The European Starling (Sturnus vulgaris) is a common, adaptable bird, recognized by its iridescent plumage and short tail. Often seen in large flocks in urban and rural settings, their widespread presence raises questions about their interactions with other bird species, especially regarding nesting. Understanding their habits clarifies their role in local ecosystems.
The Truth About Starling Nest Takeovers
European Starlings are aggressive, opportunistic birds known for acquiring nesting sites. As secondary cavity nesters, they use existing natural cavities, old woodpecker holes, or human-made structures like birdhouses, building crevices, and vents. This places them in direct competition with many native cavity-nesting birds.
Starlings often evict existing occupants, destroying eggs or killing nestlings and even adult birds. They may also build nests directly on top of existing ones. Their aggressive persistence gives them an advantage in securing limited nesting locations. This behavior is driven by their rapid breeding cycle, typically one to two broods per season, each with four to five eggs.
Impact on Native Bird Species
European Starlings’ nesting behavior affects native bird populations, particularly those relying on tree cavities or nest boxes. Species like Eastern Bluebirds, Purple Martins, Wood Ducks, and various woodpeckers (e.g., Northern Flickers, Red-bellied Woodpeckers) are vulnerable to displacement. Starlings can force native birds to delay or abandon breeding attempts.
While some native birds can re-nest if displaced, this competition raises ecological concerns. Competition for nesting sites can reduce breeding success for native birds, potentially leading to population declines and biodiversity disruptions. Although some research suggests a modest population effect, the usurpation of limited cavities remains a challenge for many native cavity nesters.
Protecting Native Nesting Sites
To protect native bird nesting sites from starlings, individuals can use birdhouses with specific entrance hole sizes. Starlings generally cannot enter holes smaller than 1 1/2 inches (3.8 cm) in diameter. Specialized designs, like starling-resistant entrance holes (SREH) for Purple Martin houses, are crescent-shaped to exclude starlings while allowing target species entry.
Monitoring nest boxes is important; repeatedly removing starling nesting material or temporarily plugging the entrance can discourage them. Avoid perches on nest boxes, as starlings use them but native species typically do not. Creating habitats that favor native species and securing potential starling nesting spots on homes, such as vents and eaves, can reduce competition.