Birdhouses and Nesting Boxes

By Jay Van Tussenbrook

   There are few things in life more rewarding than watching the emergence of a  new life into this world.  If you are lucky the birdhouse or nesting box you put up this winter has given birth to a downy little face peeking forth from the entrance, a tiny beak and two beady eyes peering out into the world for the first time.  It shakes a little, and moves awkwardly before leaping out and spreading it's newly fledged wings to flutter off into the sky.  Congratulations! Your efforts have paid off, and a family of birds has grown, if only a little, thanks to luck and your vigilant nurturing.

Luck does indeed play some role in whether or not your efforts in bird housing pay off, but there are some things you can do to skew the odds in your (and your feathered friend's) favor. To start with, you can make sure you select a house or nesting box that will both be attractive to the right kind of bird, and protect the bird's family from predators as well as the elements. 

When choosing a birdhouse there are several things to look for.  First,  consider what kind of birds you wish to attract, and make sure the birdhouse  or nesting box is appropriately sized.  Bluebirds, chickadees, swallows, wrens  and other small cavity nesters are attracted to smaller opeinings. An  opening of 1 1/4" to 1 1/2" allows these birds to enter the home, while  preventing larger species, especially starlings from setting up shop.   Flickers, ducks, screech owls and other larger birds require houses with much larger openings.Unfortunately you will not be able to  exclude pest birds from such houses by the size of the opening.

 Once you have decided which birds you wish to attract and know the proper  size home to use, make sure the home you select has these important features:

 1. Ventilation.  A proper birdhouse or nesting box should have some space  between the roof and the sides of the box to allow for ventilation.  It is  possible that without this fledglings or eggs could overheat and be  killed. Also, a wet nest might not properly dry out later inviting fungus, mold or  disease.

 2. Drainage.  There should be a few small holes in the floor to allow any  rain or moisture that does happen to get in to drain away by gravity.  Once  again without drainage the risk of fungus, mold, and disease increase, not  to mention the possibility of the home actually filling with water and  drowning or washing out the residents.  An upwardly recessed floor will also  help prevent seepage inside the home during wet weather. A long roof  overhang will help keep the interior dry as well by keeping rain from  getting in.

 3. A shaded opening.  It can be quite important to keep the opening of the  house shaded, especially in the summer since some species incubate their  eggs at very controlled temperatures, and if the temperature inside the home  elevates even a few degrees the eggs might not hatch.  Not only this, but you  run the risk of the parent birds overheating and abandoning the home, or  even dying. Many birdhouses or nesting boxes have roofs that overhang the  entrance for just this reason.

 4. A protected opening.  Predators are cunning and persistent animals when  presented with an easy meal.  Luckily several modifications in nest box  construction over the years have reduced the possibility of nest predation.  Look for homes that have a deep entrance hole, or a "predator guard" that  extends the depth of the entrance hole.  A deep entrance will prevent  raccoons, jays or cats from being able to simply reach inside and grab a  young bird.  A long roof also has the same effect.  Cats will try to sit on  top of a nesting box and watch for a chance to snag a meal.  If the roof  overhang is large enough such a tactic is useless.  Also make sure the home  you decide on lacks a perch.  Very few birds will even use a perch outside  the nest entrance, and it makes it easy for predators, especially predatory  birds, to simply sit outside the home and take advantage of your birds.

 5. Easy to clean. Most birdhouses or nesting boxes have a pivot or hinged  opening near the bottom of the house to allow for easy cleaning.  It is very  important to be sure to clean the box between uses.  Removing any old nests  will ensure that any parasites are also removed, and that the next  inhabitants will not build their nest up so high on top of the old one that  it is easy for predators to get to, or the young to fall out of.

 6. The right materials.  The best bird houses and nesting boxes are made  from wood or natural materials.  Though there are many decorative metal  houses available we cannot recommend them since it is possible that the  metal construction could contribute to the interior overheating during hot  weather.  Wood is much easier for birds to cling to as well, which helps the  young when they are emerging from the nest.  Some houses even carve little "steps" into the front wall to help. It is entirely possible for young birds  to become trapped inside the house and die.  Painting a house is also  questionable.  While it does make a house more appealing to us, unnatural  colors or patterns could attract attention from unwanted predators, not to  mention the possibilities of toxic paint poisoning the birds themselves.  It  is especially important not to paint the interior of the house since there  is a good chance that the young will end up chipping the paint and  inevitably swallowing some of the chips. 

 Once you have chosen the appropriate nest box or birdhouse the next step is  placing it so that the right birds will find and use it.

 Different birds  will be attracted to the same house depending on where you put it and how  high it is off the ground.  Most of the time placing a birdhouse or nesting  box 5 or 6 feet off the ground is good enough to attract many different  kinds of birds that will accept it as a potential nesting location, and  protect it from predators.  However some birds, like swallows and nuthatches  appreciate a little more elevation, between 10-20 feet high.  They are  simply genetically programmed to nest in higher locations that make them  feel safer from predation. This doesn't mean that a swallow or nuthatch  won't nest in a lower location, only that it is less likely.

 It is a good idea to face the nest box or house toward the north or the east  to prevent overheating from too much sun, and to keep the entrance away from  the prevailing winds which will drive precipitation into the entrance, or  generally make it difficult for the birds to use.  Strong winds are also a  good reason not to hang a birdhouse from a tree branch or limb.  The swaying  and twisting may not bother some birds, but most would much prefer their  nest to be in a more stable environment.

 It may seem like mounting the birdhouse on a nearby tree is a good idea, but  before you do, ask yourself these questions: Will the birds you are trying to  attract see the birdhouse?  How hard (or easy) is it for a cat or raccoon to  climb the tree and reach the nest? Will mounting the birdhouse on the tree  damage the tree?  Birds love trees, but mounting a birdhouse to one is not  always the best idea.  In the first place the tree's foliage might  camouflage the birdhouse so well that the birds you are trying to attract  might not even be able to find it.  Secondly, trees are extremely easy for  predators to climb. Sometimes they will climb right up to the house, sit on  the roof and reach into the birdhouse with a paw trying to grab a snack. And  on top of that, nailing anything to your tree (depending on the tree) might  actually be detrimental to your tree over the course of its life.

   It is best to mount the birdhouse or nesting box in a somewhat open area, in  clear view near a tree or bush that the birds will be able to use as a  survey point to land and check out the house before they move in.  Mounting  on a post, pole, or dead tree is preferable, however if the conditions are  right tree mounted birdhouses are acceptable.  Many birds naturally nest in  dead trees so it makes sense that mounting your birdhouse on a dead tree  would be more inviting to them.  It also lacks the foliage of live trees,  leaving the birdhouse exposed and easy to see.  By the same token, if  predators try to approach the nest there is no foliage to help conceal them  from the birds.  Mounting on a post or pole is even better, being both more  difficult for predators to climb, and easier for the birds to find.  Many  birdhouses have the ability to be mounted directly to the top of a metal  pole securely staked, buried or cemented into the ground.  The metal pole is  practically impossible for predators to climb, and there are usually several  varieties of baffles available that can be fixed below the birdhouse to make  sure they will never reach the birds.

 If you plan on hosting multiple bird families remember not to place their  homes too closely together.  Most birds are territorial and will defend the  area around their nests against interlopers. Ideally multiple birdhouses or  nest boxes should be placed about 25' apart in locations that cannot be seen  by one another.  There are a few exceptions for species like martins and  some sparrows that will nest in colonies, but for most birds this is a good  general rule.  Of course this means that you need to make sure that any  birdhouse is also far enough away from your birdfeeders and birdbaths that  your brooding bird family doesn't pick fights with any innocent bystanders  who show up to eat or bathe.  It may seem funny at first, but over time many  little fights will take their toll on your tiny bird friends, making them  aggressive, agitated, and stressed out.  They may even abandon your  birdhouse thinking it is too much trouble to defend, or be forced out by  bigger more competitive birds.  Either way it's not good for the birds.

 Bearing this in mind there are occasions when it might be alright to place two birdhouses closer together. Usually this works when the houses are occupied by different species. If the birds are not are not of the same species they will generally not compete with each other, and in fact can be quite helpful as both sets of parents will protect the area forming a kind of cooperative defense while not disturbing each other. Attempts to produce these results usually require the houses to be more like 10 feet apart or even closer, and may not always work out. The most common cooperative species we have seen are tree swallows and bluebirds. Since they generally nest at different heights they tend not to compete for nesting sites if properly placed and can actually be quite friendly neighbors.

  Finally remember that as a responsible avian landlord it is your  responsibility to clean out the birdhouse at least once a year, so wherever  you place it make sure it won't be too much of a chore. In fact, the easier  the better. Leaving your new tenants a welcome gift of fresh nesting  material is a great way to make them feel welcome.  Filling the bottom of  the new birdhouse with a layer of fresh cedar sawdust or sanitary cotton or  wool helps make the house more attractive to potential tenants.  Just make  sure that the level of the nest won't come too close to the entrance hole or  predators could too easily reach it, or the young fall right out. 

  At last you have the right house, in the right location, and now the question comes...What birds do I get? Most people try to attract the more beautifully plumaged, or voiced local birds, but as we all know, we don't always get what we want.  And for the most part we are all wise enough to  accept what we get and enjoy it.  But what can you do when your carefully  placed, well constructed birdhouse is invaded by a rude and invasive  species, like a starling or a house sparrow? Starlings and house sparrows  are both species introduced into North America from Europe.  They have  out-competed and out-bred many of the native species and threaten to slowly  eliminate many of them.  One of the reasons is that there are so many of  them that when nesting season comes they take up most of the best nesting  locations leaving the native species to try and protect their brood in more  dangerous areas.  In fact adding birdhouses to your yard or property is a  great way to help the native species try to recover, but only if they are  not usurped by those very same problem birds.

 So what can you do to keep those birds away and out of your birdhouses?   Well, it may be fighting an uphill battle but there are some things you can  do.  First, try not to attract those birds to your yard.  By not using  millet in your birdfeeders you can keep the number of sparrows and  starlings down.  Both species like millet and are attracted to feeders that use it. Suet, peanuts, and sunflower chips are also sure to attract starlings, so try not to put them out until your nesting areas are filled. Try nyjer thistle and whole black oiled sunflower instead. 

 These seeds  help encourage native species to feed at your feeders and hopefully one of  them will move into your birdhouse.  Another trick is to block up the  entrance of your birdhouse until you notice a lot of native birds, or birds  you want to nest in your birdhouse.  Then unblock the opening and  hope for the best.  Oftentimes sparrows and starlings will overwinter in an  area, or arrive first in the migrations and hog-up all the best nesting  spots, including your nest box!  So pay attention and block those entrances  up until the native species return.  It also helps to block up any natural  nesting areas around your place, like open eaves, outdoor shelves and other  spots where you know invasive species will naturally nest.  They may not  usurp your bluebird box because the entrance hole is too small, but if they  happen to build a nest in the eave of your house right next to it then  they'll defend the whole area and chase off any birds it might attract.

 Inevitably every year some of us lose the battle and end up with sparrows  and starlings anyway.  What do you do then?  Really there isn't much you can  do.  Open up the box and remove any nest and eggs, clean it out, and hope  the pesty perpetrators don't come back and start over.  Often they will.   Repeat the process...as many times...as...necessary.  It doesn't always  work.  You can try blocking up the entrance as well and maybe it will  discourage the birds enough to look elsewhere, but then when you open it up  again they might come right back.  It's an imprecise science and we are to a  certain extent at the mercy of Mother Nature.

   Every year there are also those birdhouses and nest boxes that go unused.   Nothing is more frustrating than going through all that effort to pick out  and set up a birdhouse and having it go unused all year.  The only thing to  be done is to try another location next year.  If it happens again, then  move it again.  If the house is a good one it should eventually bear you  some fuzzy feathered fruit.  Using the tips in this article you should be  able to find a good nesting box or birdhouse and a good location that  practically guarantees you a happy and healthy family of bird buddies year  after year.  Good luck and good birding!
 


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