Previous News 2002

March 18 - Following the evening's delivery of two supplemental mice, the female began feeding one of the mice to the owlets. During this feeding, the male delivered a gecko which the female passed to one of the owlets. Shortly after the male left the box, the female ceased feeding the owlets, and paused for a little while. She then picked up the mouse, and left the nest box. When she returned nineteen minutes later, the mouse was not with her. She consumed a few pieces of the remaining mouse and then resumed feeding the owlets. While nothing certain can said about the what happened to the first mouse, it's tempting to believe that she took it outside to share with her mate.

At 5:36 AM CST, the female brought some substantial prey item to the owlets. Though at first I thought this was a small bird, the presence of what appears to be a tail in some subsequent frames makes identification uncertain. If it's a mouse, it was rather small, and unusually light in color.

At 6:26 AM CST, the female returned to the nest box after bathing in the light rain that was falling. Screech owls are not at their most handsom when wet, as soaked feathers hint at a screech owl secret: how little owl there really is under all those feathers. As this frame hints, the normally full, rounded head of otus asio is an illusion of feathers; the actual head does not extend nearly so far back as one would think, even less so, in fact, than this frame suggests.

No other pre-dawn absence. First sparrow visit occurred around 11:20 AM, hours later than usual. Is the sparrow's enthusiasm for building nests dampened when the would-be construction materials are likewise dampened? There were few additional visits. Post-sunset absence one hour, temperature 75 degrees. Delivered two mice at 11:35 PM.


March 17 - No pre-dawn absence. For a change, the female seemed bothered by her house sparrow visitors this morning, and on several occasions she sat, briefly stood, guard duty in the entryway. Apparently this gave the sparrows pause for thought, because they didn't return. Post-sunset absence 40 minutes, temperature 68 degrees. At 8:06 PM CST, the female took the remnants of the last mouse from the previous night and left the nest box. In the light of the behavior observed on March 18th, it is also tempting to believe that she took this (partial) mouse to her mate, since, if her intent were merely to eat it herself, she didn't have to leave the box. The male delivered a gecko to the owlets eleven minutes later, by the way. That was just one of many geckos delivered this night. The most interesting thing about the gecko deliveries is that it shows that the owlets devote very little thought to their eating. While it seems typical of adult owls that they swallow their prey head first (even if they've already removed the actual head), the owlets routinely get it wrong and swallow the lizards tail-, or, more awkwardly still, middle-first.

The female is now spending a lot of her time each night outside the box, presumably hunting for the owlets. The youngest owlet has reached the age of ten days, and Gehlbach reports that eastern screech owls develop the ability to thermoregulate (control their own body temperatures) by the time they are 10-12 days old, so this change in the female's behavior is happening just when one would expect.


March 16 - No pre-dawn absence. Sparrows spent the day dropping nest material into the box. Post-sunset absence 21 minutes, temperature 65 degrees.


March 15 - No pre-dawn absence, although the female did slip out about an hour before sunrise to have a bath. Plenty of sparrow visits during the day. Peak daytime temperature was in the low eighties. Post-sunset absence 17 minutes, temperature 70 degrees. The female returned with a good-sized moth which she presented to one of the owlets. Throughout the hour before midnight, the male made rapid-fire food deliveries. All items were small, like caterpillars, but the level of activity was impressive. As usual, added two mice to the box to ensure the food supply would remain adequate.


March 14 - The owlets are now 10, 9 and 8 days old, so it's time for another set of photographs.

Acquired a fresh supply of large mice that should provide supplemental feedings for the owlets until they are old enough to leave the nest box. Thanks Sallie.

Pre-dawn absence of seven minutes, temperature 64 degrees. Very numerous sparrow visits during the day, during which the sparrows dumped quite a bit of nesting material on top of the female owl and her owlets. Exactly how the sparrows think this is going to help them is a mystery to me, and probably to them, as well. Peak daytime temperature was somewhere around 85 degrees. Post-sunset absence of 38 minutes, temperature 77 degrees. During her absence the male made two food deliveries direct to the owlets.


March 13 - At 6:03 AM CST the male appears to have delivered a small bird. No pre-dawn absence. House sparrows continue to drop bits of nesting material into the box, though they won't descend to its floor or perch. The female owl watches all this activity, but doesn't appear much concerned by it. Daytime nest box temperatures are reaching the mid-80s, so the kids are spending less time under mom, although they almost always remain in contact with her. The female spent portions of the late afternoon sitting in the entryway, apparently having had one too many sparrow visits for one day.

Post-sunset absence of 53 minutes, temperature 75 degrees. About 15 minutes into the female's absence the male showed-up with a large gecko which was promptly swallowed by one of the owlets. Taking advantage of the warm nightime temperatures, the female ventured outside the box repeatedly.


March 12 - No pre-dawn absence. Starlings are investigation the box again, along with the house sparrows. It's like a conspiracy of introduced species. As the afternoon arrives and temperatures in the nest box climb into the neighborhood of 80 degrees, the owlets crawl out from beneath mom to find a cooler microclimate. All the owlets are now able to open their eyes, at least a little. They don't do it very often, or for long, however. Post-sunset absence of 11 minutes, temperature 78 degrees.

Movies illustrating owlet feeding behavior are now available in QuickTime format. The large movies measure 480x705, and the medium 240x352.


March 11 - Pre-dawn absence eight minutes, temperature 52 degrees. The box was plagued well into the afternoon by birds that appear to have been house sparrows. The birds went as far as bringing a small amount of nesting material into the box and dropping it onto the female owl. Throughout all of this, however, the birds were not willing to descend to the floor of the nest box, or even to the perch. Apparently, while they lack the sense to stay out of the box, they have a suspicion or two about the big bird sitting on its floor. Like starlings, house sparrows are a European species which distinguishes itself from our native birds by being extremely aggressive, and both appear to lack the instinct of our native, non-migratory song birds to fear, and drive-away (mob) owls whenever encountered. The absence of this instinct seems odd to me, given that Europe has plenty of owl species, including the Little Owl which is similar in size to the eastern screech owl. As I've thought for some time, one of the basic problems with this pair of screech owls is that they aren't eating enough house sparrows and starlings. If the matter could be put to our other native cavity nesting birds, they would surely agree.

The female's post-sunset absence lasted eleven minutes, with the nest box at a temperature of 62 degrees.

Two mice were added to the box shortly before 1 AM on the 12th. (Running late again.) Once the female returned, she seized them immediately, and with a great singlemindedness, as though she'd been waiting anxiously all night for those mice. The male routinely makes food deliveries, but the prey is consistently small, about one good owlet mouthful.


March 10 - No pre-dawn absence. Near continuous starling visits until 2 PM, though none entered the box. Post-sunset absence 6 minutes, temperature 57 degrees. Added two mice at 11:40 PM CST. The female returned to the box seven minutes later.


March 9 - The two largest owlets can now handle whole prey as large as geckos. This was illustrated nicely at 3:15 AM CST, while the female was temporarily out of the box. The male arrived with a large gecko and offered it to the nearest owlet. Unlike his experience with the grasshopper three days ago, this time an owlet took hold of it and promptly began swallowing it. This may well be the first time this year he's been able to directly feed any of his offspring.

At 5:16 AM a cold front passed through the area, accompanied by a line of rain. It wasn't enough rain to end our local dry spell, not by a long shot, but it was enough to motivate the female to leave the nest box. She came back twelve minutes later after - what? - bathing in the rain? Getting a drink? Satisfying herself that the racket it made as it fell on the metal roof of the nest box was harmless? I wish I knew.

No pre-dawn absence. Starlings poked their heads into the box in the morning, but did not enter. Post-sunset absence 11 minutes, temperature 58 degrees.

It had been five days since the nest box was taken down to photograph the first hatchling on its birthday, and that meant it was time for new photos. I brought the box down at 10:30 PM for fifteen minutes. The female returned minutes after the box was restored to the tree, finding her family none the worse for the wear, and two mice added to the box to ensure that she and the owlets would eat well for yet another day. For his part, the male showed-up almost immediately to deliver a caterpillar, which has been his major prey item this evening.

The two oldest owlets are sufficiently similar in size that I can't tell them apart. As the photos above show, there is still a considerable difference between them and the yougest owlet, which is only three days old.

An examination of the remaining egg revealed an area of shell crisscrossed by fine cracks, but in no place was the shell punctured. It looks as though the would-be owlet died in the earliest stage of hatching. This 75% hatching efficiency is generally consistent with Gehlbach's study, so this outcome may be taken as normal.


March 8 - At 4:52 AM CST, the male delivered a sparrow to his mate. The customary tussle for ownership of a large kill took place, and the female ended-up in possession of the prey, as is normal. I wonder if these tussles serve as a means for each of the adults to gauge the hunger of the other and thus their relative need to take possession of the kill. One way or another, the male appears to give his mate the right of first refusal, and I haven't seen her refuse yet, even when she already has a store of mice and geckos accumulated in the nest box.

No pre-dawn absence. Starlings stuck their heads into the box in the morning, but did not enter. Post-sunset absence was 43 minutes, at a temperature of 74 degrees. It is the warm weather that makes such absences a possibility for the female. In colder weather she wouldn't be able to leave the owlets for a significant period until they were 10-12 days old, the age at which they acquire the ability to regulate their own body temperatures (thermoregulate).

Running a bit late, this night's delivery of supplementary mice didn't take place until after midnight on the 9th. To the owls and me, it's the same "day", of course. In a new wrinkle, the female left the box a minute and half before I inserted the first mouse. She returned eight minutes later, with the nest box at a temperature of 73 degrees.


March 7 - No pre-dawn absence. Post-sunset absence of twenty minutes, temperature 73 degrees. Warm nights, and warmer days, have seen the female doing what is called, if memory serves, "gullar fluttering," which is the owl equivalent of panting. You'll see her sitting with her mouth open at these times. What you won't be able to see is that her throat flutters back and forth, alternately drawing in, and expelling, air to cool her body. I'm surprised to see that an owl that has lived in Austin's climate all its life finds the seventies the slightest bit uncomfortable, but perhaps the relatively still air inside the nest box is the reason for that.

I placed two mice in the nest box at 11:39 PM CST. The female still dislikes the disturbance enough that she leaves the nest box when I do this, but lately she's been staying in the nest box until after the first mouse is delivered. I give her ample warning that I'm coming, and even knock gently on the side of the box with the mouse dropper before inserting the first mouse, so my presence is in no way a surprise. (In fact, she goes on alert anytime she hears my back door open.) Does her lingering during mouse delivery mean that she's adjusting to the deliveries, but can't overcome her distrust of people? If so, that's just as well; it's generally a mistake for any wild animal to become too trusting of people, given the wide variances in people.

She returned to the box after six minutes, temperature 63 degrees. She promptly began placing hunks of mouse in the mouths of the waiting, still blind, owlets who struggle to sit upright at, and between, her feet to receive the morsels of meat, sinew, bone and fur that are critical to their nutrition and digestive health. The owlets flap their stubby wings rapidly in ethusiastic anticipation of each mouthful. (I'd love to provide a movie of this, but the female has a knack for turning her back on the cameras whenever I'm trying to record such a movie. I'll keep trying.)


March 6 - The third egg hatched sometime today, one possible time is 12:36 PM CST, but there's no way to be sure. There was no pre-dawn absence, and there were no recorded starling incursions. Post-sunset absence of 25 minutes, temperature 73 degrees. While the female was gone, the male attempted on three separate occasions ([1], [2], [3]) to deliver a large, winged insect, probably a grasshopper, to the owlets, and couldn't understand why none of them would take it. Male eastern screech owls lack the instinct to tear-up large prey items and to place the pieces in the mouths of the owlets. They only know how to delivery whole prey, and in the first two and half weeks or so, that's usually more than the owlets can handle. The other food deliveries of the evening seemed to be good-sized geckos. Shortly before midnight, I delivered two mice.


March 5 - The second egg hatched somewhere between 4:15 and 4:25 AM CST. Nest box temperature dropped to 32 degrees overnight. No pre-dawn absence. Starlings repeatedly stuck their heads in the box in the early daylight hours, but did not enter. Post-sunset absence 5 minutes. At least one of the owlets is already exploring beyond the bounds of its mother. The male mostly delivered geckos and caterpillars. I delivered two mice at 11:38 PM. The female, well aware of my presence, didn't choose to leave until the first mouse was inserted. She returned four minutes later, and moved the mice into separate corners. She consumed the smaller mouse around midnight. If you have QuickTime installed, you can listen to a recording of vocalizations from the two hatchlings, but you'll probably have to turn-up the volume on your computer quite a bit to hear them.


March 4 - Pre-dawn absence of 2 minutes, nest box temperature 24 degrees. No starling visits. The first egg began hatching in earnest at 1:53 PM CST, and the entire hatching process seems to have been concluded within ten minutes. The female consumed the egg shell during the remainder of the afternoon thereby reclaiming the calcium and other key materials she'd originally used to make it. Post-sunset absence of 4 minutes, temperature 59 degrees.

The male must have learned of this first hatching when he delivered his initial food item of the night, a caterpillar, at 6:59 PM. He probably didn't get a look at the hatchling, but he lingered longer than usual, possibly listening to it.

At a little past eight PM, I brought the nest box down for the first time since nesting began. Disturbed female screech owls will sometimes abandond their eggs, but will never abandon owlets, so this was the first safe opportunity to do so, and, of course, I wouldn't want to miss an opportunity to photograph the first hatchling of the year on its birthday.

With the box down, I was able to replace the side camera compartment glass that I'd thought was fractured. It turned-out that the "fracture" lines were actually some sort of gunk that'd been distributed in a few long lines across the glass. The identity of the gunk is a mystery to me. In any case, at that point it was quicker to change-out the camera compartment glass than to clean it, so a spare pane was installed, providing a strange view of yours truly, and the compartment was restored to the nest box. During this time the hatchling and the eggs were covered with a wash cloth to help them retain their heat.

Once the camera compartment had been dealt with, the three remaining eggs were candled, revealing that all the eggs have been developing. Several of the eggs were intermittently "peeping" (really more of a squeeking noise, IMHO) which indicates that they'll be hatching in the next 24 hours. One was already in the process of hatching; you can see that the hatchling-to-be had begun to break through the egg shell using its egg tooth. Finally, the one hatchling was photographed. It was vigorous and frequently vocalized, and preferred sitting in a warm hand to sitting in a cooling nest box. By the way, its egg tooth is the tiny lump in the middle of the small white spot near the end of its beak. It is the tool a would-be hatchling uses to begin cutting through the shell of its egg, and disappears in the first week or two as the owlet grows.

With all the servicing and photography complete, I added some insulation to the floor beneath the owlets in order to prevent drafts from reaching them through the large drainage holes in the bottom of the box, added two mice to the box, and hoisted it back into the tree. The female must have watched the entire process from very nearby, because she was back in the nest box, incubating and checking-out her mice before I'd made it back to the house, which was a first for her.


March 3 - No pre-dawn absence. Nest box temperature dropped to 27 degrees overnight. No starling visits. Post-sunset absence 16 minutes, temperature 43 degrees. When she left, she took along what remained of one of the two birds delivered the previous night, and did not return with it. While she was outside, I observed her meet her mate in a nearby tree.

Breaking with recent tradition, upon returning to the nest box after the evening's mouse delivery, the female remained there to consume the mouse. Her strategy in consuming the mouse was to tear off and eat a portion of the front end, then attempt to swallow the rest, and after several minutes of effort, she'd give up and use one foot to pull the mouse out of her mouth. She'd then eat a bit more of the front, and try again. Reducing the mouse to a conveniently swallowable state required about four such iterations.


March 2 - Part 2 - No pre-dawn absence. No starling visits. No post-sunset absence. At 8:24 PM CST the male delivered his third large prey item since nesting began, a small bird. He was not anxious to relinquish the kill outright, apparently he'd hoped to share it. The female was having none of that, and a scuffle ensued. The male kept hold of the bird and left with it, followed about two minutes later by the female. He may have been standing on the owlet rail on the front of the box and feeding her pieces as she sat in the entryway. Or not. In any case, she left the box entirely for eight minutes and when she returned she was carrying the remains of the bird.

At 9:36 PM I dropped a mouse in the box. It was already defrosting when the male delivered his bird, so the female was just going to have to put up with a temporary food surplus. Screech owls will keep food caches, so this is nothing new to them. Two minutes after leaving the next box, the female came back to collect the mouse, and then left again for 15 minutes, with the nest box temperature at 34 degrees. She returned without the mouse, presumably having eaten it in bits and pieces at some peaceful, favored perch in the neighborhood.

Two minutes before midnight, the male delivered the fourth large prey item since nesting began, another small bird. This suggests that his hunting skills have matured considerably in the last week. Once again, there was a scuffle for possession of the bird, and this time the female won. A minute later she left the nest box with the bird. She returned three and a half minutes later carrying the bird, and with a few of its feathers sticking to her beak. Presumably some of its was shared with her mate, but the scuffles for possession of these last two large prey items suggest that while the male is anxious to fulfill his duty to feed his mate, in doing so he is going hungry to some extent.


March 2 - Part 1 - I was running a bit slow, so the March 1 supplemental mouse delivery didn't take place until almost 1 AM on the 2nd. The female became alert as soon as she heard me fumbling about in the garage for the stepladder and mouse dropper. It took her three seconds to clear the box after I knocked on it with the dropper, amazingly slow compared to her performance on the 28th. Hopefully she's beginning to adjust to this routine disturbance. She returned four minutes later, having satisfied herself that I'd closed-up the garage and gone back to the house, and therefore wouldn't be abusing any more owls this night. She stayed at the box just long enough to see that her eggs were intact and to collect the mouse before leaving again. She came back to the box and resumed incubation 14 minutes after that, with the nest box at a temperature of 58 degrees.

Still haven't heard a peep out of the eggs as of 3:56 AM, which suggests hatching must be at least a further 24 hours away.


March 1 - No pre-dawn absence. Starlings entered the box during the morning, but the female convinced them to leave. Post-sunset absence of only 7 minutes, temperature 62 degrees. Something about a food delivery from her mate that occurred two minutes later persuaded her to leave the nest box for a further two minutes. Not sure what that was about, though I've seen it before. Misting rain continues, and food deliveries are few and far between; there were only about five from sunset to midnight. That's the second lowest number seen since Feb. 13th.


February 28 - No pre-dawn absence. The female appears to have had to eject one starling from the box this morning. Post-sunset absence lasted 40 minutes, concluding at a temperature of 52 degrees. A mouse was placed in the nest box at 10:06 PM CST. This time I knocked on box with the mouse dropper before attempting to insert the mouse. This gave the female a chance to flee without the dropper obstructing the entryway. She took advantage of the opportunity, clearing the box a mere two-thirds of a second after I knocked. She returned 13 minutes later, staying only long enough to collect the mouse and exit the box again. She returned 16 minutes later without the mouse, and resumed incubation after a further two minutes. Nest box temperature was 50 degrees. The male managed only about 12 food deliveries on the night of 28/1, and all seem to have been small items; those that could be seen were all caterpillars. The misting rain that fell throughout would have done him no favors in locating larger prey since animals like mice make less sound moving over wet ground cover than dry.


February 27 - Part 2 - The temperature dropped to 22 degrees in the nest box on the night of February 26/27. There was no pre-dawn absence. At 8:01 AM the female swallowed the mouse her mate had brought at 1:16 AM, a sight that may have given a starling that had invaded the box shortly before good reason to reconsider its presence there, as it did not return. At 9:45 AM she swallowed the white mouse I'd provided shortly after midnight.

The female's post-sunset absence lasted 22 minutes, temperature 51 degrees.

At 10:44 PM I inserted a mouse into the nest box. I'd hoped that doing so would startle the female less than it had the previous night, but she was as desperate to escape the nest box as before. On this occasion, however, one of her wings struck the glass of the side camera compartment hard enough to crack it. There's no evidence that she was injured, as she had no trouble flying away from the box, and the recording of the event does not include the kind of loud impact sound one might expect from this description of the event. Still, although she needs the mice to supplement her diet, and will need them even more if/when the eggs hatch, this was much too close a call for my peace of mind. In future, I'll try not to let the mouse dropper project into the nest box. Instead I'll try to drop them in the entryway. She'll find this disturbing, to be sure, but it should look less threatening than something projecting all the way through the entryway and into the box.

After she left the box, she waited four minutes before returning, and spent a further minute in the entryway carefully inspecting the interior of the box, including the camera compartment glass, before going inside. She stayed only a moment to collect the mouse, then left again. She returned twenty minutes later, presumably after eating the mouse at a favorite (and safely distant?) perch. While she was away, her mate showed-up to deliver a caterpillar. He paused to call for her, then left. Between sunset and midnight he managed to make only about ten food deliveries, and all appear to have been very small items like caterpillars. It's not enough, but it is the most he's managed in that same period since the 24th, so maybe the food situation is improving a little. (Food deliveries between midnight and sunrise have been far less numerous: 4 on the 27th, 4 on the 26th, 6 on the 25th, 10 on the 24th, 4 on the 23rd.)

By the way, the camera compartment glass can easily be replaced in three or four minutes, as soon as I can safely open the box. However, that won't be until the first egg hatches, or a determination can reasonably be made that the clutch has died and would therefore be in no danger from abandonment.


February 27 - Part 1 - Shortly after midnight, I returned to insert the second mouse, which the female had elected not to take from the top of the step ladder sitting beneath the nest box during the ten minutes she spent outside the box as a result of my highly disturbing insertion of the first mouse.

She left the box even quicker the second time, but returned quicker, too; she was back in 90 seconds. This time she was faced with a white mouse, something that often confuses wild raptors, because they do not encounter them in the wild, at least not around here. The white mouse did receive some careful study, but it looks like she figured-out what it was. She finished the first (gray) mouse, and carefully set aside the white mouse for later.

Adding a touch of irony to the night, at 1:16 AM the male arrived at the nest box to deliver a mouse he'd just caught. It is only the second large prey item he's delivered to the box since nesting began 26 days ago. If he'd been able to deliver such a meal the previous night, or even six and half hours earlier, before the female began the previous evening's extended absence in order to hunt for herself, their eggs wouldn't have been placed in jeopardy.


February 26 - No pre-dawn absence. Post-sunset absence of 4 hours, 32 minutes, during which time nest box temperature descended from 43 degrees to 34 degrees. This prolonged absence is certainly a response to a severe and worsening shortage of food for five days running. Unfortunately, at this late stage of fetal development, the temperature drop experienced by the eggs may lead to birth defects, or may have already killed the fetuses. Her instincts clearly told her not to leave the eggs under these conditions, so she avoided doing so during the previous four days, but with increasing difficulty. Today, hunger finally left her with no choice but to leave her eggs so that she could hunt for herself.

As her absence dragged-on it became clear to me just how desperate she must be, and how serious this could be for the eggs, so I drove across town at 9:30 PM to collect a stock of frozen mice from Sallie (helping her band the five-week-old Otus asio owlet was I there), then came home to defrost a few mice and rig some kind of device that would allow the mice to be placed into the nest box, so there'd be no doubt of her receiving them.

With my mouse manipulator built and attached to the end of a long pole, I dropped the first mouse in the entryway of the nest box. This gesture was not appreciated by the female, who had returned to the nest box while I was still on the other side of town. She leapt out of the nest box in fear of her life, ignoring the dead mouse she passed in the entryway. She flew to a branch in the nest box tree to watch me, with my pole, climb down off the stepladder on which I'd been balancing in order to make the end of the pole reach the nest box entryway. I held up the second defrosted mouse by the tail to show her that there were mice available for the taking, then placed the mouse on top of the step ladder and retreated to the house. Two minutes after she'd fled the nest box in a panic, she flew to the owlet rail on the front of the box and slowly drew the mouse out of the entryway. Seven and a half minutes after that, she re-entered the box cautiously, carrying the mouse in one foot, and resumed incubating the eggs. She consumed the mouse a bit at a time over the next twenty minutes, until shortly after midnight.


February 25 - Pre-dawn absence of 16 minutes, temperature 64 degrees. Post-sunset absence of 26 minutes, temperature 70 degrees. Food deliveries have been in decline for the last four nights. The female is showing increasing displeasure with her situation, and the male is fast running out of time to improve his hunting skills, since the first egg may hatch as early as this Thursday, February 28. His incubating mate can afford to be short on food from time to time, but hatchlings are another matter.

Sallie, the local raptor rehabilitator, called to tell me that she'd just received a five-week-old Otus asio that was found sitting in a street in east Austin. That means the owlet hatched around January 24, and was laid as an egg somewhere around December 27. My pair of owls really did start nesting ridiculously early, but at least one pair of Austin owls has them beat, hands down. (Generally, screech owls lay their first egg about a month before the local start of spring.)


February 24 - Pre-dawn absence of 10 minutes, temperature 47 degrees. Post-sunset absence of 29 minutes, at 73 degrees.


February 23 - Pre-dawn absence of 6 minutes, temperature 38 degrees. Post-sunset absence of 38 minutes, at 70 degrees. Nothing special going on.

Today, the refurbished and upgraded prototype of this nest box was installed and made operational at the Austin Nature and Science Center. Here's wishing the folks there the best of luck in attracting a breeding pair this season.


February 22 - Pre-dawn absence of 6 minutes, temperature 48 degrees. Post-sunset absence 22 minutes, temperature 65 degrees. The picture of the day shows the delivery of a moth.


February 21 - Pre-dawn absence of 27 minutes, temperature 53 degrees. Starlings did not enter the box, but did stick in their heads. Post-sunset absence of 31 minutes, temperature 62 degrees. The picture of the day shows the delivery of a caterpillar.


February 20 - Pre-dawn absence of 20 minutes, temperature 57 degrees. Starlings entered the box repeatedly during the first several hours of the day. The female ejected them all, but made a point of staying on top of her eggs while doing so, which must have limited her effectiveness. Peak daytime temperature was 83 degrees. Post-sunset absence was 29 minutes, temperature 74 degrees. The picture of the day shows the male delivering a food item, probably a gecko, to the female.


February 19 - Pre-dawn absence of 16 minutes, including a brief return to the box in the middle. Temperature was 68 degrees. No starling visits today. Peak daytime temperature was 82 degrees. Post-sunset absence of 21 minutes, nest box temperature 75 degrees. No large prey. No excitement of any kind. My favorite picture of the day shows the female demanding food from the male. She repeated this gesture again before he left. This suggests to me that either he arrived without food, or with a small item that did little to satisfy her need for a good breakfast to start the night. Lately, there have been a good number of occasions when he has arrived on the outside owlet rail, or perhaps somewhere else nearby, but not entered the box to deliver the food he is carrying. On these occasions she has had to invest some time in calling him into the box to make the food delivery. I don't know what to conclude from this. The good news is that the female's drawn-out, plaintive hunger cries from the early weeks of nesting ceased about a week ago. I'm certain she'd still appreciate more food, but apparently the food supply has reached an adequate level for the time being.


February 18 - Pre-dawn absence of 33 minutes, temperature 62 degrees. Starlings examined the box from the entryway during the morning, but don't appear to have entered. Post-sunset absence of 21 minutes, temperature 70 degrees. Conditions have been mild and quite windy.


February 17 - Family portrait night. After entering the box with a food delivery, the male made the mistake of trying to return to the entryway by going behind the perch. This is possible, but the gap is only two inches, so it's a bit of a squeeze, and the struggle left him, it seemed to me, in the mood to pause and regain a bit of his dignity afterward. Thus was created the rare opportunity to catch a clear image of both owls at the same time.

The female's pre-dawn absence lasted only 13 minutes, and her post-sunset absence was 40 minutes.


February 16 - The male provided the most compelling demonstration yet of his hunting prowess when he brought a cedar waxwing to the female at 6:26 AM CST. This first large prey item was well received, and a few minutes later she left the nest box with it. Perhaps they shared the kill, or maybe it's just more convenient to eat something like that outside. Twenty eight minutes later she returned with the leftovers. By 5 PM she was hungry again and spent fifteen minutes finishing-off the cedar waxwing. Having been well fed, the left the box for only four minutes following sunset.


February 15 - Pre-dawn absence of just 16 minutes. Starlings entered the nest box during the day, for the first time since the 12th. They provoked little response from the female, who never left her eggs, but they only entered on a few occasions, so it may not have been worth her trouble to do respond. Post-sunset hunt of one hour, sixteen minutes. Nest box temperature had fallen to 60 degrees at the time of her return. Later, she left the nest box for 13 minutes returning at 9:28 PM CST.


February 14 - No pre-dawn hunt. Post-sunset hunt lasted two hours, twenty two minutes. Ambient nest box temperature had dropped to 60 degrees by the time she returned. Starlings probably stuck their heads into the box, but they didn't do so often enough to be caught on camera. There's no indication at all that they entered the box. Remarkable.

Nighttime temperatures were high enough to make geckos available again.


February 13 - No pre-dawn hunt today. No post-dawn starlings, either, which is extremely surprising to me. Starlings are aggressive creatures, and are not inclined to learn from their mistakes, in my experience. Madame owl earned herself a well deserved rest with yesterday's vigilance, and I'm pleased to see that she received it. I don't think this good fortune will persist for long, however. Unless, that is, she did a bit of starling hunting during her early evening outing yesterday. One terrifying, undeniable brush with death is usually what it takes to get through to a starling.

Tonight's early evening hunt lasted 5 hours, 47 minutes, and once again concluded with the nest box temperature at 50 degrees.


February 12 - No pre-dawn hunt today. Starlings invaded the box for the first time since she ejected one on the 6th. Remarkably, after ignoring the starling comings-and-goings for 45 minutes, she left the nest box for almost two minutes starting at 10:00 AM CST. When she returned she spent eight minutes sitting on the perch inside the box. From there she moved to the entry hole for a while, then left the box again, this time for a minute and a half. On returning she spent a further seven minutes in the entryway, then left for the third time for forty minutes. It was 60 degrees Fahrenheit in the nest box at the time, so I'm guessing her absence didn't pose a problem for the eggs. After returning she spent ten minutes on the perch and then 13 minutes in the entryway. At 11:36 AM she left for a further 39 minutes. For the rest of the afternoon she adopted an unusually upright brooding posture, which I suspect was intended to place her in a better defensive position than the normal beached-hovercraft posture. Starlings began cautiously investigating the box again at 4:30 PM and were soon inside. The female didn't react immediately, but after 15 minutes of this became agitated again. She must have done something at that point because the starlings stayed away for the next 12 minutes, and don't appear to have had the nerve to come back inside for the rest of the day. By 5:30 PM she was on watch in the entryway again, but minutes after she returned to brooding, the starlings were poking their heads into the entryway yet again.

I hope she concludes from all this that a little daytime hunting could solve her two most pressing problems at the same time. However, screech owls depend on stealth when hunting - they quietly sit and watch, and listen to, an area from a favorite hunting perch, and once some unsuspecting creature has given itself away, they swoop down fast and completely silent, grabbing their prey at about the same instant it discovers it was being hunted. Dogfighting starlings in broad daylight is a very different proposition, and does not play to Otus asio's traditional strengths.

I've never seen one of my screech owls offer anything remotely close to a defense as vigorous and sustained as this in response to provocation by starlings (last year the starlings actually built a nest on top of the female as she incubated her eggs [see the images, or see the QuickTime movie]). I must say after seeing this that I've never had more confidence in a screech owl's ability to cope with the challenges of nesting and raising her young. Which is a relief, because she is certainly faced by significant challenges this year. (All of this suggests previous experience to me, and leads me to wonder if she is the same female who nested here last year, now older and wiser.)

At 6:16 PM CST she left the nest box for her, now traditional, early evening hunt, perhaps relieved to be back in her own element again. She returned after six hours. The temperature inside the nest box had dropped to 50 degrees.


February 11 - No pre-dawn absence. Her post-sunset absence was 4 hours 30 minutes. As with her other extended absences, this one confused her mate when he came to the box with food only to find it empty. Around 10:30 PM CST he could be heard clearly as he sat in a tree near the nest box and called for her. It's possible that the reason he isn't acquiring large prey items is that so many of the best candidates are maintaing a low profile during the cold nights. (The thirties are cold by Austin standards; those of you facing three feet of snow will just have to make allowances for we creatures of warmer climbs.) For instance, house sparrows, which visit my bird feeders in groups of fifty or so every day, would make fine owl meals, but are probably spending their nights in tightly packed groups in the most sheltered roosts they can find, and are therefore nearly immune to attack by a screech owl. Geckos, nocturnal lizards that, while small, have been a mainstay of previous years, are in a state of temperature-induced torpor deep in their favorite nooks and crannies, and the local population of blind snakes is probably in a similar state. (It is a complete mystery to me how the male was finding earth worms last week; I'm truly hard-pressed to imagine him digging for them, but, on the other hand, I don't believe they would have been emerging from their burrows in these temperatures.) Even the neighborhood mice -- first-rate prey for screech owls, and nocturnal to boot -- seem to have reduced their activity despite the fact that the temperatures are merely an inconvenience for them. However, even when the mice are active they are active furtively; they collect bits of food and run with them back to their dens as quickly as possible, sometimes staying beneath leaf litter for the entire journey. They seldom run the risk of pausing to eat in the open, and therefore must be a challenge to hunt, especially if the hunter can't afford to spend hours watching for a mouse that may not appear at all. This is not an ideal season to be a breeding screech owl. Hopefully, the prey situation will have improved by the time the first egg hatches, probably sometime on or after February 28.


February 10 - Yesterday's mouse disappeared somewhere between 4 AM and 2 PM. If an owl claimed it, it was almost certainly the female during her pre-dawn constitutional, but it could also have been taken by any of the horde of free-roaming house cats in the area, or by the local possum or raccoon. The female's post-sunset absence was 2 hours 35 minutes. She was then absent for a further 1 hour 30 minutes prior to midnight. I'm confident she was out hunting, and after she returned to the box, she escalated her efforts to communicate the hunger problem to her mate: During the evening's food deliveries shw would swallow the offered prey and then repeatedly nip at him with her beak before he could leave the box. Her plaintive hunger calls continue.


February 9 - As on the 8th, some geckos have been delivered as food. I suspect that they are more nutritionally useful than the invertebrates that've represented all observed food deliveries prior to the 8th, so this is useful, but the female remains hungry, nonetheless. After providing our local raptor rehabilitator, Sallie, with some minor assistance in the release of a rehabbed female screech owl this evening, I came into possession of a dead mouse (the standard fare for raptors in rehab) which that owl had neglected to eat. I've placed a stepladder beneath, and in front of, the owl box, and placed the mouse on top of the stepladder where the male can't help but see it as he comes and goes with his smaller food deliveries. So far he's ignored it completely. Since Otus asio is known to scavenge from road kill - one reason automobiles represent their primary observed cause of death according to Gehlbach - this lack of interest is somewhat unexpected.


February 8 - No new eggs. Food situation unchanged.


February 7 - Temperatures dropped to freezing inside the box on the night of February 6/7, further emphasizing just how early this nesting is by local standards. Weather and food issues notwithstanding, egg no. 4 was laid this morning, probably at 8:06 AM CST.

Worms and caterpillars continue to be the only readily indentifiable food items; if anything else is being delivered, it's small enough that I can't get a look at it before it's swallowed. All of which means that the female is still underfed, and she's not happy about it, so she spends long periods of time calling for food. You can hear several of the variations of that call at the end of the food delivery movie from the 2nd, or on this morning's movie. Normally, she produces that call as her mate arrives with a food delivery, and variations of it a few times afterward, if she wants to indicate that she needs additional food. Tonight she's been calling steadily for long periods, even when there seems to be no evidence her mate is around. It appears that she wants to make her situation as abundantly clear to him as possible, even if he's just passing by as he rotates through his list of hunting sites.

A large QuickTime movie of the delivery of a worm, followed by what I've come to think of as the female's egg shuffling dance, is available. This is the first time I've managed to reduce a full-resolution (480x720) movie to a size that's even remotely reasonable, albeit at the cost of cutting its frame-rate in half to 15 fps. At 42.7 megabytes for 45 seconds of footage this movie isn't for everyone, but it does provide the best view yet of happenings in the nest box. The 32 second caterpillar delivery movie from the 2nd has been similarly reprocessed, and occupies 25 MB (only a 54% increase for a 100% increase in data).


February 6 - The female is taking her incubation duties more and more seriously. Today she was absent only for one significant period which lasted just under two hours. That's still a good bit of time to be away from her eggs, but it's a short absense compared to those of the previous nights. Worms have become a common prey item, and while they are enthusiastically received, it doesn't seem that prey is arriving in the quantities the female wants. Two possible explanations occur to me: (1) the male is a yearling, and hasn't yet fully developed his hunting skills, particularly for large prey items like birds and mice, and (2) starting nesting so early in the year has placed this period of significant nutritional need at a yearly low-point of prey availability. The starlings are back, by the way, and have built-up their courage enough to have begun entering the nest box with the female owl. She has vigorously ejected them, but this will probably do nothing to prevent an escalation of starling attempts to take over the nest box, as was dramatically demonstrated last year.


February 5 - Egg no. 3 [view the eggs from the ceiling cam', or from the side as an anaglyph]; best guess is that it was laid at 11:30 AM CST. The new egg looks a bit smaller than the first two, but should still fall within the healthy size range. The female was again absent from the nest box for long periods of the night-which still surprises her mate-but less so than on previous nights. The day was cold and rainy, and for some reason the starlings stayed away from the box. (There are more brooding owl anaglyphs: [1], [2], and [3].)


February 4 - Low-intensity nesting continues. The female broods the eggs continuously during the day, but spends most of the night elsewhere. This has caused her mate a modicum of confusion; from time to time he shows up with food deliveries only to find that no-one's home. It's possible that the nutritional demands of egg production, and the small food items her mate has typically provided, are forcing her to attempt to supplement his efforts with her own hunting. Or perhaps she just finds it difficult to adjust to the sensory deprivation exercise that is sitting in a nest box all day and all night.


February 3 - Egg no. 2 [view the eggs from the ceiling cam', or from the side as an anaglyph] was laid at approximately 3:30 AM CST, as the female owl breathed heavily and steadily at two second intervals with her tail feathers rising and falling to match. She didn't make a sound. A few minutes later, her mate appeared for a quick visit, and she decided to leave with him for a break that lasted three hours and a minute. One reason an owl might leave eggs un-incubated for extended periods, as this owl has done with both eggs so far, would be to slow the rate of development of the fetuses, and thereby cause the eggs to hatch at shorter intervals than they were laid. This is common with the first egg of a clutch, but much less so with the second egg. Although it's a point of pure speculation, I'd like to think the owl knows she'll lay a large clutch this year and is trying to keep to a minimum the age differences between the owlets that will result. Leaving speculation aside, both eggs appear to be of essentially the same perfectly normal size, which is great news given the undersized, sterile eggs that have been present in three of the previous four years' clutches.


February 2 - Still no second egg. This is a rather long delay for an eastern screech owl. By the way, there's no substitute for seeing certain things in real-time, so here's a QuickTime movie of a typical food delivery, complete with sound. (Duration is 32 seconds, size is 16.2 MB.) The food item being delivered by the male owl appears to be a caterpillar, or possibly a grub. They seem to have been the most common food item delivered so far this year. The only caterpillars I've seen in the area recently are those of the moth Ecpantheria scribonia, and those are not the species being eaten by the owls. Which just proves that the owls know more about what's going on in this neighborhood than I do. No surprise there.


February 1 - No sign of the second egg. Expect it on the 2nd.


January 31 - First egg! It appears to have been laid at either 11:50 AM, or 12:00 PM CST. Measurements derived from a ceiling camera image (that's an 8x8 inch grid superimposed on it) show the egg to be approximately 34.8 mm x 29.5 mm, which is an excellent size for an Otus asio egg, according to Gehlbach. It should weigh around 18.2 grams. So, it looks like there'll be no undersized, sterile eggs this year. Expect additional eggs at roughly one day intervals.

If you have a pair of red/cyan glasses, you can see 3D views of the egg alone, and the female owl incubating it. (Three dimensional photos represented in this way are known as "anaglyphs," by the way.)


January 30 - Second day of nest box occupation. No egg.


January 29 - First occupation of the nest box during the day. This usually means the first egg will appear 1-2 days hence.


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