1 British phenological records indicate high diversity and extinction 2 rate among late summer-flying pollinators 3 Nicholas J. Balfour1, Jeff Ollerton2, Maria Clara Castellanos1 and Francis L.W. Ratnieks1 4 1School of Life Sciences, University of Sussex, Brighton, BN1 9QG, United Kingdom 5 2Faculty of Arts, Science and Technology, University of Northampton, Avenue Campus, 6 Northampton, NN2 6JD, UK 7 Corresponding author: Nicholas J. Balfour;
[email protected], Telephone: +44 (0)1273 8 872954; Fax: +44 (0)1273 678335 9 Abstract 10 The long-term decline of wild and managed insect pollinators is a threat to both agricultural 11 output and biodiversity, and has been linked to decreasing floral resources. Further insight 12 into the temporal relationships of pollinators and their flowering partners is required to 13 inform conservation efforts. Here we examined the phenology of: (i) pollinator flight; (ii) 14 insect-pollinated plant flowering; and (iii) extinct and endangered pollinator and plant species 15 in Great Britian. Over 1 million records, spanning four centuries, were collated from the 16 historical databases of three British insect monitoring organisations, a global biodiversity 17 database and an authoritative text covering the national flora. Almost two-thirds (62%) of 18 British pollinator species have peak flight observations during late summer (July and 19 August). This was the case across three of the groups studied: aculeate wasps (71% of 20 species), bees (60%), and butterflies (72%), the exception being hoverflies (49%). By 21 contrast, there is marked temporal partitioning in the flowering of the major plant groups: 22 insect-pollinated tree species blossoming predominantly during May (74%), shrubs in June 23 (69%), and herbs in July (83%).