A look at one of the world’s truly global pests – the rock dove, or pigeon.
The rock dove or pigeon (Columba livia) is major global pest. The name ‘rock dove’ conjures up an image of a gentle, peaceful, clean bird, but in reality, its behaviour and the diseases these birds carry means they truly deserve their nickname ‘rats of the sky’.
As much as rats are considered commensal rodents as a result of their intimate relationship with human activity, pigeons can be considered a commensal bird. They are highly reliant on humans to provide them with roosting and nesting sites, and are commonly found around agricultural areas and warehouses, where they can readily access food (particularly grain).
Pigeons roost in areas above ground and as the rock dove name suggests, they are perfectly suited to nesting on ledges. Buildings therefore provide a wide variety of potential nesting places in the roof areas or on the outside of buildings, as long as there is protection from the weather.
Their nesting habits, namely that they can roost in large numbers on the outside of buildings, is one of the main causes of their pest status. The large amounts of droppings generated not only look unsightly but cause significant damage to the building and even represent a slip hazard to the buildings’ occupants!
Pigeons also carry a wide range of diseases, some of which are airborne and some of which can be transferred through their droppings, including E.coli, Salmonellosis, Cryptococcosis and Candidiasis. Another is Histoplasmosis, a respiratory disease that is caused by a fungus that grows in dried bird droppings – and it can be fatal. These health risks highlight the need for full PPE and a rigorous but controlled cleaning regime when cleaning up bird mess – preventing particles getting airborne and disposing of waste securely being key.
Pigeons can also carry a number of ectoparasites, including fleas, lice, mites and ticks. These parasites can sometimes bite humans – certainly irritating and itchy, but also potential sources of disease transfer.
Pigeons are monogamous, they remain in pairs (often for life), but will congregate in flocks, typically of up to 400 birds. Each flock has a distinct territory and the birds will range over several kilometres in search of food, but always return to their roost in the evening. They have a preference for grain and will cause significant crop damage in rural areas but in cities they will target grass seeds and berries in parks. They are quite adept scavengers.
Pigeons live for 3-4 years, with mating pairs having 3-4 broods a year, consisting of one or two eggs. The eggs are a solid white colour, hatching in 18 days. The young take 1-2 months before they leave the nest, which is longer than many other birds, significantly improving their survival rate and contributing to the birds’ success as a species/pest. They do not migrate from the area and will stay near their birth place. With this reproductive pattern, once pigeons become established their numbers can build up rapidly.
Scare techniques, such as balloons and plastic birds, rarely work for pigeons for any longer than a short period. Indeed, pigeons are probably one of the most intelligent birds on the planet, passing ‘intelligence’ tests that only humans and primates pass. For example, they have been found to recognise their reflections in a mirror, one of only six species (and the only non mammal) to have demonstrated this ability. However, the new gel repellent products on the market, which mimic ‘fire’, do appear to maintain their effectiveness for an extended period.
The key to pigeon control is to exclude the birds from potential nesting sites. The standard physical exclusion methods such as bird netting and bird spikes are generally the go-to techniques. Removing potential sources of food and water is also recommended. Remember, if pigeons are excluded from one building, they will often move to a suitable building nearby – an opportunity for additional business!
And indeed pigeon control is good business. Like rats (of the ground variety), pigeons are common pests providing a year-round revenue stream. The trick with bird control is to treat each job as a problem-solving exercise – you will need a range of products in your armoury and the bigger jobs needs significant planning. However, pest managers wishing to venture into bird control will find the distributors and manufacturers willing to provide training and offer support in quoting and project planning.