Great Yellow Bumblebee (Bombus distinguendus) ) in Ireland

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1 Great Yellow Bumblebee (Bombus distinguendus) ) in Ireland 2010 STATUS World distribution Palaearctic region Conservation status s Bombus distinguendus is showing a general decline across central Europe. It is a Biodiversity Action Plan species in the UK where it has undergone an 80% loss of range within 100 years and is now restricted to parts of north and west Scotland. In Ireland it has been forced to the margin of its range and is now found predominantly along the western coast in floral rich coastal dunes and machair. Red List status in Ireland (2006) Endangered Threat of extinction Decline of floral rich habitats, specifically unimproved grasslands. The widespread replacement of hay with silage in the agricultural landscape, which results in earlier and more frequent mowing and a reduction in late summer wildflowers, has played a major role in its decline. The now fragmented nature of this habitat in Ireland adds to the threat and makes recovery more difficult. If lost from a site, it would be difficult to return. 1

2 HABITAT & ECOLOGY Habitat Currently associated with machair, flower rich sand dunes, and dry calcareous grassland but previously known from a wider range of flower rich habitat types. Ecology Long-tongued, late-emerging species associated with meadow floras. It feeds on a range of plants but has a long tongue and therefore forages flowers with long corollas because they can reach the nectar deep in the flower head. Requires extensive areas which support a variety of flowering plants, especially those in the Red Clover and Knapweed families. Flight period April to September but will be observed in greatest numbers in June-July when the worker brood is active. Nests underground at low densities (1-2 nests/square kilometre). Nests contain relatively small numbers of workers in comparison to other bumblebee species, reaching a peak of workers by late July. SURVEYING How do I survey? Ideally survey in June-July as this is when worker brood is most active. Does not require an expert. Key Identification Features: This distinctive bumblebee is almost completely bright yellow, apart from a black band across the middle of the thorax (queens, workers and males have the same colour pattern) If attempting to discover new populations it is recommended to check species rich grasslands, machair and dunes, particularly if these occur in general areas where the species has previously or currently exists. If I find a good population how should I assess it? If you find a healthy B. distinguendus population (one where you see multiple workers foraging) then it would be very valuable to keep track of this population, ideally annually, but at least at 3 yearly intervals. Carry out a walk through the site on a sunny day when temperatures are above 15 C and winds are not above 2 on the Beaufort scale. Record the time spent, the distance travelled, and number of 2

3 bees observed. Also note what they are foraging on. Do not repeatedly survey the same areas or patches of flowers during the walk as this will increase the chance of double counting individuals. This can used to generate an approximate index of abundance of the species at the site. Where should I send information on the Great yellow bumblebee? Please send any information to the national bee database, maintained by the National Biodiversity Data Centre. CONSERVATION What does a site need to support Bombus distinguendus? 1. A range of forage sources throughout the flight period of the colony. Lotus is important in spring for the queens during the nest building phase and Red Clover and Knapweed (along with other species within the Fabaceae and Lamiaceae) are particularly important later in early summer to establish the colony. Top 6 plants used by the GYB are: Red clover (Trifolium pratense), White clover (Trifolium repens), Tufted vetch (Vicia cracca), Marsh woundwort (Stachys palustris), Marsh thistle (Cirsium palustre) & Common knapweed (Centaurea nigra). 2. Good potential for nesting. Nests are established underground, usually in the disused nests of small mammals like mice. 3. Current populations of the species are extremely fragmented. Given the restricted normal dispersal capability of bumblebees, it is unlikely to colonise new areas unless these are within close proximity to an existing site. Can we learn from experiences elsewhere? RSPB Scotland: /about.asp UK species action plan: Charman T.G. et al. Conservation genetics, foraging distance and nest density of the scarce Great Yellow Bumblebee (Bombus distinguendus). Molecular Ecology 19: Bumblebee Conservation Trust (UK): 3

4 KNOWN DISTRIBUTION AND LOCATION OF KEY POPULATIONS Where exactly does the species currently occur in Ireland? Known distribution (recorded since 1980) COUNTY LOCATION GRID DATE LAST RECORDER CURRENT REFEREN RECORDED STATUS: CE 2015 Co. Donegal Arranmore Island B /08/1985 John Breen Unknown St. John's Pt. G /07/2004 Tomás Murray Unknown Co. Mayo Doogort F /07/2004 Tomás Murray Unknown Mullet Peninsula F658339, F650355, F Dave Suddaby Unknown Mullet/Blacksod Bay Complex F6329, F /09/2004 Tomás Murray Unknown Co. Galway Inisheer L /08/2004 Úna Fitzpatrick & Inishmann L /08/2004 Úna Fitzpatrick & Unknown Unknown Co. Clare Ballyryan (Poulsallagh) Bridges of Ross, Clare Carrowmore dunes M John Breen Unknown Q /07/2003 John Breen Unknown Q /08/2004 Úna Fitzpatrick Unknown Craggycoradan R John Breen Unknown North of Cliffs of Moher R /08/2003 Mark Brown Unknown Fanore More M /07/2010 Dara Stanley Small population observed in

5 Derreen M /08/2003 Mark Brown Unknown Co. Limerick Nr. Askeaton (Barrigone) R /09/1988 John Breen Not found in (Veronica Santorum) or in 2004 (Úna Fitzpatrick & ). Assumed to have disappeared from site Co. Kerry Lough Gill Q /07/1980 M.C.D. Speight Unknown Co. Offaly Pilgrims Road N /08/2005 Úna Fitzpatrick & Unknown esker ridge, Clonmacnoise How is it faring on key sites? Based primarily on 2004 data, sites that still have healthy populations are the Mullet, Co. Mayo; Doogort, Co. Mayo; Inisheer, Co. Galway & Inishmann, Co. Galway. It is known to occur along the coast in Co. Clare but it is not understood if this is one metapopulation or a series of small populations that are now isolated. Key sites (based Grid reference(s) Index of abundance Comments primarily on 2004 data) data Mullet, Co. Mayo F6329; F6325; F6533; F6535; F6832 No current data Doogort, Co. Mayo F7009 No current data Inisheer, Co. Galway L9802 No current data Inishmann, Co. Galway L9304 No current data 5