This is an important question and, of course, you need to decide how many chickens you want to keep
before you buy your house, as well as the type of chicken you are intending to buy. It should be obvious that, if you opt for bantams, you can accommodate quite a few more birds than if you go for large fowl such as the Brahma or Cochin.
If you pack too many chickens into a coop, you will stress your birds - and stressed birds do not lay well. There will also be more bullying as they fight over space and there will also be a greater risk of disease. In addition, overcrowded birds get hot (a bit like a tube train in the summer rush hour) and this creates condensation - the presence of condensation can increase the risk of respiratory disease.
On the other hand, you can have problems if the house is much too large, particularly in winter when the combined body heat is insufficient to heat the air around the birds and they get chilled. In the depths of a very cold winter this can be overcome by providing temporary insulation around the house (such as a few straw bales), but don't be tempted to close up all the ventilation holes - it is better to let them get a bit cold than not to provide adequate ventilation!
The ideal scenario is to have a slightly larger house than the minimum for your chosen number of birds. This gives them a reasonable amount of space, and may also give you the option of being able to enlarge your flock at some point in the future.
When calculating how many birds you can fit in, there are three things to consider:
2. Floor area
3. Perch length
Assuming that there is adequate headroom, the maximum number of birds that can be accomodated in a house will be:
the smaller of
a number determined by the floor area
a number determined by the perch length
So, how do you work out the minimum number - well, read on..........
Headroom is important, particularly with large birds. Ideally, you will allow sufficient headroom above the perch a bird to stand upright - the minimum is about 200mm.
Remember to take into account the design of the house. Perches close to sloping walls can make it difficult for large birds to roost comfortably. Ark-shaped houses, for example, typically offer less headroom at the sides than those with straight sides.
The Poultry Club of Great Britain has guidelines regarding the minimum space required per bird. They state that you should allow 200x200mm (8x8 in) for bantams (which is equivalent to 25 birds per metre square) or 300x300mm (1 foot square) for large fowl (equivalent to 11 birds per metre square).
The 'gold standard' for welfare is generally considered to be the Soil Association. They specify a minimum stocking density of 6 birds per square metre for large fowl. This means that each laying bird has a floor space of 400x400mm.
You will notice that there is quite a difference in these figures. It is, of course, up to you to decide which standard you wish to adopt, but you should remember that these are still minimum figures - more floor area is usually better.
When calculating the floor space in a particular house, remember the following:
- make sure measurements are internal (or allow for the tickness of the walls and possibly roof overhangs if the manufacturer only provides external measurements)
- do not include any nest boxes (internal or external)
- do not include the area under low sloping sides
Once again, standards vary, though not as much as for perch space. For large fowl, the Soil Association requires 180mm per bird while the Poultry Club recommends 200mm. Once again, these are minimum figures - more perch space is better, especially as it allows a bird that is bullied to get away from the bully. We recommend you simply use 200mm as your guide.
Thses figures are for large fowl, and you can safely get away with less for bantams - about 120mm will do.
If there is more than one perch, then there needs to be adequate space between the perches, ideally about 150mm.
Here is an example calculation:
House size, internal, is 800x900mm. It has an internal nest box 300x200mm.
Floor area (useable) = 0.8x0.9 - 0.3x0.2 = 0.66 m2
Soil Assoc min density, large fowl is 6 per m2 so max birds = 0.66 x 6 = 3.96
The house has 2 perches, each with 800mm useable length = 1600mm total length
Allow 200mm per bird, so max birds = 1600 / 200 = 8
The smaller of the two numbers 8 and 3.96 is 3.96. Since you can't have 'part' of a bird, you need to 'round' to a whole number. It is usally best to round down, but given that 3.96 is so close to 4, in this case we would suggest that the house is suitable for 4 large fowl.
If you want to read the welfare guidelines for yourself, they are at:
Poultry Club Welfare Guideleines
Soil Association Welfare Guidelines