Cardinal Nest Watch: Part 2

This is a continuation of the story of a Northern Cardinal nest in Eliza Howell Park and of my observations of it. For the first part, see “Cardinal Nest Watch,” May 7.

As reported then, my last look in the nest had been on May 2, when I took a photo of 3 eggs.

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The brooding female was on the nest every time I checked through my binoculars during the next several days, so I did not get a close look.

On May 9, she was absent when I looked, so I approached for a brief look at what was happening. There were now 5 eggs.

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While all the eggs are similar in color and markings, I think that only the larger one is a cardinal egg. The smaller four appear to be Brown-headed Cowbird eggs. Cowbirds often remove one of the eggs of the “host” species when they lay one of their own.

I was not at all surprised by the presence of a cowbird egg, but I was surprised by the presence of four. As is typical of birds generally, a cowbird lays one egg a day; it usually places them in different nests. It must have returned to this nest more than once and/or there was more than one female cowbird imposing upon this particular host.

The cardinal returned a little later (after I took the picture) and continued brooding on what is now more of a cowbird nest than a cardinal nest.

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The next development was on May 11.

The nest is located is the wildflower field that is, by design, kept unmowed. Over the last several years, saplings and vines have emerged and have begun to threaten the future of the open flower field. Earlier this spring, I had asked the supervisor of mowing for Detroit west side parks for a one-time mowing in the spring, before the perennials were growing. He said they could do that.

I didn’t know the timing in advance, but the mowing was done on May 11, when a powerful tractor-pulled mower knocked down everything growing taller than a few inches. I happened to be there and informed the tractor driver of the location of the nest. He said he would leave that shrub standing. And he did.

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The mowing naturally drove the cardinal from the nest and I again took a quick picture.

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I was unable to visit the park May 12, 13, and 14. Sometimes a major disturbance, like the mowing of the surrounding habitat, might lead a bird to abandon the nest; I do not know whether cardinal returned to the nest after the tractor left.

When I headed to Eliza Howell on the morning of May 15, I was aware that, if all had gone well, this might be the hatching date. But all had not gone well. I found the nest empty – no birds, no eggs.

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The nest was empty and I don’t know what happened. Something removed the eggs (or hatchlings) and left no clear evidence of what that something was. In my search around the nest, I found only one very small piece of egg shell.

It is tempting to think that it might have been an animal predator, of which there are several possibilities in the park – including crows, blue jays, raccoons, coyotes, cats, and squirrels. But from no information it is hard to draw conclusions.

When I first started my walk on the morning of the May 15, I heard cardinals singing. This nest was not successful, but the pair will nest again this year, probably very soon, and definitely in a different location.

 

Cardinal Nest Watch

The watch started on April 26, when I noticed a female Northern Cardinal carrying a twig into a small bush in Eliza Howell Park. Cardinals usually have two broods a year and April is the normal time for the first in southeast Michigan.

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Photo by Margaret Weber

The closer look I took when she flew away showed a partially constructed nest. By April 28, the next looked finished or very nearly finished.

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Cardinals usually hide their nests in dense plant growth and in locations where they cannot be seen or watched from any distance. This one is quite well camouflaged, but it is low and visible (especially when using binoculars) on one side from about 30 feet. I immediately thought that this is a nest that I might be able to watch without disturbing the birds.

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The female Cardinal lays one a day until there are 3 – 5 eggs. And, like many birds, it doesn’t start incubating them until the clutch is (nearly) complete. This results in the eggs all hatching at nearly the same time.

On April 30, there was no bird present, so I approached the nest: 1 egg. On May 1: 2 eggs. On May 2: 3 eggs.

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Starting on May 3, the female has been on the nest every time I looked, so I have kept some distance and have not been able to discover the full clutch size.

Among cardinals, the female does all the brooding, while the male is nearby and feeds her from time to time (I have not yet seen him feeding her at this location).

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Photo by Margaret Weber

Cardinal eggs hatch after 11 – 13 days incubation, so I expect the next big development to be about May 14 – 16, if all goes well. Then both parents feed the young for about 10 days.

One of the questions I have is whether a Brown-headed Cowbird has laid an egg in the cardinal nest (and possibly displaced one of the cardinal eggs). Cowbirds are brood parasites, laying eggs in the nests of other birds for incubation and feeding. Another cardinal nest I checked this year contained three cardinal eggs and one cowbird egg.

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Not all nests lead to the successful fledging of young. There are a variety of reasons for nests to fail, so I will be watching to see whether the nest is destroyed or abandoned, how many eggs hatch, how many nestlings fledge, and whatever else I might observe.

The location is one that makes it easier for me to watch this nest than others that I have found, but it seems a risky location, more vulnerable to predators. But it was selected by the pair together, without requesting my opinion, so I will  simply continue to enjoy my opportunity to nest watch!