remarkably so given that much of the Malago and Pigeonhouse Stream run through a densely- populated urban area. The tributary and headwater streams on Dundry Hill are particularly notable for their wild and semi-natural conditions although most of the main stream sections to the north of Dundry Hill flow through public open space where an enlightened management regime enhances their semi-natural character. Public access is possible through much of the course of the two streams and their tributaries; this can be either formally designated as in the parks and public open spaces or unofficial as in many of the headwater and tributary stream areas. Footpaths and cyclepaths following the course of the streams through the urban areas appear to be well-appreciated by the public. The aesthetic value provided by the mature and semi-mature streamside trees to adjacent householders as well as those members of the public using the streamside paths for walking dogs, commuting, or just out for a pleasant walk, is high. There is a high potential with both watercourses to encourage the public to look out for notable species and also to monitor certain sections to record littering incidents (high on the agenda of many members of the public who approached the surveyor). Establishing community action groups to combat littering in the streams may well prove a way of enabling local residents to engage more fully with these diverse and attractive watercourses. Wood spurge Euphorbia amygdaloides from the Pigeonhouse Stream headwaters 4 Wildlife Survey of Pigeonhouse Stream and the Malago (2010) 2. Remit To undertake a wildlife survey of Pigeonhouse Stream and The Malago, and their tributaries for the South Bristol Riverscapes Project. To record all wildlife (or signs of wildlife) seen along the watercourses, including descriptions of habitats and any management currently taking place; to note any features of concern and to make brief recommendations on management if necessary. To offer an awareness of the value of the brook and its tributaries in their context of urban south Bristol. To produce a map with annotated maps detailing all relevant findings. 3. Site description The survey area comprises two main watercourses (and numerous tributaries on Dundry Hill) which flow together to form the Malago. Although the conjoined watercourse is known as the Malago it is the other watercourse –Pigeonhouse Stream–which is generally the larger of the two. The western stream (the Malago) rises amidst species-rich unimproved and semi-improved horse-grazed pastures, dense scrub, unmanaged species rich hedgerows, tall herb and scattered woodland on the northern slopes of Dundry Hill just to the south of the urban area of Bristol. It soon enters suburban south Bristol and experiences a great degree of culverting –effectively being lost from view for almost half its length under Withywood before emerging again in Bishopsworth until it is culverted once more until its confluence with Pigeonhouse Stream The eastern stream (Pigeonhouse Stream) also rises amidst the diverse and species rich landscapes of the northern slopes of Dundry Hill to flow through urban south Bristol. Only small sections of its course are culverted and it generally flows with a somewhat greater volume than the Malago. The conjoined stream, flowing north as the Malago, flows through an increasingly hard engineered landscape as it enters Bedminster with many lengths of bank comprising masonry or brickwork. Prior to its confluence with the River Avon (New Cut) the stream is culverted under them ain commercial district of Bedminster. Prior to the creation of the New Cut (1810?) the Malago flowed into what is now Bathurst Basin- one of the old docks within Bristol Harbour; here it was dammed to form a millpond, the Basin preserving the dimensions of this pond. All the streams within this survey area rise on the steep northern slopes of Dundry Hill - a landform with a complex geology but mostly Jurassic limestones and associated strata. At the foot of the hill and extending north towards the 5 Wildlife Survey of Pigeonhouse Stream and the Malago (2010) confluence with the Avon the streams flow across a gently undulating landscape, essentially a plain, overlying a geology of Jurassic Lias which is largely calcareous (lime rich) in nature and then an area of Triassic Keuper Marl with alternating bands of lime-rich and lime-poor substrate.