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I’m trying to learn more about the two-holed mansion boxes. Read one of the previous posts & the research that has been conducted with them, particularly if have HOSP problems. I’ve read the upsides, but what are the downsides besides giving HOSP even more access? Why aren’t more bluebirders using them? Of course, after seeing what happened to Philly Blues’ dead bluebird with HOSP building nest over it in a two-holed house (not mansion), it raised more questions for me. Would love to hear your thoughts on this…
Nicole
I’m not against them at all, but like you just don’t understand why more people don’t use them if they are house sparrow resistant. I can see where a bluebird can escape easier but like I’ve said it also ads more entryways for a HOSP. Kind of like a house with a front and back door. If you don’t want intruders you have to lock both. I don’t know of any other reasoning but I may try to do some googling later.
Then, I wonder how easy trapping with a Van Ert is? And would a 13 g. garbage bag fit around the two holed mansion? Those are my concerns.
Besides an extra hole for escaping, what do you like about it compared to one-holed boxes? I’ve never even actually seen one except online.Tammy
Well, there seems to be something to the extra room/floor space in the box. That is one part I didn’t quite understand. Now I think I understand that the box is designed much larger because this allows the larger bluebird to have more room to move, fend off and escape to fight outside. If you look at a fight outside in the open, bluebirds tend to have an easy time fighting the sparrows off. I tried two holes in a small box and it failed because the bluebird is still trapped in a small floor space. They cannot open their wings fully but the sparrow can move around freely since they are so much smaller and quick. I am thinking of making mansions this time around because I cannot monitor my boxes at all times.
Linda Violett’s 2-Hole Mansion was originally designed for Western (and Mountain) Bluebirds, which are slightly larger than Easterns, plus Westerns usually have one or two more chicks in a clutch. This partially explains the larger floor size of the 2hm (5 1/2″ x 5 3/4″, or 31.625 square inches).
The box is also very deep: the drop from bottom of entries to top of floor is 8 1/2″, compared to the 5 1/2″ or 6″ drop on conventional NABS-style boxes.
Some other reasons for this large, deep design are: room for the chicks to separate in hot weather; more space to exercise wings during development (Linda calls this “flutter space”); too deep for avian predators to reach the nest; “attic” space to keep accumulating hot air away from the nest; and others. You can read Linda’s design considerations concerning the floor space here.
The Defensible Box
Ostensibly, two entries provide the bird with an escape route in case of attack, so the Bluebird can take the fight outside, where it will usually defeat an attacking sparrow. We’ve all heard that. Whether Bluebirds will actually do this in every case might not be automatic, however. My opinion is that it’s a learned behavior, and dependent upon circumstances and upon the individual bird. But field tests conducted by Linda, Dick Purvis and others have proven that overall, over time, it works. Christine Boran, on her site The Woolwine House Bluebird Trail, conducted a positive, six-year test on 2 holers.Do you need a Linda Violett 2-Hole Mansion to provide two entries? No. For Eastern Bluebirds, the new Xbox (designed by Tom Comfort) will easily accommodate 2 holes, as will any box with at least a 5 1/2″ wide front.
As far as a Van Ert working in this box, the plate on the Van Ert partially blocks both holes, leaving a crescent shaped opening of about 5/8″ on both holes. To escape, the sparrow would need to wedge itself inside this crescent, then force the plate spring to open the plate further. Could it do this? In a panic it probably could. However, the box wasn’t designed with trapping in mind. In fact, if Linda got wind of someone doing this (I asked her) she would scold you with unmerciful wrath (she did me) :-).
Whether a 2-holer is right for you, your habitat and your birds can only be answered by putting these style boxes up. I do know that there are far more 2 holers in use throughout the entire country than one might imagine. If you would like to build this box, or just take a look at the plan, it’s on the Plans Page of my site.
Fred
Waleska, GA
NestboxBuilderOr….he could build you one.
There’s that. It would be the best made box you ever saw.
Gin
Atlanta, GAThank you so much, Fred! You are the man! If you don’t mind me asking, what box or boxes do you prefer using for EABL? Thanks again!
Nicole
Birmingham, AL
Thank you Nicole.
Because I’m always testing boxes there’s no telling what boxes I have up at any given time. On my two trails I mainly use six-sided (hexagon) boxes which are fitted with hooks and hung on tree limbs (Linda Violett influence). My all time favorite box is the Gilwood. I’ve modified Steve’s original design by adding an inner roof and a larger main roof (called the Gilwood II). The inside dimensions of the II are identical to the original.
Fred
Waleska, GA
NestboxBuilderSince the research is saying great things of the two-holed mansion, then why don’t you use that, Fred? Just curious.
Tammy
I don’t have HOSP here at the house and very few on the trails – they’ve not been a problem for me. I’m planning a third trail at a local golf course that has lots of sparrows, so I’ll start out with 2-holers there. I’ll hang the boxes in trees, and since the Mansion is rather heavy (don’t smirk Linda) I’ll use the much lighter Xbox with 2 holes.
Fred
Waleska, GA
NestboxBuilder
Thanks, Fred. - You must be logged in to reply to this topic.