W. Paul Gorenzel Fig. 1. Cliff swallow (Hirundo pyrrhonota) with nests on a building.
Staff Research Associate
Department of Wildlife, Fisheries, and Conservation Biology
Cooperative Extension
University of California
Davis, California 95616

Terrell P. Salmon
Wildlife Extension Specialist
Department of Wildlife, Fisheries, and Conservation Biology
Cooperative Extension
University of California
Davis, California 95616

Fig. 1. Cliff swallow, Hirundo pyrrhonota


Cliff swallows nest in colonies and often live in close association with humans. Many swallow colonies on buildings and other structures are innocuous. In some situations, however, they can become a major nuisance, primarily because of the droppings they deposit. In such instances they may create aesthetic problems, foul machinery, and cause health hazards by contaminating foodstuffs. Their mud nests eventually fall to the ground and can cause similar problems. Parasites found in swallow nests, including swallow bugs, fleas, ticks, and mites, may bite humans and domestic animals, although these are not the usual hosts. In addition, cliff swallow nests are often used by house sparrows, introducing another avian pest and its attendant damage problems and potential health hazards.

Barn swallows nesting singly or in small groups on a structure can cause similar problems but of a lesser magnitude due to the smaller numbers present.

Economics of Damage and Control

Costs of damage are difficult to quantify and vary with the particular site and the method of control employed. The cost of actual or potential damage can range from the cleanup of droppings on and around a structure, to thousands of dollars from swallows contaminating foodstuffs at a processing center or posing a danger to aircraft at an airport. Similarly, control costs vary greatly. When hosing is used, costs are primarily labor-related. Net is relatively inexpensive (from about $9 to $33 per 1,000 square feet depending on quantity purchased, 1992 prices) and is reported to be effective for 4 to 5 years before replacement is necessary. Labor and other equipment costs to install netting, however, can be quite high. For example, mounting net on a concrete versus a wooden structure, or 100 feet (30 m) versus 10 feet (3 m) above the ground can drastically increase costs. Costs for each site must be judged on an individual basis.


Scott E. Hygnstrom; Robert M. Timm; Gary E. Larson

Prevention and Control of Wildlife Damage Logo 1994


Cooperative Extension Division Institute of Agriculture and Natural Resources University of Nebraska -Lincoln

United States Department of Agriculture Animal and Plant Health Inspection Service Animal Damage Control

Great Plains Agricultural Council Wildlife Committee

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