HELP! diameter hole for chickadee?? 1 1/8"!? (1 Viewer)

Okay.. built some nestboxes for birds.. Read somewhere the diameter hole for chickadee (black-capped, which I have seen 2-3 at my birdfeeder recently!) was 1 1/8".. Then, today I read in another book , the hole size is 1 1/2", which seems very odd...

Also, after drilling this size hole, it seemed awful small...After seeing the black capped chickadee around my feeder, and noting it's size, the hole seemed even smaller!

Do I have the correct size, and is it normal for the hole to APPEAR too small for the size of bird that it is made for??

I hate to make the hole bigger, and have the box appeal to other birds, if it's not necessary...

Found this on the e nature site, hope it helps

http://www.enature.com/articles/detail.asp?storyID=608

arribaperu said:

Okay.. built some nestboxes for birds.. Read somewhere the diameter hole for chickadee (black-capped, which I have seen 2-3 at my birdfeeder recently!) was 1 1/8".. Then, today I read in another book , the hole size is 1 1/2", which seems very odd...

Also, after drilling this size hole, it seemed awful small...After seeing the black capped chickadee around my feeder, and noting it's size, the hole seemed even smaller!

Do I have the correct size, and is it normal for the hole to APPEAR too small for the size of bird that it is made for??

I hate to make the hole bigger, and have the box appeal to other birds, if it's not necessary...

Click to expand...

What I do is drill a 1 1/8 hole for chickadees and red breasted nuthatches. Then just slightly sand the edges to make it a 'bit' larger and just slightly smooth and roundish. Most important, however, is the thickness of the wood itself. If it's dimensional lumber then the 3/4" depth is a bit tight for dees...I find they go in easier if the opening wood isn't much more than 3/8 or a 1/4 thick. I once had a chicladee literally get stuck in a hole 1 1/8 that was 3/4 " in thickness.

cayoncreekman said:

What I do is drill a 1 1/8 hole for chickadees and red breasted nuthatches. Then just slightly sand the edges to make it a 'bit' larger and just slightly smooth and roundish. Most important, however, is the thickness of the wood itself. If it's dimensional lumber then the 3/4" depth is a bit tight for dees...I find they go in easier if the opening wood isn't much more than 3/8 or a 1/4 thick. I once had a chicladee literally get stuck in a hole 1 1/8 that was 3/4 " in thickness.

Click to expand...

Hmmm.. I did the same thing! I sanded the outside of the 1 1/8 " hole, so it's probbably a little bigger however, . I put a baffle over the hole, as this nestbox is on a tree. So that the wood of the nestbox and the wood of the baffle, would make my the wood thickness of the overall hole over an inch thick.. From what you are saying, I think this could present a problem for chickadees entering and exiting the hole??

Steve

Reducing entrance hole size of a bluebird box for chickadees

cayoncreekman said:

<snip>Most important, however, is the thickness of the wood itself. If it's dimensional lumber then the 3/4" depth is a bit tight for dees...I find they go in easier if the opening wood isn't much more than 3/8 or a 1/4 thick. I once had a chicladee literally get stuck in a hole 1 1/8 that was 3/4 " in thickness.

Click to expand...

I have just put up a bluebird box with an entrance hole of 1 1/2" diameter and a tunnel length of 1 1/2", i.e. twice the 3/4" of dimensional lumber, once for the wall thickness itself and once for the predator guard of the same thickness. The outside of the entrance hole is reduced with a metal plate having a hole with a diameter of 1 1/8". My hope is that chickadees can go in and out easily but house sparrows cannot.

I have no experience with it yet and comments are more than welcome.

Nest box holes always seem to look too small. However I'd stick to the size quoted as anything larger may permit another unwanted species to take over. My experience is that if the hole is a little tight then the birds will deal with it themselves. Even our small blue tits can widen hardwood ply.

arribaperu said:

Okay.. built some nestboxes for birds.. Read somewhere the diameter hole for chickadee (black-capped, which I have seen 2-3 at my birdfeeder recently!) was 1 1/8".. Then, today I read in another book , the hole size is 1 1/2", which seems very odd...

Also, after drilling this size hole, it seemed awful small...After seeing the black capped chickadee around my feeder, and noting it's size, the hole seemed even smaller!

Do I have the correct size, and is it normal for the hole to APPEAR too small for the size of bird that it is made for??

I hate to make the hole bigger, and have the box appeal to other birds, if it's not necessary...

Click to expand...

We put chickadee boxes up this year with 1 1/8" holes and the fat little birds could NOT fit in. They were very frustrated. Before we could fix it - the house wrens took over! Talk about loud birds. And our chickadees ended up in another tree with a box with a much bigger hole. Everybody seemed happy so we let well enough be - but we'll be out there with the sandpaper next year to slightly widen the chickadee boxes, and to put out some new ones just for the wrens!

I showed my daughter the bird box with the hole reducer to 1 1/8" and she wondered: "How do the birds go in the box?" I said: "Through that hole!" She said: "Through that hole? It looks like a trap!" Makes me wonder if I should remove the hole reducer and leave the hole size at the original 1 1/2"!

There is a named rule, although I forgot the name, that says that birds further up North, like in Canada, are bigger than birds of the same species but further South.

FWIW, I removed the hole reducer plate. The box has now the original hole + wooden predator guard. I measured the hole size of the predator guard to be 1 7/16", i.e. 1/16" smaller than the nominal 1 1/2". The total tunnel length (thickness of wall + thickness of predator guard) is 1 1/2".

That should be OK for chickadees to enter, no?

do re meep meep said:

I showed my daughter the bird box with the hole reducer to 1 1/8" and she wondered: "How do the birds go in the box?" I said: "Through that hole!" She said: "Through that hole? It looks like a trap!" Makes me wonder if I should remove the hole reducer and leave the hole size at the original 1 1/2"!

There is a named rule, although I forgot the name, that says that birds further up North, like in Canada, are bigger than birds of the same species but further South.

Click to expand...

Very true. Have you even seen a crow in the midwest USA or south? They aren't any bigger than magpies. It's also true with mammals. One time we helped organized a school trip of Athabaskan natives to go down to New Mexico. They were as amazed by how small the deer were as much as anything else.

I remember again, it's Bergmann's Rule about bigger animals in colder climates http://en.wikipedia.org/wiki/Bergmann's_rule

Canadian chickadees seem to require a bigger hole than the 1 1/8" suggested in the US. How much bigger? 1 3/16" at the Canadian-US border? 1 1/4" close to the Arctic?

How does the waist size of house sparrows increase further up North? For example, does 1 3/16" at the Canadian-US border exclude house sparrows?

do re meep meep said:

I remember again, it's Bergmann's Rule about bigger animals in colder climates http://en.wikipedia.org/wiki/Bergmann's_rule

Canadian chickadees seem to require a bigger hole than the 1 1/8" suggested in the US. How much bigger? 1 3/16" at the Canadian-US border? 1 1/4" close to the Arctic?

How does the waist size of house sparrows increase further up North? For example, does 1 3/16" at the Canadian-US border exclude house sparrows?

Click to expand...

That's a great question. I'd assume that English sparrows, the little devils, haven't had time in all areas for natural selection to have had much of an impact on their size. Our cats, however, are sure bigger from having eaten so many. Our geriatric cat must have eaten a couple thousand english sparrowsi n his hunting days and we still treat him to sparrows from our sparrow traps.

I talked to a couple of locals and got the impression that a 1 1/8" diameter hole excludes Canadian house sparrows, but a 1 1/4" diameter hole does not.

This makes me think of the oval hole of the Peterson box for Eastern Bluebirds http://www.birds.cornell.edu/birdhouse/pdf/songbird_holesize.pdf As you can see from the drawings, the size of the oval hole here is 1 3/8" x 2 1/4". I read a study on the NABS site (that I can't find right now) that the Eastern Bluebirds prefer the Peterson box primarily because of the oval hole. Note that compared to a 1 1/2" diameter hole, the width of the oval hole is reduced (!) by 1/8" but the height of the oval hole is substantially increased by 3/4"!

Coming back to the issue of a Canadian chickadee hole, perhaps an oval hole of 1 1/8" width and a height of 1 1/4" to 1 1/2" will pass Canadian chickadees but still excludes Canadian house sparrows.

If so, then sanding the top and/or the bottom but not the sides of a 1 1/8" diameter hole will do the trick. In case of a 1 1/2" diameter hole, shim one or both sides of the hole down to 1 1/8". Perhaps shimming with soft wood would allow a chickadee to widen the hole if it so desires.

Note that the above is conjecture, proceed at your own risk!

Following up on the oval hole issue, I have carefully watched the Blue Tit and Great Tit videos that our UK friends have posted on the net, especially those videos captured by cameras external to the bird box showing how the birds arrive _at_ and go _through_ the hole. I think I have been able to make the following observation.

The bird arrives _at_ the hole and clings to the bottom portion of the hole and front wall of the box with its feet and toes, sometimes assisted by its tail engaging the front wall. Then it bends its head forward into the hole.

And now comes a crucially important part. In order to move its body _through_ the hole, the bird needs to bend its legs to retain at least the toehold at the bottom portion of the hole. The bird needs legroom! Without legroom, the bird loses its toehold and has no means to push its body through the hole!

Man has made the holes round because it is easy to drill round holes, but I have my doubts now that the round shape is optimal for the birds.

I think that the shape of the hole needs to be oval which is taller than it is wide. This provides the necessary legroom for the bird which permits it to grab a toehold at the bottom of the hole and push itself through the hole.

The width of the hole can hopefully still be used to exclude larger undesired species. But the height of the hole would no longer exclude the desired species.

If this observation is correct, then the precise height of the oval hole is not critical as long as it provides the necessary legroom for the desired bird species to go through the hole.

The above is supported, I believe, by the oval hole officially recommended by the NABS for Eastern Bluebirds. This oval hole is a whopping 3/4" taller than the 1 1/2" diameter hole while the width of this oval hole is even reduced by 1/8"!

Coming back to the issue of Canadian chickadees having trouble going through 1 1/8" diameter holes, I suspect that the 1 1/8" width of the hole is wide enough for them, but that the 1 1/8" height of the hole makes them lose their legroom and toehold.

If that is correct, then the oval hole solution may be good news, i.e. the 1 1/8" width excludes the Canadian house sparrow, while making the hole taller, e.g. 1 1/2", would permit the Canadian chickadees to enter the box.

Comments are more than welcome!

I am trying to corroborate what I wrote in the above and estimate the width and the height of chickadees that come to my window feeder. I have drawn a rectangular grid on the inside of my window (where the window feeder is positioned) with a grid spacing of 1 1/8" in the horizontal direction and 1 1/2" in the vertical direction for close comparison with the oval hole hypothesis.

I'd like to encourage others to do the same or similar measuring efforts so that we can compare notes. Use non-permanent markers to draw the grid!

FWIW, while I was drawing the grid, those birds still came to the window feeder less than two inches away from my fingers, and although a few became scared, the others still took their food away :bounce:

do re meep meep said:

FWIW, while I was drawing the grid, those birds still came to the window feeder less than two inches away from my fingers, and although a few became scared, the others still took their food away

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Heh. Chickadees here are VERY tame. They will mob you on the local conservation areas this time of year - last weekend I went out and when I was too slow getting the sunflower seeds out, they started landing on my head!

Yeah, as I said in my 'Hello' message 10 days ago, I fell in love with my chickadees. I am now doing what I can to keep them coming to my feeder and to have a pair nest here come spring. (I don't think my bare backyard supports more than that).

I have neither House Sparrows nor House Wrens at the moment, but I am already becoming (overly?) protective having read all those bad things about those species on the net.

do re meep meep said:

...estimate the width and the height of chickadees that come to my window feeder. I have drawn a rectangular grid...with a grid spacing of 1 1/8" in the horizontal direction and 1 1/2" in the vertical direction...

Click to expand...

Obviously, camera shots with a calibrated overlay grid would allow for a more accurate estimate, but I believe that I have been able to corroborate to some degree, based on fleeting bird visits, the 1 1/8" x 1 1/2" size estimation .

Next experiment is to put a 1 1/8" x 1 1/2" mesh in front of the window feeder and see whether the chickadees can go through.

Is someone here aware of such a 1 1/8" x 1 1/2" or similarly sized mesh, perhaps for keeping house sparrows out of a feeder?

do re meep meep said:

Is someone here aware of such a 1 1/8" x 1 1/2" or similarly sized mesh, perhaps for keeping house sparrows out of a feeder?

Click to expand...

No response, and I could not find any such mesh either. The closest is wood lattice which however has diamond shaped holes. I would have to make my own wood lattice with 1 1/8" x 1 1/2" (upright) rectangular holes for making 'the next experiment', preferrably such a wood lattice with the same thickness as the front wall of a bird box.

Ouch, that can wait, there are other good things in life to attend to.

For now, I do think after several days worth of observations on my 'grid' that oval holes in bird boxes do a better job in species selection than circular holes, and that rectangular holes would do an equally good job as oval holes in that regard.

Proceed at your own risk.

I am conducting the following experiment to verify the 1 1/8" x 1 1/2" oval hole hypothesis. I made such an oval hole in a transparent plastic box that I filled with peanuts, the favourite food of my chickadees, and attached the feeder to my window with suction cups.

Thus, what the oval hole is supposed to do is to let my chickadees in and out of the box, and only them, and keep predators such as house sparrows and squirrels out of the box.