Nestbox (Dimensions)

Subj: Bluebird Nesting Houses
Date: 1/9/00 8:12:38 AM Central Standard Time
From: cvhall"at"usit.net (Claude V. Hall)
Good Morning,

To answer your question (as many others before me have done), yes. Your measurements are fine. With usiing cedar, you have chosen very wisely. The houses should last a long time.

I have here for you URLs for two web sites providing plans for bluebird nesting houses. Each proclaims "for North Dakota Wildlife," but that you may ignore! They will work just as well at Lancaster! Here goes:

http://www.npwrc.usgs.gov/resource/tools/ndblinds/peteblue.htm

and/or

http://www.npwrc.usgs.gov/resource/tools/ndblinds/treeswal.htm

Of those two, the first, for the Peterson Bluebird House, probably is preferred by the Eastern Bluebirds here in East Tennessee. It is also a bit more demanding to make. Who knows which might be preferred by central Pennsylvania bluebirds!

I do recommend that you use the 2 1/4" high by 1 3/8" wide oval shaped entry hole.

If you are interested, I have a suggestion for "predator-proofing" the entry holes which I will happily provide if you e-mail me at
mailto:cvhall"at"usit.net ...

Claude

At Dandridge, Tennessee in the foothills of The Great Smoky Mountains

From: "Gilliam, Jay" jay.gilliam"at"pioneer.com
Subject: Peterson boxes--2nd Attempt
Date: Mon, 22 Oct 2001 08:47:58 -0500

Any takers out there??

---------------

In the past I have used a 4"x4" floor in my rectangular (Iowa DNR) boxes and a 3"x3.5" floor in my Peterson's boxes because that is what the plans called for and it was easier with the nominal width boards I had available. I have been collecting wood all summer and have many more wider boards available so I have decided to make my boxes this year with bigger floors. I will be using a 5"x5" floor in my rectangular boxes. My question concerns the Peterson box. From my understanding, the interior dimensions of this box were designed for the nominal 2"x4" but that there was also an advantage of having a smaller floor. I've observed how cramped the babies are in these boxes, especially a large clutch of TRES. I am thinking of ripping down some 2"x6" boards to make Peterson boxes that have wider interior dimensions. I would appreciate any thoughts, comments, or advice on this before I start working on it. What would be the advantages and disadvantages of modifying the original plan to make it wider?? What would be a good width to use in these boxes?? Should I also make a modification to increase the length of the floor vs the 3" original plan??

Thanks in advance---

Jay Gilliam
Norwalk, IA

From: "Keith & Sandy Kridler" kridler"at"1starnet.com
Subject: Re: Peterson Boxes 2nd attempt
Date: Mon, 22 Oct 2001 22:27:26 -0500

Keith Kridler Mt. Pleasant, Texas

Well if you make ANY adjustments to ANY measurements then you do not have a "Peterson" nestbox as they are very specific about the design of this nestbox.

On the other hand if you would make the box 5&1/2" wide instead of 3&1/2" and say a 4" bottom length instead of the 3" then you would provide more room for larger broods. There is old research that shows that each young bluebird needs about 4 Square inches of floor space as they mature so that there is still room for the adults to adequately clean the nestbox. When Art Aylesworth and company started increasing the size of the floor of the nestboxes in Montana they were having an upswing in population and began to experience larger clutch sizes. I personally checked some of their boxes and saw 8 & 9 & 10 eggs and or young in nestboxes. They were using boxes with 6"x6" bottoms and Art & some of the others there were even trying some with 7"x7" bottoms. I think these were bigger than needed and some of the boxes were still about 5"x5" or 25 square inches.....Erv Davis might shed some light on whether they still prefer slightly larger nestbox floor space.

Bluebirds tend to nest in MANY different styles and sizes of nestboxes, mailboxes, paper tubes, and gourds so trying different sizes in nesting boxes is a fun way to use up scrap wood and do your very own backyard experiments. You can't call these larger boxes "Peterson" boxes and there have been others that have increased the size to 5&1/2" wide in years past and I forget what they called them but they had good success attracting bluebirds and other cavity nesters to these larger nestboxes. KK

From: DottyRogers"at"netscape.net
Date: Tue, 23 Oct 2001 12:28:57 -0400
Subject: Clutch size/box size

Hi gang,

A question for KK:

We had a cold wet spring and our blues produced more 3 and 4-egg clutches in their first brood than usual, then more 5 and 6-eggs clutches for their second or third clutches than expected.

Do you know if the bluebirds that had larger broods in larger floor-plan boxes had correspondingly smaller second broods?

--I'm perhaps stupidly assuming that each female has a potential limit for the number of viable eggs laid per season, depending on age, nutrition and condition. Been kinda wondering about this since the unexpected flip of this year's first/second clutches -- which made elegant sense under the circumstances. ...

Dot, Acton Bloobie Gang

From: "Keith & Sandy Kridler" kridler"at"1starnet.com
Subject: Re:Clutch size/box size
Date: Wed, 24 Oct 2001 09:25:23 -0500

Keith Kridler Mt. Pleasant, Texas

This subject is coming up in regards to Jay G. tossing out the idea of building a larger floor size nestbox for broods of birds he perceives to be getting too crowded before they fledge. I mentioned the larger Mountain bluebird broods and the larger boxes sometimes used in Montana. Trail monitors began using larger floor area boxes when they saw larger broods. Larger boxes does not automatically translate to larger clutch size!

I checked a wood duck box at the property I was working on yesterday and found an old bluebird nest from this past summer that completely filled the bottom of the duck box with over 100 square inches of floor space. I doubt if more than 5 birds fledged from this box. We have bluebirds laying eggs from mid to late February and will normally still be fledging young in Sept. in Texas as we have a 200+ days of frost free growing season in this area.

In Montana where Art Aylesworth was having his trail he had recorded measurable snowfall in every month of the year over about a 20 year period. (Not every month every year but snow in July or August did happen!) So the birds probably evolved to where they would lay larger clutches as in some years only one clutch might hit a "frost free" month and they do not have the luxury of nesting and successfully fledging four times as is fairly common even in the northeast corner of Texas. (These are verified by trapping both adults EACH nesting attempt!)

Diet, evolution/adaptation, health and age of the female and current weather conditions will have a huge impact on the number of eggs laid. If you have a female that is stuffing herself on insects in the spring and is starting to form a string of egg yolks in her body and then a single digit freeze sweeps through the area and not even berries can be found for 5 or 6 days then she will re-absorb those pearls of protein for her own survival. If she is already laying eggs then very often the female will "dump" the egg away from the box. She may continue laying in the nest only will not incubate this clutch and will wait several weeks and then re-nest and lay another clutch of eggs when conditions are more favorable to feeding herself and her young.

The above is very common knowledge in both the dairy and egg production industry. Cut off water, food or both and milk production and egg production will cease in just a couple of days even though the adults can survive for up to a week without water and about 2 weeks without food. Increase the amount of vitamins and essential minerals in the diet and egg and milk production increases.

Yes I know 7 eastern bluebirds can fledge from a 4" PVC pipe nestbox but nobody can ask them if they are comfortable! (I have used PVC boxes since the mid 1970's.) I have watched a soccer mom put her whole team in a subcompact car to go get ice cream across town. They would still be able to travel across the country but would they be comfortable? What if they had to spend two weeks touring Arizona in the heat of summer without ever leaving the car day or night? Without air-conditioning? With only one window that could roll down half way? What about each day the youngsters had to add another article of clothing until on the last day they were wearing a full set of winter clothes equal to the birds full feather coat!!!! Remember adult bluebirds cannot carry water to their young in the nestbox! It's no wonder young bluebirds can fly so far on their first flight!!!!

Since this is already too long it might be nice to debate advantages of different floor areas, box thicknesses, and ventilation ETC. for the upcoming nestbox building season! KK

Date: Wed, 24 Oct 2001 11:58:33 -0400
From: Tina Phillips cbp6"at"cornell.edu
Subject: Re:Clutch size/box size

Tina Phillips
Ithaca, NY

As some of you may know one of the major questions that TBN continues to investigate is clutch size variation. We know certain factors can effect clutch size such as age of the female, temperature and time of season, health of the female, food availability, high population density, and geographic location. In 2000, we used TBN participant data to calculate what factors such as latitude, longitude, egg-laying date, nest box volume, and year in which the clutch was laid had significant effects on Eastern Bluebird clutch size.

Nestbox-volume showed no effect on clutch size variation, and it has been suggested that larger boxes may actually increase the amount of energy needed to fill the nest box and nest cup. The two most significant factors were latitude and initial lay date. With multi-brooded birds such as bluebirds, latitudinal variation of clutch size is highly dependent on lay date.

In the southern part of the range, the early clutches are relatively small, clutch sizes reach a peak in the middle of the season, and clutches laid late in the season are small again. In the northern part of their range, however, clutch sizes decrease gradually with the laying date. The earliest clutches are, on average, the largest, and as the season progresses, females lay smaller and smaller clutches.

Based on the above findings, I would ask Dot what her latitude is. If she lives in the south, the model described above makes sense. If she lives in the north, there are probably other factors that would explain this phenomenon. My guess would be temperature and available food resources played the most significant role.

If anyone is interested in reading the full story about the clutch size analysis, visit the archived Birdscope article at: http://birds.cornell.edu/publications/birdscope/Spring2000/tbn_clutch_2000142.html

There is a similar article which also compares TBN data for TRES and EABL clutch size variation: http://birds.cornell.edu/birdhouse/news/geovariation.html

Andre Dhondt's work on this subject using TBN data has just been accepted for publication in the scientific journal Ibis. It is currently in press and will be out some time next year. The article is called "Geographic differences in seasonal clutch size variation in multi-brooded bird species."

Hope this helps answer your question,

Tina Phillips
 

From: "Gary Springer" springer"at"alltel.net
Subject: Existing or Living
Date: Tue, 30 Oct 2001 10:09:48 -0500

Gary Springer, North East Georgia

I've always been very disturbed that birders, even well known ornithologists, draw conclusions about nest box quality based on survival rates of the chicks. I.e.: No dead birds means good nest box.

Not only does survival in the nest box NOT mean strong and healthy, but also, life is more than survival.

Many young birds are lost shortly after fledge. Birds raised in a nest box that over heats to within a couple degrees of death during the day and cools down rapidly when night falls could not possibly be as healthy as birds raised in a nest box that gets no warmer than the outside temperature on hot sunny days and provides lots of insulation to keep them warmer at night.

After the young birds climb out of the nest box leaving it free of dead birds, the challenge of reaching maturity has only begun. A high percentage of birds are lost to predation shortly after fledge. The more healthy and strong the newly fledged bird, the better chance it will have of avoiding capture by a predator.

Further, it seems ornithologists and scientists equate survival with life.

If you are putting up nest boxes without ventilation slots that provide more than 4 square inches of ventilation while, at the same time, air conditioning your home by using electricity that is generated by burning coal, your concern for your own personal comfort exceeds your understanding or sensitivity to the threats of wild animals and the environment that supports life on the planet.

If you think these comments do not apply to you because you live in the more northern states, I would appreciate your comments about "A course in bird houses" on my web page at http://www.realbirdhomes.com/Bird%20House%20Course%20Page%20One.htm

Gary Springer,

Old Growth Forests http://www.realbirdhomes.com/OldGrowthForestspg1.htm
Real Bird Homes www.realbirdhomes.com 

Date: Wed, 17 Jul 2002 10:37:36 -0400
From: Haleya Priest mablue"at"gis.net
Subject: bigger boxes

Haleya Priest Amherst MA

KK, your thoughts and all others on bigger boxes makes so much sense, but I cringed this morning in experimenting and encouraging building bigger boxes. With such a HUGE loss of nestlings in the northern climes this year and the possibility of this becoming more of a norm because of global warming, I personally am cautious about building bigger boxes that would mean even more space to heat up for these little nestlings.

I've thought much on how to build bigger boxes and the only thing I can come up with it to set it up in the spring to have inserts or something to make the boxes smaller on the inside until the weather really warms up. Maybe someone can help brainstorm with this because like KK any excuse to make more boxes is the way to go!!!!! :-) H

Keith Kridler Mt. Pleasant, Texas
Interesting posts this past week! Mucky nests/larger nestboxes: It is always fun to try different designs and historically photo's from the 1920's show nestboxes that were HUGE compared to today's bluebird boxes. One of my old books complained that Robins were taking over all of the bluebird nestboxes and were a serious competitor. Sounds like the entrance holes were too big to me!

Historically entrance holes were not drilled round but most were cut square from one of the upper corners of the box since a brace and bit was a real pain to drill a hole with in a relatively thin board! While cutting the board you simply cut a square corner off large enough for the birds to enter. This would create a nestbox with an off set entrance hole. When drills and better drill bits became more common then we also began centering the door in the front panel. The earliest mention of a "Starling Proof" entrance hole for bluebirds comes from a 1929 publication date which states, "A bluebird entrance hole should be no larger than a precisely cut 1&1/2" square hole to prevent the Starling from using the bluebird nestbox."

OK we had some debate this past spring that building deeper/larger nestboxes would only create more work for bluebirds as they wanted to build their nest to where they could look out of the entrance hole. I
decided to experiment some and went back to the "historic" style of drilling a hole in an upper corner right near a side. I have used some 5"x8" wide bottoms and now have another 15 boxes with 4&1/4"x8" bottoms. This allows the bluebirds the chance to build either in a "back" corner or build the nest right up to the entrance hole to look out!

In limited tests NONE of the bluebirds built their nests up high enough to be able to "look out" of the box and over half built AWAY from the entrance in a back corner of the box. Nesting material in the larger
nestboxes has just about matched the AMOUNT of material in my standard 4&3/4" square bottom nestboxes. Even with the deeper boxes 8" deep compared to 6&3/4" deep MOST of the eggs are within 1" of the bottom board. So you have this really wide looking nestbox with a hole in an upper corner of the wide front and it gives the bluebirds a chance to build their nest where ever they want and the young have a chance to really spread out, which they have done to flatten the entire nest area as in a normal "small" floored nestbox.

We will never know if this is actually better for the health of the young but it is an excuse to build more nestboxes. When building nestboxes with limited tools pick out a simple design that contains all square cuts and wastes the least amount of wood! In my case I use scrap wood and cannot use all I receive.

When using Joe Huber's wonderful sparrow trap the top of the entrance hole needs to be down about 1&1/8" from the roof of the box but with Floyd Van Ert's trap you can use slot openings right to the roof and still trap sparrows or you can now drill a round entrance hole very near the roof simulating a real woodpecker made cavity closer and still be able to trap out sparrows. Build and use several styles of nestboxes and try to encourage more species using your boxes next season! KK

Haleya Priest mablue"at"gis.net

From: "Keith & Sandy Kridler" kridler"at"1starnet.com
Subject: Re:bigger boxes
Date: Wed, 17 Jul 2002 10:55:06 -0500

Keith Kridler Mt. Pleasant, Texas
Hot and cold in these "bigger" boxes: I think the Cornell Data Logger results will show that no matter how large or deep the box or how little ventilation in a box that when the adult bird leaves the nest the eggs will rapidly lose retained heat in relation to the outside air temperature IF the boxes are all out of the sun's heating rays. We have to remember that these boxes have a huge door always open in relation to the size of the cavity.

A nest should offer a little insulation and the nestcup is basically the same depth in a large nestbox as with a small nestbox. A deeper nestbox "might" lower the eggs/young down away from cooling breezes coming in an entrance hole. I feel pretty certain that with very sensitive temperature measuring devices you would be able to detect very little difference in the "attic" of a nestbox with the female in the box or out of the box. They are having trouble with some of the data loggers placed right in the nestcup almost touching the eggs showing any temperature change so I would think with heat rising in a cold box what little the female puts out will rapidly leave or dissipate in the nestbox.

These birds just don't lose very much heat through their feathers when they fluff up. It would be like one of us putting on ski clothes and entering a freezer and expecting our body heat to thaw out food 1 or 2 feet away. If we place 50 lbs. of warm meat against our bare skin we might be able to keep it warm as the female bluebirds place their bare bellies against eggs or young birds. If it was cold or frozen meat I doubt if we could warm it up. It will be interesting to see the data
collected at night in these boxes to see if on a cold night the box is warmer with the female on the nest or if there is any difference when there are 5 young birds about to fledge in a box. We have already collected the data in these boxes and this will be one of the answers I expect to see results from in their testing.

With the "bigger" boxes with 4&1/4" X 8" floor the nest is normally placed right in a corner and the nestcup is very close to three sides of the nestbox. In 12"x12" bottom nestboxes once again the bluebirds normally build a standard sized nestcup in a corner of the big box (wood duck or owl boxes or mail boxes). It will be interesting to see if those with wood duck boxes in the north this year had as high of losses of bluebirds which built in these types of nestboxes over the "standard" bluebird boxes!

This "heating of the nestbox" by the adult birds should be answered this fall when all of the data is compiled from the 25 participants as many are recording data in different styles of nestboxes! I just sent in another 4 nestcup data loggers from my boxes yesterday! It is WONDERFUL to be able to exchange ideas and thoughts on these topics practically instantaneously!!!! Special thanks to The North American Bluebird Society and Cornell for providing this forum!!! Keith Kridler