As humans have industrialised farming to feed a growing global population, pollinators – animals vital for plant reproduction – have seen their food supply decline. In the UK, intensive agriculture has eroded biological diversity in large portions of the countryside, with vast swathes of cereal crops and ryegrass pastures now replacing flower-rich habitats.

For pollinators such as bees, hoverflies and butterflies, a loss of flowers means a loss of the nectar and pollen that makes up their food. A reduction in the diversity and quantity of this food is an important factor in the widespread decline of their population numbers.

However, pollinators may have an unlikely saviour: cities. Although traditionally regarded as ecological wastelands, urban landscapes can support diverse pollinator populations. Our new research, conducted with colleagues at the universities of Bristol, Cardiff, Edinburgh, Northumbria, Reading and the Royal Horticultural Society, investigated the nectar production in different urban areas to see how they compared with one another and with rural habitats.