Not long ago, Canada geese were in the local spotlight as "pest birds." Although some consider geese welcome guests in neighborhoods and parks, others decry the mess a flock leaves behind and want the birds removed.
Several other avian species, such as double-crested cormorants, mute swans and snow geese, are considered pest birds by wildlife biologists and small-business owners. Cormorants are reviled by anglers, fishing guides and commercial fishermen because the birds are voracious feeders and are seen as competitors.
Mute swans and snow geese earn the ire of wildlife biologists because these species degrade their habitats. Swans feed on native plant species, destroying the submerged aquatic vegetation in bays and rivers that ducks, crabs and fish rely on.
Snow geese are a popular attraction when they overwinter at birding destinations such as Chincoteague National Wildlife Refuge; however, when the geese return to their breeding grounds on the Arctic tundra, their sheer numbers destroy the fragile plant life as they forage.
Backyard birders have a motlier group of pest birds to worry about: grackles, house sparrows and European starlings.
But perhaps the most loathsome species to visit our neighborhoods is the brown-headed cowbird. Cowbirds are true parasites, preying with stealth and deceit on other species during spring nesting.
Cowbirds do not build nests. Instead, the female deposits her eggs in any convenient nest already constructed. Often, the adult male harasses the prospective parents, and when the nesting birds chase him away, the female places her own eggs among the owner's. The cowbirds soon disappear, finished with their only dubious act of parenthood.
Cowbird eggs have been found in nests of roughly 200 species in North America. Their chicks are larger and often feed more aggressively. Cowbird chicks are often responsible for high mortality among nesting chicks.
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