Woodland birds benefit from suppression of a despotic competitor following creation of an artificial ‘sink’ habitat through culling

While habitat fragmentation negatively impacts native biodiversity, this
ecological process can generally be beneficial for edge-specialist species
that preferentially occupy remnant patches. In the woodlands of eastern
Australia, this process leads to domination of remnant patches by a
despotic native honeyeater, the Noisy Miner (Manorina melanocephala),
resulting in aggressive exclusion of other avifauna. Culling has been
trialled to alleviate the impacts of Noisy Miners, but has yielded only
mixed success in the short term, as recolonising miners from the
surrounding areas often occupy newly culled sites. We tested if continuous
removal of Noisy Miners could create an artificial ‘sink’ habitat that
would continually attract dispersing Noisy Miners to preferentially
colonise the ‘sink’ area, reducing miner dispersal into other areas in the
landscape and allowing recovery of native woodland birds as a
result. Over an 18-month period, Noisy Miners were regularly
removed from two colonies, and the resulting changes in both miner density
and the diversity of other woodland birds were evaluated. At one
colony, Noisy Miners routinely recolonised the area after each removal,
creating an artificial ‘sink’ habitat as miner density rapidly recovered
in between culling rounds. However, by attracting dispersing miners in the
landscape to this culling site, it follows that recolonisation pressure
elsewhere would have fallen. This was evident in this study through a
nearby area failing to be recolonised by miners post-culling for more than
one year, and also concurrently experiencing an improvement in avian
diversity in the absence of miners. This shift in diversity away from the
sink site highlights the potential of this technique to deliver
broad-scale results with relatively quick outcomes. Further, the
simplified protocol of repeated culls undertaken at a sink site is likely
to be both logistically simpler and cheaper for land managers than
attempting culling across all areas occupied by miners. Practical
Implication: Continuous removal of Noisy Miners at designated ‘sink’ sites
can attract dispersing individuals, reducing recolonisation elsewhere and
promoting native woodland bird recovery. This cost-effective approach is
simpler than widespread culling and minimises landscape disruption.
Ongoing culling at favoured sites is likely more effective than short-term
efforts across multiple locations, providing a practical strategy for
managing native species exceeding ecological carrying capacity.