Types of cage, nest-box etc. suitable for ship rats.

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Ship rats are extremely active and need space to climb - the same sort of climbing-space you would give chipmunks or chinchillas. The ideal is the sort of aviary-cage zoos use for marmosets: but failing that a base of 3 square feet (e.g. 2' by 18") and several storeys high would be reasonable - something like a large chipmunk cage, or a parrot cage with shelves added. However, a colony of ship rats doesn't need much more space than one rat.

¾" bars of the sort often seen on chinchilla or parrot cages will do to hold an adult rat, but babies can get through these, and need ¾" square mesh or ½" bars: the kind seen on hamster or finch cages.

Because ship rats need as much climbing-area as possible, wire cages are best. Tanks are not a good idea unless enormous and full of branches. In any case all rats are prone to chest-problems in stuffy conditions, so tanks can be harmful unless very large and airy. Tanks if used must never be left in direct sun.

Ship rats do not cope well with cold: they need an ambient temperature of at least about 65°F in order to do well.

Cages should not be placed near curtains, or too close to the wall, as rats will chew both cloth and wallpaper if they can get at them. Also watch out for little hands - and teeth - grabbing your clothes and picking holes in them as you walk past. They will enjoy being given paper, cardboard and cloth to shred - a big piece of rag hung on the outside of the cage, so they have to wrestle with it to pull it through the bars, provides hours of harmless fun.

Most rats like toys to play with. As they chew everything in reach, toys should either be very durable - plastic, metal and/or fairly hard wood - or very cheap e.g. cardboard boxes, loo-rolls, twigs. Offcuts of 4"-bore plastic pipe make ideal playthings, and most parrot toys are suitable. They do not generally use wheels. Ship rats particularly like climbing and should be given perches, branches etc..

Hard-shelled nuts with the shells still on, such as almonds, cobs, Brazil nuts etc., make great boredom-breakers for rodents: but unfortunately they are very hard to obtain except at Christmas. They may also appreciate the sort of puzzle-toys sold for parrots and hamsters, where small treats - grapes, peanuts etc. - have to be fished out from the inside of a small container.

Sawdust should not be used for floor-litter as it leads to sore eyes and snuffles. Wood-chip and flake are OK.

Some authorities in America consider that the use of wood-shavings is harmful to rats, since experiments have shown that they can cause identifiable changes in liver-function in Norway rats. However British rat expert Angela Horn, writing in issue #115 (January/February 2000) of Pro-Rat-a, the journal of the British National Fancy Rat Society, had this to say:

"...the shavings provoking worries in the USA were cedar and pine, because essential oils given off by these shavings had been found to cause changes in liver enzyme levels. ...there does not seem to be any hard evidence that this actually causes harm. ...a rat liver expert... explained that rats with raised levels of the enzymes in question would burn off fats more quickly. This meant that they did not put on as much weight as they otherwise would, which on balance means that they were likely to live longer. On the other hand, higher death rates have been recorded amongst baby rats reared on cedar, probably because they were not putting weight on quickly enough. However, all this is slightly academic... in the UK because neither cedar nor pine shavings are widely sold here. Shavings sold for pet litter here are almost exclusively spruce, which in studies has been shown to have little effect on animals compared to pine and cedar. Some rat owners prefer to avoid shavings for cage litter. I use Bio-Catolet recycled paper litter instead, as it is more absorbent."

Ship rats like a nest-box, with plenty of soft bedding that they can fluff up and burrow under, but it must be quite big. If no commercial large box is available, use e.g. cardboard box, lunch-box with hole cut in, length of pipe.

Soft hay, old clothes or soft, shredded paper make good nesting material. Never use human-style cotton-wool, and avoid proprietary cotton-wool bedding sold for pets unless it is clearly described as short-fibre and safe, as some of these beddings contain long, indigestible fibres which can lead to cat-type fur-balls if swallowed - a much more dangerous condition for a rat than for a cat, since rats cannot vomit and so cannot sick them up (in the middle of the living-room floor waiting to be trodden in by early-morning bare feet) the way cats do.

Ship rats are less inclined to pee in their own bed than are Norway rats, but an absorbent layer in the base of the nest-box is still useful.

Personally I put a grid of ½" mesh in the box, turned down round the edges to make a rim so that the grid stands clear of the floor. Hay or other bedding goes on top of the grid: underneath it goes a layer of cat-litter, to soak up the urine as it runs off the bedding.

They enjoy things they can sit on top of - the higher-up the better - and plenty of things to swarm up. Provide plenty of perches, shelves etc. - but large plain walls of wire mesh or bars are also good for climbing. They also like a ceiling of mesh or bars that they can hang upside down from.

In addition, many ship rats like to "loop" - flipping from the floor to an upside-down position on the roof and then back again, over and over. In some inbred strains this becomes an obsessive behaviour, but in most cases it is just a harmless way of taking exercise, as it is in chipmunks. If your ship rats enjoy looping they will like to have at least a small area of solid shelf about 15" below the wire ceiling, to give them a base to do their back-flips from.

They are quite secretive, and like to have lots of things to lurk in.