Northern colletes  (Colletes floralis)

This mining bee is classified as Rare in Great Britain, and is listed on the UK Biodiversity Action Plan (BAP) list (3).

This medium sized bee is mainly black, but has tawny red hairs covering the top of the thorax and paler hairs on the face (2) (4). The abdomen is black, but with narrow white bands of dense white hairs (4). The females are slightly larger than the males and have glossier, darker, and longer abdomens (2) (4).

This bee is scarcely but widely distributed across Europe (2), being known from the Atlantic fringes of Ireland, Scotland and northern England, southern Norway, and scattered in Sweden and Finland (4). Elsewhere, it is restricted to alpine habitats in central Europe, the Pyrenees and the Balkans (4). In the United Kingdom, it is present mainly on the western isles of Scotland, including the islands of the Outer Hebrides, as well as in Northern Ireland and on the Cumbrian coast (3) (4). It inhabits low altitudes in northern regions but mountainous regions further south (3). Whilst it is rare due to its restricted habitat preference, this solitary bee is known to be locally abundant at some sites (3).

On the Scottish island locations, it populates machair grasslands which have an abundance of flowers and are based on shelly soils (2). It appears to prefer nesting on gentle, southerly-facing slopes where vegetation is low and sparse, and is only active when warm (2).

This bee is active from mid June to late August (2). Despite showing preferences for the pollen of certain plants, such as those in the parsley family (Apiaceae), the species in fact forages on a very broad range of plants that also includes Rubus, Thymus, Daucus, Eryngium and Jasione, and possibly even has the broadest pollen spectrum of any bee in its genus (4).

It is a solitary bee, meaning that it nests on its own, without a colony of workers. This bee nests in the ground, sealing the nest with soil. Whilst the bee is solitary, the females nest in local aggregations digging burrows 20 to 26 cm deep. They produce a secretion from glands in their mouths which they use to coat the inside of the burrow before laying their eggs in sealed cells. Each cell contains a food reserve comprised of regurgitated nectar and pollen that will feed the larva and then support the pupa through the winter while the bee develops. In June, the male bees emerge first and fly around the nests waiting for the females to emerge, and for the lifecycle to begin again (2).

This bee has a small UK population, restricted by the amount of very specific habitat it requires. A mixture of threats face the species, including habitat loss due to conversion to farmland, inappropriate grazing regimes, and climate change. The increasingly warm UK climate is a concern as this bee exists in a specific “climate envelope” (2) (3) (4).

Some nesting sites of this bee are within Sites of Special Scientific Interest (SSSIs) and other reserves, giving them improved protection and the benefit of management plans (3). This species has a Species Action Plan (SAP) which encourages landowners and site managers with a population of northern colletes on their land to help protect the species. Research and surveys of the species and its range are planned to encourage the perseverance of current populations (3).

The UK Biodiversity Action Plan for this species is available at UK BAP.

For more information see:

Royal Society for the protection of Birds – Biodiversity (September 2004):
http://www.rspb.org.uk/biodiversity/RSPBandbiodiversity/lead_partner/inverts/colletesbee/index.asp

UK Biodiversity Action Plan (September 2004):
http://www.ukbap.org.uk/UKPlans.aspx?ID=235