We use an experimental approach to evaluate the effectiveness of removing nests of a dominant competitor to create vacant nest boxes for a critically endangered parrot. We compared the number of times that Tree Martin (Petrochelidon nigricans – the dominant competitor at nest boxes) perched at or entered nest boxes intended for Orange-bellied Parrot (Neophema chrysogaster – the subordinate nest competitor) over three time periods (before, immediately after and one week after experimental nest destruction). In the before period, rates of nest attendance by martins in treatment and control nests were not explained by treatment group. After experimental nest destruction, total attendance at boxes by martins rose to a mean of 6.1 visits over three five-minute surveys in the treatment group, compared with 3.3 visits at control boxes. Within individual surveys, martins visited treatment boxes 4.4 times per survey one week after nest destruction, compared with only 1.6 visits in the control group. Martins in the treatment group rapidly rebuilt their nests and laid replacement clutches, and within a week, all boxes were reoccupied. Nest destruction did not increase nesting opportunities for the parrot, and increased vigilance of the dominant competitor may in fact reduce nesting opportunities in nearby boxes. Our study suggests that removing martin nests is an ineffective management action for alleviating nest competition for this parrot.