- Spatula clypeata (Linnaeus, 1758)
Northern Shoveler, Shoveler
Value of species
Game (hunting) species
Spatula clypeata (del Hoyo and Collar 2014) was previously placed in the genus Anas.
This species has an extremely large range, and hence does not approach the thresholds for Vulnerable under the range size criterion (Extent of Occurrence <20,000 km2 combined with a declining or fluctuating range size, habitat extent/quality, or population size and a small number of locations or severe fragmentation). Despite the fact that the population trend appears to be decreasing, the decline is not believed to be sufficiently rapid to approach the thresholds for Vulnerable under the population trend criterion (>30% decline over ten years or three generations). The population size is extremely large, and hence does not approach the thresholds for Vulnerable under the population size criterion (<10,000 mature individuals with a continuing decline estimated to be >10% in ten years or three generations, or with a specified population structure). For these reasons the species is evaluated as Least Concern.
The global population is estimated to number c.6,500,000-7,000,000 individuals (Wetlands International 2015). The European population is estimated at 170,000-233,000 pairs, which equates to 340,000-466,000 mature individuals (BirdLife International 2015).
Trend Justification: The overall population trend is decreasing, although some populations may be increasing and others have unknown trends (Wetlands International 2015). This species has undergone a small or statistically insignificant increase over the last 40 years in North America (data from Breeding Bird Survey and/or Christmas Bird Count: Butcher and Niven 2007). The European population trend is estimated to be stable (BirdLife International 2015).
Behaviour This species is highly migratory although it may be present all year round in parts of Europe (del Hoyo et al. 1992). It arrives on the breeding grounds from March where it breeds in solitary pairs or loose groups in the northern spring (chiefly from mid-April to June) (Madge and Burn 1988, del Hoyo et al. 1992). Males undergo a post-breeding moult migration from early-May to early-June (females moulting one month later) during which they are flightless for 3-4 weeks (Scott and Rose 1996). The autumn migration chiefly occurs between September and October (western Europe), during which the species is likely to travel on a broad front (e.g. across Arabia and into Africa) (Scott and Rose 1996). The species is usually found in pairs or small parties (Johnsgard 1978, Madge and Burn 1988) although it often congregates when feeding (Kear 2005b) (flocks of 20 or 30 to several hundred individuals occur in favoured areas in Africa [Brown et al. 1982] and large concentrations form at stop-over sites on migration) (Madge and Burn 1988). The species forages diurnally and roosts communally at night (Brown et al. 1982). Habitat It inhabits permanent shallow freshwater wetlands from sea level up to 2,900 m (Ethiopia) (Brown et al. 1982, del Hoyo et al. 1992, Snow and Perrins 1998), preferred sites being those surrounded by dense stands of reeds or other emergent vegetation whilst being free of overhanging trees or fringing forest (Snow and Perrins 1998). Copious submerged aquatic vegetation sheltering abundant planktonic invertebrates is a valuable habitat characteristic (Johnsgard 1978). Suitable habitats include well-vegetated lakes and marshes and with muddy shores and substrates in open country (Madge and Burn 1988, del Hoyo et al. 1992, Kear 2005b) (e.g. grasslands) (Johnsgard 1978, Brown et al. 1982), as well as oxbow lakes, channels and swamps (former U.S.S.R.) (Flint et al. 1984). It also frequents artificial waters bordered by lush grassland (Snow and Perrins 1998) such as sewage farms, rice-fields (Kear 2005b) and fish ponds (Musil 2006). In the winter it can be found on coastal brackish lagoons (Madge and Burn 1988, del Hoyo et al. 1992, Kear 2005b), tidal muflats (del Hoyo et al. 1992, Kear 2005b), estuaries (Madge and Burn 1988), coastal shorelines, fresh and brackish estuarine marshes (Johnsgard 1978), inland seas and brackish or saline inland waters (Snow and Perrins 1998), occasionally occurring (briefly) on marine waters during migration (Madge and Burn 1988, Snow and Perrins 1998) (although it generally avoids very saline habitats) (Johnsgard 1978). Diet Its diet consists of small aquatic invertebrates such as adult and larval insects (del Hoyo et al. 1992) (e.g. caddisfly larvae, damselfly and dragonfly nymphs, adult beetles, bugs and flies [Johnsgard 1978, Brown et al. 1982]), molluscs (del Hoyo et al. 1992), planktonic crustaceans (Snow and Perrins 1998), the seeds of emergent and aquatic plants (del Hoyo et al. 1992, Kear 2005b) (e.g. bulrushes and waterweeds) (Johnsgard 1978), annelids, amphibian spawn, tadpoles, spiders, fish and the vegetative parts of aquatic plants (e.g. duckweeds) (Johnsgard 1978, Brown et al. 1982). Breeding site The nest is a scrape or depression (del Hoyo et al. 1992, Kear 2005b) on the ground in tall grass, among hummocks, in the open (Flint et al. 1984) or (rarely) in bulrush marshes (Kear 2005b). Usually the species nests close to water but if grass cover is unavailable in the wetland site it may also nest far away from water under bushes, in hayfields or in meadows (Flint et al. 1984, Kear 2005b). Although it is not a colonial species, several pairs may nest in close proximity (Madge and Burn 1988). Management information A study in the Czech Republic found that fish ponds with a fish stock density of less than 400 kg/ha, water transparency of more than 50 cm, mixed fish stocks (e.g. tench and pike or perch) rather than monospecific stocks (e.g. of carp), and systems that include ponds with fish fry (to provide areas with low fish competition and high invertebrate availability) are more successful in supporting breeding pairs of this species (Musil 2006). The cyclical removal of adult fish from an artificial waterbody (gravel pit) in the UK attracted nesting pairs to the area by causing an increase in invertebrate food availability and an increase in the growth of submerged aquatic macrophytes (Giles 1994). The removed fish (dead or alive) were sold to generate funds (Giles 1994).
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