Did you know that animals as well as humans use ladders? The most well known type of animal ladder is found in rodent cages; gerbils, mice and rats use ladders to get between different floors of a large cage.  There are more types of animal ladders than just that one though.  Below we take a look at the uses of ladders with animals and how this has influenced ladder design and application for humans.

Ladders for domestic animals

It's possible to buy a ladder for a boat allowing dogs to swim in a lake or the sea and climb back aboard without the owner having to lift a wet dog.  They are lightweight plastic ladders which fold away and can be fixed to the back of a boat but look more like a small set of stairs than what we might recognise as a ladder.  Dog ladders are also available for indoor use to allow an older pet to climb onto a bed or sofa when they are too old to jump up, or too small to reach a high bed.  A lot of people try to keep their pets off the furniture, but if you are one of the people who does like their pet sat next to them then this could be the solution.  Again, they look more like small sets of stairs and could also be used with small children for the same purpose.

People living in apartment blocks with cats also use ladders to provide access for the cat to and from the flat.  Although cats are generally very nimble and agile, it can be a struggle for them to access a second (or higher) storey window from the ground without some form of help.  Cat ladders do not look like ladders in the traditional sense, but rather is a plank with treads (also known as cleats) nailed to it at intervals, allowing the cat to walk up the plank without slipping back and down the plank without sliding down. There are also some styles which use a central pole with treads nailed centrally, making a set of rungs the cat can climb up easily, but thereby restricting access to less nimble animals such as dogs, foxes or other wildlife.  It is difficult to buy a cat ladder as they generally need to be made specifically for the situation, taking into account heights, angles and the considerations of neighbours. Because of this, the design of cat ladders varies greatly depending on the materials available, the ability of the person building it and the agility of the cat itself. Some cat ladders provide the animal with access to a lower windowsill, some go round the corners of a building in order to allow access into a back garden and some go from a window to the nearest available object from which the cat can access outside areas. There are also spiral staircase designs, ladders which are formed from a central pole with platforms for the cat to jump between and ones which zig-zag down the side of a building like a commercial fire escape.  By using a cat ladder it is still possible to allow your pet to go outside of its own accord even if you live in a flat.

Ladders for farm animals

Ladders for animals are also used in farming and smallholding. Grazing sheep can be provided with a ladder to help them escape from deep ditches and streams around their field. Ladders used for livestock follow the plank and cleat design of the cat ladder described above. This style of ladder is also used in chicken runs to allow the chickens access in and out of the coop.  The ladder is not usually fixed to the coop and is only put up during the day and taken down at night so foxes cannot access the coop. The ladders have hooks at the top to fit over the door sill and hold the ladder in place while allowing easy removal. If the coop has a door then the ladder can be left there permanently as long as the door is closed each night to prevent foxes getting in. There is another style of chicken ladder that is said to be fox proof, although there is some debate about the efficacy of them. They do look more like a ‘normal’ ladder and are usually quite steep to deter foxes from climbing them. Some can be a single pole with treads on either side, and some have two rails with rungs in between.  These ladders can be made very cheaply with some small branches and string to lash the rungs to the rails.  The ladder only has to support the weight of a chicken, and ideally not the weight of a fox!

There are Even Ladders for Fish!

One animal that uses ladders is quite surprising; fish.  Fish ladders help fish swim upstream in places where there is a height difference or obstacle, such as a dam.  They are also known as fishways or fish passages. The oldest style is called ‘pool and weir’ and is formed of several small pools and dams designed to slow the water flow down and provide a pool for the fish to rest in before jumping up to the next level. There are several of these types of fish ladder in England.  A similar style of fish ladder uses a slot at the side of each small dam to allow the fish to pass through without needing to jump.  Each fish ladder is constructed with a particular species in mind; salmon are strong enough to jump through fast flowing water but other smaller fish are not. Salmon also need a stronger outflow of water at the end of the ladder to draw them into it. Baffle fishways are constructed to allow several species of fish to pass through by creating several different speeds of water through a series of small obstructions.

Humans take inspiration from animal ladders

Thinking back to chicken and cat ladders, these terms are also used for a type of roofing ladder and roof access ladder.  The roofing cat ladder has hooks at the top that fit over the apex of a roof, like a poultry ladder, and sits flush to the roof. They can also be known as cleat boards or crawling boards and originally were constructed from wood in the same style as a poultry ladder. Modern cat ladders for roofing work are readily available and they are made of metal; constructed in the same way as a normal ladder with two rails and narrow rungs that fulfill the same function as the cleats on a wooden board. They also have hooks at the top to keep them attached to the roof, and bearer bars attached under the ladder at regular intervals to stand the ladder proud of the roof tiles allowing more foot room when climbing. You can turn a standard ladder into a cat or roof ladder with an s-shaped hook that attaches to the top two rungs of the ladder and then hooks over the roof ridge at the other end.

Cat ladders are used for roof access on (mainly) industrial buildings. They often have a safety cage around them above a certain height in order to provide protection for the person climbing them. They can be almost completely enclosed meaning that access to even the base of the ladder is restricted to only authorised people.  Cat ladders are usually used for fire escapes and for maintenance access, especially on industrial buildings. You may also find cat ladders on water towers, motorway bridges and signs, grain silos and anywhere else that requires regular access at height. The term 'cat ladder' is also used sometimes to refer to a chicken ladder (described above) as they also follow the plank and cleat design of a chicken ladder.

In Angels Camp, California, residents in the late 19th century constructed a wooden chicken ladder to help them walk up and down their particularly steep street.  The ladder is still in place and in use today, another example of how chicken ladders are used by humans.  It's not very likely that there will be a human application of a fish ladder but it is interesting to see how both humans and animals can benefit from the same type of ladder design.