The magpie and the grapes: increasing ozone exposure impacts fruit consumption by a common corvid in a suburban environment

BACKGROUND The Eurasian magpie Pica pica is a resident bird species able to colonize farmlands and anthropized environments. This corvid shows a wide trophic spectrum by including fruits, invertebrates, small vertebrates and carcasses in its diet. A camera-trap experiment was carried out to test the effect of different ozone (O-3) concentrations on potted Vitis vinifera plants, which resulted in different grape consumption rates by suburban birds. The test was performed at an Ozone-Free Air Controlled Exposure (FACE) facility, consisting of nine plots with three ozone (O-3) levels: AA (ambient O-3 concentration); and two elevated O-3 levels, 1.5x AA (ambient air with a 50% increase in O-3 concentration) and 2.0x AA (ambient air with a 100% increase in O-3 concentration). Camera-traps were located in front of each treatment area and kept active for 24 h day(-1) and for 5 days at a time over a period of 3 months to monitor grape consumption by birds.RESULTS We collected a total of 38 videos. Eurasian magpies were the only grape consumers, with a total of 6.7 +/- 3.3 passages per hour (mean +/- SD) and no differences across the different O-3 treatments. Grapes in the AA treatment were consumed significantly more quickly than those in the 1.5x AA treatment, which in turn, were consumed faster than those in the 2.0x AA treatment. At 3 days from the start of treatment, 94%, 53% and 22% berries from the AA, 1.5x AA and 2.0x AA treatments had been eaten, respectively. When the O3 was turned off, berries were consumed at the same rate among treatments.CONCLUSION Increasing O-3 concentrations limited grape consumption by magpies probably because O-3 acted as a deterrent for magpies, although the lower sugar content recorded in the 2.0x AA berries did not affect the consumption when O(3 )was turned off. Our results provided valuable insights to mitigate human-wildlife conflicts in suburban environments.(c) 2023 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.