PIGEON BIOLOGY AND CONTROL

Michael Harband, central region manager for Agserv, outlines the various control options for dealing with the feral pigeon, Columba livia.

The feral pigeon, Columba livia, was originally introduced into Australia prior to the 1870s. Our feral pigeon population is descended from domesticated wild rock doves, which were first released into Victoria. The pigeons can now be found across wide areas of Australia, in all major cities, with the exception of Darwin.

Biology

Their lifespan in the wild is up to four years, but they can live up to 16 years in captivity. Feral pigeons mate for life and can have three to four broods a year with clutches consisting of one to two eggs. The eggs hatch in about 18 days and the squabs (chicks) leave the nest at 35 days. Feral pigeons become sexually mature by six months, so a population can grow rapidly without natural predation or human intervention. Breeding season is typically between July and February, but they can breed year round under the right conditions. Primarily a seed feeder, pigeons will sample most foods and can be often found foraging and pecking at the ground.

Impacts

The feral pigeon is a non-migratory bird that will roost at or near their birth site. It has adapted to live completely in our urban environment. As a result, the presence of feral pigeons can cause negative impacts on the urban environment and public health through:

• Faecal contamination of food and water sources, resulting in the spread of diseases that can be found in dry bird faeces, such as Salmonella and E.coli Indirect pest problems in building from the parasites found on pigeons and in their nesting materials, such as the bird mite
• Damage to buildings, structures, machinery and public properties through debris from nests and the high uric acid content of pigeon faeces
• The additional costs to businesses through cleaning and nest removal
• Bird strikes to transport. Feral pigeons can pose a serious risk to aircraft especially as they flock in large numbers. Between 1991 and 2001 the Australian Transport Safety Bureau (ATSB) recorded 53 bird strikes involving feral pigeons, with 16.9% resulting in damage to the aircraft and 30.9% involving more than one bird.

Control options depends on bird pressure

Before we look at control measures for a population of birds at a specific site, we need to understand ‘bird pressure’. The term ‘bird pressure’ measures how determined a bird is to remain in the area.

• Heavy pressure: The bird is nesting or roosting at this site, as there is adequate shelter from the elements and predatory animals. There would also be a food and water source a short distance away.
• Medium pressure: This is a resting site overlooking a food and water source. The bird will not roost or nest in this area.
• Light pressure: There is no food source or sheltered area at site and the birds stop there briefly during the day.

As the feral pigeon is not a protected species in Australia we have many control measures to choose from. While not being protected, we must always remember to look at humane control measures.