The fear of odor problems caused by backyard chickens is unwarranted. Chickens themselves do not smell- only their feces that have the potential to stink, which is also true of feces from dogs, cats, or any other animal that leaves waste in the yard. But unlike dogs and cats, who leave waste on the lawns of their neighbors or in public places, chicken waste in an urban setting is confined to the coop & run, due to ordinances disallowing them to free range.
It’s also important to realize that the maximum number of chickens a city allows is just four. Four small hens weigh less than 20 pounds collectively, and generate less waste than one average dog. (In Ferndale, we currently only allow 3 hens.)
Furthermore, chicken manure is a highly valued fertilizer that can be used in the garden, whereas waste from dogs and cats cannot because of the parasites and human diseases it can harbor. According to Dr. Hermes, OSU Extension Poultry Specialist, “Once added to the compost or tilled into the soil, the odor-causing compounds are no longer able to cause objectionable odors.” This statement is an exact quote taken from his letter in support of chickens in Salem, OR. http://www.salemchickens.com/
The reason people fear an odor problem is because their only experience with chickens (if they have any at all), is a farm or commercial poultry operation. In these situations, chickens are viewed as a commodity and are raised with the intention of profit from meat or egg production. Under those circumstances, hundreds, if not thousands, of chickens are often kept in crowded conditions with poor ventilation or regular cleaning. As a result, ammonia can build up and these facilities can stink. In contrast, people who want to raise hens as pets in the city are not looking to make a profit: they want eggs laid by healthy, happy chickens that they treat like pets. A few small birds housed at least 10’ from adjacent dwellings and in close proximity to the owner’s home, are extremely unlikely to create an odor problem for neighbors.
Composting chicken manure is a wonderful bonus to keeping chickens- the high nitrogen content of their manure breaks down high carbon items quickly and efficiently (sometimes almost too quickly, see blog: http://backyardfeast.wordpress.com/2011/05/09/composting-chicken-manure-watch-the-heat/) Adding the manure to compost eliminates any smell associated with the manure.
Additionally, there are steps urban chicken keepers can take to reduce the chances of odors even further: use a deep litter method of bedding, or use sand. I prefer the sand method in my run, where the chickens spend most of their day- it wicks moisture away, eliminating odor and the attraction of flies, drying out the manure in the same way cat litter does. I clean the run and coop once per day, throwing the waste into my composter; the only thing you can smell in my chicken run is their pine bedding and the flowers in the surrounding garden. With proper practices, no small scale chicken coop should EVER smell strongly enough that neighbors would notice.