Chick Mortality: Why Chicks Die in Week 1-2
TL;DR: Chilling, dehydration, and failure to find feed or water account for most chick deaths in the first two weeks, followed by pasty butt, overcrowding, predators, and diseases including coccidiosis and pullorum. Most of the leading causes are management problems you control through brooder setup and daily checks, not diseases you treat after the fact.
Why Do Chicks Die in the First Two Weeks?
The first two weeks carry the highest mortality risk of a chick’s entire life, and most of that risk comes from a short list of management failures rather than disease: chilling, dehydration, starve-outs, and pasty butt. A chick’s body is still developing the systems that let an adult bird handle temperature swings, find food and water reliably, and fight off routine pathogens, which is exactly why the brooding basics — heat, space, feed, water, protection — matter so much in this window.
Knowing which causes are preventable through setup and daily checks, versus which are genuine disease risks that need specific treatment, is the difference between a keeper who loses chicks to fixable problems and one who catches issues before they become losses.
What Are the Top Non-Disease Causes of Early Chick Loss?
Chilling, dehydration, starve-outs, pasty butt, overcrowding, and predators account for most early chick deaths that have nothing to do with disease at all — they’re brooder management and housing problems.
| Cause | What it looks like | Why it happens |
|---|---|---|
| Chilling | Lethargic, huddled, cold to the touch, not eating | Brooder temperature too low or drafty; see our brooding temperature guide |
| Dehydration | Weak, sunken appearance, not drinking | Chick never found the waterer, especially after shipping or a rough hatch |
| Starve-out | Weight loss despite feed present | Chick never learned where feed is, sometimes from a weak start at hatch |
| Pasty butt | Dried droppings blocking the vent | Stress, temperature swings, or shipping; blocks the vent completely if not cleared |
| Overcrowding | Piling, trampling, smothering | Too many chicks for the brooder’s actual floor space |
| Predators | Missing chicks, signs of entry | Rats, cats, or birds of prey reaching an unsecured brooder |
Every one of these is addressed directly by getting the brooder itself right — size, heat, predator-proofing — and by daily hands-on checks rather than assuming a brooder that looked fine at setup stays fine without monitoring.
What Is Pasty Butt and How Do You Fix It?
Pasty butt is when droppings dry and stick over a chick’s vent, and left unaddressed it blocks the vent entirely, which is fatal because the chick can no longer pass waste. It’s common in the first week, especially in chicks that have been shipped or stressed, and it’s one of the few early problems that’s simple to fix by hand if caught in time.
Check each chick’s vent daily during the first week. If you find a blockage, gently soften it with a warm damp cloth and clear it carefully rather than pulling at dried material, which can injure the chick’s skin. A chick with recurring pasty butt is worth watching closely for other stress signs, since it’s often a symptom of something else — a brooder that’s too hot or too cold, or a chick that’s already weaker than its littermates.
How Does Chilling Actually Kill a Chick?
A chilled chick becomes lethargic, stops eating and drinking, and can die within hours if the chilling is severe or prolonged, because a young chick cannot yet generate enough of its own body heat to recover without help. This is why getting brooder temperature right — and checking it against chick behavior rather than trusting a single thermometer reading — matters more in the first two weeks than at any later point in a chick’s life.
See our brooding temperature guide for the week-by-week temperature schedule and the specific behavioral signs — piling, distressed peeping — that tell you a batch is getting cold before it becomes an emergency.
Which Diseases Are the Real Risk in the First Two Weeks?
Coccidiosis and pullorum are the two disease risks most specifically associated with young chicks, and both have dedicated ManokHub guides with full symptoms and treatment protocols — this article won’t re-explain either disease, since guessing at treatment from a summary is worse than using the full guide.
- Coccidiosis. Bloody or dark reddish droppings are the key warning sign in chicks as much as in older birds. See our full coccidiosis guide for symptoms and the complete treatment protocol.
- Pullorum (fowl typhoid and pullorum). A bacterial disease that specifically hits young chicks hard, often traced to infected breeding stock passing it through the egg itself. See our fowl typhoid and pullorum guide for the full picture rather than treating it as a minor issue.
- Internal parasites (worms). More of a growing-bird risk than a day-one risk, since chicks pick up worm eggs mainly once they start pecking at the ground, but a heavily contaminated brooder environment is still a contributing factor. See our internal parasites guide for signs and treatment.
None of these are guesswork diseases — if you suspect any of them, go straight to the dedicated guide rather than treating based on a summary, and don’t dose a young chick with anything without checking the product label and, where the situation is serious or unclear, a veterinarian.
What Daily Checks Catch Problems Before They Become Losses?
A short daily check — vent cleanliness, feeding and drinking behavior, spacing, and general activity — catches most of the causes above before a fixable problem turns into a dead chick. This takes a few minutes per day for a small batch and is the single highest-leverage habit in the first two weeks.
- Check vents for pasty butt, especially in the first week.
- Watch feeding and drinking behavior. A chick that isn’t visiting the feeder or waterer needs individual attention.
- Look at how chicks are spread out. Piling signals cold; spreading to the edges and panting signals too hot.
- Note any chick that’s quiet, hunched, or separated from the group. This is often the earliest visible sign that something’s wrong, before droppings or other symptoms show up.
- Confirm the brooder is still predator-secure — a gap that was fine yesterday can be enlarged overnight by a determined rat or cat.
How Much of This Is Actually Preventable?
A large share of early chick losses trace back to chilling, dehydration, starve-outs, and overcrowding — all of which are directly under the keeper’s control through brooder setup and daily monitoring. That doesn’t mean every loss is preventable; disease can still hit a well-managed batch, and predator pressure varies by location in ways a keeper can reduce but not always eliminate entirely.
Being honest about this split matters for how you respond to a loss. A single chick lost to a cause outside your control isn’t a sign you’re doing something wrong. A pattern of losses tracing back to the same preventable cause — chilling every cold night, for example — is a sign the brooder setup itself needs to change, not that this batch was simply unlucky.
The Honest Limits Here
This guide names the well-documented, commonly cited causes of early chick mortality and how to reduce them through management. It does not attempt to give a mortality percentage or hatch-rate statistic, because no single number applies across different climates, brooder setups, breeds, and management styles — anyone citing a precise percentage without a specific, comparable source is not giving you something you can rely on. For any chick showing signs of coccidiosis, pullorum, or another specific disease, go to the dedicated treatment guide rather than relying on this overview alone.
Start with the brooding basics and brooding temperature guide to prevent most of what’s on this list, and check the coccidiosis, fowl typhoid and pullorum, and internal parasites guides directly if you suspect disease in your flock.
Frequently Asked Questions
Why do chicks die in the first two weeks?
Chilling, dehydration, and failure to find feed or water are the most common causes, followed by pasty butt, overcrowding, predators, and diseases like coccidiosis and pullorum. Most of the top causes are management problems, not disease.
What is pasty butt and why does it kill chicks?
Pasty butt is when droppings dry and stick over the vent, blocking it. If not cleared, the chick cannot pass droppings at all, which is fatal. Check chicks daily in the first week and gently clean any blockage with a warm damp cloth.
Can chilling actually kill a chick?
Yes. A chilled chick becomes lethargic and stops eating and drinking, and severe or prolonged chilling can kill within hours because a young chick cannot generate enough body heat on its own to recover unaided.
Is coccidiosis a risk for young chicks?
Yes, chicks are especially vulnerable, and bloody or dark reddish droppings are the key warning sign. See our full coccidiosis guide for symptoms and the treatment protocol rather than guessing at home.
What is pullorum disease?
Pullorum is a bacterial disease that specifically affects young chicks, often traced back to infected breeding stock passing it through the egg. See our fowl typhoid and pullorum guide for the full picture rather than treating it as a minor issue.
Do worms cause chick deaths in the first two weeks?
Internal parasites are more of a risk as chicks grow and start pecking at the ground than in the very first days, but a heavily contaminated brooder environment can still be a factor. See our internal parasites guide for signs and treatment.
How much of chick mortality is actually preventable?
A large share of early losses trace back to chilling, dehydration, and starve-outs, all of which are directly under the keeper's control through brooder setup and daily checks. Disease and predator losses are harder to eliminate entirely but are reduced by the same basic biosecurity and housing practices.
What should you check on chicks every day in the first two weeks?
Vent cleanliness, whether they are eating and drinking normally, whether they are spread out evenly or piling, and general activity level. A chick that is quiet, hunched, and separated from the group needs attention immediately.