Egg no. 1 of 2013

The first egg of 2013 was laid sometime this morning, about five weeks ahead of last year’s schedule. Expect the Nest Box Cam’ page to be fully updated later today.

Also, I’ve seen Chris Cooley’s work on the new “Owl Nest Box” app for iPhone and (and, new for this year, iPad). It’s looking good, but work is still underway. Regrettably, quickly making last year’s app available on the App Store is out-of-the-question due to Apple administrative policy, although it will still work for those who already have a copy.

Owl Cam’ Goes Live for Pre-Nesting Activity

Owl Cam’ viewers can now witness the current pre-nesting behavior. With an owl consistently spending the day in the nest box, I’ve fired-up the nest box cam’, even though nesting may still be some weeks away, and have modestly improved the main page, primarily with the simple addition of the small, five minute, time-lapse movie from 12 hours earlier (it sits directly beneath the current five minute time-lapse movie). With an owl spending the day in the box, and various courtship activities taking place primarily in the hours after sunset, there will almost always be something to watch (with a bit of continued luck).

How Owls Turn Their Heads Without Tearing Arteries

Thanks to Ruth F. for this article on an aspect of vertebrate physiology that I'd never even considered: How Owls Spin Their Heads Without Tearing Arteries.

Hum… Try, Try Again

The microphone in the nest box has been a source of maddening frustration ever since I installed it years ago. The problem has been a humming noise that comes and goes on a period ranging from hours to months, thereby making systematic debugging of the setup impossible. At its worst, the hum drowns out virtually all of the sounds the mic is supposed to be capturing in the nest box, and, more than once in the last few months, the hum has even included what I assume to be the banter of an AM radio station.

I've suspected every part of the system at one time or another (including the video portion, since degradation of the picture often accompanied the hum), tried more things to get rid of it than I care to remember or recount (including some very good suggestions from readers – thanks for those, by the way), and every time it goes away and I think I've finally solved the problem, it's back again in hours, days, weeks, or months.

Saturday afternoon/night I made yet another attempt to solve the problem. The AM radio station experiences, and subsequent reading about crystal radios, started me wondering about pretty much the only unshielded wiring in the side camera compartment that houses the microphone: the five or six foot length of cable permanently attached to the mic itself. Needing only about one foot of that cable to reach from the mic to the audio/video modem, the rest of the mic's cable is wound into a tight little bundle to keep it out of the way. Wondering if that was functioning as a radio antenna, I decided to try a cheap trick to shield it: wrapping it with aluminum foil and grounding the foil. For good measure—and because I'm guessing, rather than engineering, my way through this problem—I even grounded the springs that suspend the microphone.

So far, the hum is gone, which would be very satisfying if past experience didn't suggest that this "success" could be a mere coincidence, and that the infernal hum could come back at any time, possibly after spending months lulling me into a false sense of accomplishment. Anyway, slightly more than 24 hours into this experiment, so far, so good. Fingers crossed that the problem stays fixed. (Remember: guessing, not engineering, so superstition fits right in. And, yes, I am ashamed of that, but wish me luck, anyway.)

Owl Reaction

This attempt to banish the infernal hum seemed like a quick and simple operation that I could accomplish in maybe thirty minutes. So, when I finally found the energy to tackle it late Saturday afternoon, I thought I'd have the box reassembled and back in the tree before dark. My estimate was only off by about two or three hours.

That meant that the latter stages of the work (including some unrelated maintenance work that I noticed the need for while I had the box down) was supervised by a pair of screech owls that didn't think highly of my efforts. Nonetheless, they got on with the business of calling to each other and meeting on a limb of the nest box tree, in standard mating season protocol. Whether they've mated yet, I have no way of knowing. However, if the egg gestation period is a month, then they should be mating any time now. (Since it's been a relatively warm winter, they might even be ahead of their usual schedule.)

Readers suffering from some of the more extreme forms of boredom can watch the video above, which consists of several fragments of what my system automatically recorded while I was working on the box, muttering to myself, blinding the camera with my head lamp, making terrible noises with aluminum foil, and talking to my feathered critics. (The criticism starts after about twenty seconds.) My calls of "pretty bird(s)" are how I always call for my owls (seldom works) or respond to any owl calls directed at me. Once upon a time, I'd try to emulate their calls, but I gave that up when I learned from Fred Gehlbach that the reason such calls get results from the owls is because they think there's a rival in their territory, a prospect that forces them to show-up to defend their home turf, and causes them significant stress. Since then, I've used my own call of "pretty bird" as a way of identifying myself to the owls. Whether having me around is good, bad, or insignificant, they can decide for themselves, but at least they have a way of knowing what and who they're dealing with.

Keeping Squirrels out of Owl Nest Boxes

I've been lucky this year and had no problems with squirrels in my screech owl nest box. Significantly, I think I know why.

Upper-left: Screech owl nest box in gray.
Middle: Fox squirrel nest box in green.

Though I've seen fox squirrels taking an interest in my squirrel nest box at various times, for lack of built-in video cameras or other instrumentation, I remained unclear as to what, if anything, was going on in there. However, lately, I've seen a good sized female relaxing on the horizontal board that serves the double-purpose of being a stand-off from the tree limb that keeps the nest box hanging vertically from a non-vertical limb, and as a walkway from the tree trunk to the entry hole in the bottom of the box. Around these parts, it's the right time of year for a fox squirrel to have her winter pups (well fed, as I expect my bird feeder ensures, a fox squirrel can produce three litters a year). Taking the afternoon air on that horizontal board, Mme. Squirrel could easily listen to her pups’ activity in the nest, while keeping an eye on everything going on around her, and from a position of complete safety, so it’s a good arrangement for her.

It’s gratifying to see the squirrel box serving its intended purpose, but I’ve also come to a reasonable degree of confidence that it’s serving an additional role: keeping other squirrels out of the screech owl nest box. The way it does this is very simple: fox squirrel territoriality. While they may tolerate each other to varying degrees in foraging encounters, they do not seem willing to allow other fox squirrels to setup a nest in the tree that holds their own nest. (Perhaps in really enormous trees there’s room for “my side; your side”-style compromise, but around here, even when a tree contains multiple squirrel nests, they all seem to be property of the same squirrel or matriarchal family group.) So, having an established squirrel nest more-or-less next door to the screech owl nest box ensures that it has a squirrel preventing all other squirrels from moving in, and you could not ask for a better, or more devoted, defense than squirrel self-interest.

So, if you've been having a problem with squirrels in your screech owl nest box, perhaps building and installing a squirrel nest box (similar dimensions to a screech owl box, but with an entry hole in a rear corner of the floor, and, perhaps, multiple internal levels) nearby is worth trying. And please report your results back here.

The Best Screech Owl Photo I Never Showed You

Readers with long memories may recall my mentioning that I'd setup an experiment during the last week of my 2012 screech owl nesting. The experiment was a home-brew motion sensitive trigger for my digital SLR camera, with trigger and SLR mounted such that they could catch the adults as they flew back and forth from the nest box. (You can see the sensor in the photos; it's the white plastic thing with the exposed pale wood behind it, mounted under the owlet rail. The clamp on the bottom edge of the nest box is providing mechanical isolation for the cable running to/from the motion sensor. Yeah, it was a kludge, but you have to get real-world experience before you can know how to finalize a design.) The experiment worked, albeit with a host of first-time-in-the-field problems that meant the experiment lasted only part of one night. Nonetheless, it was worth nearly being killed by a folding ladder with a very poor sense of timing about when it should fold, the frustration of having to cancel the experiment after a matter of hours, etc., because it produced the photo below.

Delivering a june bug to the nest box.
May 23, 2012, 10:47 PM CDT.

This photo shows the delivery of a june bug, probably Rhizotrogus majalis. And I believe it answers my question about the more-or-less round, white food items that I've seen, via the internal infrared camera, delivered year after year, but which I’ve never been able to identify. The beetles roll-up, to the extent that they can, into a defensive shape, and their shells reflect near-infrared light well, so they appear white in such illumination. Combine that with the low-resolution of standard-definition closed circuit video cameras, and there’s not much to go on in terms of making a species identification. However, combine this high-res, color external shot with the internal shots that followed, and the mystery is solved, at long last.

The motion-trigger experiment produced some other photos of interest, too. I’d intended to post all of them sequentially with commentary, but since I keep failing to do that, I’ve started with my favorite, and will take it from there.

Mme. Owl Spends the Day in the Next Box

Mme. Owl, in a move that I hope has nothing to do with impending eggs (it’d be about 10 weeks too early for eggs around here), spent the entire day of January 2nd, 2013, in the nest box, starting at 6:28 AM CST and ending at 6:01 PM CST. The movie below shows all of the portions that triggered automatic recording. (In future, I will allow movement in more of the nest box to trigger recording.)

January 2nd, 2013, 6:28 AM to 6:01 PM CST
706 MB MPEG-4 movie, of 47:47 duration.

If impending eggs aren’t the source of this daytime stay, it may be that one of the several construction sites up the block disturbed or destroyed her normal daytime roost, forcing her to seek alternate, but safe and familiar, accommodations.

The perch in the nest box continues to be a well-liked feature, as you can see, though I wonder if an adult screech owl would prefer that it was another half inch, or thereabouts, further from the far wall, to allow ample room for tail feathers, etc. With the floor of the box only measuring 8" x 10" (which is larger than the 8" x 8" usually recommended), I wanted to try the perch experiment, but keep it out of the way of normal owl business as much as I guessed was possible. However, the years have proved it is popular enough with adults and owlets alike that allotting it more space might be appropriate. And it's not merely a perch for the adults, or a climbing target for the owlets; both adults and owlets will hide beneath it when they feel threatened. It might provide very little protection, but it seems clear that any protection is immediately recognized as better than none.