Gerbil digging and burrowing: how deep to go

Why do gerbils dig?

Because it is what gerbils are built for. The RSPCA says wild Mongolian gerbils dig burrows as deep as 1.7 m (5.5 ft) that run 6 to 8 m (20 to 26 ft) sideways, and Gerbil Care UK shows wild burrows with separate chambers for nesting and storing food. As prey animals, the RSPCA says, they need to be able to hide and dig at all times: the burrow is their safety, their larder and their bedroom.

In a tank, digging is also how they spend their energy. Gerbil Care UK says gerbils without enough to dig in show stress, such as scratching at the glass or digging at nothing. The RSPCA describes digging in one corner over and over as a sign that the home isn't right, and suggests more enrichment, more hiding places or a deeper tank. A gerbil with real tunnels to build is a busy, calm gerbil, and watching a colony work underground through the glass is one of the best things about keeping them. Our gerbil behaviour guide explains more of what they do and why.

How deep should gerbil bedding be?

At least 20 to 25 cm (8 to 10 in) across the whole tank, and deeper wherever you can. The sources agree on the minimum and differ on how far to go.

PetMD's 1 to 2 inches is a general small-pet figure and leaves nowhere to tunnel, so we don't follow it. We'd go with 25 cm (10 in) as the minimum everywhere, and 30 to 40 cm (12 to 16 in) on the digging side if your tank is tall enough. Woodgreen adds one limit: leave enough room above the bedding for a gerbil to stand on its back legs without touching the lid, which is about 12 cm (5 in) for an adult.

What size tank do I need for 2 gerbils?

At least 100 × 50 × 50 cm (39 × 20 × 20 in), which Woodgreen sets as the minimum for a pair, or a 40-gallon tank in US sizes, which Oregon Humane Society gives as the minimum for two. For burrowing, the depth of the glass matters as much as the floor. Gerbil Care UK says the solid base should be at least 40 cm (16 in) deep, because shallower bases can't hold enough bedding. It rejects some well-known cages for that reason alone, such as the Ferplast Karat 100 and Domster 100, whose solid bases are only 25 cm (10 in) deep.

Large gerbil tanks for deep digging

If you want a deep, large gerbil tank, these are some that Gerbil Care UK has measured, with plenty of floor for tunnels.

A 40-gallon breeder fish tank, about 36 × 18 × 16 in (91 × 46 × 41 cm), is the easiest large tank to find in the US. It has a 16 in (41 cm) glass depth, enough for 25 cm (10 in) of bedding with standing room. Our gerbil cage size guide has the full table by number of gerbils, and our best gerbil cages page has where to buy.

What bedding is best for burrowing?

A mix, not one product. Soft paper bedding on its own is comfortable but collapses, so add materials that bind. Gerbil Care UK's tested mixes use paper bedding, shredded cardboard such as Green Mile, meadow hay, brown packing paper and egg boxes, and it says this kind of mix holds tunnel structures well. Woodgreen suggests using two or more of shredded paper, shredded card, small cardboard squares, unscented hemp, soft paper bedding, soft green hay or organic soil.

• Paper bedding as the base, dust-extracted and unscented
• Shredded cardboard to give the mix body
• Meadow or orchard hay, which Gerbil Care UK says binds tunnels together
• Egg boxes, plain cardboard and brown paper torn into pieces
• Plain toilet paper for lining the nest

Leave out sawdust and wood shavings, which Woodgreen says can harm skin and airways; the RSPCA also warns against sawdust. Gerbil Care UK says timothy hay and straw are too sharp. Never add cotton wool or fluffy fibre bedding, which can wrap round legs. Our gerbil bedding guide compares every type.

How to build a burrow-friendly gerbil tank

This order gives gerbils a head start and helps tunnels hold. It follows the layered method Gerbil Care UK and Woodgreen describe.

1. Put heavy things in first. Woodgreen says to place heavy items before the bedding. Stand the nest box on the floor of the tank, where Gerbil Care UK puts it, so it ends up buried at the bottom of the burrows.
2. Lay a base of cardboard. Cover the floor with shredded cardboard or paper bedding a few centimetres deep.
3. Build up in layers. Add bedding about 5 cm (2 in) at a time, with a handful of meadow hay and a little torn cardboard in each layer. Press each one down lightly with your hand.
4. Bury starter tunnels. Lay cardboard tubes at an angle down towards the nest. Gerbil Care UK uses brown postal tubes 76 mm (3 in) wide and says any tube should be at least 7 cm (2.75 in) across.
5. Go deep on one side. Fill the digging side to 25 to 40 cm (10 to 16 in). The activity side for the wheel, sand bath and water can be firmer and shallower.
6. Scatter food on top. A little of the daily food scattered over the surface makes them dig and forage from day one.
7. Add nest paper. Lay plain toilet paper on top. The gerbils carry it down themselves.

Our full gerbil cage setup guide covers the activity side and layout.

Why do my gerbils' tunnels keep collapsing?

Usually because the bedding is too loose, too fluffy or too shallow. Check these in order:

• Is it at least 25 cm (10 in) deep? Shallow bedding can't support a roof.
• Is there hay and cardboard in it? Pure paper bedding slumps.
• Was it pressed down? Loose bedding fresh from the bag has too much air in it.
• Are there buried tubes or a nest box for the tunnels to start from?
• Was it fully cleaned out recently? New bedding takes time to settle and be shaped.

A cave-in is not a crisis: gerbils simply dig again. Fix the mix at the next top-up rather than rebuilding the whole tank.

How to clean without wrecking the burrows

Spot clean often and fully clean rarely. Oregon Humane Society says full clean-outs aren't needed more than once a month if there is enough bedding, because losing their hard-earned burrows and scent too often stresses gerbils. The RSPCA suggests a deep clean every two to three weeks, keeping some used but clean bedding. Deep tanks spread the mess thinner, so they can go longer. Lift out wet patches, droppings and old fresh food from the surface every few days, and leave the tunnels alone. When you do a full clean, keep a few handfuls of the old clean bedding, as Woodgreen advises, so the tank still smells like home. Our gerbil cage cleaning routine sets it out step by step.

Dig boxes and other digging toys

A dig box gives gerbils a second kind of digging. Woodgreen suggests a tray or box of organic compost or coco soil, watched so it doesn't dry out and turn dusty. A plain cardboard box filled with hay and a scatter of food, which Gerbil Care UK calls a forage box, works the same way for free. Keep sand for the sand bath, and never use garden soil, which the RSPCA says can carry bacteria or parasites. More ideas are in our gerbil enrichment guide and best gerbil toys.

For everything else your gerbils need, see the complete gerbil care guide.