The short answer: Chickens go broody when a hormonal surge — primarily prolactin — overrides their normal laying cycle and drives them to sit on a nest of eggs until they hatch.
If you’ve walked into your coop and found a hen sitting flattened on the nest, feathers puffed, growling at your hand, you already know what broodiness looks like. Understanding why do chickens get broody helps you predict it, manage it, or use it to your advantage if you want to hatch chicks. Prolactin levels spike in response to the feel of eggs beneath the breast, the warmth of a full nest, and the lengthening daylight of spring. A hen’s body temperature rises to around 105°F (40.5°C) under the breast to incubate eggs, and she may sit for 21 days straight, leaving the nest only once or twice daily to eat, drink, and dust-bathe. This article walks through when broodiness hits, what causes it, what it looks like in practice, and how to handle a committed broody.
When Do Chickens Get Broody
When do chickens get broody most reliably? Spring and early summer — typically March through June in the Northern Hemisphere — when longer days trigger a hormonal sequence the hen’s body evolved for. Daylength of 14-16 hours tips the pituitary gland toward prolactin production, which suppresses the laying hormone (LH) and initiates incubation behavior.
That said, broodiness can strike any time of year, especially in:
- Breeds with strong maternal instinct (Silkies, Cochins, Buff Orpingtons, Brahmas)
- Coops where nest boxes are left full of eggs for several hours
- Hot weather spells that mimic the warmth cues of late spring
- Hens that have just completed a laying clutch of 10-14 eggs
Most hens go broody for the first time between 12 and 18 months of age — after their first full laying season. Younger pullets rarely go broody because their prolactin response is still maturing. Older hens (3+ years) may cycle in and out of broodiness more frequently as their laying rate naturally declines.
A key data point: hens bred for commercial egg production — White Leghorns and production-strain Rhode Island Reds — have had broodiness largely selected out. They may go broody once in three or four years, or never. Heritage and dual-purpose breeds are far more likely to go broody every season.
Broody Hen Causes
The broody hen causes that matter most are hormonal and environmental, and they interact. The hormone prolactin is the proximate cause — it drops estrogen and progesterone, stops the ovulatory cycle, and tells the hen’s brain to stay on the nest. But something has to trigger that prolactin surge.
Primary broody hen causes:
| Trigger | Mechanism | Preventable? |
|---|---|---|
| Accumulated eggs in nest | Tactile stimulus under breast | Yes — collect eggs 2x daily |
| Long daylight (14+ hrs) | Pituitary light response | Partially — use blackout coop |
| Warm ambient temperatures | Reinforces incubation instinct | Difficult |
| Breed genetics | High baseline prolactin sensitivity | Not without breed change |
| Social contagion | One broody hen can trigger flock-mates | Somewhat — isolate early |
Social contagion is underappreciated. I’ve watched a single Cochin go broody and, within a week, pull two Buff Orpingtons and a Wyandotte in with her — all piling onto the same nest box. Removing the first broody quickly often prevents a cascade.
The broody hen causes that are hardest to control are genetic. Silkies are the extreme case: some Silkie hens go broody three or four times per year regardless of season, nest contents, or flock management.
Broody Hen Behavior
Broody hen behavior is hard to miss once you know what you’re looking for, but new keepers sometimes mistake it for illness. Here’s what distinguishes a broody from a sick bird:
Classic broody hen behavior signs:
- Sitting tight on the nest — won’t leave when you approach, sometimes for 20+ hours at a time
- Flattened posture — feathers spread wide, wings dropped to cover imaginary eggs
- Growling or hissing — vocal warning before pecking; the peck can draw blood
- Feather-pulling on the breast — the hen plucks her own brood patch to put warm skin against eggs
- Dramatic poop — broody droppings are large, dark, foul-smelling, and infrequent (she’s holding it for hours)
- Trance-like state when removed — put her on the ground and she stands briefly puffed before waddling back to the nest
The one that catches owners off guard is the temperature. A broody hen’s breast runs noticeably hotter than her normal body temperature. If you slide your hand under her, you’ll feel real heat — she’s turned herself into a 105°F incubator.
Broody hen behavior off the nest (during her 15-30 minute daily break) looks alarming: puffed up, walking stiff-legged, eating and drinking very fast, then rushing straight back. She’s not sick. She’s on a mission.
If a broody is sitting on an empty nest or on fake ceramic eggs, she’ll persist just as hard. The tactile stimulus of something egg-shaped under her is enough to maintain the hormonal loop.
Breaking a Broody Hen: What Actually Works
If you don’t want to hatch chicks, a broody hen is a problem — she’s not laying, she’s hogging a nest box, and she may be losing weight. Breaking broodiness quickly protects both production and her health.
The most reliable method is a wire-bottomed cage elevated off the ground — often called a “broody breaker.” The cool air flowing under her belly interrupts the breast-warming feedback loop that maintains prolactin levels. Place food and water in the cage; most hens snap out of broodiness in 3-5 days. A Silkie may need a full week.
Methods that don’t work well: dipping her in cold water (stressful and only temporary), moving her to a different location on the same bedding, or simply removing eggs repeatedly without addressing the nesting drive.
Once she breaks, expect 2-3 weeks before she resumes laying as her hormones restabilize.
Conclusion
Understanding why do chickens get broody comes down to one word: prolactin. That hormone, triggered by genetics, daylength, nest warmth, and accumulated eggs, flips a hen from layer to incubator. Knowing why do chickens get broody lets you anticipate which breeds will brood most, which months carry the highest risk, and how to intervene (or encourage it, if you want chicks) before the behavior becomes entrenched. For further reading, look into how to successfully break a broody hen using a wire-bottom cage, or how to use a broody hen to hatch and raise purchased hatching eggs.
Helpful answers
Frequently Asked Questions
Can a hen go broody without any eggs in the nest?
Yes. A hen will go broody on an empty nest, fake eggs, golf balls, or nothing at all. The hormonal trigger is partly genetic and environmental — accumulated eggs speed up the process, but a highly broody breed like a Silkie may sit on bare wood. The drive comes from within, and the nest is just where it expresses.
Does having a rooster make hens go broody more often?
No. The presence or absence of a rooster has no effect on broodiness. Broodiness is driven by prolactin, which is independent of fertilization. A hen sitting on unfertilized eggs is just as hormonally committed as one sitting on fertilized ones.
How long does broodiness last if you just leave her alone?
If left undisturbed with no eggs or fake eggs, most hens will break naturally after 21 days — the length of a normal incubation cycle. Some persistent individuals (again, Silkies) may go 30-35 days. Breaking her earlier with a broody-breaker cage spares her unnecessary weight loss.
Will a broody hen lose weight?
Yes, noticeably. A hen eating and drinking only 20-30 minutes daily for three weeks can lose 15-20% of her body weight. Breeds that go broody frequently — Silkies, Cochins — are adapted to this, but still need monitoring. Weigh her at the start and check weekly; supplement with high-protein treats (scrambled eggs, mealworms) if she drops below a healthy condition score.
Is broodiness contagious in a flock?
Functionally, yes. One broody hen occupying a prime nest box, fluffed and settled, provides a visual and behavioral cue that can trigger latent broodiness in genetically predisposed flock-mates. Isolating the first broody within 24-48 hours reduces how often you see a cascade of broodies pile onto the same nest.