News Archive 2013

March 29 – My thanks to everyone who weighed-in on the “what’s that dove?” question from the 27th. The overwhelming consensus, with which I concur completely, is that the dove was a white-winged dove. Any screech owl that can master hunting white-wingeds will never want for food, and its offspring will always have full bellies. Here’s hoping we’ll see repeat performances in the near future.

As far as the timespan from midnight to 7:14 AM CDT went, however, there was no sign of such hunting prowess, as shown in this compilation of food delivery video (MPEG-4, 346.9 MB). At 23 minutes, 53 seconds it’s not a movie everyone will want to watch (or be able to download in a reasonable amount of time), but if you want to see every food delivery made during those 7¼ hours, here’s your chance. This was a period typical of recent (warm) nights in terms of prey types and amounts.

BTW, I’ve returned to the photos taken on March 18th and added a photo of egg no. 4 that clearly shows the cracks in its shell early in the hatching process.

March 278:29 PM CDTMme Owl entered the nest box dragging behind her, with one foot, the largest kill this year: a dove of some kind (MPEG-4, 61.3 MB; the dove is only visible in the first 40 seconds, but I included the full movie for the general interest of viewers). It looks to me to be too large to be an inca dove. A mourning dove has been suggested by one viewer (thanks RCG). However, I see neither at my bird feeder or in my neighborhood (which doesn’t rule out the possibility that they are here, it just makes me think of them as unlikely finds). Especially in the case of the inca doves, the aggressive white-winged doves appear to have displaced them. If what Mme Owl brought in was actually a white-winged dove, and the wing-edge markings appear consistent with that possibility, that would make this the largest prey item I’ve ever seen any of my owls deliver to the nest in 13 years of observation.

Typically weighing 4.9 oz, a white-winged dove is within the carrying capacity of a screech owl which, if memory serves, The Book of Owls states will take prey as heavy as themselves, typically 5.8 oz, with females generally weighing more than males.

If it is a white-winged dove, and one or both of my owls has learned to hunt them (as opposed to finding one that was already dead), then the food problems are over for this owl family. And the local white-winged dove population could certainly do with some thinning.

March 266:03 AM CDT – Injected a mouse into the entryway, where it remained, in sight of Mme Owl. For a change, she only delayed retrieving it for about three minutes, and proceeded immediately thereafter to feeding the owlets that she was brooding against the roughly 30° F temperature.

March 2511:39 PM CDT – After brooding the owlets for some time, Mme Owl left the nest to hunt. I took that opportunity to inject a mouse into the nest box, in the hope that, when she returned, she’d be able concentrate on feeding and brooding the owlets, rather than leaving them alone while she hunts. At least for a while. In practice, one mouse doesn't go far with four owlets (and Mme) to feed.

Mme Owl returned about five minutes later, but has thus far failed to notice the mouse on the nest box floor. Nonetheless, for the moment, she’s staying in the box with the owlets.

March 24Night – A cold night, windy and in the upper 30s F. Mme Owl stayed out hunting for the owlets as long as she could, but eventually had to give into their needs to maintain consistently high body temperatures (AKA “thermoregulation,” something they cannot do for themselves as yet), and had to confine her activities to brooding the owlets for the rest of the night, and until the temperature rises to a level that will allow them to be safe without her.

Late Afternoon – Seeing no cached food in the nest, I injected two mice into the nest box several hours apart. (One mouse made it only as far as the entryway, where it loomed above Mme Owl, the other made it to the far walland floor of the box – I'd thought the first approach would be superior, but judging from the lady’s reaction, it doesn’t appear to matter....) Both were received by Mme Owl in much the same way: with ear tufts raised in agitation, both were astutely ignored for long periods of time, before she inevitably took possession of them, and then became occupied with the question: cache it, or feed the kids now. The first mouse went the latter route, the second the former.

12:28 AM CDT – Injected a mouse into the nest box. Had hoped to catch Mme Owl while she was in the nest, but she was already in the entryway as I left the house, and she left as soon as I called to identify myself. The mouse was injected anyway, as one of the adults observed and trilled from a nearby tree.

March 23 – The eldest owlet turned one week (seven days) old this afternoon. Happy anniversary, kiddo. By the way, although it has happened slowly, it will already be evident to viewers that the owlets are becoming darker as their hatchling white fuzz is replaced by the beginnings of gray feathers. Meanwhile, food deliveries, even with the help of Mme Owl, are small. Geckos are the largest prey I’ve observed. I’d expect better results from Mme Owl, but she may not be hunting normally (not for as long, and/or not from as many of her favorite hunting perches), given the need she’ll feel to return to her nest and look after the owlets. There’s also the possibility that, while a lot of critters (including the owls, of course) are acting like spring arrived a month early, other parts of the ecosystem may be operating on different clocks and throwing off the usual level of available prey.

March 225:58 PM CDT – I just injected a mouse into the nest box (the mouse is light colored, and therefore hard to see on camera, because it blends in with the owlets and bedding material). So far, same pattern or reactions as described in the 12:15 AM update.

3:25 PM CDT – One of the owlets—the eldest, presumably—opens its eyes for the first time that I’m aware of.

2:14 AM CDT – Demonstrating that male screech owls lack the instincts that tell a female how to feed owlets, in this movie (MPEG-4, 69 MB), Mr. Owl shows-up with a moth for the owlets, first trying to offer it to them from the entry hole, and then standing mystified on the perch as the enthusiastic, but tiny, owlets don’t reach up and take it from him, as his mate would. Eventually, he gives-up and leaves, taking the moth with him. To his credit, he gives it one more try, and that time thinks to descend to the owlets’ level and offer it to one of them. That works.

Male screech owls know the owlets must be fed, and will feed them (or attempt to), but they lack the instinct to tear-up large food items for the owlets. So, unless the owlets can handle the whole prey items a male brings, they’re out of luck. I’ve seen a male offer a whole cedar waxwing to an owlet half its size, with no idea why the hungry owlet isn’t taking and eating it.

12:15 AM CDT – Injected a mouse into the nest box, to encourage Mme Owl to stay in the nest and brood the owlets, rather than go out hunting. Her reactions to mouse injections, at the risk of anthropomorphizing, run something like this: They start with "who dares disturb me," move to indifference (“I'm not even going to look at whatever just arrived”), then to “wait a second ... that looks familiar and interesting,” to “I must investigate it thoroughly and find just the right place to cache it,” to the final stage of “on the other hand, I could use it to feed myself and the kids.”

March 2112:11 AM CDT – Just injected a mouse into the nest box. Mme Owl hasn't realized what it is yet, so she’s still acting annoyed by the disturbance, rather than pleased by the mouse. The same thing happened the last time I gave her a mouse, so this isn’t surprising. (Several minutes later she decided to give-up on indignation and put the mouse to good use: she fed half of it to the owlets and herself, and set the rest aside for later.)

The motivation for giving her a mouse is that she’s gone out to hunt several times tonight, when, at a temperature in the mid- to upper-50s F, she should be staying in the nest to keep the owlets warm.

March 20 – Food deliveries haven’t been what they should be. I could supplement with enough mice to make Mr. Owl’s hunting problems irrelevant, but, without the “Bring food!” feedback from his mate, he might never do any better, and better is definitely going to be required in the future. So, providing too much supplementary food seems as bad as too little, maybe worse.

Supplementation aside, food deliveries are taking place, they’re just not the large prey that will feed Mme Owl and the owlets, while leaving some leftovers to tide them over during the day. Here’s one movie with two such food deliveries (MPEG-4, 123.4 MB): a gecko, and cricket (along with a strand of grass). All of the owlets are visible at the same time on several occasions, and Mme Owl was kind enough to face the camera throughout the feeding, so you can see how it’s done. (For one thing, it’s done with her eyes closed, because she can’t risk an eye injury.)

Photograph of egg, and sign reading “Ant Eviction – Don’t Panic.”
Egg no. 4 with cracks in shell indicating that hatching has begun.
All three hatchlings and egg no. 4 in hand.

March 186:38 PM CDT – Making-up for confiscating her cache of geckos this morning, I injected a mouse into the nest box via the entry hole. Mme Owl did not fly out in panic, this time. Instead, she stayed put on the floor with the owlets and merely raised her ear tufts in annoyance at the disturbance. She made no effort to examine the addition to her nest until some time later when she moved to the perch. Then she seemed to see it for the first time, and realized to her surprise what a treat had come out of nowhere.

4:19 PM CDT - Owlet no. 4 hatched successfully.

6:50 - 8:26 AM CDT - Mme Owl left the nest not long before dawn. Since I was still up and watching when she did that (having been attempting to nail down the details of laying and hatching times for the owlets), I rushed out to bring the nest box down, find-out where the ants were based, remove them, and make sure they didn't return.

Couldn’t find a nest anywhere. Nor was it evident from watching the ants where they were entering and exiting the box. In the end, I pulled out all the modules (roof, and both sides) to dust their sockets with Sevin-5 pesticide. Ordinarily, I don’t use pesticides, but to keep owlets safe, I’ve done it before, and will do it again. This stuff is what eliminated the first ant invasion the of the nest box a few years ago. No surface to which the owls or owlets is directly exposed was touched with the pesticide, but I hope that whatever pathway the ants were using is now lethal to them.

My friend Sallie, the raptor rehabilitator, recommended Sevin-5 for this purpose, telling me that when she receives birds in danger of dying from being covered in parasites, fire ants, etc. that are too numerous to attack and remove individually, she’ll actually dust the bird with this stuff, on the grounds that the parasites will kill it for certain, so anything that buys the bird a chance to survive, is better for the bird than the alternative.

Regrettably, I did have to remove a cache of four geckos (some partly eaten, some not), because I couldn’t be certain that they hadn’t been touched by any of the hastily applied Sevin-5 dust, so there’s no food in the box anymore. I’ll give Mme Owl a mouse later today, to make it up to her and the owlets. I could do it sooner, but I think she’s been through enough this morning. Although, until the songbirds woke-up and noticed her observing the box cleaning process from a branch about fifteen feet from where I was working, she was calm and made no protest; she just kept an eye on me, and, undoubtedly, listened to the owlet and egg sounds coming from the inside pockets of my jacket (owlets in one pocket, egg in the other). Unfortunately, as soon as a bluejay noticed her, she had to head for cover.

Having played Mme Owl to the owlets and the unhatched egg (some body had to keep them warm, since I don't happen to have an incubator lying around), I can say that the three hatchlings are strong, active and look perfect, and the egg is alive, peeping, and portions of its surface are cracked in promising ways. There was no hole, but I’m assuming the cracking is a step in that direction. The owlet weights are 20.9, 22.2 and 18.9 grams, ±0.2 grams. The egg is 15.1 grams, with the same margin of error.

Photos later, if any of them are worth a darn.

March 17 – Egg no. 2 hatched at 2:53 AM CDT, ±27 minutes. Egg no. 3 hatched not long afterwards, at 4:27 AM CDT, ±12 minutes. The three owlets appear healthy and strong.

As of its most recent appearance at 11:36 PM CDT egg no. 4 had not hatched.

Ants have been attracted in growing numbers to the nest by the food cache. The last time this happened they setup a nest in the attic camera compartment, so I’m concerned about that happening again. I’ve been waiting for a time when I was here and Mme Owl was gone to bring down the box and deal with the ants. So far, that hasn’t happened.

March 16Time Unknown – Egg no. 2 hatched. That happend sometime during the night of March 16/17, but on which side of midnight I can’t say yet. Details to be determined.

7:27 PM CDT – Sunset is officially at 7:41 PM CDT, and Mme Owl will be out of the box for a little while at some point afterward (as soon as it is reasonably dark, perhaps at 8:05 PM CDT, which is evening civil twilight), so viewers watching the time-lapse views (the attic view ought to be best) will have a good chance of spotting owlet no. 1.

5:20 PM CDT – Egg no. 1 has hatched successfully, and a hole has appeared in egg no. 2.

2:48 PM CDT – All four eggs are still intact. That is not a problem, however; hatching can take 24 hours. All the same, if egg no. 1 hasn’t hatched by sundown when Mme Owl takes her constitutional, I’ll probably bring the box down to get a direct look at the situation, re-weigh the eggs, etc.

4:47 AM CDTA hole in one egg was clearly visible (the dark spot on the bottom-right egg). From that starting point the owlet will cut away the egg shell. Its mother will not help it until is out of the shell, which, presumably, is a test of the hatchling’s viability. However, after that, she’ll do everything in her power to care for it.

2:45 AM CDT – The first sound of hatching was heard at one minute into this movie (MPEG-4, 31.1 MB) and again, more clearly, eleven seconds later. (Note Mme Owl’s sudden and consuming interest in what’s going on beneath her.) This is the peeping egg stage; the owlet hasn't escaped its egg, but is making sounds from within. It may, or may not, have already punctured the egg shell using the temporary egg tooth at the end of its beak.

March 15 – No hint of a hatch, but the first hatching ought to be due very soon, since we’re now (at the end of March 15th) beyond last year’s maximum hatch time.

On the plus side, for the first time in the cam’s history, the views from the attic camera are being made available live (long story - don’t ask). In some cases, the views from above may make it easier to get a good look at the eggs, and/or the (forthcoming) hatchlings.

And now, a movie (MPEG-4, 63.6 MB). This one features the delivery of a small gecko, some preening of the female by the male—a means, I believe, of trying to placate her about the food situation (alternately, if you consider placation too much to expect from an owl, think of it as a way of reinforcing a pair-bond stressed by hunger)—and ends, after a while, with Mme Owl doing some routine egg shuffling.

March 14 – Still no hatchings.

March 13 – As expected, no egg has hatched yet. So, the big news is that there’s no news. By way of consolation, good reader, have a movie (MPEG-4, 59.8 MB). It begins with the male delivering an apparently tailless gecko to his mate, and continues for a while as he sits on the perch making barely audible sounds that I normally associate with a mother screech owl encouraging her owlets to eat, even as Mme Owl begs for more food from below. Then the male leaves, Mme Owl does some preening, a little intermittent food begging, some egg rolling (the hunkered-down, shimmying), and the movie concludes with Mme Owl incubating calmly while making regular, but low rate, food begging sounds.

March 12End of Day Edition – No evidence of egg hatching today, which is not surprising; I haven’t even heard a peep sound, yet (that sound comes from an owlet, still in its egg, and starts about 24 hours before hatching). However, blog readers will have noted that I recently stated that hatching could occur tomorrow, March 13th (based on a 28 day incubation), while people reading this page will have noted that on February 24th, I estimated March 18th (based on bad math, as far as I can tell).

And so to some fresh number crunching, in which I show my work.

The age of the first egg was 27 days, 18 hours and 43 minutes, ±94 minutes, as of the local end of March 12th. If last year’s data is representative, we can expect hatching of the first egg around 30.6 days after it was laid.

Last year the gap between the laying of eggs no. 1 and 2 was 2 days, 15 hours and 23 minutes, ±117 minutes. This year it was 2 days, 13 hours and 45 minutes, ±55 minutes. I’d call that a remarkably close match that suggests last year’s data could be applicable, at least for this year’s egg no. 1. If the time from laying to hatching (30 days, 13 hours and 35 minutes, ±61 minutes) is also similar, expect hatching of this year’s egg no. 1 between 5:34 PM and 8:08 PM CDT, Friday, March 15, 2013. Of course, factors like the unusually warm winter Austin is having this year may move-up the hatch time, since the warmer weather could have provided some free, low-grade incubation even before Mme Owl began her own incubation work in earnest after the arrival of egg no. 3.

New viewers take note: Hatching is almost never seen, since it normally occurs beneath Mme Owl, and she is then in no hurry to leave the hatchling, because it cannot survive for long without her body heat (ambient temperatures are, as you would expect, relevant: if it is 100° F in the nest, Mme Owl can safely be away from her brooding duty far longer than if it is 40° F). So, even if you are watching the cam’ at the exact moment egg no. 1 hatches, you are unlikely to know it has happened.

The Cam’ Returns Edition – Two weeks of forced downtime have come to an end, just in time, I think, for the hatching of the first egg to be shared. My thanks to everyone who helped make this possible. The cam’ would not have returned without you.

Several people have asked if Mr. Owl’s hunting skills have improved during this time. The answer appears to be no. Food deliveries are still primarily caterpillars with a smattering of other insects, like grasshoppers. A few geckos may be delivered on the warmer nights when they are out and about, but I don’t believe Mme Owl is getting a proper diet, nor one well suited to the forthcoming owlets; there just aren’t enough vertebrates to, for instance, build healthy bones.

I am hoping that the first sight of a hatchling will kickstart whatever instincts (if prey selection has an instinctive component), or good judgement, Mr. Owl has been lacking thus far, and cause him to seek large (by screech owl standards) vertebrate prey.

If that doesn’t work, I have mice in my freezer. Of course, if I have to feed Mme and the kids, I’m going to want visitation rights.

February 24 – Four eggs and holding. Welcome to the dull phase of nesting, folks. If Mme Owl were going to lay one of the rare five or six egg clutches, an additional egg should have appeared by now, so I think we can safely conclude that we have a typical four egg clutch. From now until somewhere around March 18th, it'll be all brooding, all the time. Vital work, of course, but it doesn't make for the most riveting viewing.

Apologies for the lack of updates, recently. Life is being complicated, and, since the arrival of egg no. 4 there hasn't been much to say - Mr. Owl continues to specialize in caterpillars, with the occasional june bug and roach thrown in for good measure. Insects are easy, but a balanced diet requires vertebrates. So, that remains a concern. I can only hope that a month of listening to his mate beg for food will make Mr. Owl try (and try again) at capturing mice, and small birds. (Cedar waxwings are almost exclusively the only bird my generations of screech owls have hunted; presumably the large flocks in which cedar waxwings exist draw attention to themselves, and rules-out perfect cover for every member of the flock, unlike, for instance, a few isolated chickadees that can easily find deep cover, and draw little or no attention to themselves.)

By the way, I've been trying to nail down the time at which egg no. 4 was laid by reviewing the many snippets of video that were automatically captured the night it was laid. So far, I think I've spotted the moment the egg was laid, but can't prove it, because no unambiguous views of all the eggs — views that would definitely rule-in, or -out, a fourth egg — can be found anywhere near that time. I can currently say that my best guess is 8:05 PM, but, thus far, I can only say with certainty that it was somewhere between 7:53 PM and 11:51 PM. I should probably just accept that margin of error and move-on, but that seems to be against my nature.

February 20Egg no. 4 appeared sometime after sunset today. Details to follow.

February 18Egg no. 3 was laid today somewhere between 6:14 and 8:12 AM CST. Mme Owl has not begun brooding in earnest, yet, so she was absent enough on the night of the 18th/19th for me take down the nest box, photograph, weigh, and measure the eggs. I've designated them A, B, and C in the table below, because I have no idea which is the first, second or third egg laid.

Egg Weight ±0.2 g Major Axis Minor Axis
A 20.6 g 36.48 mm 32.53 mm
B 19.7 g 36.37 mm 32.14 mm
C 19.8 g 35.74 mm 31.79 mm

Food continues to be a problem, because Mr. Owl appears to deliver nothing but caterpillars, and Mme Owl spends long periods of time calling for more food with little effect. Far larger, and more nutritious, prey is available; Mr. Owl has to stop going for the quick and easy junk food, and start bringing big prey with bones; Mme Owl likely needs the calcium. That may be one reason why she hasn’t been consistently brooding at night even after the arrival of the third egg: she needs to go hunt for herself.

February 16 – An unusual day in as much as Mr. Owl decided to spend the day in the nest box along with his mate. This seems to happen most years, the day after the first egg appears. In this case, it wasn't until the second egg was laid.

Mme Owl has spent her nights outside the next box, so few food deliveries have been caught on camera. All of those that have been caught have involved caterpillars, which are easy to catch, but it would take an awful lot of them to fill the belly of one screech owl, let alone two. So, I suspect a lack of hunting skill from Mr. Owl, in which case, he’s definitely not the same male who was present last year, and he’s probably only about ten months old.

He clearly needs to improve and quickly; his arrival in the nest box was greeted with feed me calls from his mate, and she persisted in such calls for most of the rest of the day. I think she had an important point to make.

February 15Mme Owl returned to the nest at 6:46 AM CST. Prior to that time, her mate made several unsuccessful attempts to deliver caterpillars to her in the nest box.

She spent part of the noon hour on the perch again, but only for four minutes. At all other times, she was on top of the egg, but not in a brooding posture.

By 6:25 PM she seemed interested in leaving the nest for the night. She exited at 6:39 PM and returned at 6:43 PM. There was a good reason: Egg no. 2 was laid sometime between 6:44 PM and 7:19 PM CST, I’ve never seen a screech owl laying an egg, so I have no idea what the process might look or sound like to an independent observer, or even how long it might take. Nonetheless, after reviewing the video captured during that time period that, I’m confident that some vital part of the laying process occurred at 7:13:59 PM CST. The video segments captured during that time are linked to below. See what you think.

  1. MPEG-4 movie (63.9 MB) from 6:43:52 – 6:48:06 PM CST
  2. MPEG-4 movie (64.7 MB) from 6:51:58 – 6:56:07 PM CST
  3. MPEG-4 movie (63.7 MB) from 6:56:15 – 7:00:29 PM CST
  4. MPEG-4 movie (63.5 MB) from 7:05:12 – 7:09:26 PM CST
  5. MPEG-4 movie (62.6 MB) from 7:13:54 – 7:18:03 PM CST
  6. MPEG-4 movie (63.5 MB) from 7:18:47 – 7:22:55 PM CST

Video recording is triggered by significant motion, therefore the gaps between these consecutive recordings represent periods during which Mme Owl moved little.

She stayed with the eggs until 8:27 PM, left for seven minutes, stayed with the eggs again until 8:55 PM, and then she left the nest for the evening.

February 14Mme Owl returned to the nest box at 5:58 AM CST, and remained there until leaving for the night at 6:41 PM CST. Apart from a roughly forty minute period on the perch during the noon hour, she spent nearly all of her time in the nest not so much brooding egg no. 1, as standing over/near it. This is consistent with her instinctive desire to delay development of the first egg or two in order to reduce the time between their hatching. True brooding will probably not begin (apart from times of dangerous cold) until the second or third egg has been laid.

February 13Mme Owl left the nest box at 1:37 AM, shortly after receiving a food delivery from her mate. Because her behavior suggested that nesting might start early, and the first egg could even be imminent, I used the opportunity to perform an hour and forty minutes of maintenance - once again trying to do something to make the audio hum go away, replacing last year's bedding material with fresh pine shavings, replacing a few of the internal slats that squirrels had removed years ago, and adding a few coats of paint to portions of the exterior that needed touching-up after 10 years of Central Texas weather.

Mme Owl returned to the nest box about twenty seconds after I'd put the nest box back in the tree, and returned to my house, then she promptly started making a depression in the wood shavings for forthcoming eggs. Egg no. 1 was first sighted at 6:49 AM.

She brooded the egg until 12:18 PM, then more-or-less returned to brooding from 2:04-5:57 PM, a period during which she seemed to make no special effort to keep the egg warm.

She left the nest at 7:09 PM, and had not returned by midnight.

Pre-season activity reports can be found on my blog.

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