Read about the plight of Ireland`s Twite in
Transcription
Read about the plight of Ireland`s Twite in
SPECIES FOCUS Twite at Raghly Point, Co Sligo. – Mark Carmody Twite Carduelis flavirostris Derek McLoughlin reports The Twite has a fascinating disjunct global range with one population occurring here in northwestern Europe and a second population over 2,500km away in eastern Turkey,Tibet and western China. It is said to be the only Tibetan faunal element to occur in Ireland. This separation most likely happened at the time of the last glaciation some 10,000 years ago. About 100 years ago, Twite had been recorded in all Irish counties except those of the midlands. However, by 1970, the first breeding atlas shows that populations had become largely confined to the extremes of the western seaboard, from Donegal to Kerry. A further decline of over 50% was noted in the 1988-1991 Breeding Atlas. These declines gave rise to its inclusion in the Red Data Book, where its conservation status was listed as ‘indeterminate.’ Breeding populations Today, probably less than 100 pairs of Twite breed in Ireland. North Mayo and west Donegal form the breeding strongholds, accounting for up to 85% of the estimated Irish population. Small breeding populations also occur in west Kerry, northwest Galway, north Donegal and along the north Antrim coast. Mainly due to its ‘little brown job’ appearance and the isolated areas where it occurs, historical data on Irish Twite demographics has been sparse and largely anecdotal. As a result, it is difficult to determine the current population trend; however, a continuing decline seems apparent. WINGS SUMMER 2010 Winter populations Although winter populations vary largely from year to year, the estimated Irish winter population is thought to be in the region of 1,000 birds. Winter populations of Twite are found near their breeding colonies. The largest of these winter populations occurs in the strongholds of north Co Mayo and west Co Donegal. Over 300 birds winter on the Mullet peninsula, Co Mayo, with over 100 wintering near Sheskinmore National Nature Reserve, Co Donegal. Although many of these birds comprise local breeders, there is evidence of Twite that bred on the western isles of Scotland amongst them. It is most likely that the flocks that appear along the east and north coasts of Ireland also originate in the western isles. Nesting Nesting habitat for Twite in Ireland comprises good quality long heather and occasionally bracken. Irish nest sites are almost invariably situated close to the top of wild, north-facing sea-cliffs. Interestingly, many of the colonies in Ireland are found near Peregrine nest sites. As the Twite, at just 13g weight, The Twite is one of only three passerine species to appear on the red list of Birds of Conservation Concern in Ireland (BoCCI). It is also included in the Irish Red Data Book of endangered species.With an apparently declining population, it is currently at risk of extinction as a breeding species in Ireland. does not offer an appetising meal for Peregrines or for other potential predators such as Hooded Crows and Ravens, this seems to offer a degree of protection for the nesting Twite. The nest site they choose tends to be within 2-3 kilometres of extensively farmed holdings (i.e. those farmed at low intensity using traditional mixed farming methods) and particularly those with species-rich pastures, small weedy roads and roadside verges, saltmarshes and some disturbed ground. Foraging Twite target the seed of a wide variety of plant species during the breeding season, depending on their availability, and particularly: Dandelion, Annual Meadow Grass, Common Sorrel, Common Chickweed and Sea Plantain. Freshwater streams provide an important habitat for bathing, drinking and picking up grit. 15 Twite foraging at Raghly Point, Co Sligo. – Mícheál Casey In England and Scotland, Twite show a similar preference for meadows that were rich in seeding wildflowers and avoidance of reseeded pasture and freshly cut fields. Movement patterns Twite in Ireland remain in their breeding areas from late April to September or October and generally overwinter within a 30km radius. Colourringing studies (including those I carried out as part of my research into Twite in 2005-2009, funded by the National Parks and Wildlife Service) have shown that some Scottish breeding birds also winter here. Two such examples of movements between Ireland and Scotland are of a bird that was ringed at Termoncarragh in April 2007, which was resighted during the following breeding season on Islay, and also, in the same season, a bird ringed at Sheskinmore National Nature Reserve, Co Donegal, was resighted and photographed at Machrihanish Bird Observatory on the Mull Of Kintyre. Even more interestingly, this bird was photographed in a flock of Twite, several of which had been ringed on the west coast of England the previous winter. Winter season Winter flocks, such as those found along the Dublin, Louth, Antrim and Donegal coasts, target disturbed ground, drift lines and areas of saltmarsh. There they forage for the seeds of plants such as Where to see Twite Summer: Probably the best place in Ireland to see Twite is in their foraging areas in the small villages of north Mayo or west Donegal.The easiest time to observe Twite at this time of year is in July when parties of juveniles forage busily with their constant “tveeite” chatting call. Glasswort, Sea Arrowgrass, Orache and Sea Mayweed. The saltmarshes adjacent to Lough Foyle, Co Derry, often sustain between 100-150 Twite each winter season. On the Mullet peninsula, cattle ring-feeders provide a very important source of seed throughout the winter. These feeders are used to provide haylage (a cut forage grass with a moisture content between that of hay and silage) to cattle throughout the winter season. The haylage is generally harvested locally, and often contains large densities of seeds of Dandelion, Sorrel and Thistle, which the Twite target. However, the use of cattle ring-feeders often results in a large amount of damage to the land due to constant poaching by cattle. As the predominant Winter: Twite are very mobile in the winter time and can be found in varying numbers right around the coast of Ireland.The most regular spots are: Mullet peninsula (Mayo), Raghly Point (Sligo), Sheskinmore (Donegal), Myroe Levels (Derry), Belfast Docks (Antrim), Soldiers Point (Louth). Twite, Raghly Point, Co Sligo. Note the colour rings on one bird; this helped in tracking its movements. – Mark Carmody 16 W INGS SUMMER 2010 How you can help Another portrait of Twite at Raghly Point, Co Sligo. The Bird Atlas (2007-2011) survey would benefit from your volunteer input. Roving records and timed tetrad visits are used to develop a map for each species. This information is vital in any conservation programme as no species can be protected efficiently without data to base objectives on. – Mark Carmody If you see a Twite, particularly during the summer months when they are breeding, go to http://www.bto.org/birdatlas and help in the conservation work. habitat type on the Mullet peninsula is machair (flat sandy plains), this poaching eventually leads to the destruction of this Annex I habitat. This raises a conflict in conservation interests, and in terms of biodiversity, it is ultimately an unsustainable supplemental food source for Twite. Threats to Twite Changes in current land-use represent the main threat to Twite in Ireland. Overgrazing and burning in the nesting areas, which results in grasses dominating, and undergrazing, which results in shrub encroachment, are both detrimental to nesting habitat. Further threats to nesting habitat include afforestation and peat harvesting of blanket bogs. The threat from climate change is very hard to predict for a species like Twite. However, one potential impact has already been observed in the southeast of England where saltmarsh erosion has resulted in the loss of important wintering grounds. Where sea-level is predicted to rise, loss of saltmarsh may be inevitable. Conservation Due to concern over a declining population, the Twite is currently on the red list of Birds of Conservation Concern in Ireland. It was listed in the 1993 Red Data Book as ‘indeterminate’ due to the lack of data on its population status in Ireland. However, based on current information, Twite meet the IUCN Red Data Book criteria of ‘endangered’ and therefore can be considered to be at high risk of becoming extinct in the wild in Ireland. The Twite is currently in a very precarious situation and is undoubtedly vulnerable to extinction here. To conserve populations in Ireland it is vital that we pursue the design and implementation of conservation prescriptions with urgency. We not only have an obligation to protect our own breeding and wintering birds, but we also play a part in conserving the winter visitors from Scotland, where WINGS SUMMER 2010 conservation efforts are underway to prevent further severe decline of their current population of about 5,000 pairs. Conservation measures for Twite, including the maintenance of traditionally managed meadows, late cutting of meadows, the provision of cereal plots and the sustainable management of the uplands, would benefit the greater biodiversity in these areas, and particularly bird species including Red Grouse, Skylark, Tree Sparrow and Linnet, all of whose populations have declined in recent years. As Twite breed and winter at sites within 30km of each other, specific conservation actions for Twite can be aimed initially at these areas, which will benefit Twite throughout the entire year. The conservation story of Twite can be a very positive one if we take adequate steps to protect them now. Dr Derek McLoughlin commenced the first study of Twite in Ireland in 2005 and completed his PhD on Twite in 2009.The study was funded by the National Parks and Wildlife Service and was supervised by Dr Don Cotton (Sligo IT). Derek will be continuing his research into the Twite’s breeding ecology in 2010 through funding from The Heritage Council Wildlife Grant Scheme 2010. He can be contacted at Laghloon,Westport, Co Mayo. Watch on video Mícheál Casey of BirdWatch Ireland’s Sligo Branch captured some lovely footage of Twites at Raghly Point, Co Sligo, in February. View his clips at: http://www.vimeo.com/9639019 and http://www.vimeo.com/9628632. Male Twite (from video clip) showing characteristic pink rump. – Mícheál Casey 17