Sunday, February 8, 2009

Birdhouse basics

Spring is almost here and in this part of the world, February is an important time to think about birdhouses. February is when birds begin courting and looking for nesting places. Having a bird nest and raise its chicks in your yard is very gratifying for wildlife gardeners. Now is the time to install bird houses and to do seasonal maintenance on them (see below).

Although it is fun to see birds nest in your yard, there are many things to consider before hanging a birdhouse. Know what species of bird you want to attract and have reasonable expectations. Birdhouse need to be designed for a specific bird species to be successful and to not foster exotic, invasive species (like European starlings and house sparrows in much of North America, including Missoula). Generic bird houses that are sold all over actually encourage nesting by exotic birds, and this make life harder for our native birds. These houses infuriate me because people buy them thinking they are going to help native birds. Actually, the opposite is true.

Here I describe houses and pertinent information for four common, easy to attract species in the Missoula area: red-breasted nuthatches, black-capped chickadees, house wrens and northern flickers. Where I live these can all be enticed to use nest boxes in your yard. Even in our small lot, we have often have chickadees, nuthatches and flickers nesting simultaneously. Although this information is tailored toward Missoula, I suspect that this information may be appropriate to a lot of wildlife gardeners.

Nest boxes
All four of these species are cavity nesters (that is, they nest in hollow spaces in dead trees), so they require box-like houses that simulate tree cavities. The reason I encourage people to cater toward cavity nesters is that these birds are having a tough time, from habitat loss, loss of snags (nesting sites), to competition from invasive birds (typically secondary cavity nesters). Chickadees, nuthatches, and northern flickers prefer to excavate the cavity themselves, because this assures a clean home free of pests and predators (see video below, I find this adorable). House wrens, on the other hand, will only use empty boxes.

Plans for a chickadee, nuthatch or wren box are identical and northern flicker boxes are much larger. Here is a link for nest boxes for both houses.

Unless you live near a large expanse of open space or prairie or see bluebirds regularly, I do not recommend you build and install bluebird boxes. More often than not these get used by European starlings and house sparrows. Again, it is really important to know what birds you are targeting and have realistic expectations.

Although northern flickers are common, they are declining across much of their range. Northern flickers are incredibly important species since they are the largest, most abundant primary excavator and they occupy a wide variety of habitats. The ability of flickers to create cavities is crucial for the survival of many other secondary cavity nesting birds. Birds that use abandoned flicker nests range from chickadees to American kestrels.

A nest box for chickadee sized box has an opening that is 1 1/8” diameter- an opening bigger than that will encourage starlings and house sparrows. Do not use a perch for any of thee species- they do not need them. In addition, perches encourage exotic birds, and since few native birds need them there is no reason for a perch.

Chickadees, nuthatches and wrens will add nesting material for their nest. Chickadees use animal hair, fur, and moss. Nuthatches will shred up bark into various layers of increasingly soft bedding, and they also smear sap on the outside of the hole to discourage insects and parasites from bothering the nestlings. It is really fun to watch them do this. You can help chickadees by providing fur (see picture below- one of the best uses for a squirrel, more about squirrels in a post to follow), animal hair or sphagnum moss in your yard for them.

Flickers will nearly completely remove all the wood chips for the box and they do not require any nesting material. Another benefit to having he house filled, is that is discourages use by non target birds like house sparrows and starlings, which will not excavate. However, once the flickers excavate their nest box, often European starlings will follow. It is crucial to remove the starlings, their nests (they bring in nesting material), or otherwise dissuade them from taking the flicker’s nest box.

General box information

  • I recommend using western red cedar for the box construction, a naturally decay- and insect-resistant wood, which needs no protection from the weather it should last for many years. Fill and pack it with fine wood chips or coarse saw dust each year. I fill my boxes with Douglas fir (typically chips from my thickness planer), but you can use any species except cedar, teak, or mahogany. These species contain oils that prevent rot and insect damage but the dust can irritate nestlings.
  • Place the box from 6- 15’ from the ground and face the hole away from prevailing winds and weather (usually east).
  • Place the house in an area where you can easily observe it.
  • Install the house by February, but the earlier the better- you will be amazed how quickly birds discover it and return to it.
  • Clean out the box after the breeding season. A good time to do that is in early fall. I like to leave the box empty in the winter- birds will use them as winter roosts.

Nest box selection times
Red-breasted nuthatches are the first to begin excavating their selected box- they begin excavating in early to mid February (between February 5 and 21 at my house) and they are usually complete by the first week of April (April 1-9) when they begin to fill their boxes with nesting material.

Black-capped chickadees start excavating about a month after nuthatches, with peak excavating around first week of April (from March 25- April 4), until middle April when they bring in nesting material (April 11-15).

Northern flickers are on a similar schedule as chickadees and they begin excavating in late March – early April (March 24-April 8), but they search for nesting locations in February and may do some exploratory excavating as early as the beginning of February.


  1. Thank you for such an informative post (and charming video). We only see flickers in our garden in the Sierra Nevada foothills when they come for their annual "stripping of the pyracantha" visit. We'd love to have more of their company. Perhaps proper quarters would attract them.

  2. Thanks so much! A timely reminder. I must admit I'm intimidated by the mounting. I've often heard that only a metal post or possibly a mount on a tree, high up, will do or the neighbor's cats will have a feast... Any advice? Birds do seem to nest in my neighbor's redwood trees, and the mourning doves like the grape arbor, but I'm not sure about the cavity nesters.

  3. Thanks for your comments; I am really happy some of this information is helpful.

    Mounting a box on a metal pole is a good idea- it will keep away cats, squirrels, raccoons, etc... but it may not be necessary or the most aesthetically pleasing. The main problems with flicker boxes, in particular, are starlings and a metal pole won't help. To get around cats and other animals reaching into the box you can add an extension to the hole- simply a 1x or 2x piece of wood with a hole cut out and place it over the access hole. This is also a great remedy for a birdhouse with a hole that is too large in diameter. I have made several of these for my neighbor, whose boxes used to attract house sparrows. Another option to keep cats out is to cover the bottom few feet of the post with metal flashing. Cats are a huge problem where I live, for example, this fall I watched as a neighbor's cat killed a flicker in my yard- the flicker was feeding on the ground like it was supposed to, so a metal pole or other devices for the house would not have helped! Let me know if you have any questions about my suggestions and I can send some pictures.

    Thanks again and good luck with the birds, I really do enjoy this time of the year when they are staking out their little claims on nest boxes, but keep a vigilant watch for invasives!

  4. Thanks for your useful information. It came just in time when we were considering buying bird houses. I enjoyed reading your post.

  5. What a lot of great information! Thank you so much for taking the time to do it. I'm glad to have found you via Blotanical. Though spring is still a long way from visiting NS, I'm enjoying the thoughts of it as I look out on my glacier and at the fluffed-up birds at the feeders.

  6. Great post...very informative. I've heard leaving dryer lint outside gives birds nesting material. Any truth to this?
    Also, I've got a plastic "miniature log cabin" mailbox that I took down last year and replaced. Wondering if this will make a good home if I cut a hole in the front. I'll keep searching. I'll check back.

    PS:Cardinals are my favorite singers.

  7. Hi Dan,
    Thanks for your comments. As far as nesting material, it all depends on the bird species and their individual preferences. The lint might work (it certainly would not hurt), we have tried wool, cat hair, and other soft things, but the chickadees only seem to like using squirrel fur (see above), and sphagnum moss that we set out. Nuthatches use bark they finely strip off trees and our bent willow furniture. Give it a try, though, birds that build their own nest (as opposed to using nest boxes) might use it.
    As far as the log cabin, again, you will need to tailor that to a specific bird (see comments and concerns about hole size and perches, above). But beyond that, I do recommend wood for nest boxes for two reasons, one the birds like to (or need to) modify the boxes, and the nestlings need a rough surface to climb up. If the sides of the inside are too slick, they may not be able to grasp them. You could cut little groves below the entrance hole or otherwise roughen it on the inside, but again, wood is good.
    I hope this helps, and thanks for visiting.

  8. Hello, please let us know how many birdhouses we can install in 1.5 acres. We moved to new house, and had no idea about Chickadees, till they made holes in the foam corners of our house. we got two Chickadee houses, but only one is now occupied.

  9. Hey Neighbor.. Just an FYI, the link you posted for Flicker and chickadee houses is not working. We built a box and just today have a chickadee pair looking to move in.. They haven't gone in yet but they keep poking their heads in and have been for a couple of hours. I'm wondering if they CAN'T get in and maybe I should make the hole bigger because it looks like they're trying hard.. Its about 1" I think. Is it normal for them to be so cautious?

  10. Hi Deke and Jessica,
    Thanks for the comments and for the tip about the link- I fixed it, and changed it to Cornell's site.
    As far as the chickadees- great news they were so quick to investigate your box. Hard to say what they were thinking. They are cautious and curious, and they may have already claimed a nest box for this year. So they might be checking it out for next year. I doubt if the hole is too small, though 1- 1/4" diameter is perfect. If it is too small of a hole you will probably see them trying to enlarge it by pecking at it. Check the size and you may want to enlarge it, but don't make it larger than 1-1/4". Good luck and let me know how it goes!
    Thanks again for stopping by my blog.

  11. I had a wren successfully nest in a bird house last year in my garden after 15 years with no takers. Now I am watching anxiously for them to return. I did not clean out the box. Should I now? Do the often return? And when do they typically start building? I live in the mid-Rattlesnake.

    1. I love house wrens! They are great to have around- little bird; big voice. They can sometimes be tricky to attract. They are nest parasites, and their arrival is coincidental with primary excavators like chickadees and nuthatches, having completed excavating. It might help to have a few empty and clean boxes set up to greet their arrival. Good luck!

  12. I am happy to have found this information about birdhouses. I did not realize that the material used to make a birdhouse was so important. It is good to know that western red cedar is a good choice. Something else to consider would be to ensure that the entry hole is big enough for birds to enter.