Top Causes Of Death In Backyard Chickens - Randy's Chicken Blog

There’s an unpleasant fact about keeping backyard chickens that none of us probably thought about at all when we brought home our first little peeping bundles. Someday they will all die. Death is the elephant in the coop. We don’t like to think about it or talk about it, but we can’t ignore it. It is important, actually, to wonder about what causes the lives of the birds in our backyard flock to end, and there’s nothing gratuitously macabre about finding the answers.

There are people who have made a career out of studying why people die. If you’re searching for the answer to this important and frequently asked question, it isn’t hard to find. I did a quick Google search and learned from the CDC that in 2018 the top five causes of human death, in the US, in order, were heart disease, cancer, unintentional injuries, chronic lower respiratory diseases, and stroke. The WHO has the statistics for the world and lists the top five causes of death, worldwide and in order, to be cardiovascular disease, cancer, respiratory disease, lower respiratory infections, and dementia.

It’s great that somebody is compiling cause-of-death information about people, right? But what’s the cause-of-death story with chickens? Sad fact: Until very recently, nobody knew. Why not? Because prior to the backyard flock movement, it hadn’t ever occurred to anybody to do that research. Chickens, as you already know and I will tactlessly mention anyway, have traditionally become dinner long before the end of their natural lives. And, in general, veterinary science has been more interested in flocks than individual birds. In commercial flocks, if there’s an infectious disease that has the potential to wipe out an entire flock, that’s significant and bears looking into. If one bird is doing poorly, that bird is simply culled—no muss, and sadly, no fuss. Basically, the underlying cause of death of geriatric chickens has been unknown because there haven’t been any geriatric chickens and nobody has cared.

But you and I care, of course. Backyard chicken folk rightfully regard their birds as pets and companion animals. If Henrietta is under the weather, you and I want to know why. Thus, the blossoming of a plethora of books, websites, blogs and podcasts dedicated to Henrietta’s health. Plus, the proliferation of veterinarians who will examine, diagnose, and care for individual sick chickens. And Henrietta is not going to become pot pie even when her egg production decreases. She’ll remain in your loving care until she dies of natural causes. What we backyard chicken folk need to know is what all the various “natural causes” really are. What forms will the angel of death take when it ultimately visits each bird?

At last, there’s a scientific study that has collected the cause of death of a statistically significant number of backyard fowl over a wide-ranging geographical area in order to put together some meaningful information on the cause of death of backyard flocks that are allowed to live out their natural lives.

The study “Causes of mortality in backyard poultry in eight states in the United States” was a combined effort by researchers in nine academic institutions and research centers and was published in the Journal of Veterinary Diagnostic Investigation in 2019. Over a three-year period, from 2015 through 2017, these researchers collected and performed necropsies on 2,687 birds (The vast majority, 96%, of the birds submitted in this study were chickens but turkeys, ducks, and geese were also included) from eight states (California, Colorado, Georgia, Hawaii, Iowa, Pennsylvania, South Carolina, and Texas) to determine cause of death of each one. What they learned from this study begins to fill in the gaps in our knowledge about why our backyard chickens die, and as more information is collected by similar studies, it could have a definite effect on our chicken husbandry practices and how we interact with our flocks.

The necropsy results were reviewed by veterinarians who placed each cause of death into one of four broad categories and named those categories with descriptive terms that are a bit vet-jargon-y. (Rest assured that I’ll provide definitions later in this article.) The four categories are infectious, noninfectious, neoplastic/lymphoproliferative, or undetermined. Then they broke down each broad category - infectious diseases were subdivided into bacterial, viral, parasitic, or fungal diseases, and they made note of which of ones could potentially spread from poultry to humans. Noninfectious categories included nutritional, developmental, toxic, and traumatic causes of death. Neoplastic/ lymphoproliferative diseases, diseases caused by and characterized by tumors, were categorized by where the tumors appeared in the body and if they were caused by a virus (as is the case in Marek’s disease and the leukosis/sarcoma cluster of diseases).

When the results were categorized by primary cause of death, almost half of the birds died from some type of neoplasm. Neoplasms, simply stated, are tumors. In chickens, tumors are often caused by viruses, as in Marek’s Disease. Over a third of the birds in the study died of an infectious disease. Around two in ten died from a noninfectious process, and the rest, about 5%, died from undetermined causes.

The necropsies showed that almost seven in every ten birds had more than one cause contributing to their death. So, when the results were categorized by all causes of death, rather than just the primary one, the numbers shifted a bit. Neoplasms (1131/2687) and bacterial disease (1135/2687) were essentially tied for first place, with both being found in 42% of the birds. Parasites were found in 28% (755/2687) of the birds. A noninfectious malady was discovered in 16% (444/2687). Nutritional, management, or environmental problems were found in 10% (261/2687). And viral disease was seen in 7% (195/2687). Other causes of death included trauma, fungal disease, toxins, and developmental issues. (Note that the percentages add up to more than 100% since some birds had more than one disease.)