How chickens thermoregulate
As the planet continues to warm we will see more extreme heat. In our summer months we can expect below median rainfall and well-above average temperatures across Australia.
With chicken coops becoming an increasingly common feature of suburban backyards, we need to look after our feathered friends when urban temperatures reach extremes.
If the air is 45 degrees, a bird’s body temperature is going to increase to a similar or higher temperature, unless they spread their accumulating heat somewhere else. Chickens have a few options:
- They can’t sweat, but chickens can radiate heat into the surrounding air. By spreading their wings, they can expose the sparsely feathered skin beneath, and increase the blood flow to their wattles, combs and feet. Unfortunately, this mechanism becomes less effective as the temperature rises.
Chickens can also shed heat through conduction: by contact with cooler objects such as water, the ground, rocks or walls. As long as there is something cool around, snuggling up to it will effectively transfer across some heat.
Chickens can also reduce excess heat through evaporation. Like dogs, birds do it via their respiratory system; some even pant by fluttering the muscles in their throat to help. Alternatively they’ll shed heat from their gastrointestinal tract by defecating.
Evaporated water needs to be replaced, otherwise both these mechanisms can rapidly lead to dehydration and electrolyte loss. High humidity combined with temperatures above thirty degrees are particularly dangerous.
Signs of heat stress in chickens
Chicken owners need to be vigilant for signs of heat stress in their flocks.
Any of the following signs indicate that steps should urgently be taken to help chickens shed their heat load:
- Spreading wings and holding feathers erect
- Breathing rapidly with an open mouth
- Reduced eating and foraging
- Increased drinking
- Reduced egg production
- Staggering, disorientation, collapse and seizures
Broody hens who stay in nest boxes away from cool water and ventilation are particularly at risk, as are chicks and older and overweight birds.
First Aid for Heat stressed birds
Chickens can be gently dunked in cool, but not icy, water and then transferred to a cool area to recuperate. Subcutaneous fluids can also be beneficial, as can adding electrolytes to water for short periods.
Speak with your veterinarian if you have any concerns about heat stress in your flock.
What can you do?
1. Protect the coop from the hot westerly sun. Plant non-toxic vegetation around the coop to block the westerly sun. Deciduous plants allow the sun to access the coop in winter. If vegetation isn’t possible, tarps and other structures can be used. When building the coop, align it to minimise westerly exposure.
2. Ensure there are multiple shady areas within the coop and run. This allows the chickens to spread out as much as possible and ensures there’s a shady spot for any hens that are loners.
3. Provide dust baths in cool areas. Chickens use dust bathing as a means of cooling off.
4. Provide good ventilation and lower perches and nest boxes. Heat rises, so lower roosting perches as much as possible. A hatch in the roof allows heat to escape. Leave hutch doors and windows open. The access hatch to nest boxes can be propped open slightly for better ventilation.
Consider a reflective coop roof. Don’t paint coop roofs in dark colours. If the roof is becoming too hot, insulate the underside to prevent the heat 5. radiating through.
6. Ensure multiple sources of cool water are available. Ice blocks can be placed in water containers. Ensure water sources are in shady areas.
7. Feed in the coolest part of the day. Digestion produces heat. Avoid high energy foods like cracked corn, scratch mix and bread when the weather is hot.
8. Consider misters and fans on timers. A light water mist in shaded areas can help birds shed their heat load, but take care that feed doesn’t get soaked and make sure the coop doesn’t get too wet as this can predispose to aspergillosis and coccidiosis.
9. Provide frozen treat foods. Vegetables and leafy greens can be combined with water and frozen into blocks for the hens to peck at. Frozen watermelon is another cooling treat.
10. Provide shallow, water filled dishes for foot wading. Ensure they are changed regularly to ensure the water stays cool and doesn’t become contaminated with faeces.
- BOHLER, M., CHOWDHURY, V., CLINE, M. & GILBERT, E. 2021, Heat Stress Responses in Birds: A Review of the Neural Components. Biology (Basel) 2021 Nov;10(11):1095
- WEBER STATE UNIVERSITY, Avian Thermoregulation.
- UNIVERSITY OF MINNESOTA, Preventing Heat Stress In Poultry
- ASHLEY,W., Managing Backyard Chickens During Periods of Extreme Summer Temperature.
- NAGA RAJA KUMARI, K., NARENDRA NATH, 2017, Ameliorative Measures To Counter Heat Stress In Poultry. World’s Poultry Science Journal, Vol 74, Issue 11