(verb) The organized, systematic elimination of unwanted birds; to remove, exterminate or destroy undesirable birds. Birds may be culled if they are considered a threat to native birds through hybridization that may affect the genetic purity of local birds or if they aggressively usurp territory from other species; if they are considered a threat to humans through the spread of disease or posing a threat for airplane strikes; or if the local bird population growth is unhealthy and requires a reduction so the remaining population can be stable. In general, the term cull is applied only to large scale activities rather than the removal of just a few birds.
The most common species to be culled are invasive birds, often because their populations are able to grow unchecked outside their native range. European starlings, house sparrows and rock pigeons are frequently culled in areas where they compete with local species. In some cases, birds that breed excessively without natural limitations on their brood success are also culled, such as Canada geese in urban areas where there are no predators to limit their numbers.
Culling can be accomplished in several ways. Large flocks may be hunted, poisoned or trapped, or the cull could be more subtle during nesting season when eggs are deliberately damaged to prevent excessive population growth. Many hunting agencies use culling to control game birds and will adjust the hunting licenses issued to coordinate with the desired population control.
Culling is understandably controversial among birders. While in many cases it can be seen as necessary to protect struggling native birds, protests are often organized about the effectiveness of different cull methods being used as short term measures instead of long term population management techniques.
Photo – Canada Geese © David Merrett