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Downy Woodpeckers commonly use nestboxes to roost, but rarely do they nest in them. Here’s a quote from Bet on Sialis.org:
“I have never heard of a Downy Woodpecker NESTING in a nestbox. However, they often ROOST in nestboxes and artificial snags. In a nestbox, they often “excavate” the interior, leaving woodchips behind (and sometimes gray downy feathers from preening.) They may also try to enlarge the entrance hole. Former Downy roosting and nesting cavities may be used by secondary cavity nesters, or enlarged by larger woodpecker species.”
Last year a downy completely destroyed the entrance on one of my boxes after it was finished roosting in it. Then it just left.
If it were me, I would take that box down. Boxes mounted on tree trunks are fast food restaurants for predators. The safest way to mount a nestbox high in a tree is by hanging them on a limb at least five feet from the main trunk. Of course this requires special equipment, such as the nestbox hook and a painter’s pole for hanging and retrieving.
To answer your question on fledglings getting out of a deep box, Bluebird chicks would have no trouble. Easterns do have a tendency to build higher nests in deep boxes.
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.
Any uneaten bits of wet dog food might turn rancid which would promote unhealthy bacteria. Don’t know if they would eat dry dog food as I never tried that. When I as raising mealworms, I fed them carrots and bits of cabbage. Both these provide both nutrients and moisture, but unless you’re keeping mealworms long term, as long as they’re alive they’re nutritious without adding any supplements. Dusting worms with calcium is a good thing for the birds, but unless you overfeed worms to the extreme, it’s not necessary.
I didn’t think about that dimension until you mentioned it. Great call girl.
Great! Hope your luck improves against those pesky Starlings!
Is the wire you used bendable? If so you might be able to adjust it down to 1 3/8″ or so.
Steve G. told me an interesting story about Starlings and the Gilwood. He trapped some starlings, put them inside a few Gilwoods, and waited. Within minutes, they ALL escaped. But he rarely had Starlings even attempt a nest in his Gilwoods. I asked him why, if they could squeeze themselves under that wire, that they didn’t nest there.
“It’s way too much work for them, having to squeeze in and out so many times during a nesting cycle. In studying Bluebird behavior, I realized that birds pay attention to this. Combined with a floor that’s really too small for their needs, they usually give up on a Gilwood and go elsewhere.”
The subtleties of a nestbox design are sometimes not so subtle after all.
You are welcome, my friend.
As far as boxes go, I guess I’m a hopeless nestbox junkie. (Hey, that icon looks like a two-hole mansion box). See?
I addressed the subject of slots on my website, Nestboxbuilder.com, as there is a misconception on why slot boxes work to deter sparrows in some areas (if they work at all):
“Nestboxes with a horizontal slot rather than a conventional round or oval entry were designed to be less attractive to House Sparrows. These boxes are usually very shallow and have a small nest cavity. In some areas House Sparrows do not favor this combination, while in other regions slot boxes have no effect in deterring them. It is generally agreed that the small, shallow cavity of a slot box has more to do with deterring House Sparrows than the slot itself.”
Two of the original slot box designs, the Troyer and the Hughes, have a very small floor: 3 1/8″ x 3 1/2″, for a total floor space of only 11 square inches. Because the fronts on these boxes angle outward as they go up, the higher the nest is built, the larger it becomes. But the bird doesn’t see this on initial examination – it sees only that tiny floor. Additionally, these two slot designs are very shallow – about 4 1/2″ from bottom of slot to top of floor. This “drop” on traditional NABS style boxes ranges from 5 1/2″ to 6″.
Regional habitats also play a role in whether birds will accept or reject a box, slot or otherwise. If competition for cavities is severe, birds will be forced to nest in whatever is available, including slot boxes with tiny floors and shallow drops. If there are plenty of cavities for the birds to choose from, sparrows, in particular, will look for the larger cavity.
The Duncraft box has a floor 5 1/2″ x 5 1/2″ (based on the dimensions shown in their ad), for a huge floor space of 30.25 square inches. Ironically, this large floor actually defeats the original premise of it being “sparrow resistant” (the Foster and Smith box appears slightly smaller, but it’s not small enough). And as Gin pointed out, a slot entry will actually make it easier for a sparrow to drag in all the trash this bird uses to build its nest.
So the truth is, simply putting a slot entry on a box doesn’t do a thing to deter sparrows. The slot, a small floor size and a relatively shallow drop must all be combined into the design to even begin to hope it’s unattractive to sparrows.
Hope this helps…
As Phil Robertson says on Duck Dynasty, “Ev Body Happy Happy Happy” :-)
Yeah, Gin. How right you are.
I was told many, many times that the Powerpoint presentation was “almost finished”, but after two years of bugging the folks up there, I gave up. Then I see NABS finally gets it done but I was disappointed to see that they were charging for it, when it should be free, especially to affiliates. I haven’t seen it. And now I will pinch my lips and say no more about NABS (more correctly I’ll just stop typing).
Linda Violett designed the 2-Hole Mansion for her native Western Bluebirds, so it’s a fairly large (and heavy) box with its 31.6 square inch floor. For Eastern Bluebirds (Linda affectionately calls them “pygmy bluebirds”) and other small cavity nesters like Tree Swallows, Chickadees, Nuthatches, etc., you can go smaller, from the 15 square inch Gilwood up to the more common 22 square inch boxes like the Xbox, NABS, etc.
A common misconception is that the 2-Hole Mansion should be hung in a tree. It works just fine as a pole mount. Conversely, just about any box can be hung from a tree limb. I say “just” because lifting and retrieving a really heavy box with a painter’s pole extended to 14 feet is, to put it mildly, an athletic endeavor.
I wrote a piece on hanging boxes that’s published on my website, Nestboxbuilder.com. This article was put together with the help of the three most knowledgeable hanging box experts out there, Linda Violett, Dick Purvis and Lee Pauser. It’s written from the perspective of a raw beginner, which I was at the time. This season, I have twenty boxes hanging from tree limbs all over the county. I’m well out of my rookie season with hanging boxes, but there’s a lot yet to learn.
- This reply was modified 4 years, 3 months ago by River.