Rosturra, Co. Galway; Bird Survey Report

JULY 2001


Martin Brennan, MSc.


CONTENTS

1. INTRODUCTION
2. SITE DESCRIPTION
3. SURVEY METHOD
4. COUNT POINTS
5. RESULTS
6. COMMENT
7. RECOMMENDATIONS
8. BIBLIOGRAPHY
9. MAP

 

1. INTRODUCTION

Rosturra Wood, Co. Galway.
(Grid Reference: M 76 01)

A network of 16 sites countrywide has been selected under the project known as The Millennium Forests the objective of which is to restore or create native woodlands. Rosturra is one of them. Ecological surveys are being conducted to establish baseline data which will inform management decision making and provide knowledge for the complimentary educational and promotional aspects of the project. This study of avifauna forms part of that broader ecological survey.

 

2. SITE DESCRIPTION

Rosturra Wood is situated about 3 kilometres north-east of the village of Woodford and about 3 kilometres west of Lough Derg in County Galway. It is at an altitude of approximately 60 meters above sea level. The site contains a diversity of woodland habitats including remnants of semi-natural oak woodland; mixed woodland; young birch woodland and Norway/sitka spruce woodland of various ages ranging from a recently replanted 3 years old crop to stands of 9-13 years, 20 years, 30 years and 35 years. The study area, comprising approximately 114 hectares, is shown outlined in red on the map attached. It forms part of a more extensive area of forest.

 

3. SURVEY METHOD

The survey was conducted using the point count method. Points were selected to represent the diversity of woodland or habitat types within the study area, subject to the limitations imposed by the requirements of this method - e.g. minimum distance of 200 meters between points. Within the chosen habitats points were randomly selected where the extent of the site so permitted.

Two counts were conducted. These took place between 05.30 hrs and 09.30 hrs on 1st May and 4th June 2001 respectively in favourable weather conditions.

Two separate recording bands were used at each point:- <30m and >30 meters.

All birds, whether detected by sight or sound (calls or song) were recorded.

Birds in flight and those recorded outside the official counts are shown separately and are excluded from computation of densities and from other statistical analysis.

Densities are derived from compounding the two counts for each point by taking the higher count for each species at ranges 0-30m and 0 to infinity as used in the IPA system {Blondel, Ferry and Frochot (International Bird Census Committee 1977)} - (Bibby et al 1985).

Abundance is based on recordings within the point - i.e. within the 30m radius.

 

4. COUNT POINTS

Counts were conducted at eight points within the study plot. As far as practicable these represented the diversity of habitats within the site as a whole and a good spread of locations throughout the entire block. A brief description of the habitat at each point follows. These are specific to the habitats within the 30m radius but would be typical of the habitat generally, with only minor variations expected between any specific points chosen within it.

Point 1.
Mature mixed woodland of oak (Quercus petraea) and ash (Fraxinus excelsior) (predominantly oak - planted 1887), with some understorey of hazel (Corylus avellana), holly (Ilex aquifolium), blackthorn (Prunus spinosa), willow (Salix spp.) and bramble (Rubus fruticosa). Ground vegetation was predominantly rushes (Juncus spp.) and grasses (Graminaea) with occasional ferns (Filiscopsida) . Canopy was closed.

Point 2.
Clearfelled area which had been replanted with sitka spruce (Picea sitchensis) and birch (Betula spp.). The site was characterised by ridges of soil and stumps, with bare ground and some dead wood. Ground vegetation, where present comprised grasses, rushes and occasional bramble.

Point 3.
Thirty years old sitka spruce. Canopy closed except for a small area where a number of trees had been removed. Understorey was absent except for occasional holly. Ground vegetation consisted of moss (Bryophytes) and occasional wood sorrell (Oxalis acetosella).

Point 4.
Plantation of young sitka spruce ranging between 1.5 and 2.5 meters feet tall, with a couple of spindly ash from the earlier crop remaining. Bramble scrub had spread throughout the site with occasional birch and willow scrub (up to 1.3 meters) also. Heather (Calluna vulgaris), bilberry (Vaccinium myrtillus), woodrush (Luzula spp.), grasses and ferns were also present.

Point 5.
Birch woodland. Trees were approximately 9 meters tall with holly understorey. There were occasional ash and rowan of similar height present also. Ground vegetation consisted of moss, woodrush and ferns.

Point 6.
Twenty years old sitka spruce with occasional birch. Canopy closed. No understorey but trees had not been pruned, resulting in branches to ground level. Ground vegetation consisted of mosses, occasional heather and Sphagnum.

Point 7.
Hazel/birch/willow scrub with bramble also on a damp site. Some open space. Ground vegetation consisted predominantly of rushes, grasses and woodrush. Some fallen trees were rotting in situ.

Point 8.
Remnants of semi-natural oak woodland - a small clump of mature oak trees with open space between. Birch, willow, holly and bramble scrub. Ground vegetation consisted of rushes, woodrush, grasses and ferns.

 

5. RESULTS

Species Richness
The number and variety of bird species varied from point to point and ranged between 8 and 16 (Table 1). The 8 points give a cumulative total of 22 bird species. A further 5 (Table 11) were recorded within the study area outside the formal counts bringing the total number of bird species for the entire property to 27. In addition the Duchas Conservation Ranger, Ciara O'Mahony, has recorded sparrowhawk (Accipiter nisus) in this property.

Three species only were recorded at all points - blackbird, woodpigeon and wren - although not all within the inner band.

Taking the total number of bird species recorded at each point the broadleaved woodland (sites 1 and 8) displayed the greatest species richness, followed by the 20 years old sitka spruce and broadleaved scrub. Least diversity was in birch woodland. However, by taking only those bird species recorded within the inner 30m band the picture changes somewhat. The broadleaved woodland still records the greatest species diversity followed now by the 30 years old spruce, and by the 20 years old spruce and broadleaved scrub in equal place. The clearfelled area displayed very poor species richness, with only one bird species recorded within the 30m band.


Table 1. Bird Species Recorded at Rosturra in Summer 2001.

SPECIES
POINTS
1
2
3
4
5
6
7
8
Blackbird (Turdus merula)
/
/*
/
/
/
/*
/*
/*
Blackcap (Sylvia atricapilla)
-
-
-
-
-
-
/
/
Blue Tit (Parus caeruleus)
/
-
-
-
-
-
/
-
Chaffinch (Fringilla coelebs)
/
-
/
/*
/
/
-
/
Chiff Chaff (Phylloscopus collybita)
/
-
-
/
/
-
-
-
Coal Tit (Parus ater)
/
-
/
-
/
/
-
-
Cuckoo (Cuculus canorus)
/*
/*
-
/*
/*
-
/*
-
Curlew (Numenius arquata)
-
/*
-
-
-
-
-
-
Dunnock (Prunella modularis)
-
-
-
-
-
-
/
/
Grasshopper Warbler (Locustella naevia)
-
-
-
-
-
-
-
/
Goldcrest (Regulus regulus)
/
-
/
-
-
-
-
/
Great Tit (Parus major)
/
-
-
/*
-
-
-
/
Jackdaw (Corvus monedula)
/*
-
-
-
-
-
-
-
Mistle Thrush (Turdus viscivorus)
/*
/*
/
/*
/*
/
-
/*
Pheasant (Phasianus colchicus)
/*
/*
/*
-
-
/*
/*
-
Robin (Erithacus rubecula)
/
/*
/
-
-
/
/
/
Rook (Corvus frugilegus)  
/*
-
-
-
/*
-
-
Song Thrush (Turdus philomelos)
/*
-
-
-
-
/
-
-
Tree Creeper (Certhia familiaris)
/
-
-
-
-
-
-
-
Willow Warbler (Phylloscopus trochilus)
-
-
-
/*
  
/*
/
/
Wood Pigeon (Columba palumbus)
/*
/*
/
/*
/*
/*
/*
/*
Wren (Troglodytes troglodytes)
/
/
/
/
/
/
/
/
                 
Number within 30m radius
10
1
8
3
5
6
6
9
Total Number
16
9
9
9
8
11
10
12

(Note: / = recorded inside 30m zone; /* = recorded beyond 30 zone; - = not recorded)

 

Table 11. Additional species recorded outside formal counts.

S P E C I E S
L O C A T I O N
Bullfinch (Pyrrhula pyrrhula) Compartments 56182C and 56184P
Jay (Garrulus glandarius) Compartment 56180M (Sub 2)
Mallard (Anas platyrhynchos) Compartment 56178B (in a drain)
Siskin (Carduelis spinus) Compartment 56184P
Snipe (Gallinago gallinago) Drumming over Compartment 56184P

 

Abundance
The three most abundant species in each habitat varies (Table 111) reflecting the preferences of the individual species. One species - wren - featured amongst the most abundant on six of the seven sites and it was the only species recorded within the 30m band on the clearfelled site.


Table 111. The most abundant species at each point.

SPECIES
P O I N T S
 
1
2
3
4
5
6
7
8
Blackbird
1
-
3
1
-
-
-
-
Chaffinch
2
-
-
-
2
-
-
-
Wren
3
1
-
3
1
1
2
1
Great Tit
-
-
-
-
-
-
-
1
Robin
-
-
1
-
-
-
3
-
Goldcrest
-
-
2
-
-
-
-
-
Chiff Chaff
-
-
-
2
-
-
-
-
Coal Tit
-
-
-
-
3
2
-
-
Mistle Thrush
-
-
-
-
-
3
-
-
Willow Warbler
-
-
-
-
-
-
1
1
Dunnock
-
-
-
-
-
-
3
-
Blackcap
-
-
-
-
-
-
3
-

Note: species are ranked in order of abundance 1 to 3 (1 = most abundant), where species ranked equally they are given the same number in the order; - = not recorded.

 

Density
Bird density for the study area as a whole was 36.4 birds per hectare.

 

6. COMMENT

Amongst the eight habitat types studied broadleaf woodland (Point 1) supported the highest number of bird species. This reflects the maturity of the woodland with good vertical stratification - ground floor vegetation, an understorey and a canopy. In terms of species richness this was followed by the less dense oak wood and scrub (Point 8). The additional bird species found on this latter site are typical of the more open woodland and varied habitat - some dense birch/willow scrub and dense ground vegetation with wet areas - blackcap, dunnock, willow warbler and grasshopper warbler. Within the 30m band of these two combined sites 14 of the recorded bird species were found.

In sharp contrast the recently clearfelled area, with bare ground, poor herb layer, and only occasional bramble, hosted just one species - wren - within the inner band. The open nature of this site, affording unimpeded audio and visual recording, also accounts for the relatively high number of other species recorded outside this band. Some, such as blackbird, mistle thrush, robin and wood pigeon were on the edge of the felled area with sound clearly audible from the count point. They are likely to use it for feeding but not for breeding or nesting.

The species recorded in both conifer plots (Points 3 and 6) were similar, and typical of such woodland. The birch woodland was relatively species poor and the young establishment conifer plot (Point 4) was surprisingly so given the scrub nature of the site.

 

7. RECOMMENDATIONS

This property contains a diversity of woodland habitats supporting relatively good species richness. With a replanting programme in progress an opportunity is available to better integrate individual forest blocks into an overall more cohesive unit in the interest both of biodiversity and aesthetics. This could be done by encouraging or planting more broadleaves around existing conifer plots where they are generally absent, so as to connect them with the rest of the forest and the newly developing broadleaved areas.

Allow willow and birch to colonise edges, or plant margins of broadleaves along roads, rides, rivers and drains.

Plant or encourage the development of pockets of berry-producing scrub and broadleaves.

Maintain some open areas or glades where herb vegetation can develop - these may be combined with the development of the scrub edges on roadways, e.g. at bends.

Where possible in the replacement of any young conifers with broadleaves plant mixed crops unless the intention is for instance to have woodland of pure species, e.g. oak woodland.

Do not plant the main tree species right out to the road/ride or compartment edge so as to allow for a phasing from open space to scrub to canopy - relevant also to hardwood crops of single species.

Monitor impact of the forest programme and operations on bird community.

 

8. BIBLIOGRAPHY

Anon (Forest Service) - Code of Best Practice - Ireland (2000).

Anon (Forest Service) - Forest Biodiversity Guidelines (2000).

Bibby, C. J.; Burgess, N. D. & Hill, D. A. - Bird Census Techniques (1992).

Fitter, R.; Fitter, A. & Blamey, M. - The Wild Flowers of Britain and Northern Europe (1974).

Higman, S.; Bass, S.; Judd, N.; Mayers, J. & Nussbaum. R. - The Sustainable Forestry Handbook (1999).

Humphries, C.J.; Press, J.R. & Sutton, D.A. - Trees of Britain and Europe (1981)

Mullarney, K.; Svensson, L.; Zetterstrom, D. & Grant, P.J.- Collins Bird Guide (1999)

Mutch, W. -Tall Trees and Small Woods, How to Grow and Tend Them (1998).

Peterson, R.; Mountfort, G. & Hollom, P.A.D. - A Field Guide to the Birds of Britain and Europe (1954).

Richards, A.J. - British Birds, A Field Guide (1979).

Sutherland, W.J. & Hill, D.A. (Eds) - Managing Habitats for Conservation (1995).

 

9. MAP

Legend
Study area : outlined in red
Count Point : number in yellow circle