Tuesday, May 26, 2015

Titmouse Chicks Develop

This is a continuation of our monitoring of the Black-crested Titmouse pair in our nest box.

May 26 - In the evening, I grabbed another color image of the nestlings at 3 days old. Note that along the crown, back, and wings, dark patches are developing where feathers will grow. They look like centipedes attached to the chicks. The female seems to have spent longer periods of time away from the nest box today.

May 27 - Watched an episode on video where female brought fed a large worm to one of the chicks which later regurgitated it, spending nearly 30 minutes trying to expel the worm from its mouth.

May 28 - This morning, on her first departure, the female removed the large snake skin piece from the nest box. This evening, another still shot of the chicks shows that the older ones have feather patches on their foreheads and dorsal line as well as further development on the trailing edges of wings, plus more differentiation between the eye globe and the place where the eye opening is.

May 29 - Some interesting developments today. First, we saw one of the larger chicks making repeated thrusts, trying to push itself out of the nest cup. You can see this in the infrared image below. Second, the female has started removing larger fecal sacs from the nest box rather than consuming them on the spot. Finally, we are seeing new details on the developing chicks, In the color picture, you can see further feather growth, scales and claws on the feet, and a more definite eye slit and ear hole.

May 30 - Last night, the female spent stayed away from the nest box again. Her last feeding was around dusk. Overnight temperature low was 70F, compared to 66F past few days. Perhaps she thought it was too warm to brood on the nest. She returned at 07:00 with another large caterpillar and did diaper duty, eating at least three smaller fecal sacs and then leaving with a larger one. Feeding arrivals have continued at about 10 minute intervals again. My necessary weed-whacking in the vicinity of the nest box did not interrupt feeding arrivals though when I made my closest and noisiest approach, she did stay in the nest longer than usual.

The largest chick shows wing development as it pushes out of the nest cup. In the video snippet it shows early preening behavior.

Progress shot shows obvious feather growth

Looks like mom is sleeping elsewhere again tonight. Seems that brooding is over for this batch of chicks. We watched a video on-line in which a Tufted-Titmouse family was filmed with a webcam. In that sequence, we saw the male participating in feeding both the female as well as the young. No idea what happened to the male of our pair. Are Black-crested different in that regard or did the male get killed early on?

May 31 - Morning feedings today consisted of much larger food items including moths and legged insects. She has some trouble getting them oriented correctly to go down.

This evening's progress image shows partially open eyes on the two oldest chicks and continued wing development. Tomorrow was the day we expected the eyes to open.

June 1 - Regular feeding cycles again today. During the heat of the day, the chicks seem to be spreading themselves out to cool down. They try to stretch their necks far out of the nest cup. Eyes on the two oldest chicks were partially open as of yesterday. Images and video highlight how much of a developmental gap there is between the chicks that hatched on May 23 and those that hatched on May 24. There seems to be more than one day's difference in growth, probably because the larger chicks receive more food or (possibly) because those two eggs received extra incubation before the other eggs were laid, though we can't be sure that the eggs that hatched first were laid first. 

The infrared video shows that the bigger chicks are succeeding more often at getting fed.

June 2 - First round of the inevitable today. Overnight, the smallest of the nestlings died, most likely due to not getting enough food. The mother actually hauled the body off at around 09:00. That is pretty impressive. I feared that I would have to go out and remove it myself.  

This video shows the largest nestling testing its wings and highlights the huge size difference between the first two nestlings and the later ones. You can see how the larger chicks rise up to get food, so much so that the smaller chicks are almost invisible. Their mouths are certainly no where in range of the mother. I see no evidence of older chicks bullying the younger ones. It seems to be purely a matter of reach.

June 3 - Based on lack of breathing, it looks like another one of the two smaller chicks died overnight just after 05:30. The remaining small one is hardly attempting to open its mouth when the mother arrives. I assume it will not last the day either. Last night, we inserted a remote temperature probe into the nest box to get an idea of how hot it gets. Heat might be a stress factor but simple starvation seems more likely. Over the course of the day, the temperature in the box peaked at 93F, not much higher than the external peak temperature of 92F. This is some relief as our readings indicate that this is still a safe temperature.

At 17:45 I could see the third chick still moving its head and having labored breathing. By 20:00, there was no motion at all. Every on-line resource we read indicated that we should remove the dead nestlings. We were concerned that we are close to the time frame in which we need to stop disturbing the nest to avoid premature fledging. Since the female had made no attempt all day to remove the chick that died overnight, we chose to step in and remove both the dead chicks after the female had stopped visiting the nest for the day. Surprisingly, the older two did not react much to my pulling the bodies out from under them. I think that this is past their normal "bed time," so they were not expecting a feeding.

The progress pictures we took beforehand show tail feathers and also the two dead chicks.

This next video is a depressing as it documents the last moments I could find of each of the nestlings and subsequently their removal, the smallest by the female and the next two by hand.

June 4 - Two remaining nestlings still doing well. The received regular feedings. Further feather development but nothing distinctively different. The video sequence of one of them performing a more thorough wing-feather preening gives a good view of the head and eyes. After dark, we added a predator baffle to our external camera pole so that we could confidently move it up close to the nest box as we look forward to capturing fledging sometime next week.

June 5 - Continued progress on growth. This is probably the last evening we feel comfortable inserting the iPhone in the vent slot to get a color image. The chicks are acting much more alert to visual stimulus now.

Below, one of the videos shows wing spread out where we see all of the primaries, secondaries, and coverts. Another video shows a feeding sequence in which the chicks stand and flutter their wings. On the menu appears to be a new item - a large spider. Mid morning, while the female was in the nest feeding the chicks, the video captured a second adult titmouse landing on the nestbox, investigating the hole, and flying away.

After dark, I rearranged the cameras again. I moved the big security camera back to get a wide view of the possible tree into which the chicks might fledge. I mounted the second Hawkeye camera 18" away from the nestbox opening to get view of the female or chicks perched at the nestbox hole.

June 6 - Another episode in which the additional titmouse flew onto the nest box while the female was feeding the young. This was repeated three times. We saw snake-hissing from the female in response. The slightly larger nestling is still getting more of the food. I was able to identify 35 feeding arrivals by the female over the course of the day from 06;40 to 19:00.

June 7 - Another very hot day. Temperature in the nest box hit 95F late afternoon. I was able to identify only 29 feeding arrivals today. Both of these seem small. Smaller chick still not getting same amount of food. I observed the larger chick lightly pecking at the beak of the smaller.

There was also a repeat encounter with our interloper adult. This time we got a good mug shot of it. Here is a view of first the mother arriving to feed the chicks followed by the other adult who first comes when the mother is feeding, gets hissed at and then comes back to peer in to the nest box after the mother leaves

Another episode of interest was captured when we got back home today. At 16:54, the video captured the mother arriving at the nest box with a bug. Danielle was throwing a toy for Vali in the yard. The mother waited at the nest entrance watching the dog. Instead of going in, she headed back out, presumably to a nearby tree. A minute later she came back to the nestbox with the bug and did not pause as she entered to deliver it.

June 8 - Chicks are growing fast. They are almost as large as the mother, though not completely feathered in on the backs. Yet another round of the mystery adult at the nest box. There was at least one round where the female brought in a bug so large that neither chick could eat it. She eventually hauled it away.

June 9 - This is day 17 for these two eldest nestlings. In this shot the crest is evident as are the throat feathers.

We are very close to fledging. Today's milestone was that both nestlings got enough hang-time with their flapping to grab a hold of the slats on the inside of the box. One of them took a peek outside the box for the first time this evening at 19:11.

June 10 - Day 18 for the remaining nestlings, the latest day documented in Sialis for fledging of titmice.  Sure enough, today was graduation day. At 13:00 the first nestling had another extended view out the nest box hole. It fledged at 15:25, landing in the tree just next to the nest box.

The second nestling had a quick peek soon after but didn't jump... at least, not then.

My wife, who works from home, says that she checked the nestcam just before 17:00. and realized that one of the titmice had fledged. She went and checked around the box to see if it was on the ground, but she couldn't find it. Coming back inside to check the recording to find out when it had fledged, she caught the second titmouse preparing to jump and was able to watch it fledge live at 17:08. She went back out to see where the bird had gone and eventually spotted the whole family together in a tree in our neighbor's yard. Unfortunately they had moved on before she had a chance to set up the camera to get a shot.

It looks like the mom came back for a feeding at 17:07. Moments after the mom flew back out, the second nestling fledged at 17:08. It flew past the nearby tree and out of camera view. Curiously, at 17:38, the mother came back to the box with food for the chick and found the nest empty, which we think is after the time that Danielle reported seeing the whole family together. Perhaps the mom can't count and wanted to make sure that the nest was empty?

I got home from work at 19:00 and was not able to locate either of the fledglings. We have a definite case of empty nest syndrome!

See my YouTube playlist to watch a complete set of the titmouse videos.

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