Myth Buster: Are Cedar Shavings Toxic To Chickens?

One of the wonderful things about the internet is with the click of your mouse you can find the answers to your questions on innumerable topics. Or can you? It seems to me for each post I find espousing a particular point of view you can find an equal number suggesting the opposite. It becomes a bit of landmine navigating through all kinds of advice sending you in different directions. I find this to be true on chicken sites as well with articles purporting ‘the real truth about …’, ‘the shocking effects of …’, ‘why you should never – or always …’. I think lots of us read those articles and take them as the gospel without doing our own investigating. I have always heard that cedar shavings are toxic to chickens, which surprises me as I have used them for years with no ill effects. So that got me curious about the why of it all.

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When I was a kid I kept hamsters, gerbils and guinea pigs and used cedar shavings. As I recall that was the only bedding available in pet stores and they are still marketed for those animals today. I know, I know – I shouldn’t be comparing small mammals to chickens because they have different respiratory systems. Of interest though, is when you wade through articles on chicken sites about the ‘toxicity’ of cedar shavings folks often use studies in people or rats to support their arguments about the so-called ‘dangers’ of aromatic woods. Why quote a study about workers in the lumber industry inhaling potentially carcinogenic wood dust and attempt to link it to chickens? 

All woods release chemical emissions – the amount and type are influenced by species, which part of tree they came from (heartwood or sapwood), and growing location. Softwoods (coniferous trees) mostly emit terpenes and aldehydes, while hardwoods (deciduous trees) are known for carbonyl compounds and alcohols. Those emissions, known as volatile organic compounds (VOCs), refer to an organic (carbon) compound that evaporates readily to the atmosphere at room temperature.

Terpenes are aromatic compounds which create the characteristic scent of many plants, such as cedar, pine, herbs and citrus peels. In nature, those terpenes protect the plants from animal grazing or infectious germs by repelling predators or acting as antimicrobials. Aromatic hydrocarbons (phenols) are what gives wood their distinctive scents and are the reason why cedar is used to repel moths and other insects and pine is a common ingredient in disinfectants. Cedar has been used to make canoes and for woodworking because it is long-lasting due to the antifungal and antibacterial properties of cedrene (a type of terpene).

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Is Cedar Really Toxic?

I found a lot of anecdotal evidence (much of it quoting the same sources), but nothing that definitively pointed to cedar being a toxic material for coop bedding. Here’s a synopsis of what I did find:

• It is that strong-smelling cedrene, which is thought to irritate the respiratory systems of birds. Of course, any environmental stressors are not good for your flock’s immune system, but do we know under what conditions cedar might be a problem, or not?
• Studies of lab rats have shown that cedar can irritate their respiratory systems. One of the differences I can see between rodents and chickens’ exposure to the off-gassing from shavings would be that rats live on, or in, their bedding 24/7. Chickens, on the other hand, are outside 8-16 hours/day depending on the time of year and usually sleep on roost bars raised off the coop floor during the night.
• Organic compounds decrease when wood is exposed to air and allowed to dry. Most manufactured shavings are a by-product of the lumber industry which would air dry or heat treat those shavings prior to sale. And once a package is opened and shavings are spread around the floor of the coop the VOCs will further lose their potency.
• Almost all sources that declared cedar was toxic suggested using pine shavings as an alternative. The reality is pine also releases VOCs (pinene) and there is no clear data on whether it is a safe material for chicken bedding or not.
• In an article published in The Chicken Whisperer Magazine, Dr Brigid McCrea, Associate Professor and Poultry Specialist at Delaware State University recommended cedar shavings for coop bedding.
• I did find one study that concluded, “Wood-based bedding materials do not negatively affect the production potential of poultry. In addition, the antimicrobial potential of wood may help to counter the load of certain pathogens in environment of birds.” Unfortunately they didn’t clearly state whether cedar – or pine for that matter – were considered problematic or not.
• In studies in people, terpenes have been connected to psychological and physiological benefits. “Exposure to cedar wood oil was found to enhance natural killer cells’ activity in the immune system, increased parasympathetic nervous activity and decreased sympathetic activity, strongly suggesting that cedrol elicits a relaxant effect.”

My Experience

I am someone who isn’t just interested in anecdotal stories, but the science that backs our position. I see far too many folks saying “I’ve always done it this way, therefore …”. In doing an internet search I wasn’t able to come to the conclusion that cedar was toxic and should never be used as bedding.

I live on a small island off the west coast of Canada. I’m surrounded by a temperate rainforest, largely made up of Red Cedar and Douglas Fir trees. I’ve kept chickens for more than 11 years. I started off buying shavings at the local feed store: sometimes pine and other times a mix of hemlock, spruce, fir and pine. Several years ago, I reached out to local woodworkers and asked if I could have their planer shavings for my birds. I’m not picky: as long as the wood is untreated and dry I take whatever they offer: arbutus, maple, alder, fir, and yes, red cedar and lots of it.

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I haven’t bought shavings for several years and have worked out a strategy for how I use them:

• My coop is well ventilated with 4 opening windows, some of which stay open (to some degree) year round.
• The shavings usually don’t come from freshly cut wood, but that which has been air, or kiln, dried.
• I use cedar in the nest boxes in an attempt to repel external parasites like mites and lice.
• I don’t use cedar with young chicks.
• I’m not keen on sawdust as a bedding material so that is reserved for the droppings board, which is easy to clean with a large kitty litter scoop.
• I generally try to mix cedar with another type of shavings if possible.
• I’ve never had birds with respiratory infections, but I wouldn’t advise using cedar in that instance.

Credits: Tuomas Alapeiti et al; Cambridge University Press; Chicken Whisperer Magazine; LittleChickenRacing Team.

All Photos: Bitchin’ Chickens