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Nestboxes (Depth)Related posts may also be found under Nestboxes - Floor Size. In addition to Messages that have appeared in the Bluebird Mailing Lists on this topic, the following are on the Audubon Society of Omaha website: From: Keith & Sandy Kridler [kridler"at"1starnet.com] Keith Kridler Mt. Pleasant, Texas I am on Linda's side preaching for the deeper boxes. In the 1979 Sialia issue 1 volume 1 they show a version of my PVC nestboxes that they altered from my original PVC boxes, these NABS PVC nestboxes were sold for years & made from 1/4" thick walled PVC pipe and had a minimum 10" distance from top of floor to entrance hole AND they also installed a wood block of 2"x4" material for a "predator" guard to protect the nestbox contents. At this time NABS was very much into deeper boxes, thicker box fronts and only using the 1&1/2" round entrance hole. In recent years we are seeing more and more smaller, shallower nestboxes approved and larger entrance holes KNOWN to admit starlings also being approved. IF starlings can enter a nestbox then all other predators will be able to reach further into the nestbox as larger holes increase the amount of body parts and also increase the angle the arm, leg or neck can stretch into the box. These nestbox changes are based on what research shows the birds prefer and not necessarily what is actually happening to the birds in all predator situations! In The Bluebird Monitor's Guide we do cover the problems of starlings,
magpies, jays, grackles ETC. raiding nestboxes and if you build the Gary
Springer Chalet with the full wood block added as is drawn, (or add this same
wood block to the other boxes) Starlings will not be able to reach into the box
and down to a nest of eggs. IF birds raiding nests are a problem then I believe
we also mention that larger and deeper boxes are to be used. We do mention that
IF starlings or other birds become a problem then you should add the extra "wood
block" these really are not predator guards but Right now there is a TREMENDOUS gap between what Purple Martin landlords are doing at preventing starlings and their "predation" and what the majority of bluebird trail managers are doing. I believe starlings are predators, plain and simple and if the Purple Martin movement succeeds in adding the SREH (starling resistant entrance hole) to all purple martin houses then millions of starlings will be forced to search out other nest sites taking them from native cavity nesters or invading buildings to nest! We used basic plans in the BMG and if you carefully read the tips, hints and suggestions then you will be able to adapt nearly ANY nestbox in your community and make it safe for the birds. I know this box depth issue is very important and will probably trend back to deeper & larger boxes over the next 10 years and I am glad Linda brought up this topic! We CANNOT allow adult birds be stripped or driven from nestboxes as these are just the 30-40% of the birds that survived the winter and the species depends on them! Send me an e-mail if you wish a personalized copy of The Bluebird Monitor's Guide. KK From: Linda Violett [lviolett"at"earthlink.net] Quick note before dashing to work . . . I, also, have heard the folk tale about birds building deeper nests in deeper boxes to end up with the same "reach" space. But please look at the nest photos on my web page at: http://home.earthlink.net/~lviolett/NestPics.html. Most were taken during 2000 in 7.5" hole-to-floor boxes. Last season (2001) most boxes were already switched to 8.5" hole-to-floor boxes. Nests were built the same in 8.5" drops--a few deep, but most were just the average 2"-3" nests with the deep cup. 2001 finished nests can be viewed at: http://home.earthlink.net/~lviolett/newbegin.html Can you see any difference between the two years? Or between what you see between these photos and on your own trail? Occasionally, females build a deep nest (I think they could be new to the
trail). Others will practically build their nests on the floor--even in boxes
with 8.5" drops--could be that some females might have "lost" chicks or eggs in
previous years in shallow boxes. Michael Wheatley wrote: The TBBH floor-to-hole is about 14" but is horizontal. The nest requires minimal material, is built quickly and easily, and no predator reach is sufficient to access the nest, short of a snake, which crawls fully into the box. From: Ann E S Wick [jwick"at"mail.tds.net] Linda and BLUEBIRDL readers: Please be careful when you use terms like "folk tale" regarding the building of high nests in deep boxes. Every Eastern Bluebird pair that has used a deeper box on my trails has built a deep nest, so this is NOT a "folk tale" on my trails here in Southern Wisconsin. (I know for a fact that some of these females are experienced nest builders because they are banded I have recaptured them in consecutive years.) In the case of nests built practically on the floor, I have found (via banding) that these are often females who experienced a nest disruption, were ready to lay eggs, and needed to construct a nest quickly. "Never say never" is my best advice to bluebirders everywhere. Just when you think you can make sweeping statements, an exception seems "pop up." I use what works best for me on my trails. Others will eventually find out what works best for them on theirs! Ann Wick Quick note before dashing to work. . . I, also, have heard the folk ... From: Linda Violett [lviolett"at"earthlink.net] Very interesting, Ann. Could you give us an idea of how many times this occurred on your trail along with any other details you might recall? I believe your trail is comprised mainly of Peterson boxes? It is important for each of us to share what we personally observe on our trails and I can say, without hesitation, that boxes with 6.5 inch hole-to-floor drops are not sufficient to protect nestlings on my trail. And, it seems others are beginning to experience similar avian problems with shallow boxes on their trails as well. The nest photos you see on my web pages are taken early in the season when I and the female bluebirds have plenty of extra time waiting for egg-laying. The vast majority of the nests in these deep boxes are built by year-round resident bluebirds, are built at a leisurely pace and are finished at normal height. A fine example of this can be seen on the "Claimstraw" series taken during 2001: http://home.earthlink.net/~lviolett/Photos/claimstraw/ You can see the prolonged nestbuilding sequence--some females taking their
sweet time over a period of weeks to begin laying out the nest ring and finish
up. The "Shappel" series is almost comical. After the claimstraws were laid
down, the female(?) bided her time between 2/24 to I carefully watch these little habits for behavioral clues and it is a wonder
of today's technology to be able to share it on line with other bluebirders.
Ann, is there any chance you can share a photo series of your high nests in deep
boxes? It would be an interesting comparison. Ann E S Wick wrote: ... From: Linda Violett [lviolett"at"earthlink.net] The link to the claimstraw page is: http://home.earthlink.net/~lviolett/claimstraws.html Linda Violett From: The Doctor [sytyf"at"yahoo.com] Hello fellow birders, There has been several posts concerning the depth of the nestbox (ie. bottom of the entrance hole to the floor). I have tried many different house designs trying to get the nestlings at least 2 inches below the bottom of the hole. I have tried dozens of nestbox configurations resulting in a wide variety of inside volumes of the nestbox. I thought that if I made the inside volume of the nestbox bigger, the nest 'size' being a constant would result in the nestlings sitting further below the hole: WRONG !!!!!! My conclusion is as follows: Regardless of the inside volume or depth of the nestbox, the female bluebird built a 'deep bowl' nest in which the nest sidewalls were no more than 5/8 of an inch below the bottom of entrance hole. I have incorporated a false floor into my nestbox design, basically a 2 X 4 block fit in the bottom of the nestbox. When the block is removed, the nest and nestlings have been lowered 1 1/2". This 'height adjustment' has never concerned the Bluebird parents and I don't make the 'height adjustment' unless I feel that it is absolutely necessary. My nestbox design opens from the front. At a depth of 2 1/8" below the entrance hole, 25 square inches is provided for the nestlings. I read some where that 4 square inches per nestling (usually 4-6 nestlings in a typical EABL brood) was required for adequate nest cleanliness and maintenence. The 4 square inches per nestling also provided enough room for the nestlings to compete for food, grow and stretch their wings. At 5/8 of an inch below the entrance hole, there are about 32 square inches of area. It seems that experienced Bluebird moms actually will build the nest in a corner of the nestbox which is 7-9" from the entrance hole. The extended area gives ample room for the nestlings to hide from predators that can't reach into or physically enter the nestbox. Coupled with a minimum 6" roof overhang, an extremely sloped roof (plexiglass covered) and a good raccoon guard, well I think that I am almost finished with my nestbox/predator guard design. I've been told that I over analyze/engineer everything. NOTE: if you feel that you need to go further below the entrance hole than 2 1/8", make the false floor thicker. JUST REMEMBER to leave ample room for the nestlings at the "new nest level". This is working well for me and I hope that you get good results too. Bob Sitarski a.k.a. The Doctor Jackson County Indiana & Clay County Illinois From: Linda Violett [lviolett"at"earthlink.net] A good test for this season would be to have everyone take a measurement of the nestcup-to-floor distance of the nest compared with the hole-to-floor distance of the box. This is easily done by inserting a thin wire into a newly-finished nestcup until the wire hits the nestbox floor (without pressing down on the nestcup). This measurement would be done at the deepest point of the nestcup. The "sidewalls" (rim?) is not a point of reference. Nestlings will be gathered in the nestcup, not the rim. The Doctor wrote: ... From: "Gary Springer" springer"at"alltel.net Regarding deeper nest boxes and the distance from the nest box hole down to
the bottom of the nest cup upon which the eggs and chicks rest, my On my trails, more than 50 percent of the time the Eastern Bluebird builds the nest high enough so she can look out the hole while sitting on the nest. I have also experimented with false bottoms in nest boxes as Bob Sitarski has mentioned. The reason I used the removable platform in the bottom of the box is that I suspected the birds might prefer a shallower box since the female could build her nest up to the hole with much less effort. But, it became clear that the birds here preferred the full 7" deep box without the platforms so I abandoned the idea. Apparently the bird enjoys nest building. However, it has never been a concern to me that the Eastern Bluebird builds a tall nest that puts the eggs very close to the entrance hole because, when incubation begins, I simply remove as much nest material from the bottom of the nest as is necessary to lower the eggs to about one inch off the floor. I hate to ruin the incubating female Bluebird's view, but, because increasing the distance between the outside world and the eggs and chicks seems to make them safer from predation from Jays, Starlings and other avian predators, a good view isn't an option on my nest box trail. Gary Springer (The 7" noted above is the distance from the center of the hole to the nest box floor) PS I believe a deeper and slightly larger box with a hole of inch and three quarters should be offered in addition to bluebird sized nest boxes to accommodate larger cavity nesting birds. The larger hole in this larger nest box would be reduced to accommodate whichever species occupied the box. From: Linda Violett [lviolett"at"earthlink.net] Linda Violett - Yorba Linda, Calif. Thank you for mentioning that the nest material volume that you are seeing
built by bluebirds in the deeper boxes is standard. As you know, a standing
argument against using deeper boxes has been that bluebirds will build their
nests up to the hole anyway, so why build deeper boxes and have bluebird do all
the extra nest work to build the nest up to the hole. (And, it could very well
be that bluebirds in boxes with large oval holes will build high nests in order
for a quick exit.) This was debated on Bluebird-L not too long ago. Thanks to
Jim McLochlin's archives, those posts can be reviewed at: As far as floor space, the trend in our area seems to be toward larger boxes because of the poor conditions caused by using the smaller boxes. Our area coordinator, Dick Purvis, plans on switching to larger boxes and is now recommending a 25 sq. inch minimum. Historically, he has used boxes with approx. 4x4 floors. I do not believe Dick is changing to larger boxes because of house sparrow problems. But it is interesting to note that Dick has had more than the normal amount of house sparrow problems this year using the smaller boxes, while my established trail continues to be sparrow free. And, again, thanks to Jim McLochlin for documenting these discussions. As stated before, I do not know why my established trail continues to be free of house sparrows but in a few years we may be close to an answer and the detailed logs of all single-box test sites will updated through next year. As Keith states, it is " . . . hard to think without some form of intervention we will ever keep them sparrows out of the boxes totally passively . . . " and if I had not seen it happen on my own trail, I would have lost faith at the sparrow-laden test sites this year. The value of this year's online notes will depend on whether the reader sees the glass as half empty or half full. In other words, take a look at Vaqueros. All three sites had house sparrow
problems last year using small 1-holed boxes. This year, two out of three sites
(converted to large 2-holed boxes) have nesting bluebirds with NO house sparrow
problems. Please note that those two boxes became house sparrow free without
*any* intervention on my part. Same thing at the golf course this year . . .
completely passive at FOUR of five sites; except for the "Restroom" site, all
others had/have bluebirds nesting with no sign of house sparrows . . .
completely passive. Why? I don't know. There will be someone who will be able to
read these archives, look at the logs and come up with some answers. Keith & Sandy Kridler wrote: I like the larger floor area boxes I am using due to the fact the ... From: owner-BLUEBIRD-L"at"cornell.edu on behalf of Keith & Sandy Kridler Keith Kridler Mt. Pleasant, Texas 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 Date: Thu, 25 Jul 2002 17:29:24 -0400
Date: Mon, 23 Sep 2002 22:05:12 -0700 Linda Violett - Yorba Linda, Calif. Thanks for the report. On the sad instance where you suspect crows took the nestlings, can you share with us the type of box, the inside "drop" dimension from the bottom of the hole to the top of the floor and the type of guard used? In the past, my trail had chicks lost to competitors/predators until deeper
boxes were provided. But even 7.5" drops didn't keep nestlings safe from the
following: Finally, the above problems ceased when the hole-to-floor drop was increased
to about 8.5" and full circle face guards were added. I'd take a guess your
hole/floor drop is around the standard 6.5 inches. KimMarie Markel wrote: Date: Tue, 24 Sep 2002 03:15:32 -0700 (PDT) Linda, Dan Sparks ... Date: Tue, 24 Sep 2002 03:40:49 -0700 (PDT) Tom, Dan Sparks ^ ... From: DottyRogers"at"netscape.net Hi gang; We had some very deep (would have to measure) screen-tops that we reroofed and found that blues simply built their nests higher to compensate for the depth. Has anyone else had this experience? Dot; eastern MAss From: "BONNIE A. YEAGER" dement"at"frognet.net Hi Dottie, Fred Yeager, -- Original Message ----- Hi gang; ... Date: Tue, 24 Sep 2002 13:22:49 -0700 Linda Violett - Yorba Linda, Calif. Dan, the roof overhang measurement varies on my trail; and it isn't much of a factor because my trail consists of hanging boxes which are out of reach of most ground-based predators. Now, if I were using post-mounted boxes (like most folks) and had to worry about ground-based predators in *addition* to avian competitors/predators, the boxes would be built even deeper than the 8.5" hole-to-floor drop--or I'd be using something similar to the Y-Box Fred Yeager is designing (scroll to last picture at: http://home.earthlink.net/~lviolett/ When you consider most bluebird boxes only have a drop of 6.5" (which leaves
only a few inches of air space above the nest/chicks), it seems a small miracle
of nature to have birds fledge at all. Equally amazing is that modern bluebird
box plans continue to show approx. 6.5" hole to floor drop specifications as the
recommended standard. Daniel Sparks wrote: ... Date: Tue, 24 Sep 2002 13:54:47 -0700 Linda Violett - Yorba Linda, Calif. Dotty and All, I can only attest to the accuracy of what I see on my own trail and on my trail, bluebirds tend to build normal nests in deep boxes. See photos of the average nests in my boxes at: http://home.earthlink.net/~lviolett/claimstraws.html When looking at the photos, it is easy to visualize the actual size of the finished nests pictured on this "Claimstraw" page because the box floors are about 6" wide and I put squiggly "ladders" all over the interior. Therefore, anyone can view the bare box floors without the nests, get an approximate measurement based on the height of the squiggly "ladders" to see the relative height of the finished nests plus the approximate depth of the eggs/nestcup in relation to the box floor. These photos were taken to document the straws I see placed in my boxes prior to nestbuilding (claimstraws) and they are typical, average nests on my trail of deep boxes. Please read the past discussions on box depth vs. nest height which have been
archived by Jim McLochlin (Best of Bluebird-L) at:
http://audubon-omaha.org/bbbox/bestofbbml/boxesdepth.htm See July 2002
posts where Keith Kridler has experimented with wide/deep boxes this year and
reports average nest material in his boxes. And Fawzi Emad has experimented with
wide/deep boxes this year and reports average nest material in his boxes. DottyRogers"at"netscape.net wrote: ... From: "BONNIE A. YEAGER" dement"at"frognet.net Hi Dottie, Fred Yeager, ... From: "Keith & Sandy Kridler" kridler"at"1starnet.com Keith Kridler Mt. Pleasant, Texas I believe one of the very first really deep nestboxes that became popular in an area was the Bauldry nestbox with a hole to floor measurement of 11&1/8". It was designed deep because of the tremendous losses due to raccoons that were learning to raid wood post mounted nestboxes in the Midwestern states. Over time bluebirds that used these very deep boxes and built very shallow nests remained out of the reach of the raccoons. Those birds that continued to build very high nests or continued to use shallow nestboxes were eaten. Over a 5-10 year period more deep nestbox styles were added and bluebirds adapted, evolved, learned that to survive they needed to build a shallow nest. Soon the raccoons perfected ways to raid these deep nestboxes even with front entrance boards that were 2&1/4" thick. A shift to deeper entrance hole guards and pole mounted guards made use of very deep nestboxes to stop cats and raccoons obsolete. We are seeing a whole host of flying predators that are learning to raid nestboxes all across the country. In many areas cavity nesters (nestboxes) are the easiest bird nest to locate for a reliable food source! Some counties have hundreds of the same style nestbox and mounting pole used with tens of thousands of identical boxes across a single state! If a predator learns how to reach the contents in one they can do so across an entire state! If a hawk can see a mouse hundreds of yards away surely they can learn to see bluebirds, swallows ETC. peeking out of a nestbox and learn to reach in or attack the tiny blue "bomber" on it's maiden flight just like the fighter pilots of World War II did to both sides! I believe in Linda's case the number of starlings and losses to hawks has the birds in her area learning to search for cavities that are deeper and can protect them better. Most of the woodpecker cavities (bluebird sized) I have collected from tree trimmers in my area are around 16" deep which would offer some protection to these builders from most predators. Most of these early deep nestboxes had either 4"X4" or 4"x5&1/2" floors with the entrance centered in the 4" width. These are really too small for most birds to fully extend their wings and be able to fly from the floor to the entrance hole. So the different species will either have to "hop, jump or climb" to exit the nestbox. IF you build wider nestboxes where the birds can open their wings and "flap" to assist them to the exit hole they might be less inclined to build the nest up to where a simple hop with get them to the exit. I experimented this past summer with boxes between 4"X8"5&1/2"x8" floors and found that putting the entrance on the wide side where they could "fly" to the entrance actually had the birds building VERY shallow nests, often with their eggs only 1/2" off of the floor board. Some people say the birds wish to build up high enough to be able to "look out" of the entrance hole so on half of these boxes I drilled the entrance hole "offset" and NOT centered in the wide front board. Only one pair of bluebirds actually built their nest directly under the hole with most building either in the far back corner or centering the nest in the middle of the bottom board. It would be nice to video tape the different species and observe them inside the nestbox and see exactly how high they can jump to reach an exit or how much they use their wings in various sized nestboxes. How much does the slickness of the inside of the entrance board affect their exits? Individual birds experiences will also dictate their choice of nest height. Only by experimenting with various nestbox sizes will each of us find out some of these answers on our unique trails! Remember that these birds are ALL individuals and may look for a different style each nesting! We could ALL easily adapt to either eating at home or ONLY having McDonalds restaurants to go out and eat at....Vary your birds "diet" of nestboxes this coming year and watch how they react over the next 310 years. KK Date: Wed, 25 Sep 2002 15:21:07 -0700 Linda Violett - Yorba Linda, Calif. Keith, there are many interesting avenues to travel in the box depth discussions, but let's focus on the tree swallow segment for a moment because tree swallows are frequently mentioned when discussing nestbox depths for bluebirds. It seems very odd that trail monitors would put bluebirds at risk in shallow boxes just in case tree swallows would be at risk in deeper boxes. But the question still needs to be asked: Do deeper boxes actually put tree swallows at risk? Two years ago in a post to Bluebird-L (7/2/00), you wrote: "I heard that they are scrapping the Hill Lake deep box because Tree Swallows "Prefer" this over Peterson and other shallow nest boxes. It seems those using only Hill lake boxes are mostly raising Tree Swallows." [End of 7/00 excerpt by KK] Since the Hill Lake box has about 11" drop from the hole to the floor, deep boxes would not seem to put tree swallows at risk. And, if tree swallows successfully nest in the really deep Hill Lake boxes with 11" drops, a less drastic drop of around 8" would, theoretically, be an improvement (for both swallows and bluebirds) over the current 6.5" standard drops. Please clarify. Keith & Sandy Kridler wrote: ... From: "Keith & Sandy Kridler" kridler"at"1starnet.com Keith Kridler Mt. Pleasant, Texas We found two young doves in a nest still this past weekend, 23 days into dove season! The only places the Tree Swallows are nesting in Texas is in natural cavities that are located over water. They are choosing areas of drowned timber. Texas will add another 1&1/2 million acre feet capacity of new reservoirs in the next 20 years so the population of tree swallows will rise. The swallow species dominate nestboxes across the northern range of all three species of the bluebirds. Those of us in the southern half of the country will only rarely have a nesting swallow in a bluebird box. Since I don't have access to the swallows on my trails I have to rely on what I read from other trail operators and pick up in other newsletters. A lot of this information contradicts what is being published in the next door state! Dick Tuttle of Ohio is probably the foremost expert on Tree Swallows as he has scientifically evaluated nearly every aspect of their nesting behavior and their competition with the Eastern Bluebird. I personally believe if a swallow is too weak to climb out of a nestbox that is 8" deep and has the front board correctly roughened up to create a ladder for the swallows that then these birds are probably going to be too weak to stay airborne and maneuver enough to feed themselves. Normally when you hear of hundreds of tree swallows dying in (deep) nestboxes you also have hundreds of Purple Martins dying in their houses that are only 1" deep. When it is too cold for insects to fly the birds that rely on only this food source will also die. I really don't know what is the perfect depth for swallows but I have found that my nestboxes have slowly gotten deeper and with thicker fronts that have improved fledge numbers for me. Long term data collection should be providing the needed information! It doesn't matter what type nestboxes birds prefer IF we are losing a higher percentage from shallow nestboxes. I would really like for Dean Sheldon and some of the other northern swallow/bluebird landlords to chime in on this debate! KK From: "Fawzi P. Emad femad <at> fpemad <dot> com Hi KK and all. In the park (Rachel Carson Conservation Park) I have seven sites of paired boxes (the paired boxes are 22' apart.) There is a creek running through the park, hence it is attractive for swallows (TRES.) The boxes are on a cleared grass area, hence attractive for Bluebirds (EABL.) For the past four seasons, I am having the *same* number of TRES and EABL fledging from these 14 boxes. The boxes are all homemade, a couple are Peterson, the rest are various sizes of boxes, mostly similar to the NABS box. They are all not very deep (5" to 6" from floor to bottom of entrance hole.) None has a predator guard of any kind. All (except Peterson) have deep saw cuts inside the front under the entrance so all babies and weaker birds can easily climb up and out. I have not had any predation, and only one casualty of unknown reasons. The poles used are 3/4" EMT conduit, and the boxes are approximately 5' above ground. It may be luck, or may be soon predators will learn how to find and eat the babies, but so far we have been lucky. Also perhaps the park is so rich with life that predators don't bother to climb up a pole to get a meal, they may have plenty to eat on the ground. So many factors, so many locations, it is hard to make any rules. Just four miles from the park, here at home, all my boxes have predator guards. We have neighbors' cats...! Fawzi Fawzi Emad in Laytonsville, Maryland ----- Original Message ----- ---snip--- Date: Thu, 26 Sep 2002 19:07:00 -0700 Linda Violett - Yorba Linda, Calif. Thank you, Keith. Box depth is important because a lot of "missing chick" mysteries may be due to unidentified avian problems. It is difficult to pinpoint any problems to jays, crows, starlings or hawks since there are no telltale footprints, etc. left behind. But, because multiple avian problems (jays, crows, starlings and hawks) showed up on my suburban bluebird trail, logic tells me it is happening on other trails in some form. Progressively deeper boxes were built for this suburban trail and 8.5" hole-to-floor drops finally protected western bluebirds from jays, starlings, hawks and crows (my boxes are also 6" wide and have full circle guards). Most bluebirds make full use of the extra box depth and there doesn't seem to be any drawbacks to bluebirds using these deep/wide boxes. Therefore, monitors who suspect any avian predation or had unexplained
missing eggs/chicks last season should put deeper/wider boxes at those problem
sites and track the difference. Then watch to see if the unexplained missing
eggs/chicks problem start showing up in the NEXT available shallow boxes. If
that happens, you have found an effective safeguard. Keith & Sandy Kridler wrote: ... From: "Bruce Burdett" blueburd"at"tds.net Linda, et al, I have never used the standard 3/4" lumber. I find it makes too flimsy a box for my taste. It warps too readily, it's inclined to split, and it doesn't provide much insulation. I guess I must simply be blessed up here, since I have very little predator or House Sparrow interference. Bruce Burdett, SW NH From: "Bruce Burdett" blueburd"at"tds.net Keith, et al, Date: Fri, 27 Sep 2002 18:38:30 -0400 Haleya Priest Amherst MA From: Larry A Broadbent [mailto:rockets "at"mnsi.net] ... I'd like to see a new standard for measuring the depth of a nestbox. I believe the depth of a nestbox should be measured from the Bottom of the Entrance Hole to the Top of the Floor. This should be included in all new or updated plans. I just spoke with the Director / head of the Canadian Prothonotary Warbler recovery team here in Ontario, Canada. He is with Bird Studies Canada. I've asked him if he could use his position as one of the top Prothonotary Warbler experts in North America, to try and get Cornell Lab's - TBN to remove their Prothonotary Warbler Plastic Milk Carton plans from their website, and replace them with a proper wood nestbox plan(s). Hopefully we will be able to get TBN to make a positive change on this issue. Regards, Larry A Broadbent Chatham, ON Canada From: lviolett [mailto:lviolett "at"earthlink.net] Yes, Larry, in time, the critical hole-to-floor depth will most likely be given the attention it deserves and two measurements should replace the "depth" measurement: 1) "drop" (below-the-hole measurement), and 2) "attic" (above-the-hole measurement). I routinely refer to the hole-to-floor depth/drop when speaking of nestbox dimensions because it is critical that Bluebird boxes on my trail are built with 8.5" hole-to-floor drops to protect chicks from avian predators. From: BlueBird [mailto:bluebirdfriend "at"innerlodge.com] Linda, are your measurements from the center of the hole, or from the "bottom"? Also, do you know what your most likely predators are? TIA, Dusty From: lviolett [mailto:lviolett "at"earthlink.net] Dusty, when I refer to hole-to-floor measurements, it is the measurement from the bottom of the hole to the top of the floor. Avian predators include starlings, crows, jays, hawks. There was a suspected attempt by grackles and the chicks were immediately transferred to a box with an 8.5" drop. All avian predator problems (i.e., problems caused by large birds reaching into the box to get eggs/chicks) ceased on my trail when boxes were changed to 8.5" hole-to-floor drops. From: BlueBird [mailto:bluebirdfriend "at"innerlodge.com] Thanks, Linda. I'd been using 8in., and wasn't sure to just where your measurements were made. In any event, I think I'll increase that by at least another 1/2 in. for future boxes... I've had little in the way of predation on my trails. A gopher snake once gobbled up 5 TRES hatchlings, from a fence post-mounted box. I'm certain, cuz we found that rascal inside it sleeping off his dinner. And an avian predator once cleaned out 3 ready-to-fledge ATFL, from a hanging box. But that box had had it's hole "enlarged" by an itinerant woodpecker of some sort over the winter, and I'd not installed a patch as I didn't want to do it with the new tenants already ensconced. ... Dusty San Jose, Ca. [Note from webmaster: Thread continued from Predator Guards] The tube predator guards are designed to increase the distance between a predator's reach into a box. As Keith mentioned, predators can view the awkward entry and exit of cavity nesters using exterior contraptions. Rather than using exterior add-ons, increased hole-to-floor depth of the box provides greater distance between the predator and chicks without the disadvantages to adult birds using exterior add-ons. The design I use on my trail can be viewed at: Let's have an active, lively discussion on exterior add-ons vs. Linda Violett From: RBALTRUNAS"at"cs.com [mailto:RBALTRUNAS"at"cs.com] Good idea, but can the added depth prevent chicks from getting out? they have to jump up. The first to go can climb on their brothers and sisters, but what about the last one or two they gotta jump up or climb on something. to get to the hole. There's a limit to how far down you can go. A built in stairs or ladder might work, Ron From: rob barron [mailto:rebel1956"at"comcast.net] I think the only predator proof box is a well monitored box, but we aren’t helping the survival of a species that can’t successfully reproduce without human intervention. They aren’t Labrador ducks or California condors! I bevel the front entrance so it slopes inward from the top, and raise my table saw blade to 1/16th of an inch and make climbing grooves every 1/8th inch so the little buggers have something to climb up. I also make what starts out to be an octagonal box and graft on a straight front that makes the nest cavity farther from the entrance hole, and put in two sealed Lexan peep holes in the top to let light in to deter house sparrows, based on a recommendation from Jimmy Dodson. It seems to be working well so far. ... From: Linda [mailto:linyl"at"alltel.net] Could you give more description of the octagonal box with the straight front and Lexan holes at the top? I'm having trouble visualizing this box. Thanks for any information. Linda in NW GA I don't have a website yet but when I get home from work I'll take some photos and put them on Kodak's picture sharing site and send a link to that. My design probably isn't practical for large scale bluebird trails because cutting and assembling a box that ends up having eight sides takes a little more time, and the practical end result is just a nest box that is deeper from the entrance hole to the "nest cavity" portion. I just they looked cool and the bluebirds seem to find them immediately. I've been using 3/4" For the windows, I just happened to have some Lexan left over from building cages for large bull snakes and thin clear plastic wasn't strong enough to keep an 8 foot bull snake in. When the Lexan ran out I started using the thin clear plastic sold at home improvement stores, which is a lot cheaper than spending $180 on a 4x8 sheet of Lexan. I sandwich the plastic between two sheets of plywood with a 1 inch circle already cut out and then use a carbide hole saw with the drill bit removed to cut the plastic circles for the windows without leaving a hole in the middle of them. Then I use a 1" Thanks, [Note from webmaster: Additional posts from this thread on lexan and light and heat are found under Heat, Part 3. From: Torrey [mailto:torrey_canyon"at"yahoo.com] Sent: Friday, January 27, 2006 10:52 AM Subject: increasing the hole-nest depth Ron wrote: > Good idea, but can the added depth prevent chicks from getting Torrey replies: Tree Swallows build "shorter" nests than Eastern Bluebirds, generally less than 2" tall compared to 2-3" tall. Once they're about 2 weeks old, TRES chicks cling to the inside front of the box so they can stick their heads out & get fed by the parents. All nest boxes should take these activities into account. Most of the boxes i get are donations from Scout troops, etc & most of the time they're made of very smooth wood. If there is a rough side, people tend to put it on the outside, where it looks nice but doesn't do the birds much good. I always roughen the inside of the front, from right under the hole all the way to the floor, so that birds have something to grip while climbing out. I have some small pieces of harware cloth left over from making Noel guards last year, so any replacement boxes this year will have hardware cloth ladders. (& yes, i'll be careful about sharp pointy edges.) Having a rough surface will also help early spring Tree Swallows. They can get trapped in a regular box, either not having enough energy to get up to the hole or not enough room to flap effectively, & then they'll starve. (Healthy TRES don't have this problem.) Having said all that, i like the idea of a deeper box. Torrey Wenger From: bluebirdsnbirdfeeders"at"gmail.com [mailto:bluebirdsnbirdfeeders"at"gmail.com] I build my nest boxes deep also. Since I build out of new lumber I put 4 grooves spaced about 1/2 apart below the hole. Deep boxes are a lot safer from predators if you monitor them regularly. If you don't monitor your boxes regulary then a predator guard is not a bad idea. My preference is not too use predator guards unless you have a lot of predators around. If you don't have a lot of predators, just monitoring your box is sufficient. ... From: Lawrence Herbert [mailto:lherbert"at"4state.com] Sent: Sunday, January 29, 2006 8:00 PM Subject: depth + random placement Bluebirdsters - I subscribe to the depth of the nest box as a critical control point for many predators. Feral cats, however, simply wait at the bottom of the box for a parent - or fledgling - to be at the entrance. One other very important point is to randomly place your nest boxes instead of having them in the same spot year after year. This is a lot of trouble, I know, but, in nature, cavities tend to be "random." Predators, therefore, have to search them out. Good birding, Larry H. Joplin MO.
My attempts to help the single parent have resulted in disaster. The meal worms I offered attracted a scrub jay, and he kept chasing the female BB, once following her to the nestbox and sticking his head in. A little while ago I heard her chirping incessantly. She was perched on the porch roof with an insect in her beak but didn't go into the nestbox. My husband got out the ladder and looked in, and he said it looks like there is only one chick left and he wasn't sure it was alive. I suspect the jay has taken the hatchlings. This is the first time I've had anything like this happen. The nestbox is the deepest one I could find -- a chalet style, and it has a wooden predator guard on the front. I know the chicks will stretch up to be fed, which makes it easier for a predatory bird to reach them. Now I'll watch to see if the female will go into the box, and I'll try to keep the jay away. Later I'll check the nest myself and see how much damage is done, although I don't know what to do about it now. Looks like the meal worms were not a good idea after all. I did put cat food out for the jay, but he wasn't interested in it since he knew the mealworms were available, and the chicks. Bad day. Barbara in Cloverdale, CA From: lviolett [mailto:lviolett"at"earthlink.net] Sent: Wednesday, May 31, 2006 3:27 PM Subject: Re: Single parent :- ( Barbara, thanks for your observations. Even though you didn't actually see the Jay with a baby in its beak, that is the most likely suspect. Happened on my trail, too. Check the box immediately. If the last chick is alive, lower the nest as far as possible and snug the chick to the back corner. For the Old Timers: How to build the box: http://home.earthlink.net/~lviolett/construction.html Linda Violett From: Maynard Sumner [mailto:m-r-sumner"at"juno.com] Sent: Wednesday, May 31, 2006 8:40 PM Subject: Re: Single parent :- ( Yes, the deeper box should be better as far as big birds trying to get the babies. What I run into here in Michigan is that you can go out and take part of the nest out each day but the female will add to the nest so she can see out of the hole. A lot of my birds will not use a deeper box. I know you may say "well if you would give them just the deeper box they would get used to them and just use the deeper box". Now we are back to if we use all the same box and they do not like your box you are going a whole year with no birds. I will keep on mixing my boxes so I will have some birds. Not all the holes in trees are the same. This goes back to you are working too much for the birds and it is not fun anymore. Maynard Sumner From: Keith & Sandy Kridler [mailto:txbluebirder"at"sbcglobal.net] Sent: Wednesday, May 31, 2006 10:41 PM Subject: Shallow or deep nestboxes Keith Kridler Mt. Pleasant, Texas I just got off the phone with a lady who I helped more than 12 years ago solve a raccoon problem. Now in the last week a long armed raccoon raided five nestboxes in one week at a park and figured out how to get around the deep entrance hole guards after all these years. Each of us needs to watch and experiment and mostly observe what we see. I also talked with a man yesterday who watched a Carolina Wren remove three eggs from one of his nestboxes that was being used by a Red Belied Woodpecker! This Carolina Wren removed eggs from the woodpeckers on three different nesting attempts that he saw! He has been bluebirding for more than 20 years and had not watched these wrens do that with any other species. This morning four of our Texas Master Gardeners went and helped children K> These nestbox fronts are 11&1/2" with the entrance hole 1" down from the top. I use 1" thick roof boards and this way the 6D or 2" long nails cannot be driven down into the entrance hole by inexperienced box builders. I guess this makes this batch of boxes 8 inches deep. In the past a LOT of people would install some thick wood blocks in the bottoms of deep side opening nestboxes. When the birds built their nests they would remove the wood blocks and lower the nests with eggs down deeper. From: Robert Barron [mailto:rebarron"at"gmail.com] Sent: Wednesday, May 31, 2006 3:46 PM Subject: Re: Single parent :- ( Hi Linda, We're mostly preaching to the choir here compared to the public at From: Linda Violett When deeper boxes were discussed in the past, folks like Gary Springer and Ann Wick said deeper boxes have no advantage because the majority of birds on their trails build nests high enough so they can look out the holes. And, logically, if there is no advantage to deeper boxes, why should anyone go to the extra expense of building deeper boxes and wasting the extra couple of inches of lumber? Yet, as Barbara's disaster post indicates, there *is* an advantage of having deeper boxes. And I can state that birds using the 8.5" hole-to-floor drops on my trail do not build nests high enough that they can look out the holes. Bet Zimmerman has recently done a nestbox design pro/con comparison. She researched over 50 boxes. Bet, can you tell us how many box designs out of those 50+ have hole-to-floor drops greater than 6 1/2 inches. How many over Linda Violett From: emcooper"at"bayou.com [mailto:emcooper"at"bayou.com] Sent: Thursday, June 01, 2006 10:47 AM Subject: Re: Single / Deeper Boxes It seems like we go in circles with this discussion. There are many folks (like Evelyn, LA From: plkldf"at"comcast.net [mailto:plkldf"at"comcast.net] Sent: Thursday, June 01, 2006 3:52 PM Subject: Re: Single parent :- ( Paul Kilduff First, Barbara, I'm sorry for your loss! What an incredibly maddening and saddening thing to have happen! Bad day, indeed. I think you're still not sure the jay actually did the damage.... Linda, I like your name "face guard" for the hole extender. I note that Barbara says the box has a wooden predator guard on the front. Barbara, is that the same as a face guard? How thick is it? I like mine to be 1-1/2" thick ("2x4"). Combined with the thickness of the wood that seems to make enough of a tunnel that large birds like EUST and jays and MOBI can't reach in, at least as far as I know. It may be that I'm stuck in the past, but I wonder if maybe a thicker face guard might not be just as effective as a deeper box, and a lot easier to accomplish. If Barbara's box is a Springer Chalet, I think he does specify 2x4 for the face guard. I don't like lowering the nest because I think the birds know better than I how high they need the nest to be. However, I do want to keep larger birds from being able to reach in, and I *believe* the 2x4 face guards are doing that. (By the way, following Linda's urging larger floor sizes, I have been making my boxes with a combination of 1x6 for the front and back and 1x8 for the sides and floor lately, making the boxes open from the front for cleaning i/o one side, and giving me a 33 sq in floor, if not mistaken. I like the idea of letting them stretch their wings -- it makes sense to me and I've been making my new boxes accordingly.) Barbara, as I say, I don't know exactly what you have on the front of your box - would a 1-1/2" thick face guard solve your problem, assuming it is the jay which took the nestlings? If you do have a face guard made from 2x4, do you think it's possible that a a scrub jay (we don't have scrub jays here but it seems to be a big bird) was able to reach in past 2-1/4" of wood to get to the babies? What do others think? .... Paul in Baltimore From: Bet Zimmerman [mailto:ezdz"at"charter.net] Sent: Thursday, June 01, 2006 5:20 PM Subject: RE: Single / Deeper Boxes I now have about 82 nestbox styles and variations listed here: Anyway, of those 12 I do have info on: . Designs with hole-to-floor drop over 6.5": BAN EABL (Nebraska Game and Parks); Nature House Not sure about Texas Bluebird Society boxes? Bet from CT From: David Gwin [mailto:David.Gwin"at"cityofcarrollton.com] Sent: Thursday, June 01, 2006 5:48 PM Subject: RE: Single / Deeper Boxes Howdy, All: You can also look at a modified Peterson-style box. The modification should focus on adding 2 inches to each of the exterior dimensions. All other cuts are per the original Peterson design. (FYI - Instead of 2x4s, you will use 2x6s. The resulting boxes look great, are very solid and long-lasting and this new box solves the referenced space challenge and all of the avian predator access issues. Based on your entrance hole diameter ... the larger size of the box will also work for flycatchers and woodpeckers. I have built and installed several of these over the years and they are some of my all-time favorites ... especially as hanging boxes. Enjoy, From: Pauline Tom [mailto:ptom"at"austin.rr.com] Sent: Thursday, June 01, 2006 6:30 PM Subject: Re: Single / Deeper Boxes Bet, You asked about the hole to floor measurement on the "Texas Bluebird If I add and subtract correctly ... it's 7 1/2 inches from bottom of hole TBS calls our box style the "TB-(Texas Blues)-style. Pauline Tom From: Herb Kelley [mailto:herbsho"at"centurytel.net] Sent: Thursday, June 01, 2006 11:46 AM Subject: Re: Single / Deeper Boxes Guess I will jump in here. With that said and sort of off the point, I am pleased to report that I Herb Kelley From: plkldf"at"comcast.net [mailto:plkldf"at"comcast.net] Sent: Friday, June 02, 2006 6:03 AM Subject: re: single parent :( Hi, Barbara, 3/4" is a lot to a bird.... From: Maynard Sumner [mailto:m-r-sumner"at"juno.com] Sent: Friday, June 02, 2006 3:32 PM Subject: Re: Shallow or deep nestboxes This is what I have been saying all the time. I would all one more thing. If two or three different boxes are working for you, you should mix them up so that if one kind of box is not getting birds you will have some that the birds will use. I am not saying do not use a shallow box or a deep box but use what is working for you. Maynard Sumner From: lviolett [mailto:lviolett"at"earthlink.net] Sent: Tuesday, April 24, 2007 11:46 PM Subject: Re: Nest Height & Box Depth Thanks for sharing the hole-to-floor measurement. I have no idea why most Bluebird boxes are built with about 6.5" hole-to-floor. I've been asking that question but no one has come up with an answer that makes any sense to me other than cheaper manufacturing and shipping costs.
Since the nest doesn't have eggs, yet, you might want to take a couple of fingers and scurry it around in the center of the nest so that no nest material is removed, but a deep pocket is formed for cozier roosting. It might encourage the female to rethink her nest design where she still has nesting material up the sides but the eggs/chicks will be near the floor.
Linda Violett
Yorba Linda, Calif.
From: Keith & Sandy Kridler [mailto:txbluebirder"at"sbcglobal.net] Keith Kridler Mt. Pleasant, Texas First of all, 95% of all of the early efforts at bluebird conservation were with the Eastern Bluebird. 90% of all of this effort was North of the Mason Dixon line. 99% of all of the literature compiled and written about was from this area. The number 1 natural cavities that Eastern Bluebirds used in this area were created by Downy Woodpeckers. 6">7" deep was pretty well standard as was the 3">4" diameter cavity they create. ALL other woodpeckers created cavities that Starlings would use to nest in and they removed any nesting native birds. Nestboxes that are too deep in this area of the country were traps for Tree Swallows. There fore if you did not want to find boxes filled with dead Tree Swallows EVERY spring you would build and install a nestbox shallow enough that they could climb out of it. You can TELL people they need to saw toe hold kerfs under the entrance holes for Tree Swallows if they build deep nestboxes BUT few home style nestbox builders would do that. So you publish nestbox plans and print out information that the masses CANNOT screw up. Again look at the 1&1/2" thick wood blocks that were recommended to be added to the fronts of nestboxes back in the "good old days". If you take a 6" AGAIN back in the "good old days" you could go to the store and buy a 1"x10" IF you monitor your nestboxes and remove the old nests as soon as young fledge the "normal" height of a bluebird nest is 2">4" deep, add on the wood block and you can keep the starlings or grackles from reaching into and then down to the nest of eggs. Here again you have to monitor your boxes and see what types of predators you will have! Deeper nestboxes DO NOT help at ALL for stopping House Sparrows or House Wrens or flying squirrels or snakes or fire ants ETC. An 8 or even a 10" deep nestbox will actually SELDOM even stop a raccoon from reaching into and then down to a nesting female bluebird. They have VERY long wrist bones and long fingers and can reach into a deep hole and then down and grasp a single feather and pull the birds out of the box. EVEN if the four legged predators cannot reach the female bird on the nest or her eggs or babies they often abandon the nest or at least move on to other "greener pastures". House cats on the other hand have a hard time reaching into a hole and then bending their wrists as they must then use short fingers and short claws to hook a baby bird. Back in the "good old days" farm boys trapped out the fur bearing surplus of animals each winter, reducing predation the next year. Back just a generation ago if a stray cat or stray dog was harassing your livestock or chasing your birds at the bird feeder you shot the animal and NEVER worried about neighbors suing you. Anyway if you actually go back 30 years there were PLENTY of deeper nestboxes, thicker fronts on nestboxes. Back then nearly everyone built their own nestboxes and if you needed bigger or deeper nestboxes you made them. Today a handful of companies build 90% of all of the boxes and there are just a few people out there who remember when they whacked their thumb with a hammer while building a nestbox. The short answer about the 6" depth of the box is that in the Northeast, cold weather on average kills more bluebirds than all of the predators. From: lviolett [mailto:lviolett"at"earthlink.net] Keith points out that deeper boxes will not prevent losses from: Keith says monitors (in the old days) would build boxes according to what they can build from a standard fence board. Hmmmm, I'm imagining what could be built if standard fence boards were 9 feet tall. Fast-forward to today when most nestboxes are commercially manufactured. Every 1/2" of hole-to-floor depth that is added to a nestbox will narrow down the number of predators that can reach into a nestbox and cause disaster. Monitors such as Bob Walshaw using a hanging box system do not have to worry about the majority of ground-based predators. But hanging trails still risk losses from Jays, Crows and other large avian predators if boxes have only the standard 6.5" hole-to-floor measurements. Boxes on my trail were not fully protected from predation by Jays, Crows and Hawks until hole-to-floor drops were gradually increased to 8.5" WITH wooden face guards. As to whether deeper boxes (8.5" hole-to-floor) are death traps for Tree Swallows, I have heard BOTH that Tree Swallows prefer deeper boxes and that deeper boxes are death traps for Tree Swallows. In the past, I would have automatically accepted the Tree Swallow issue as a possible reason for the 6.5" shallow boxes. But now I realize that much of what is repeated is Should we deliberately and intentionally put the majority of native cavity nesters at risk by continuing to build/buy shallow boxes based on what we During the next few months, monitors will be writing in about opening a box and instead of seeing a cluster of nestlings, will be staring at an empty nestcup. Happened on my trail and it was caused by avian predation of boxes that were built too shallow based on standard box measurements. After building deeper boxes with 8.5" drops plus the wooden face guard, the trail became safe from large avian predators. I still have not heard any logical reason (outside of profit margins) why 6.5" is the standard hole-to-floor measurement in the vast majority of nestbox designs. Linda Violett From: Evelyn Cooper [mailto:emcooper"at"bayou.com] Keith writes: "Again look at the 1&1/2" thick wood blocks that were recommended to be added to the fronts of nestboxes back in the "good old days". If you take a 6" You simply add a 4 or 5" long piece of scrap 2x4" to the box but you save the expense and weight of adding a total of 10 more inches of 1X lumber if you had to add the extra 2&1/2" to fronts, backs and sides to increase the depth." Read this carefully. Read what Keith says about having MORE of a drop on these standard size boxes using the 1 1/2" inch wooden guard. This is some of the reasons we use the standard size box. Only, we recommend a 2 1/4" We save lumber and can utilize scraps for the wooden guard. We are fortunate enough to get rough lumber from a saw mill and the boxes are true 1" The things Keith listed that the deeper holes do not do are in fact truth. Some things and standards from the "good ole days" are still great to consider and use. Evelyn From: lviolett [mailto:lviolett"at"earthlink.net] It seems some folks are having difficulty with the concept of building deeper boxes and/or calculations. AVERAGE 6.5" deep boxes + 3/4" box face + 3/4" wooden guard = about 8" Rather than adding outside tunnels (Noel guards, etc.) to shallow (standard) boxes, deeper boxes can be built. So why do we (Bluebirding community) keep recommending that 6.5" Linda Violett From: Kelley Family [mailto:herbsho"at"centurytel.net] Linda, I agree that deeper nestboxes are better. I build my boxes 8-81/2" deep depending on the thickness of the scrap wood I have availible for the floor. I think the problem being addressed here is that some people, my memory says Keith recently put the % as high as 90, do not build, but buy their boxes. From: Evelyn Cooper [mailto:emcooper"at"bayou.com] Herb, you make a good point about the higher percentage of people that have to buy their boxes and it is probably true of the List. Keith mentioned a guard you can find at www.birdguardian.com. He stated that if you have several boxes in your yard and the guard is not on some of them, the bird will usually take the one without the guard. Deeper boxes work for some, others do not like them because the female builds the nest right on up to the entry hole. My input on the subject was for people that already have very good standard boxes out there and they could make them safe with the thicker guard if they have access to building and the know how. This is my situation and I can do it. They absolutely are safe with proper guards. For us making them in such volumes for workshops and festivals, the standard is more practical and I am considering asking our builders if we can also make the entry hole guards. We have gone to the majority of top opening front doors and the guards fit so nice on them. We have piles of scraps we could use for that. If we could get attention to our needs because of avian predators, maybe eventually a nice wooden guard could be manufactured or a light weight plastic more like the thicker wooden guard that the birds would like. I am day dreaming. Evelyn From: lviolett [mailto:lviolett"at"earthlink.net] Yes, Herb, I agree with everything you say and very glad that you are also using deeper boxes. We've got NABS board members and officers (past and present) on this List. Linda Violett From: Jimmy Dodson [mailto:rocks_and_flies"at"hotmail.com] I believe Keith's post about box depth provides answers this question quite nicely. Also remember that there are multiple box designs out there for EABL that are good. Lots of use for all. "Successes" and "failures" varying for numerous reasons... again, different places, different circumstances and variables... and different reasons & choices by the folks placing them. Jimmy Dodson From: lviolett [mailto:lviolett"at"earthlink.net] Keith seems to recognize that the NABS 6.5" hole- to-floor dimension is insufficient. His "Texas" box has a hole-to-floor drop of 7.5" (a full inch deeper than standard). That 7.5" drop (with avg. wooden face guard) will prevent MOST large avian predators from reaching in. But NABS is the organization which sets standards. There should be someone from NABS who can state whether 6.5" hole drop is what they believe is in the best interest of Bluebirds or whether it is based on getting a box out of a single fence board: http://www.nabluebirdsociety.org/eastwestbox.htm Linda Violett From: Evelyn Cooper [mailto:emcooper"at"bayou.com] Yes, it did and he stated that the deeper boxes do not stop the climbing predators. The extra weight and cost factor is a great consideration. Evelyn From: Evelyn Cooper [mailto:emcooper"at"bayou.com] Keith wrote: "If you take a 6" This does not indicate that Keith thinks the NABS 6.5 drop is insufficient. Evelyn From: Evelyn Cooper [mailto:emcooper"at"bayou.com] I don't think there is MORE cut down, but the drop from the 6.5 and add 2 1/4ths to the front makes an 8 3/4ths drop which is good. Mine is 9.5 with the inch door. Evelyn From: Keith & Sandy Kridler [mailto:txbluebirder"at"sbcglobal.net] Dr. Lawrence Zeleny was the founder and driving force behind the North American Bluebird Society. His book "THE BLUEBIRD, HOW YOU CAN HELP ITS FIGHT FOR SURVIVAL" was published in 1976. It was the FIRST bluebird book printed and the ONLY one ever printed by someone with more than 50 years of bluebirding experience at the time of printing. As I re-read the chapters on nestbox construction and predators last night I was going to copy a few paragraphs to show the reasoning behind depth and size of nestboxes and size of entrance holes ETC. The problem is I would need to actually copy most of the book. As he states in his book about the "basic" bluebird sized nestbox he goes to great detail as to why the nestbox is at LEAST 6&1/4" deep. This is ALL about the reach of a Starling into a nestbox and combines this with the AVERAGE height of a bluebird nest and this determines IF a Starling can destroy the eggs or baby birds. He goes on in the section on Predators to state,"Protection against raccoons can also be provided by deeper nestboxes, ones in which the distance from the bottom of the entrance hole to the floor is eight or ten inches instead of the usual six." He goes on to mention that often the bluebirds will build taller nests or the trail monitor will not remove old nests in time and the coons will then raid the nestboxes with higher nests. He goes on the mention how it helps to make the entrance holes 1&1/2" thick (or more but that bluebirds mostly shun nestboxes with entrance holes deeper than 1&1/2". At the time of this books printing the ONLY raccoon guard that would absolutely stop raccoons was a cone shaped sheet metal guard 36" in diameter. Again he goes on to mention the predators the deeper nestboxes will stop, he adds, "Charles W. McQuillin of Zurich, Ontario, has found the ten inch deep boxes to be quite effective in his area, and suggests attaching a piece of sheetmetal to the front of the box surrounding the entrance hole to discourage raccoons from gnawing at the wood as they sometimes do." Larry mentions that in 1976 that there were only three avian predators actually and they were Starlings, House Sparrows and House Wrens. It is interesting that Starlings ONLY appeared along the Beltsville MD. trail AFTER 1950 and it took until about 1965 for them to dominate the nest cavities in that area. Starlings did not become a problem for the Montana bluebird groups until the 1980's, then only in certain areas. He mentions the crows, jays, magpies, grackles ETC. but with the "basic" nestbox up to that date they were seldom a problem. AGAIN as he often states in his book that IF you have problems go ahead and build a deeper box or install better guards. We are ALL free to write articles and submit research an ANY aspect of building and using nestboxes for NABS. I personally would like to see Evelyn take that one state park trail she is having problems with and replace half of the nestboxes with a copy of Linda V. two holed hanging mansion and half with a standard nestbox for a couple of years. Keep good records and she can PROVE to Linda and Bob Walshaw that snakes climb trees in that park:-)) Evelyn with her entrance holes 3 inches deep is already PROVING that Dr. From: bluebirder2838 [mailto:bluebirder2838"at"comcast.net]
Sent: Friday, April 27, 2007 8:43 AM Subject: Question re: Texas Blues Nestbox 55 degrees and raining/ Marlborough, CT Grass is greening up and bulbs are blooming 3 active nests in 7 nestboxes on 3 acres—1 CArolina WRen w/ 5 eggs in propane tank lid 1 EAstern BLuebird nest w/ 1 egg in Gilwood box 1 TUfted Titmouse (or BlackCapped Chickadee) in Horizontal Box Just a quick question to find out if any New England List members have in actual use the Texas style nestbox called the Texas Blues Nestbox (made from the Texas Bluebird Society plans)---URL: http://texasbluebirdsociety.org/documents/nestboxplans.pdf My husband made the Texas Blues Nestbox TB-1B for use in our yard in conjunction with a nestcam (the thinking was: deeper box = better focal length for the camera) which he purchased for me as a present. He made it from extra pieces of clear pine 1 X 6s and altered the plan slightly to make a downward sloping roof. He cut kerfs inside the box under the entrance hole. The wood was left untreated. It is very smooth. He is a very fine woodworker who can make furniture quality wood projects, so he made me an elegant nestbox using quality wood pieces that he had hanging around. We put the Texas box in the same place that the old regular sized NABS box that the bluebirds have used successfully many times (and were checking out for this season). Since we installed it, NO birds have gone inside it. They land on the box, drop to the hole, look inside, and then fly off, every single time. At first we thought that the hole size was slightly off (Forstner 1 ½”) so we “dremeled” the hole size to an oval 1 5/8” in case we had plus-sized bluebirds. Still, no one will enter the nestbox! Could it be that we used higher quality “smooth” pine and the birds think it looks unnatural? Could it be that the side vent slots let in too much air and light (designed for Texas heat) for New England bluebirds? Should we give up and just make a deeper NABS box to accommodate the nestcam? Donna in Marlborough, CT From: Evelyn Cooper [mailto:emcooper"at"bayou.com] One thing that stood out to me that went along with Dr. Zeleny's recommendation of the deeper box was it was stated one problem was that monitors could not get back to check the trail in time when higher nests were built and the climbing predators got them anyway. These higher nests being built is quite common. When a person has a large trail even a week or 10 days can make the difference. I had a person tell me just yesterday they missed the weekly check and found a problem that a check might reveal more information about that could possibly have saved a life. So, I think each person has to figure out what is most beneficial to them. I am not against deeper boxes, but do not think they should be approved as the standard way to go when the 6.5 box with minor add ons can do the same. Just ask Emily of NC if snakes climb trees! Remember the post she gave about the snake out on the limb right above her nest box and her husband shot the snake and this List was pretty much in an uproar for several days. It is in the archives if anyone doubts it. So, I can use my energy (what I can spare at the park) trying to get the two legged predators straight on this one! Evelyn From: Bob Walshaw [mailto:walshaw1"at"cox.net] Regulated trapping is helping the raccoon and other predator problems here. The Oklahoma Wildlife Department just raised the yearly Raccoon limit from 30 to 40. Also, no question that snakes climb trees here. I have watched big blacksnakes go up the side of large oak trees on the rough bark. I am just not finding that they go down the From: DrDodson"at"aol.com [mailto:DrDodson"at"aol.com]
Sent: Friday, April 27, 2007 10:27 AM Subject: Nest height in Gilbertson PVC boxes Just an observation. From: Duane Rice [mailto:drbirdsong4"at"hotmail.com] Donna,
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