Wednesday, May 6, 2015

First Titmouse Egg

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

May 6 - This morning, the female returned to the nest at 06:55 with no materials. She shuffled around the existing pile for several minutes and then settled down, occasionally moving bits around. She appears to have laid the first egg between 07:00 and 07:05 after which she pulled back to quickly look at it and resumed sitting on it and pulling materials around. She left the next box at 07:20 after what seemed to be a "recovery period."

I was surprised that the egg was laid today as the nest had no well defined central structure. I gather that the titmouse has a range on how much of a bowl is formed before laying begins. Sialis has a nice set of pictures of various titmice nests and a good description of the nesting process.

During the course of the day, she made 4 more deliveries of grass and fur at 11:40, 12:59, 14:35, and 15:53. During this process, she ended up covering the egg completely.

At this point, we are expecting eggs to be added, one each morning, until she is ready to start incubating the full clutch. Still no certainty that she will not abandon the nest so we will continue to avoid the area of the yard where the nest box is located.

May 7 - The female laid a second egg this morning between her initial arrival at 06:40 and departure at 07:15. The DVR skipped recording much of the intervening action.

This titmouse is definitely not following my script. This evening, she came back to the box at 20:00 and has not left. She appears to be incubating already with only two eggs. Sialis says that incubation begins after laying the penultimate egg and that three to nine eggs are laid, five to seven being most typical. So, she might lay a third egg, though it might not be viable.

May 9 - There are definitely at least three eggs in the nest as can be seen from this image just before her daily departure this morning.

May 10 - Now up to five eggs, so she is actually still on schedule for one egg a day.This shot taken just after she left the nest at noon. I am still confused as she still seems to be incubating. Is she, perhaps, not really heating them, just resting above them?


May 11 - Still clearly five eggs in the nest this morning as observed at 07:50 after her morning departure.Over the course of the day she left ten times,remaining away between 10 and 15 minutes. Several of those time she returned with additional nesting material, dropping it near the nest cup, and incorporating it later after she had settled her self back down.

May 12 - Still five eggs and continuous incubating except for 10 minute exits. With the new fur and continual scooting around over the eggs, a well defined nest cup has formed.

May 15 - I was surprised to observe that the female spent the entire night from 20:50 to 07:15 away from the nest box. I have also not seen the male since nest building completed. I had thought that he would be feeding her during this time. Is that why she was away ... an unwed mother struggling with a night job? Anyway, today back to the usual routine with eight absences of 10 minutes each.

May 17 - We added a bug attracting light in the yard last night. This morning at 09:00, the presumptive male made a quick landing on the roof of the nest box, flew down to the opening and then flew away. We did not hear any calls between them on the video, though she did react slightly to some noise. The male did not bring any food.

May 18 - Another day of regular trips away from the box with material brought in to augment the nest. At noon, she brought in a large chuck of snake skin. My readings indicate that this material is added to the nest to discourage egg predators. Research has shown that predators such as flying squirrels are less likely to predate a nest with snake skin in it.

May 20 - Another day of brooding and bringing material after her presumed feeding trips. She brought in another big piece of snake skin. Seems that she just about has a full snake in there.

All monochrome images taken with Hawkeye Nature Cam from capturing in infrared mode.

Story continues with egg hatching.

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