Bluebird Update 7.21.15

This morning’s (7/21) check of our six bluebird nest boxes indicated that the season is at an end. There will be no further nesting this season. The three nest boxes that had nesting material within have not been added to or manipulated in any manner.

A paper wasp lives in the nest box at the Sailboat Pond and an orb weaver (spider) resides at the Picnic Dome nest box.

 

The paper wasp taking advantage of an otherwise empty nest box at the Sailboat Pond (7/21/15).
The paper wasp taking advantage of an otherwise empty nest box at the Sailboat Pond (7/21/15).

 

The spider's home at the Picnic Dome (7/21/15).
The spider’s home at the Picnic Dome (7/21/15).

 

A close view of the spider tucked away for the day.
A close view of the spider tucked away for the day.

 

The Cow Pasture nest box produced four bluebirds this season. The Bungee (Take Off) nest box fledged four Carolina Chickadees. The Sailboat Pond looked promising early on when it contained four chickadee eggs. However, a house wren raided the nest, destroyed the eggs and the nest box remained empty for the duration of the season, except for a persistent paper wasp.

The Amphimeadow nest box safely harbored seven bluebirds of two broods until they were ready to fledge, four in the first brood and three in the second go around. The nest box at the Picnic Dome came up empty this year, but not for lack of trying on the part of the birds.

The Picnic Dome nest had five bluebird eggs in mid April. When house wrens arrived in town, back from their winter haunts to the south, this nest was cleaned out, eggs and all. The wrens built their own nest in the box and laid six eggs. This nest was later emptied of eggs by what I assume was a rat snake and lay empty for the remainder of the season. Since, a spider has taken up residence in the box.

Over at the Butterfly House, two broods added seven bluebirds to the local avifauna. Like the Amphimeadow, there were four birds fledged from the first brood and three from the second.

 

The first inspection of the nest boxes was on March 17 and the last on 21 July.

 

The totals for 2015:

Total Birds Fledged – 22

Eastern Bluebirds Fledged – 18

Carolina Chickadees Fledged – 4

 

Compare with last year’s totals.

 

The totals for 2014:

Total Birds Fledged – 33

Eastern Bluebirds Fledged – 27

Carolina Chickadees Fledged – 6

That’s 11 fewer birds overall in 2015 as compared to 2014, 9 fewer bluebirds and 2 fewer chickadees.

 

And, the totals from 2013 were:

 

The totals for 2013:

Total Birds Fledged – 33

Eastern Bluebirds Fledged – 20

Carolina Chickadees Fledged – 13

 

And, 2012:

 

The totals for 2012:

Total Birds Fledged – 26

Eastern Bluebirds Fledged – 20

Carolina Chickadees Fledged – 6

 

Why are this year’s numbers lower than the previous three years? Speculation may lead one to believe it was this year’s heat that caused fewer birds to fledge. Looking back though, house wrens destroyed five bluebird eggs and five chickadee eggs. If those eggs were allowed to hatch, and the nestlings fledge, the numbers would be right up there with the previous three years.

But, there are nest failures in every year for a variety of reasons, predation, infertile eggs, and the weather to name several. The heat may indeed have been a factor in this year’s lower numbers. Nevertheless, there are now 22 more birds flying around the Museum’s outdoor areas. I think that’s a good thing.

 

Some averages:

Avg Birds Fledged per year since 2012 – 28.5

Avg Bluebirds Fledged per year since 2012 – 21.25

Avg Chickadees Fledged per year since 2012 – 7.25

 

See you next year!

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