Soft Release Guide for Mice

        Mice require different release locations depending on the species, but the way you soft release them will be the same. In this short guide I will describe where to release, how to make the box, how to get your mice in their soft release box, and how to set up the release.

How to Make a Release Box:

        There are a few key aspects to a good release box. Just because your box does not or can not meet all the requirements doesn't mean you can’t use it or shouldn’t release your mice, but you should try to include as many key aspects as possible. A cardboard box filled with food and wedged under a pricker bush is still better than hard release!

Key aspects -

1. Be hard to chew into, sturdy. A wooden or hard plastic box is best. You can make a release box out of a small plastic bin.
2. Has 2 small mouse-sized exits/entrances. Ideally these will not be right next to each other. You can cut holes into a plastic bin.
3. Has predator guards. These are just walls in front of the entrances that prevent raccoons or other animals from reaching in and grabbing the mice or their food/nest. These can be accomplished by adding walls inside a wooden release box, or by putting a cardboard box or smaller container inside a plastic release bin.
4. Has more than one room. This is less important but good to include if possible- generally one chamber for a nest and one chamber for a large stockpile of food will do.
5. All chambers should have two exits. If you add a smaller box inside a release box, make sure to add 2 holes and don't line them up with the exit holes (because then a raccoon can reach right into the nest- use the box as a predator guard!).
6. Can not easily be opened. This can be as simple as duct taping a bin closed or as fancy as adding locks to a wooden release box. The key thing is just that an animal can not easily lift the lid off it.
7. Is water-resistant. A wooden box or plastic bin is already plenty water-resistant- just be sure not to put exits on the top as that may let rain into the box.
8. Is made of safe materials. Not all wood or plywood glues are safe- some are toxic if ingested. Please be sure to use safe wood (such as oak, birch, or poplar) and either don't use plywood or use safe plywood (such as Purebond brand plywood). Use an animal safe glue such as elmer's wood glue to construct a wooden box.

Example of a wooden release box -

This box uses eye hooks and latches to lock the box shut, and hinges to allow it to open so I could check inside the box easily. There are two exits/entrances.

The inside of the box has 2 main chambers and several walls to keep the mice safe and provide a chamber for a nest and one for a food hoard. Notice the wooden walls in front of the exits- these are the predator guards that prevent raccoons from reaching into the nest or food hoard. All chambers and hallways have 2 ways to go so the mice always have an escape if another mouse or a snake gets inside the box. The walls were glued on with elmer's wood glue and secured with clamps while it dried.

Example of a plastic release box -

This release box was a plastic bin with a couple other boxes inside. The first box was smaller and cut two holes into it, then put nesting material inside. Then I put this box inside a larger box, which also had two holes cut into it. I filled the larger box with food.

The box had two exits once closed.

The larger box was then duct taped to the floor of the plastic bin release box. The bin already had two holes cut out of it, on either side. The red circles show where the holes were- two holes to exit the cardboard box, and two to exit the bin. The box itself acted as a predator guard and the holes did not line up, so raccoons could not reach inside.

The entire thing was then duct taped shut to prevent raccoons or other animals from opening the box.

How to get mice inside the box:

        Once your box is made, put it inside their enclosure if possible. Allow them to nest inside it and store food inside. Once they have a nest made, you can put more food into the box so there is plenty of food when they are outside and release them! Don't use anything too fancy for food- rodent block and some seeds is perfect. Nuts or other tasty foods may have a strong scent that raccoons, rats, other mice, chipmunks, etc will want to take. Rodent block makes sure they have food but doesn't attract other animals more than necessary. No fruits or veggies either as these may also attract animals and can mold if they aren't eaten quick enough.

If you can not fit their release box in their enclosure, put plenty of food and nesting material in the release box and let the mice nest in a smaller box that you can then move into the release box. Be careful to block off holes to the box when moving it, and empty the enclosure BEFORE release to be certain you have every mouse in the box and are not leaving any hidden in the enclosure somewhere. Consider stuffing the exits to the release box with nesting material (such as cattail fluff, crumbled paper towels, hay, etc) to prevent the mice from bolting immediately- with the exits lightly blocked they have time to settle and work their way out when they are not so frightened by the move.

Release Locations:

        Different species of mice (and other small rodents) will require similar habitats for the most part but there is variation. The criteria are still similar. A release location ideally is near a water source such as a pond, stream, or vernal pool, and should have plenty of low growing plants to hide in. In some habitats there are not a lot of low growing plants, but soft release is still possible. In habitats where it is possible, plenty of low growing plants like bushes, tree saplings, ferns, grasses, etc. provide plenty of cover for newly released mice to explore and stay hidden from other animals, and also offer food as well.

Peromyscus (deer mice) -

In general, deer mice should be released in forests or fields. However, some species will require different habitats. Please be sure to properly identify your mouse's species and choose the correct location- please check out the mouse release guide in the pinned posts, or (if it is not uploaded yet or if you’d like other opinions) please make a post in the group and we can identify the mouse for you. Releasing where the mouse was found is always a good option if possible (such as if they were found while hiking, camping, in your house but you are okay with them in the yard, etc.).

The most common species (eastern deer mice, white-footed mice, western deer mice, etc) are found in varied habitats such as forests and grasslands. Western species may live in different habitats, such as the canyon mouse who lives in arid, rocky areas and the cactus mouse who lives in mountainous and dry desert habitats.

Mus musculus (House mouse) -

        House mice have evolved with humans and are a commensal species, so they need access to humans. This makes release locations difficult depending on where you live. They can be released in parks, old buildings, sheds, campgrounds, your own backyard if you are okay with them living there. Please try to release where they hopefully will not go into an actively used house, but can exist on the edges of human areas. They should not be released deep in a forest or field, though a wooded area close to people is okay.

Other species -

        For other species such as jumping mice, kangaroo rats, etc. please check out the habitat sections of the rodent release guides and/or do your own research into their habitats if the species is not included. Always feel free to ask in the group where to release a specific species.

Possible mouse release locations - notice how much undergrowth there is.

How to set up the release box at the release location:  

1. Release boxes should be hidden whenever possible. Place the box under a bush (bonus if it's a pricker bush), inside a hollow log, in dense vegetation, etc.
2. You can cover them with a green, brown, or camo tarp if you have the ability to.
3. Cover the box with leaves, ferns, and other vegetation.
4. Weigh the box down with a brick, large stone, etc. Be careful not to choose something that will crush or damage the box. By weighing it down, you protect against raccoons and other animals from messing with the box.
5. Optionally, place some branches over the box to hide it further.
6. Place a water bowl nearby for an easy water source when they first venture out. Place a branch or other item inside so if a mouse falls in, they can climb back out.
7. There should be plenty of food inside the box before you get there so you don't need to open the box and risk them taking off and not knowing where their box is.
8. Be sure to remove anything covering the release box’s exit holes you may have used to keep the mice inside when transporting the box with the mice inside before you leave.

Wooden White-footed mouse release box under a rose bush with an empty water bowl.

Wooden White-footed mouse box hidden under leaves and weighed down with bricks.

Plastic White-footed mouse release box hidden under a rose bush.

When to take the box back:

        Some mice need more help than others and some will be ready to leave very soon. Be sure to leave the box for a couple weeks and check back after some time. You can open it and see if they are inside or if it looks like there is a well made nest inside- if there is just a pile of nesting material they likely have already left. If they are not there and it doesn’t look inhabited anymore, you can take it back. If you think they are still using it, don't take it back yet but you can leave more food. There is no harm in leaving it if you aren't sure! Some mice may stay for a week, some may stay for a couple months. It's always better to wait and get it later than to take it too soon. Just be sure to take it back at some point so you don’t litter.

Remember your mice came from the wild and most of them want to return to it. Release is scary, but soft release works and you can take pride in knowing you gave them their freedom back! Without you they never would have had that chance.