The 2002 eastern screech owl (Otus asio hasbroucki) nesting season is now complete in this urban Austin, Texas, nest box. Four eggs were laid, three hatched, and three owlets left the box three and half weeks later. One owlet is missing and presumed dead, and two are in the care of a licensed wildlife rehabilitator who is treating them for the wide assortment of parasites they acquired from food provided to them by their unwitting parents. The condition of the owlets is improving, and a full recovery is anticipated. Once recovered they will be trained to hunt, and released at the nest box site.
The views shown here were provided by one or more tiny monochrome video cameras that are sensitive to both visible and near-infrared light. During the day, the camera "sees" by the normal daylight that streams in through the entrance hole, but the extreme lighting contrast between the portions of the interior that are in direct sunlight, and the dark floor of the box where most of the action takes place, can make it difficult for the cameras to produce high quality images. At night, however, arrays of infrared illuminators take over from the sun and the entire interior is consistently illuminated and clearly visible. (Meet the nest box internals.) So, the best viewing is at night. Since the owls are nocturnal, that seems appropriate.
June 8 - The owlets continue to do fine in the care of Sallie, the raptor rehabilitator. Sallie provides them with a flight cage where they can stretch their wings, all the mice they can eat, and lots of other screech owls to keep them company.
May 6 - The veterinarian's tests show the owlets to be free of parasites at long last. Consequently, Sallie has moved them into her screech owl flight cage where they can finally try out their wings, and will have a variety of other Otus asio's to keep them company, from the surprising fellow who hatched on or about December 27 of last year, to Crosby, the surrogate father to all her young screech owls, who hatched on or about 1991.
May 4 - The owlets have completed 14 days of Panacur treatments and finally appear to parasite-free. While they need to be tested by a veterinarian in order to confirm this, they are both breathing normally, which is a very good sign.
May 1 - Sallie reports that the owlets have responded well to their new medication, Panacur, and have finally ceased mouth breathing as a result. They'll receive the medication for another three days, and then prudence will likely require that a vet examine fecal samples to verify that the owlets truly are parasite-free. Once they receive a clean bill of health, they'll finally be allowed to reside in a flight cage with other screech owls, which should be a treat for them. It is also a precondition for the start of their vitally important hunting lessons.
April 29 - The owlets have been diagnosed with yet another parasite, roundworm. Because their recovery has been dramatically slower than expected, the drugs used to treat them have been changed. The two owlets continue to live together in a small cage which is intended reduce their level of activity and maximize the energy available to them for recovering from the effects of the parasites. Sallie feels bad that young birds who've been anxious to try-out their wings for so long continue to be deprived of any real opportunity to do so. She has a good point, but I'm just relieved they're still alive, and that their prognosis remains very good, despite their startlingly slow recovery. There can be no doubt that they would not have survived in the wild with this collection of parasites.
I periodically encounter the adult owls when I'm in my back yard in the middle of the night, and the clacking of beaks that greets me on those occasions shows that the adults have not forgotten my involvement in the abduction of their surviving owlets. This verbal abuse from the treetops is most pronounced when I'm in the vicinity of the nest box tree, which suggests that the adults still consider it to be their nest site. They do not appear inclined to renest this year, but their interest in the nest box suggests that they'll be back next year.
April 6 - The owlets received additional treatment for their parasites during the week, and continue to improve. The eldest continues to mouth-breathe most of the time, but remains alert and energetic. While the owlets remain in quarantine from Sallie's other screech owls, pending total elimination of their parasites, they do live together in the same cage, so they have each other for company.
April 1 - (No foolin') - Sallie sent the following report on the owlets: "The kids are coming along nicely. The eldest is eating better now. He's still afraid of me (after all that's what he's supposed to be), but will now allow me to feed him bites of mouse after he's had his medicine. No. 41 [the eldest owlet] still sneezes fairly frequently, but doesn't mouth breathe as much as he used to. The youngest is eating better too."
By the way, the reference to "ringworm" in one of the previous news items was the result of sleep deprivation on my part; it should have been "hookworm".
March 29 - You Win Some, You Lose Some - (This time it turns out that we mostly win.) - I stayed up the entire night of March 28/29 in order to keep an eye on the eldest owlet, so I could ensure that, if he also chose to leave the nest and fell to the ground, he would be safely placed in the nest box tree, just as I'd done with the middle owlet. He did not choose to the leave nest that night.
About half an hour after dawn I went out to see if I could spot both the middle owlet, and one or more of his parents who would be guarding him during the day. The enraged protests of the local songbirds allowed me to quickly locate one adult (probably the female) on guard duty in a nearby tree, but I had no luck finding the middle owlet in the nest box tree, the tree the adult was sitting in, the crepe myrtle tree so many owlets have mistakenly sought refuge in before, any of the nearby shrubs, and not even amongst the several brush piles in the yard. Of course, in a tree as large as the nest box tree, it would be easy to miss an owlet, so there was no way to know the significance of his apparent absence. The obvious good news was that an adult was steadfastly on guard despite the continuous provocations of the neighborhood songbirds.
During the afternoon, I repeated this search for the middle owlet on several occasions, and broadened it to include the entire back yard, and all that I could see of neighboring yards. The adult was still on guard, but I still couldn't spot the owlet.
After sunset I returned to the back yard to watch the guarding adult. My guess was that its first move of the night would either be to move closer to the owlet's hiding place to reassure it, or to fly away to find the owlet a meal, revealing the owlet's location when it returned to deliver the prey. The adult flew away, but did not come back while I was there to watch for it.
Plan B for locating the owlet was even easier: wander around the yard observing which areas were most aggressively defended. About the time the adults actually start attacking you, you know an owlet is very nearby. Unfortunately, there were no attacks; not even audible warnings. In fact, there was no indication that the adults were in the area at all, which was puzzling given that the eldest owlet was in the nest box waiting for food deliveries to begin. Repeating plan B every hour or so produced no results, and by 11 PM, there still hadn't even been a single visit to the nest box.
It seems clear that the adults had concluded that there were no owlets left to protect, or feed. Explaining the former requires the death of the middle owlet, and my inability to find its body suggests that whatever killed it also carried it away. Explaining the latter is more difficult. Both adults had observed--and even fed--both owlets at the box at the same time during the night of March 28/29, although one owlet was inside the box, and the other on the external owlet rail at the time. Is it possible that not having seen both owlets in the same field of view at the same instant, their mental owlet counters remained set to one?
Earlier in the evening, Sallie had informed me of the day's test results on the youngest owlet, and they were the worst of all: At least four separate parasite species were found, including Capillaria and flagellated protozoans. Treatment would require at least a week in Sallie's care, which meant that the youngest owlet could either be returned to its parents, or it could survive; there was no middle ground. Needless to say, we both chose the latter without hesitation.
Counterintuitively, it's the youngest owlet's need for extended treatment that constitutes the silver lining of this grimly dark cloud. It does so because the apparent accidental abandonment of the eldest owlet in the nest box becomes an opportunity to take that owlet into Sallie's care as well. This is important for more than merely solving the obvious problems of the owlet's care and feeding; in order to be certain of killing all the hookworm and syngamus parasites in the eldest owlet a second dose of the relevant drugs is required seven days after the first. Sallie had concluded, and I agreed, that returning the middle and eldest owlets to their parents was more important that guaranteeing their total cure, since those parasites aren't necessarily fatal, at least in adult birds, and the first treatment had already resulted in a huge improvement in their conditions. (We also hoped that they might still be in the nest box when the time for the second dose rolled around.) Placing the eldest owlet in Sallie's care not only allows the second treatment to be administered, but allows proactive treatment for the other parasites found in the youngest owlet - parasites to which the eldest must also have been exposed, even if they weren't yet obvious in his lab tests.
So, the two surviving owlets will not only end-up healthier than they ever would have been, but they'll have each other for company, and they'll get free medical & dental (not that they have teeth), all the mice they can eat, Sallie to take care of them and later train them to hunt, and, once the parasites are all guaranteed dead and gone, all the other screech owls she's caring for as companions and surrogate parents.
Later this year they'll be released here in my yard, at which point they'll probably be the healthiest screech owls in the area. If their parents have written-off the nest box due to this apparent failure, we might even see it claimed by one of these kids next year.
The key events of this year's breeding season can be summarized something like this: The breeding pair of adults survived. Four eggs were laid, and three hatched. The owlets were subsequently infected with a wide variety of parasites whose combined effects would almost certainly have killed them, directly or indirectly. One of those owlets is missing, presumed dead. The remaining two will be cured of all their parasites, trained to fend for themselves, and returned to what passes for "the wild" hereabouts. Final score: Two go in, four come out. It's not at all what I'd hoped for when this breeding season began, and some of the details are downright depressing, but the outcome is actually quite good, and is due entirely to the knowledge and dedication of Sallie, our local raptor rehabilitator, and those who've assisted her. I can't thank you enough, Sallie.
I'll be providing photos of the owlets as they grow and are readied for adult life, so come back for a visit once in a while.
Finally, let me thank everyone for the supportive emails during the course of this season. Running this web site is a two month endurance test each year, and without that support, I wouldn't be able to keep it going.
March 28/29 - It's been far too eventful an evening to describe properly with the energy I have left. Sacrificing completeness and accuracy in favor of brevity and simplicity, it can be reduced to something like this:
Having been diagnosed with both syngamus and hookworm--as though either one wouldn't have been enough--the eldest and middle owlet received treatment for those parasites, and doses of subcutaneous fluid to make-up for them being slightly dehydrated. They were returned to the nest box this night, and soon displayed far more energy than they ever had before, and almost no mouth-breathing. That energy was immediately put to use in climbing the interior of the box, with each owlet succeeding in reaching the entryway at one time or another. The middle owlet, showing the greatest energy of all, ventured out onto the owlet rail and promptly fell into the yard beneath the box where it sat innocently staring at the world around it in fascination. This is endearing, but is not the right thing for an owlet on the ground to do. (The right thing is to run to the nearest tree and climb it, very fast.)
Fortunately, Sallie and I were still observing them on TV at the time, and the owlet was quickly retrieved. Judging that it was still days too early for the owlets to leave the nest, and that both of the parents might not yet be aware that the owlets had returned, let alone ventured out of the box, we chose to return this owlet to the box, taking the opportunity to band it at the same time.
The youngest owlet was then removed, because Sallie observed symptoms of hookworm. It will be treated on the 29th, and returned to the nest that night.
With the box restored, the middle owlet waited only an hour or so before venturing into the entryway again. (By this time it was March 29th.) After sitting there for perhaps twenty minutes, it went out onto the owlet rail on the front of the box. I was sure it was going to fall-, or jump-, off again, and resolved to watch it until it did, so I could make certain that it would find its way back to the safety of the tree and to get it started climbing a major limb that would take it high into the safety of the canopy before daybreak.
During the period it sat out on the owlet rail, both parents came to the box with food, and therefore discovered that after loosing two owlets the previous night, they had gained one this night. Seeing that one owlet had left the nest (even though it had gone no further than the owlet rail) their defensive instincts kicked into highest gear. This is important because owlets leave the relative safety of the nest a week before they are able to fly. During this week the adult owls are more defensive than at any other time of the year.
Around 2:10 AM CST on the 29th, the middle owlet fell off the rail after an unsuccessful attempt to climb the front of the nest box. I ran out to the tree and soon found the owlet hiding next to a clump of grass. Retrieving a step ladder I'd prepositioned for this purpose, I picked up the owlet, placed the ladder beneath a limb that would take the owlet straight to the high canopy of the tree, and climbed onto the ladder so I could place the owlet on that limb.
Having declared its independence by leaving the nest box (for the second time that night, no less), it was less sympathetic than usual to the insult of being handled, and showed this by clamping its talons firmly into my hand. I expected no less, but this did mean that it took a bit of time to separate the owlet from the hand, and to pursuade the owlet to clamp itself to the tree limb, instead. While I was balancing on the step ladder attempting to affect this transfer, one of the agitated parents landed an impressive blow to my head, by way of explaining that I was not at all welcome. This, of course, is their right, and once the owlet was safely established on the limb, I beat a hasty retreat to the house, with the parents urging me along from the trees overhead.
This leaves the matter of the eldest owlet. How long will it choose to remain in the nest? I hope it will stay long enough for the youngest owlet to be returned, and for both of them to receive the official bands that might someday provide me with a final fragment of their life stories.
March 27 - Eldest and middle owlet were removed from the box for examination by a veterinarian who is an expert with birds. The youngest owlet, who was not showing the symptoms of syngamus infection, was left in the box, allowing nesting to continue.
March 25 - When Sallie examined the owlets on the 21st she advised me to watch one of the two eldest owlets for "mouth breathing", i.e. breathing through its mouth rather than its nostrils, since this would be a sign of a health problem. Each night I've watched for this, and the bad news at this point is that one of the large owlets is always breathing through its mouth, and the other seems to be routinely doing so, as well as sneezing at times. The good news is that all the owlets are still active and alert, so the problem hasn't become serious for them yet. The probable source of the problem is the syngamus parasite. If that parasite is responsible, the problem is curable, and the current plan is to remove the affected owlets on Wednesday night so they can be taken to Sallie's most trusted vet for detailed examinations, and whatever treatments are appropriate. With luck, they can be returned to the nest before the youngest owlet leaves it. If that doesn't happen, it may not be possible to reintroduce the owlets to their parents, and they may have to spend some time in Sallie's care while they receive their hunting training. That's not the way any of us would like to see things turn out, but it would ensure that the owlets have a shot at adulthood.
March 24 - At 1:04 AM CST, one of the parents arrived in the nest box to deliver some long, slender food item (worm, snake, extra long gecko?), and then exited carrying one of the mice delivered a few hours earlier.
March 23 - The supplemental mice are still received with enthusiasm, which is not to say that the female is happy about their delivery; for the last couple of weeks she's been leaving the nest box almost any time she hears me open my back door at night.
At 7:23 PM CST the female brought some large prey item to the owlets, and spent the next six minutes tearing it apart and feeding it to them. She then stored the remainder in a corner and left the nest box.
March 22 - The male delivered a mouse at 3:26 AM CST. At 5:32 AM, he delivered a small bird, to which the female doesn't appear to have pressed a strong claim, so he left with it. The female left the nest box for six minutes before sunrise, temperature 42 degrees. Shortly after eight in the morning, starling visits commenced, but soon ceased for the day. At 11:09 PM CST, the female arrived with a prey item large enough that it had to be torn up for the owlets, but it didn't last long, and there was no clear indication of its identity.
March 21 - The male delivered a mouse a bit before 4:30 AM CST. There were only a few starling vists, early in the morning and late in the afternoon. The afternoon visits prompted the female to sit guard duty in the entryway for a few short periods.
Sallie was able to come by this evening to give the owlets a check-up, so there are new color pictures of the owlets. The previous set of pictures had raised some questions about the health of one of the owlets, but all passed their examinations. So far, so good.
It seems odd to me that the youngest retains his egg tooth, but there it is. Perhaps he's holding out for the promise of a quarter under his pillow. The middle owlet was so anxious to have a look at the outside world, he kept trying to fly off my hand. He hasn't the feathers or the strength to take off, but he already has the determination. The youngest was also very interested in having a good look at the world, so both of them spent very little time looking toward the camera; strange noises had to employed to momentarily attract their gaze toward the lens.
March 20 - No pre-dawn absence. There were many visits by starlings, including descents to the floor of the box. These up-close-and-personal meetings with the starlings seriously agitated the female owl and she made repeated attempts to plunge her talons into the starlings by way of explaining to them her claim to the nest box in the simplest possible terms. Since she couldn't effectively employ talons evolved for pouncing on prey from above in these face-to-face to fights, she couldn't do a lot about the starlings' learning disability, and that made it a day of random skirmishes. She seems to have been too concerned about guarding her owlets to sit guard duty in the entryway,even though the owlets certainly would have been safe while she was doing so.
One small bird was delivered at some point early this evening, along with a large number of smaller prey species including geckos, crickets and moths. When I delivered the now traditional pair of supplemental mice shortly before midnight, the well-fed female, upon returning to the box, simply stacked them neatly in a corner for later use.
I didn't bring down the box tonight to take the new color photos of the owlets, because I'd like to have Sallie, the local raptor rehabilitator, present when I do so in order to give the owlets a medical once-over. Rehabilitators' schedules are unpredictable, and this evening Sallie found herself having to take-in a barred owl. I'm sure it will go nicely with the parliament of screech owls, the pair of barn owls, the Harris' hawk, and the crested caracara she's already looking after. Here's hoping they'll all be fine.
March 19 - No pre-dawn absence. Sparrow visits resumed early, but were quickly stopped when the female spent a bit of time on guard duty in the entryway. Visits to the nest box didn't resume until after five in the afternoon, but the sparrows weren't involved; the starlings were back. Their visits were short-lived, however, as the female went back to guard duty not long afterward, not leaving the entryway until about ten minutes after sunset. The female didn't return for 32 minutes, temperature 75 degrees. The rest of the night she was in and out as she alternately hunted, and cared, for the owlets. The arrival of a thunderstorm induced her to leave the box for a leisurely shower. Unfortunately, the same thunderstorm made it impractical to bring down the box and take the latest set of owlet photos. Hopefully tomorrow.
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--[ Other Years | Chris W. Johnson ]--