Bird Surveys
Bird surveys were carried out on the following sites:
Bird Survey Report
JULY
2001
Martin Brennan, MSc.
CONTENTS
1.
INTRODUCTION
2. RESULTS
3. GENERAL PRINCIPLES
4. COMMENT
1.
INTRODUCTION
As
part of a broader ecological survey of the network of 16 sites
which constitute The Millennium Forests a detailed study
of avi-fauna was conducted in those six which are designated as
candidate National Heritage Areas or proposed Special areas of
Conservation.
These are:
1. Rosturra, Co. Galway
2. Muckross, Co. Kerry
3. Portlick, Co. Westmeath
4. Cullentra, Co. Sligo
5. Rossacroo, Co. Kerry
6. Ballygannon, Co. Wicklow
The study was conducted during the summer of 2001 using the point count method. A summary of the findings follows together with a brief discussion and an outline of the broad principles governing the management of forests in the interest of their bird populations. It outlines the ideal strategy. In managing the forests to fulfil a range of other objectives certain compromises will be necessary, however, these principles should form the backdrop against which the plan is developed, as they tend to satisfy other ecological requirements also, and are the basis for the sustainable management of the forest generally.
A more detailed stand-alone report on each individual site is attached with specific recommendations pertaining to that site.
2. RESULTS.
Bird species richness varied from site to site and ranged between 21 and 31 species (Table 1), giving a cumulative total of 44 species for the six sites. The variation is influenced by a number of factors, including the nature of the woodland, diversity of tree species, composition and range of habitats. In general mature broadleaved woodland supported the greatest bird species richness. Clearfelled sites displayed low species richness, and scrub was shown to be a valuable habitat in terms of the range of species which inhabit it.
Additional species associated with an adjacent aquatic habitat in two particular sites are listed in Table 11.
Table 1. Bird species recorded at each site in Summer 2001.
SPECIES |
SITES |
|||||
1 |
2 |
3 |
4 |
5 |
6 |
|
| Blackbird (Turdus merula) | / |
/ |
/ |
/ |
/ |
/ |
| Blackcap (Sylvia atricapilla) | / |
/* |
/ |
- |
/* |
/ |
| Blue Tit (Parus caeruleus) | / |
/* |
/ |
/ |
/ |
/ |
| Bullfinch (Pyrrhula pyrrhula) | /* |
- |
/ |
/* |
- |
- |
| Chaffinch (Fringilla coelebs) | / |
/ |
/ |
/ |
/ |
/ |
| Chiff Chaff (Phylloscopus collybita) | / |
/* |
/ |
/ |
/ |
/ |
| Coal Tit (Parus ater) | / |
/ |
/ |
/ |
/ |
/ |
| Cuckoo (Cuculus canorus) | / |
- |
/ |
/ |
/ |
- |
| Curlew (Numenius arquata) | / |
- |
- |
- |
- |
- |
| Dipper (Cinclus cinclus) | - |
- |
- |
- |
- |
/* |
| Dunnock (Prunella modularis) | / |
/* |
/ |
/* |
/ |
/ |
| Grasshopper Warbler (Locustella naevia) | / |
- |
- |
- |
- |
- |
| Goldcrest (Regulus regulus) | / |
/ |
/ |
/ |
/ |
/ |
| Great Tit (Parus major) | / |
/ |
/ |
/ |
/ |
/ |
| Greenfinch (Carduelis chloris) | - |
- |
/* |
- |
- |
- |
| Grey Wagtail (Motacilla cinerea) | - |
/* |
- |
- |
- |
/* |
| Heron (Ardea cinerea) | - |
- |
- |
- |
- |
/ |
| Hooded Crow (Corvus corone cornix) | - |
/* |
/* |
- |
/* |
/* |
| Jackdaw (Corvus monedula) | / |
- |
/ |
- |
- |
/ |
| Jay (Garrulus glandarius) | /* |
/* |
- |
/ |
- |
/ |
| Linnet (Carduelis cannabina) | - |
- |
/* |
- |
- |
- |
| Long-tailed Tit (Aegithalos caudatus) | - |
/* |
/ |
/* |
- |
- |
| Magpie (Pica pica) | - |
- |
/ |
- |
- |
/* |
| Mallard (Anas platyrhynchos) | /* |
- |
- |
/ |
- |
/* |
| Meadow Pipit (Anthus pratensis) | - |
- |
- |
/ |
- |
- |
| Merlin (Falco columbarius) | - |
- |
- |
- |
/* |
- |
| Mistle Thrush (Turdus viscivorus) | / |
/ |
/ |
/ |
/ |
/ |
| Pheasant (Phasianus colchicus) | / |
/ |
/ |
/ |
/ |
/ |
| Raven (Corvus corax) | - |
- |
- |
- |
/ |
/* |
| Reed Bunting (Emberiza schoeniclus) | - |
- |
/ |
/ |
- |
- |
| Robin (Erithacus rubecula) | / |
/ |
/ |
/ |
/ |
/ |
| Rook (Corvus frugilegus) | / |
/ |
/ |
/ |
/ |
/ |
| Sedge Warbler (Acrocephalus schoenobaenus) | - |
- |
/* |
- |
- |
- |
| Siskin (Carduelis spinus) | /* |
- |
- |
/* |
/ |
- |
| Snipe (Gallinago gallinago) | /* |
- |
- |
/ |
- |
- |
| Song Thrush (Turdus philomelos) | / |
/ |
/ |
/ |
/ |
/ |
| Sparrow Hawk (Accipiter nisus) | - |
- |
/* |
- |
- |
/ |
| Spotted Flycatcher (Muscicapa striata) | - |
- |
/ |
- |
- |
- |
| Swallow (Hirundo rustica) | - |
- |
/* |
- |
- |
/* |
| Tree Creeper (Certhia familiaris) | / |
/* |
/ |
/ |
/ |
/ |
| Willow Warbler (Phylloscopus trochilus) | / |
- |
/ |
/ |
/ |
/ |
| Woodcock (Scolopax rusticola) | - |
- |
- |
/* |
- |
- |
| Wood Pigeon (Columba palumbus) | / |
/ |
/ |
/ |
/ |
/ |
| Wren (Troglodytes troglodytes) | / |
/ |
/ |
/ |
/ |
/ |
| Number of species recorded during counts | 22 |
12 |
25 |
22 |
20 |
22 |
| Number of species recorded outside counts | 5 |
9 |
6 |
5 |
3 |
7 |
| Total Number of Species | 27 |
21 |
31 |
27 |
23 |
29 |
Note
1: / = recorded during official counts; /* = recorded outside
counts; - = not recorded
Note
2: Site Nos as follows:- 1 Rosturra; 2 Muckross; 3 Portlick; 4
Cullentra; 5 Rossacroo and 6 Ballygannon.
Table 11. Acquatic Species recorded at Portlick and Cullentra.
SPECIES |
PORTLICK |
CULLENTRA |
| Arctic Tern (Sterna paradisaea) | / |
- |
| Black-headed Gull (Larus ridibundus) | / |
- |
| Coot (Fulica atra) | / |
/ |
| Cormorant (Phalacrocorax carbo) | - |
/ |
| Great-crested Grebe (Podiceps cristatus) | / |
- |
| Heron (Ardea cinerea) | / |
/ |
| Lapwing (Vanellus vanellus) | / |
- |
| Little Grebe (Tachybaptus rufcollis) | / |
- |
| Mallard (Anas platyrhynchos) | / |
- |
| Moor Hen (Gallinula chloropus) | / |
/ |
| Mute Swan (Cygnus olor) | / |
- |
| Redshank (Tringa totanus) | / |
- |
| Tufted Duck (Aythya fuligula) | / |
- |
| Whooper Swan (Cygnus cygnus) | / |
- |
| Total Number | 13 |
4 |
Density
Densities
varied, and ranged between 22 and 40 birds per hectare (Table
111). The age and composition of the woodland influenced density,
with for instance, extensive clearfelled areas where density was
low, reducing overall density in the forest.
Table 111. Bird Densities.
Location |
Density
in Birds Per Hectare |
Rosturra |
36.4 |
Muckross |
24 |
Portlick |
40.13 |
Cullentra |
27.2 |
Rossacroo |
22.4 |
Ballygannon |
34.3 |
3. GENERAL PRINCIPLES
In the context forest management, with the objective of optimising or enhancing its value for avi-fauna, the principal must be to satisfy the birds' requirements throughout the seasons. These are a food supply, shelter/perching, suitable nesting sites and ideally water.
Diversity of age class. The forest may not have the potential to satisfy all of those requirements at each stage of the cycle, or may only satisfy the requirements of a limited number of species at a particular phase before the maturing woodland results in their replacement by species better adapted to those developing conditions. A diversity of age class will thus result in a greater diversity of bird species by combining all species associated with each stage, (e.g. ground nesters at establishment stage - pipit, followed by scrub species before canopy closes - dunnock, and canopy dwellers in the mature crop - tits).
Diversity of tree species. Individual bird species have adapted to living in particular forest environments. Thus for instance siskin are found in conifer or alder woodland, warblers generally in scrub, and treecreepers in predominantly broadleaf woodland. A diversity of tree species will thus result in greater bird species richness. This can be achieved by planting pure crops or stands of mixed species. In the context of the Millennium Forests where the restoration of oak woodland, for instance, may be an objective, planting of pure stands may be desirable. However where such planting is not required mixed woodland generally appears to support a greater diversity of bird life. A mosaic of species connected by corridors such as roads or rides offers a good alternative.
Diversity of habitats. Birds have adapted to living in specific habitats. Thus, a wetland within a forest encourages species such as reed bunting and sedge warbler, as well as being the location for drinking and bathing for all other inhabitants of the wood. Open spaces and scrub attract warblers and stonechat; stone walls attract tits; buildings swallows and possibly barn owls. An effort should thus be made to incorporate as much habitat diversity as possible into the overall forest design for optimum bird species richness.
Management. Routine management should be employed to enhance the forest environment for birds - it need not be unnecessarily tidy, fallen branches and dead wood should be left where they pose no threat, broken branches should be left un-pruned as they may provide nesting holes and ivy provides food and nesting places. If the forest environment is right it will attract those birds which would be expected to inhabit it, without recourse to artificial means.
Forest Operations. Forest operations should be carried out when they have least impact on breeding and nesting birds - outside the nesting season. Consultation with the local Duchas Conservation Ranger and Birdwatch branch should take place in advance of any operations to ascertain if any rare or protected species inhabit the site.
Monitoring. In the longer term all sites should be monitored to assess the impacts of the forest programme and strategies on the avian communities.
4.
COMMENT
None of the count points in this study were located on roads or
rides. However, both from the location of the actual points and
from the locations of the bird species recorded (whether within
or beyond the fixed band), it is clear that they are important
in terms of diversity. Woodland edges, (not just the external
edges but divisions between compartments, along roads, rides and
drains/streams) where a margin of scrub and young broadleaves
existed, combined with the open areas associated with them, provided
suitable habitat, particularly for warbler species - blackcap,
chiffchaff and willow warbler. It was noticeable that where such
a margin was absent, specifically at the edge of conifer woodland
these species were poorly represented. Willow and birch scrub
phasing into the taller trees and denser woodland was particularly
suitable for these species. The provision of or facilitation of
scrub development is recommended. It may be necessary to implement
a programme of phased coppicing of such scrub in the longer term
to maintain good structure and optimum conditions.
Edge effect. The value of edge effect is generally well recognised, but underutilized in the forest environment. Its benefit can be internalized by planting or encouraging the development of a margin of scrub and young broadleaves along roads and rides. The value of scrub in terms of bird life is significant. This is clear from the results of the study and particularly in relation to the Portlick site. In developing the scrub margin the main crop should be retained well back so that there is space for a phasing from open space to herb, scrub and canopy. This need not be uniform so that in places, particularly in smaller blocks, the forest can close over roads to create a forest interior environment and generate diversity along the road.
Scrub. Scrub, as well as providing suitable habitat for a range of species, provides valuable autumn and early winter feeding for birds, particularly thrushes, including the migratory redwing and fieldfare. It can also support extremely high densities of birds as well as affording good cover for roosting. A range a native, berry-producing species are invaluable in this regard - hawthorn, blackthorn, elder, holly and bramble. Gorse also is a valuable scrub species and ivy enhances the environment for birds, but should be controlled. Planting of clumps of such scrub is recommended, together with berry producing trees such as rowan, whitebeam, wild cherry and yew. A programme of phased or rotational cutting of the scrub may be necessary in the longer term in order to maintain patches at different stages of growth.
Open space. It appears that there is no provision to retain or develop open spaces within any of the forests studied. They enhance the forest environment in terms of diversity of herb vegetation, insect life and ultimately avi-fauna. Combined with the beneficial edge effect and developed in association with margins of broadleaf along roads and rides they have potential to enhance biodiversity withi the forest. Road junctions, bends or edges present opportunities for such habitats.
It was of note that compared to afforestation sites previously studied the reforestation sites were generally unsuitable for ground nesters such as meadow pipit and skylark due to the lack of or unsuitability of ground vegetation and its structure. Monitoring would provide useful information in this regard.
If there is a need to enhance the forest environment for particular bird species nesting boxes can be erected. While these have potential to enhance conditions it should not be necessary for the more common species, although it should not be discouraged. However, it is an approach which might more appropriately be adopted in particular circumstances such as an experimental/research project or as an attraction/educational feature for the public. There is the added work, little as it may be, of monitoring, cleaning out and maintaining the boxes. This approach is best suited to rarer species such as raptors, where the objective is to attract them to a forest and assist them in becoming established, by providing suitable nesting sites which might otherwise be absent. Published literature on this subject is scarce. Where such species are known to exist it is an approach worth exploring and pursuing - e.g. osprey, an occasional visitor to Lough Ree.
In conclusion the development of a management plan which incorporates the above principles and formulates strategies to implement them will enhance the forest environment for birds and improve the biodiversity value of the forest generally.