In their native range, swamphens are often observed away from wetlands and can damage grain and vegetable crops (Ripley 1977, del Hoyo et al. 1996, in Pranty et al. 2000). They have also been observed preying on nestlings and adults of different passerine species (McKenzie 1967, Egan 1992, Fitzsimons 2003), as well as eggs (Binns 1953, Fitzgerald 1966, Brown 1997) and ducklings from different waterfowl species including chestnut teal (Anas castanea) (van Tets 1965), Pacific black duck (A. superciliosa) (Nixon 1983, Bonser 1984), domestic muscovy duck (Cairina moschata) (Lowe 1966) and black swan (Cygnus atratus) eggs and cygnets (as cited in Balasubramaniam & Guay 2008).
Purple swamphens are known to be highly territorial and aggressive, and often fight amongst themselves and with other species over food (Johnson & McGarrity 2009). In large numbers, these aggressive invaders could have negative impacts on native birds (Johnson & McGarrity 2009).
A recent introduction to Florida, the purple swamphen has expanded from coastal southeast Florida into the Everglades Conservation Areas, and has been observed on Lake Okeechobee. Its ecological similarity to the native common moorhen (Gallinula chloropus) and purple gallinule (Porphyrula martinica) have prompted efforts to eliminate this member of the rail family (Hardin 2007). It is not clear what negative consequences could result from the presence of non-native species such as these, but Avery and Moulton (2007) argue that while the opportunity exists to remove them from the Florida landscape, it should be done. It makes little sense to wait and study the situation to see what impacts might accrue. As management action is delayed, populations of these species will increase and spread, making it that much more difficult and expensive to implement effective corrective measures later (Simberloff 2003, in Avery & Moulton 2007).
Location Specific Impacts:
Florida (USA) (United States (USA))
Competition: Its ecological similarity to the native common moorhen (Gallinula chloropus) and purple gallinule (Porphyrula martinica) have sparked concerns (Hardin 2007).
Economic/Livelihoods: Although they have not been seen feeding on crops, these birds could potentially impact Florida's agricultural industry if their numbers were to increase (Johnson et al. 2009). In their native range they are known to cause significant damage to crops, and they could become an agricultural pest, particularly to South Florida's rice farming industry (Johnson et al. 2009).
Ecosystem change: Outside of artificial habitats, exotic birds in Florida (with the possible exception of the European starling) have not yet shown an ability to reproduce widely. In 2000 Pranty et al. wrote that it was premature to consider the purple swamphen a threat to Florida’s native wetlands and avifauna. However having expanded their range outside of suburban Pembroke Pines and with their high reproductive potential and the abundance of wetlands in Florida it seems reasonable to consider the purple swamphen a potential threat to native species and habitats.
Predation: Purple swamphens may prey on the ducklings of different waterfowl (Pearlstine & Ortiz 2009).