European starlings (Sturnus vulgaris) cause damage to agricultural crops. When significant numbers are present starling flocks may descend on fruit and grain crop fields to forage, causing massive damage and can have a heavy economic effect. European starlings are extremely aggressive omnivores, and will compete with native fauna for food. Open bill probing is most commonly used for ground invertebrates, which is their preferred food. Hence this provides the European starling with an evolutionary advantage over frugivores. Fruit damage is often found to be caused by a higher proportion of juveniles, which have underdeveloped probing skills. Usurping nests by contamination (as well as physical competition) is also a major problem (e.g. native parrots use little, if any, bedding, whereas starlings will rapidly fill and contaminate tree hollows). European starlings are also a public nuisance and can damage infrastructures, roof linings, etc. and negatively effect aesthetics (Weber 1979).
Location Specific Impacts:
Western Australia (Australia)
Competition: European starling (Sturnus vulgaris) aggressively competes with hollow-nesting birds for food and nesting sites. A study in NSW shows that up to 34% of the available natural nesting hollows are occupied by the European starling, displacing a number of species of native parrots. Similar figures can be expected in Western Australia if the starling population is not kept under control (WWF-Australia, undated). Species particularly at risk are the western rosella, black cockatoos, corella, purple-crowned lorikeet, red-capped parrot, elegant parrot and the blue bonnet.
Disease transmission: European starling (Sturnus vulgaris) are associated with the transmission of up to 25 diseases including Psittacosis. Studies have shown that accumulated starling droppings found under their roosts serve as a medium for the growth of the fungus Histoplasma capsulatum which directly contributes to the occurrence of Histoplasmosis in humans (Department of Agriculture (WA) 2007).
Economic/Livelihoods: Department of Agriculture (WA) (2007) states, "The Department of Agriculture will be spending more than A$700,000 this year to prevent European starlings (Sturnus vulgaris) establishing feral populations in Western Australia,..." (Department of Agriculture (WA) 2007). Despite such large preventative cost, analysis of the economic impact of starlings to Western Australia indicates that it is cost-effective to prevent the widespread establishment of starlings, considering the fact that S. vulgaris constantly gorges on cultivated grain and horticulture crops (particularly grapes and olives), fouls wool and compets with stock for feed. Additionally, starlings can damage buildings, vehicles, fences, roads or equipment by pollution with droppings or nesting material, and are excessively noisy at their roosting sites. Where large flocks of starlings roost at night the weight of birds and volume of droppings flatten reed-beds and cause damage to trees and other vegetation and can result in complete destruction of the plant life (Department of Agriculture (WA) 2007).
Interaction with other invasive species: European starling (Sturnus vulgaris) are known to cover large distances when searching for food. Consequently, this makes them ideal host for weed dispersal. A number of weeds such as the bridal creeper (Asparagus asparagoides), bitou bush (Chrysanthemoides monilifera) and blackberry (Rubus spp.) are already well-established in the Southwest Australian Ecoregion. Research indicates that many weed seeds have a higher germination probability after being passed through the bird's digestive system (WWF-Australia, undated). This invariably leads to the further spread of these invasive weeds, thereby altering the balance of the ecosystem.
Competition: Sturnus vulgaris compete for food with native bluebirds (Sialia sialis) (Dobson, 2002 in Varnham, 2006).
United States (USA)
Competition: A study on the status of the purple martin Progne subis population finds that the reduction in nesting by martin populations in buildings in Sacremento coincided with the explosion of European starling (Sturnus vulgaris) populations during the 1960s and 1970s (Airola and Grantham, 2003).