Hens have been laying eggs, sitting on them and and hatching them for centuries without human interference. Considering their ancestors the jungle fowl still manage to maintain a reasonably healthy species population despite the hens nesting on the jungle floor where they may stay for twenty four days or more while they wait for their young to be sufficiently mobile to roost in the trees with the rest of their group.
Until comparatively recently the domesticated chicken has survived in rural villages, farms, smallholdings and estates all over the world with the minimum of human intervention and without coops and without custom built nest boxes.
The availability of coops and nesting boxes has meant the modern hen has learnt to adapt to new nesting environments in an incredibly short period of time and this I would argue is a testimony to the intelligence of the species in general.
I became interested in what makes the ideal nesting site having had many hens over the past seven years, make nests in various places away from their coops. I could find no common factor in seclusion, height (I had one hen make a nest in the top of a rotting palm tree stump) material or degree of protection.
The only common factor I could find with all the various sites was, in each site the hen had been able to make a basket with the site material and these baskets all had an indentation in the base of the nest in which the hens laid the eggs.
The nesting behaviour of every hen I have observed, with, or without, a roosters assistance has been the same. The hen chooses a site and then scratches the ground. If there is loose material such as straw, wood shavings, cut grass, e.t.c. this material is scratched to the perimeter, or sometimes completely away in the case of a nest box with an open front and the hen settles on the base material. Once the hen has laid her clutch she positions herself in a manner that enables her to cover the maximum number of eggs. This way she can control the temperature and humidity of her eggs with maximum efficiency. During the next 18 days the hen will turn her eggs at regular intervals.
The ability of the hen to turn her egg in these 18 days helps to prevent development deformities. For the last three days of incubation the hen must keep the eggs in a particular orientation to facilitate hatching. The overall success of egg hatching is attributed to the hens ability to turn the eggs in the first few days of incubation.
Most chicken keepers make their nesting boxes with the same material as they use for egg boxes; wood, metal, or plastic. Often these boxes are partially filled with loose bedding material such as straw. It is not possible for a hen to scratch out a hollow in the bases of these boxes and she must rely solely on her ability to manoeuvrer her eggs into the optimal position.
Here is an entertaining challenge for the reader. Place a dozen eggs in such a box. Mark one side of each egg and see if you can turn all the eggs so the mark is facing upward using the palm of your hand and one finger to represent a hens beak.
I first noticed the impossibility of this task with a young hen called Cheepy ( a very small bantam) a number of years ago.
Cheepy was rescued from a nest she had made on an exposed bank and put in the isolation coop with a dozen of the twenty something eggs she had accumulated. The isolation unit has a removable plywood floor. Plenty of straw was provided and I used to sit and watch cheepy sitting for many hours over the incubation period. Cheepy’s frustration at trying to control the position of her eggs was evident. No sooner had she pulled couple under her when another couple would roll out to the edge of the straw nest.
I took the plywood floor out after a couple of days of watching this and cheepy immediately dug a hollow in the now exposed earth into which she rolled the eggs. She could now sit on top of the eggs and turn them without them rolling away from under her and arrange the straw around her to help maintain humidity and warmth. She hatched 10 of the 12 and checking later the two unhatched weren’t fertilized.
A much happier Cheepy sitting on 12 eggs on an earth floor in the isolation coop.
I’ve watched the much larger Maran and Maran bantam crosses have similar problems controlling eggs during sitting on man made nest bases. On hard surfaces the Marans in particular seemed to have great difficulty in supporting their weight in a position that allowed them to sit on top of the eggs and they arranged the eggs around their bodies and under their wings, their legs tended to splay outwards because their feet were unable to find a grip on the flooring. This wouldn’t be a problem in the comparatively short time it takes to lay an egg but prolonged periods of time in such a position resulted in two hens having tendon strain due to splayed legs.
In the last three days of incubation the hen communicates with the embryos and the embryos with each other. These communications allow the hen to assess the development rate of the clutch and by adjusting the position of herself relative to the eggs slow down, or speed up the embryos development, thereby ensuring that the embryos hatch within a time frame that permits the maximum number of hatchings before she has to leave the nest with her chicks to find food and water; usually 24 hours. This also means that all the chicks that hatch develop at approximately the same rate and the situation I have encountered here where there may be a 36 to 48 hour gap between hatchings is avoided and all the chicks have a relatively equal size and development state which maximises all the chicks chances of survival in competing for resources as they develop.
Many chicken keepers make broody boxes which are placed inside the coop and often separated from the rest of the coop in some fashion. This can compound the problems already mentioned.
In order to successfully incubate eggs the hen not only has to control temperature but also humidity.
Chickens do not have sweat glands so they cannot impart moisture to the eggs environment through sweating; they are reliant to a greater or lesser degree on atmospheric conditions. In dry climates in particular in such sheltered arrangements this can be problematical. In a natural setting i.e. outside on the ground, there is in all but the most extreme environments some dew fall that moistens the ground and the hens body heat will convert this into vapour helping to maintain humidity levels in the site locality.
There is one final problem with the interior closed broody coop and that is in a ‘natural’ setting a hen will leave the egg clutch at some point each day to feed, drink and defecate, but equally important, dust bath.
The importance of dust bathing and having the opportunity to defecate away from the nest site for broody hens cannot be emphasised enough. It helps the hen keep her nest site free of parasites and clean of droppings which attract further parasites. Many of the hens I’ve observed have preferred slightly damp soil for dust bathing while sitting on eggs. While this is conjecture it seems possible that the hen moistens her plumage in such baths and this helps with maintain humidity when she returns to the nest site.
With the above in mind and my experience with Cheepy I decided to experiment with a different nest box arrangement using the same isolation coop that Cheepy hatched her 10 chicks in.
The most obvious course was to simply remove the plywood base of the isolation coop leaving bare earth underneath. However, this left a coop security problem. It would be relatively easy for a ground predator to dig underneath the coop.
I wanted the coop to be moveable so the next most obvious solution; make a security skirt around the outer edges of the entire coop dug a few inches into the ground wasn’t an option.
I stapled a mesh to the underside of the coop next and filled the bottom two or three inches with plain earth. The hens seemed interested in this arrangement but the earth quickly dried out and with the ground scratching of both roosters and hens when making a nest and the mesh below became exposed. While having exposed mesh didn’t pose much of a problem for the hens, if chicks were hatched over the exposed mesh there seemed to be a risk that the chicks toes could get caught in the holes.
Isolation coop showing mesh base.
During my research for the book I’m writing I made contact with someone in Finland who also uses a multi coop arrangement for his chickens. He keeps a relatively rare Finnish breed of chicken which he is trying to preserve and re-populate. He had found similar problems with nest boxes and he is particularly interested in maximising the clutch hatchings from his sitting hens. He found that a large clod of soil cut from a semi bog environment which grew lichens and the small roosted plants made an excellent nest box base. The plant root system helped hold the soil together and thus helped preserve the hollow his hens scratched out when making nests. He also suggested spraying the hen and soil with a plant mister once a day to help maintain the moisture content of the nest base.
The climate where I live is dry and it took me some time to find a suitable patch of ground from which I could dig a section of turf which has well enough established plant roots system to hold the soil together when the hens scratched a hollow.
Next I had to wait for a suitable hen to go broody and sit, preferably one that had used the nest box in my house. The hens that have used this nest box in the past have been transferred to the isolation coop on day 17 so that when the chicks hatch they have immediate access to natural ground, the coop being at ground level. This allows the mother to take the chicks in and out of the coop at will.
This year such an opportunity arose and I cut a turf which had long grass growing on it. I cut it about 4 inches thick and at the dimensions of the coop floor plan and placed it in the coop on top of the wire base. I also made a hollow in the soil and on top of this a placed a layer of straw in which I carefully placed the hens eggs in as near to an identical arrangement as they had in the nest box.
In the past when hens have used the nest box in my house it had taken a few ‘placings’ of the hen to get her to accept that the coop is where she should sit. The hens tend to leave the coop and return to the nest box in the house, despite there being no eggs in the box.
For this particular hen it took two attempts before she settled. She had 4 eggs which while she sat in the house nest box had been spread around her body under her wings. In the nest in the isolation coop she sat with the eggs underneath her breast, her feet gaining ground purchase on the outer edges of the hollow. She hatched all four eggs within 12 hours, one chick didn’t survive.
Given I’ve watched over twenty hens sit and hatch chicks in a variety of circumstances here now and what I’ve learnt through the experiences of others I have made contact with over the last seven years who also keep chickens I’m left with little doubt that the ability of the hen to control the orientation, temperature and humidity of her eggs is vital to maximise clutch hatching success. I’m also left with little doubt that the ‘modern’ nest boxes made with solid floors is far from ideal. Such nest boxes are constructed for the convenience of the keeper and are liable to give rise to many of the problems outlined above.
Unfortunately the opportunities to test various alternatives are dependant on conditions outside the chicken keepers control; one needs a broody hen, an appropriate alternative nesting box and the time and patience to observe and note the various outcomes. The main problem for me had been trying to reproduce what nature provides without any human assistance.
It’s my intention to continue experimenting with soft base nest boxes.
(Unfortunately I didn’t take any pictures while the turf base was in place. At that time I had no idea that I would be writing an article before I had finished experimenting and before I finished the book.)
The picture below demonstrates the problem that some hens have with posture due to nest boxes constructed with a hard base. This is Fudge. She has been sitting on her eggs for two days. When she first started sitting both her legs were underneath her body and her body weight was supported by both legs. After some hours of trying to maintain body contact with her eggs the eggs moved from underneath her and formed a ring around her body and under her wings; one leg jutting out at an angle.
Isolation coop with plywood base.
Isolation coop with front in place
Isolation coop with butile matt. I tried this to reduce egg breakages and give the hens feet more grip.
Mel and Cillin not overly impressed with the nesting arrangement.
Mel and Cillin creating a hollow in the ground in the run in preference to the coop.
Nature, she’s a hard act to follow, even in material science.