Bluebird Update 4.18.17

As of Tuesday morning (4/18/17), we have 10 eggs and 16 hatchlings in our six nest boxes. All 10 eggs belong to chickadees. Three of the nestlings are bluebirds and 13 are chickadees. We lost five bluebird eggs though the nest destroying behavior of another species of bird.

When I last looked into the nest box at the Cow Pasture it had five blue eggs within its pine straw and grass lined nest. This morning, it was empty. As my mind quickly searched for an answer as to why the eggs were missing, it didn’t take long to figure out that the culprit had come in via the air.

An empty bluebird nest at Cow pasture (4/18/17).

I have predator guards on all nest poles. Though not absolute in their protection from predators, they’re pretty good at keeping unwanted critters from the nests. It wasn’t a snake that seized the eggs, nor a raccoon. It was a bird.

There at my feet, were five blue eggs. Some of the eggs had wide cracks in them, others small holes. A snake or a raccoon would have eaten the eggs. The suspect? A house wren.

The eggs at the base of the nest box pole (4/18/17).

House wrens are notorious for tossing out the eggs of other birds, even removing entire nests from their nest cavities, man-made or otherwise, and building a stick nest of their own inside. And although the bluebird nest was still intact inside the nest box, I suspect it was the next thing to go. The odd thing about this behavior of house wrens is that they may not use the nest at all!

The male house wrens arrive first in spring and may build several nests in anticipation of the female’s appearance. It’s the female who decides which nest of the male’s industry she wants to utilize. She may even build a nest of her own. Our bluebirds may have lost their eggs for naught.

The chickadee nest on the service road in Explore the Wild had 6 eggs last week. Today (Tues. 4/18) it has 6 very tiny, hungry hatchlings.

Six tiny hatchlings at the ETW nest (4/18/17). Compare size of hatchlings to finger.
Mouths agape, as I snap a photo of the little chickadees (4/18/17).

Last week the chickadee eggs at the site of the old Bungee Jump were just beginning to hatch. At the time, three of the five chicks had already emerged from their calcium coated capsules. The remaining two eggs have likewise hatched and all the birds are showing feather growth.

Feathers appearing on the chickadees in Bungee nest (4/18/17).

I was a bit surprised when I opened the nest box on the service road to Into the Mist. Two weeks ago there were 4 eggs in this chickadee nest. One week ago an adult was incubating and refused to get off the nest so I could have a look and count her eggs. I didn’t want to unduly disturb her so I left the count as it was, at four. This week there are 7 eggs in the nest. This is the highest count of eggs in one nest I’ve seen here at the museum (previous high, 6). I hope they all make it.

The highest egg count of any nest so far on museum bluebird trail (4/18/17).

Over at the Woodlands nest box, 2 of the 5 chickadee eggs in that nest have hatched. Two naked and blind hatchlings greeted me as I opened the nest box door.

Three more eggs to go at Woodlands (4/18/17).

The Butterfly House bluebirds who had been incubating three eggs last week, now have three nestlings to feed.

Three young bluebirds at the Butterfly House nest (4/18/17).

Although we lost one nest to house wrens we still have five nests going strong. The ETW nest, Bungee and Woodlands nests contain a total of 13 chickadee nestlings (6, 5, and 2 respectively). The Mist and Woodlands nest hold 10 eggs (7 and 3 respectively). The Cow Pasture nest is empty, having been destroyed by a house wren, and the Butterfly House nest contains 3 bluebird nestlings.

See you next week!

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