Objective: maintain open space for birds
Definitions
● Nesting = when birds lay eggs and protect their chicks.
● Roosting = when birds are resting, sleeping or preening, i.e. this is an energy-
saving behaviour.
● Scrapes = shallow depressions with gently sloping sides that hold water
intermittently.
● Shorebirds = birds of the order Charadriiformes; includes waders, gulls and terns
that use coastal habitats for feeding, roosting and/or nesting.
1. Description
Vegetation influences how shorebirds and other waterbirds use salt marshes and tidal flats. Shorebirds have different requirements for nesting, roosting and foraging and these requirements also vary among species (Ma et al. , 2010). Vegetation management may be needed to create suitable nesting, roosting and foraging sites if no alternatives are available. Vegetation will develop when water levels are low, but this may be at odds with shorebirds’ requirements for shallow water (for roosting) and for dry surfaces (for nesting). Therefore, depending on the target species/behaviour, regular clearing of vegetation may be necessary to maintain open space and this may need to be coupled with regular flooding and draining. But be mindful about the nesting period to avoid that nests are washed away. There are some important things to consider and evaluate first before taking this action, such as the fact that salt marsh habitat may only be a suitable roost site for a few days in the entire tidal cycle because it will get inundated at high tide for most of the days (Chi-Yeung Choi, pers. comm.).
2. Evidence for effects on biodiversity
Birds : When roosting, shorebirds are more abundant when there is less vegetation (Jackson et al. , 2019). When foraging, dense vegetation cover can prevent accessibility for foraging (Bancroft et al ., 2002). When it comes to breeding, needs differ among species. Several species of shorebird prefer to nest in unvegetated, open areas and shallow scrapes on the ground in coastal areas (Conway et al. , 2005; Ausden, 2007), particularly gulls and terns. Others prefer light or even full cover, such as Arctic-breeding shorebirds, Black-tailed Godwits Limosa limosa , Lapwing Vanellus vanellus and Eurasian Curlew Numenius arquata (Ward Hagemeijer, pers. comm.). Dense vegetation is avoided. In coastal habitats like salt marshes and tidal flats, most species are towards the ‘open’ end of the scale for their breeding preferences. At a site in Texas, USA, an entire Caspian Tern Sterna caspia colony relocated to an area where the vegetation was cleared and the sand was smoothed with a tractor (Roby
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