Action: Protect individual nests of ground-nesting birds
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- Two replicated, randomized, controlled studies from Sweden found providing nest exclosures offered some benefits to ground-nesting birds. One study found that protected nests had higher average daily survival rates than unprotected nests for both common redshank and northern lapwing, however, this study also reported higher predation of adult redshank on protected nests. One study found that the average hatching rate for southern dunlin was higher for protected rather than unprotected nests. This study also found no difference in the number of fledglings, breeding adults or new recruits during two periods with and without nest protection.
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 minimize the chances of parents abandoning nests.
Supporting evidence from individual studies
A replicated, randomized, controlled trial in 2002 and 2004 at three grazed pasture sites in south-west Sweden (Isaksson et al. 2007) found that nests protected with cages (truncated cone steel cages with 6.5-8.5 cm spacings between vertical bars and 4 x 4 cm steel netting on top) had significantly higher average daily survival rates than unprotected nests for both common redshank Tringa totanus (99.7% for 34 protected nests vs 96% for 32 unprotected nests in 2002) and northern lapwing Vanellus vanellus (99% for 37 protected nests vs 97% for 153 unprotected nests in 2002 and 2004). However, there was higher predation of adult redshank on protected nests and possibly higher abandonment by lapwings (nine redshank adults from eight protected nests were predated vs a single bird from 31 unprotected nests).
A replicated, controlled before-and-after study from 1999 to 2004 on pastures in southwest Sweden (Pauliny et al. 2008) found that the average hatching rate of southern dunlin Calidris alpina schinzii nests was significantly higher for nests protected by steel cages (20 cm high truncated cones with 7.5 cm gaps between vertical bars and 4 x 4 cm steel mesh covering the top) than for unprotected nests (67% of 25 protected nests survived to hatching vs 41% of 61 unprotected nests).Protected nests were also more likely to hatch more than one chick (80% of 25 protected nests vs 57% of 60 unprotected nests). Predation rates on brooding adults were unaffected (7% of 57 adults at protected nests predated vs 13% of 16 adults at unprotected nests). However, comparing 1993-1998 (when no nests were protected) with 1999-2004 (when some nests were protected) revealed that there was no significant change in either the number of fledglings/breeding adults or the number of new recruits/breeding adults produced by the study sites.
- Isaksson D., Wallander J. & Larsson M. (2007) Managing predation on ground-nesting birds: the effectiveness of nest exclosures. Biological Conservation, 136, 136-142
- Pauliny A., Larsson M. & Bloqvist D. (2008) Nest Predation Management: Effects on Reproductive Success in Endangered Shorebirds. Journal of Wildlife Management, 72, 1579-1583