Efficacy of intervention to relieve nest box competition for Orange‐bellied Parrot Neophema chrysogaster

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.