Action: Provide nesting habitat for birds that is safe from extreme weather
- A small from New Zealand found Chatham Island oystercatchers Haematopus chathamensis used raised nest platforms made from car tyres (designed to raise nests above the level of storm surges). The success of these nests is not reported.
- Two replicated, controlled studies from the USA found that the nesting success of terns and waders was no higher on specially raised areas of nesting substrate, compared to unraised areas, with one study finding that a similar proportion of nests were lost to flooding in raised and unraised areas.
In habitats prone to flooding, inundation with water may be a significant cause of mortality. Providing nests or nesting habitat that is protected from water (e.g. by being raised) may therefore increase reproductive success.
Supporting evidence from individual studies
A replicated, controlled trial in on alkaline flats in Oklahoma, USA, between 1991 and 1994 (Koenen et al. 1996), found that nesting success of least terns Sterna antillarum and snowy plovers Charadrius alexandrinus was not higher on nesting ridges designed to protect nests from flooding, compared to nests not on ridges (terns: 53% of 32 nests on ridges vs. 53% of 28 nests off ridges; plovers: 79% of 22 nests on ridges vs. 62% of 26 nests off ridges). The proportions of nests lost to flooding were similar on and off the ridges for both species. This study is also discussed in ‘Protect bird nests using electric fencing’.
A randomised, replicated and controlled paired study on three saltmarsh islands in Virginia, USA, in 2002 (Rounds et al. 2004) found that hatching success of four ground-nesting bird species (American oystercatchers Haematopus palliatus, common terns Sterna hirundo gull-billed terns S. nilotica, and black skimmers Rynchops niger) was no higher sections of oyster shell piles artificially raised by 15-20 cm than on control (unraised) areas of piles (common terns: 60% of 15 nests hatching at least one egg on raised areas vs. 42% of 26 on control areas; gull-billed terns: 62% of 13 nests on raised areas vs. 89% of nine on control areas). Too few oystercatchers or skimmers nested for comparisons to be made. No species showed a significant preference for either raised or control areas. The authors note that whilst there were no significant differences between hatching successes, raised nests at three of the five shell piles studied survived flooding whilst unraised nests did not.
A small study on Chatham Island, New Zealand between 1998 and 2004 (Moore & Williams 2005) found that up to seven pairs of Chatham Island oystercatcher Haematopus chathamensis used raised nest platforms made from car tyres (designed to raise nests above the level of storm surges). The success of these nests is not reported. The effect of moving the nests up the beach is discussed in ‘Move nests whilst birds are using them’.
- Koenen M.T., Utych R.B. & Leslie D.M. Jr. (1996) Methods used to improve least tern and snowy plover nesting success on alkaline flats. Journal of Field Ornithology, 67, 281-291
- Rounds R.A., Erwin R.M. & Porter J.H. (2004) Nest-site selection and hatching success of waterbirds in coastal Virginia: some results of habitat manipulation. Journal of Field Ornithology, 75, 317-329
- Moore P. & Williams R (2005) Storm surge protection of Chatham Island oystercatcher Haematopus chathamensis by moving nests, Chatham Islands, New Zealand. Conservation Evidence, 2, 50-52