Action: Physically protect nests with individual exclosures/barriers or provide shelters for chicks of storks and ibises
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A randomised, replicated and controlled study from Cambodia found that giant ibis Thaumatibis gigantean fledgling rates were higher for nests in protected trees than controls.
If fencing does not work to exclude predators (for example, predatory birds), or is not a viable option, it may be possible to protect individual nests using a variety of cages and exclosures. These must be able to allow chicks and adults to get in and out, but not predators and should be quick to install to minimise the chances of parents abandoning nests (see ‘Can nest protection increase nest abandonment?’).
Unfortunately, because each cage is over a nest, it is possible that predators will learn the association and that providing the exclosures will actually increase predation on either adults or chicks (see ‘Can nest protection increase predation of adult and chick waders?’)
The effectiveness score for this intervention included a combined assessment of the evidence for chicks of ground nesting seabirds, chicks of waders, chicks of storks and ibises, and chicks of songbirds.
Supporting evidence from individual studies
A randomised, replicated and controlled study from 2004-2006 in northern Cambodia (Keo et al. 2009) found daily survival rates of nests during the nestling period and average fledging rates were significantly higher for 24 giant ibis Thaumatibis gigantea nests in trees fitted with predator exclusion devices (an 80 cm wide strip of hard, smooth plastic, fitted at least 1.5 m from the ground) than for 28 nests in unprotected trees (daily survival rates of 99.9% for protected vs. 99.3% for unprotected nests, leading to overall survival rates of 90% vs. 61% respectively; and average fledging rates of 1.9 chicks/nest vs. 1.25 chicks/nest respectively). Protected trees were also more likely to be re-used in the next year (73% vs. 9%, 22 trees monitored).