As adaptable nest-makers with protected by law as a native species, swallows can often be a tricky pest to control.
The welcome swallow, Hiruno neoxena, is the most common swallow in Australia, widespread over most of the country except the northern areas where the barn swallow may be more commonly encountered. Their pest status comes from their habit of building mud and grass nests on the outside of buildings. The challenge is that as a native species, they are afforded protection under both State and Commonwealth legislation, placing restrictions on control methods.
The welcome swallow is a small bird 14-17cm in length with a glossy blue-black back, with a bright chestnut face and chest, a white belly and deeply forked tail. The chestnut chest colouration distinguishes it from other swallows (the barn swallow has a dark chest band) and the deeply forked tail is the key point of difference to the similar species of martins and swifts, which have shorter, more square tails.
Swallows are expert flyers, catching insects on the wing, and will often be seen flying low over grassed areas and expanses of still water. In areas of abundant insect life, large flocks of swallows can develop.
In the natural environment, swallows build their nests on the side of cliffs or in caves. In developed areas they are more than happy to build their nests in the eaves of buildings, in roof voids or on the underside of bridges and other structures, anchoring the nest in the join between vertical and horizontal surfaces. Especially when there are large numbers of nests, there are the standard bird problems of the mess from droppings and potential disease and the presence of parasites, but there will also be a significant amount of noise.
Exclusion is the best control method and as a native animal, using methods that harm or kill the swallows can incur significant fines. The use of bird slopes will prevent nests being built and will prevent access to potential nesting areas.
Spikes tend not to be effective – they tend to be more effective for larger birds – as swallows can land and build nests around spikes. Fake predatory birds or snakes are also ineffective, as is the use of noise-emitting devices or lights to scare them, which tend not to work as swallows are used to human activity. Indeed the use of lights may actually make the area more attractive to swallows as they will pull more insects into the area. Lights should be turned off at night in areas prone to nesting.
If there are swallows in the area, it is definitely a smart move to implement an exclusion program as once the swallows have started building their nests, removing them is a challenge. Nests can be removed by knocking or washing them down, and can be effective, but must be started at the first sign of nest building. All traces of mud must be removed otherwise they will be tempted to rebuild the nest.
Being a native animal they cannot be harmed or killed (except under special license) and so once eggs have been laid in the nest, removal of the nest is not allowed. One option reported to have some success is to let the swallows build the nest but then place a tennis ball or similar in the nest as soon as the nest is complete, preventing egg laying and re-nesting at the site. However, once swallows have identified a potential nesting site, any nest removal must be followed up with the necessary exclusion techniques.
More information on bird pests.