Wetlands are significant sources of atmospheric methane. Methane produced
by microbes enters roots and escapes to the atmosphere through the shoots of emergent
wetland plants. Herbivorous birds graze on helophytes, but their effect on methane emission
remains unknown. We hypothesized that grazing on shoots of wetland plants can modulate
methane emission from wetlands. Diffusive methane emission was monitored inside and
outside bird exclosures, using static flux chambers placed over whole vegetation and over
single shoots. Both methods showed significantly higher methane release from grazed
vegetation. Surface-based diffusive methane emission from grazed plots was up to five times
higher compared to exclosures. The absence of an effect on methane-cycling microbial
processes indicated that this modulating effect acts on the gas transport by the plants.
Modulation of methane emission by animal–plant–microbe interactions deserves further
attention considering the increasing bird populations and changes in wetland vegetation as a
consequence of changing land use and climate change.