Bee visitation to flowers throughout New York City

Abstract

As urbanization increases, it is important to understand how ecosystem services are provisioned in cities. In this study, we used four years of citizen science data to analyze bee visitation to flowers throughout the five boroughs of New York City. Volunteers monitored one of nine focal flower species for a maximum duration of 30 min, noting when a bee landed on the flower, counting up to a total of five bee landings. Five bees were observed in 63 % of the observations and bumble bees were the most commonly observed bee morphotype (49 % of all observations). The nine focal flowers varied in the rate of bee visitation and the types of bees that visited. Comparing different urban habitats where focal flowers were located, community gardens had the highest bee visitation rate, followed by parks, private gardens, and rooftops/terraces. When comparing the explanatory value of individual spatial scales from 50 m up to 1500 m, the 500 m buffer scale was found to be the most informative. The proportion of grass/shrub and tree canopy at the 500 m radius scale both affected bee visitation. The proportion of buildings at the 500 m scale also had a positive influence in one model suggesting that a heterogeneous urban landscape may provide benefits for bee activity. Overall, our results highlight that wild bees are active throughout many areas of New York City, likely providing variable, yet substantial, pollination services to wild and cultivated plants.