Woodpeckers attacking the posts
Woodpeckers aren't just interested in trees. They are also eyeing the electricity and telecommunications distribution poles. The damage they cause is significant, so much so that it represents the second cause of pole replacements at Hydro-Québec.
A Pileated Woodpecker perches at the entrance to its hollowed-out nest in an electricity utility pole.
You may have seen or heard them banging non-stop on a pole in your neighborhood or in your yard. You probably smiled wondering if those woodpeckers had fallen on your head. Why are they attacking poles?
For three reasons: to drum, which serves to mark their territory, it is harmless. But also to feed and nest. And that's a whole different story. Multiple drilling can affect the integrity of the posts.
A woodpecker hole at the top of a post
The affection of woodpeckers for poles is not new: this phenomenon was already observed in the days of the telegraph. Since then, the amount of poles in Canada has multiplied, as has the number of woodpeckers. The national breeding bird survey indicates that between 1990 and 2014 the population of Pileated Woodpeckers doubled in Canada and tripled in Quebec.
As a result, Hydro-Québec, which manages a park of 2 million posts, has seen the activity of woodpeckers progress on its facilities.
Dan Mastrocola is an engineer and head of pole maintenance at Hydro-Québec Distribution.
“You see places that weren't affected and are now becoming more and more affected. If we look at the numbers from 2012 to 2021, we've had over 100,000 poles documented with woodpecker damage. About 12,000 poles need to be replaced. »
— Dan Mastrocola, engineer and head of pole maintenance at Hydro-Québec Distribution
A pole has a lifespan of approximately 60 years. It is generally at the end of this period that it is replaced. However, repeated attacks by woodpeckers can accelerate its degradation and force its premature replacement. At Hydro-Québec, woodpecker activity has become the second cause of pole replacement, after age.
It has long been believed that woodpeckers were more interested in old poles because they are more susceptible to being invaded by carpenter ants, the woodpecker's feast. But this is not the case! Hydromega electricity supplier learned about it in 2015, in Dokis, Ontario.
Hydromega distribution line in Dokis, Ontario, some poles of which were attacked by woodpeckers.
“It's something we've never experienced before. The plant had been in operation for about two years, and we had about fifty poles out of 500 already damaged. A 10% of the line, which is not negligible. »
— Sébastien Tilmant, Environment and Asset Optimization Manager at Hydroméga
This episode kicked off a joint research project that brings together Hydroméga, Hydro-Quebec and the University of Quebec in Montreal. Researcher Pierre Drapeau from UQAM has been interested in woodpeckers for several years. In this case, its gaze is mainly on Pileated Woodpeckers and Northern Flickers.
A Northern Flicker watches the surroundings from its nest dug into a power utility pole.
The damage caused to poles by woodpeckers is of two different types. First, we note the feeding holes, which can be multiple and shallow. They are used to reach colonies of carpenter ants. Then the birds can dig their nest inside the posts; in this case, the cavity they create is much larger.
This nesting cavity, in the heart of a pole, has a diameter of about 15 cm and a height of about 50 cm.
“For a woodpecker, a Hydro pole is a snag dead on the ground. That's how it should be seen. What makes it settle on a pole rather than in the middle of the forest? That is a question that is currently open. »
— Pierre Drapeau, professor in the Department of Biological Sciences at the University of Quebec in Montreal (UQAM)
Pierre Drapeau and his colleague Philippe Cadieux, from UQAM, in the field for research on woodpeckers
In the field, in a natural environment and near power lines, Pierre Drapeau and his team have begun research to document the habits of woodpeckers, their feeding radius, the state of the forest in which they live. , etc.
Among the hypotheses being studied, is it possible that woodpeckers opt for poles when the nearby trees are not large enough? to dig a nest there?
In parallel with university research on woodpeckers, Hydro-Québec must, during frequent visual inspections of its poles, improve the description of the holes dug by woodpeckers. Depending on their size and number, we must estimate the moment from which the post will have lost too much of its mechanical resistance.
On a test bench, Hydro-Québec conducted tests to measure the loss of efficiency of poles damaged by woodpeckers. Securely held at one end, a winch pulls the cable attached to the top of the post until it breaks. Dan Mastrocola, who supervises the tests, notices from the first tests sometimes significant capacity losses.
“We saw from 10 to almost 40% capacity loss. It is quite important. Indeed, at more than 40%, in theory, the post should be replaced. »
— Dan Mastrocola, engineer in charge of pole maintenance at Hydro-Québec Distribution
Un post damaged by woodpeckers (green mark) is subjected to a mechanical resistance test on a Hydro-Québec test bench.
Replacing a pole costs $5500 or more, depending on what equipment is installed on it or how close it is to an access road. Electricity distribution companies therefore try to protect some of their poles from attacks by woodpeckers using physical barriers, including wire netting or rigid enclosures. However, their effectiveness is sometimes limited.
The other option is to turn to composite posts, which are unassailable by woodpeckers. As their cost is higher, electricity providers want to install them at strategic locations on the power line, likely to be frequented by woodpeckers.
This is part of what the research project intends to accomplish: to determine environmental factors that would make it possible to anticipate areas at risk. But the game is not settled in advance, because woodpeckers have a reputation for being tenacious!
The report by André Bernard and Vincent Laurin is broadcast on the show Découverte on Sundays at 6:30 p.m. on ICI Radio-Canada Télé.