Non-target impacts of weed control on birds, mammals, and reptiles.
The impacts of invasive plant control on native animals are rarely evaluated. Using data from an eight-year study in southeastern Australia, we quantified the effects on native bird, mammal, and reptile species of (1) the abundance of the invasive Bitou Bush, Chrysanthemoides monilifera ssp. rotundata, and (2) a Bitou Bush control program, which involved repeated herbicide spraying interspersed with prescribed burning. We found that overall species richness of birds, mammals, and reptiles and the majority of individual vertebrate species were unresponsive to Bitou Bush cover and the number of plants. Two species including the nationally endangered Eastern Bristlebird (Dasyurus brachypterus) responded positively to measures of native vegetation cover following the control of Bitou Bush. Analyses of the effects of different components of the treatment protocol employed to control Bitou Bush revealed (1) no negative effects of spraying on vertebrate species richness; (2) negative effects of spraying on only one individual species (Scarlet Honeyeater); and (3) lower bird species richness but higher reptile species richness after fire. The occupancy of most individual vertebrates species was unaffected by burning; four species responded negatively and one positively to fire. Our study indicated that actions to remove Bitou Bush generally have few negative impacts on native vertebrates. We therefore suggest that controlling this highly invasive exotic plant species has only very limited negative impacts on vertebrate biota.