Have you ever gazed up at a bell tower, the sunlight glistening off the stone façade as the tintinnabulation of bells resounds overhead, and wondered: What are those spikey things? If you are scrupulous in your observations, you might see rows of stainless steel spikes or needles poking up along ledges, window sills, roof lines, and parapets. What are these spikes for?
Those spikes have nothing to do with the bells and everything to do with the birds. Rows of spikes are an effective and humane deterrent for pigeons, seagulls, crows, and other similarly-sized birds. When spikes are placed along a flat surface, like the colonnade of a belfry, it prevents birds from landing, roosting, or loafing about. The spikes do no harm to the pigeons in any way. They simply make the space unaccommodating for perching.
Now, we love our feathered friends just as much as you do, but birds (especially pigeons) can pose a real nuisance and harm to bell towers. Their droppings may contain harmful pathogens which can threaten the health of bell ringers and bell tower maintenance teams. Three human diseases – histoplasmosis, cryptococcosis, and psittacosis – are linked to pigeon droppings. Nasty stuff indeed.
As a communal species, one pigeon nesting in a belfry can quickly become a whole flock of pigeons nesting and the problem exponentially grows. Pigeons that nest in protected areas can breed continuously; a single female pigeon may lay up to six clutches of eggs a year. More pigeons, more problems.
Pigeon droppings contain astringent ammonia and acids that can deface a bell tower with unsightly discoloration. Droppings can also deteriorate concrete and spur the oxidation (rust) of structural beams. In fact, this accelerated degradation has been named as a contributing factor to the 2007 collapse of a Minneapolis freeway bridge, which killed 13 people and injured about 100 more.
Image: Pigeons roost on a bell at the historic Inveraray Parish Church, Scotland.
If pigeon droppings can do that to a bridge, imagine what it can do to bells. Not only can accumulated droppings distort the tone of a clear-sounding bell, it can also weaken the infrastructure that both supports the bells and allows them to freely swing, magnifying the risk of a thousand-pound bell crashing down through the wooden floors of a bell tower. A few rows of stainless steel bird spikes can prevent all that damage.
Of course, some bell towers maintain an altogether more natural deterrent. The Campanile at the University of California, Berkeley, is home to pigeons’ deadly enemy: the peregrine falcon. A falcon can make a quick and tasty meal out of a pigeon, thus naturally shielding the structure from problematic pigeons.
A row of bird spikes or a couple falcons sends a clear message: Sorry pigeons, this bell tower isn’t for roosting. Take your business elsewhere!
