[cobirds] Early Results - Nest Boxes- USAFA

Hi COBirders,


This is a real early report on nest box use at the Air Force Academy because there are some surprising early results!
Lots of data-crunching only for those interested. I'd appreciate insights or comments, especially about the Pygmy Nuthatch numbers.

While migration doesn't seem particularly busy early this season, it appears that nesting birds ARE busy.


A little history - I have been keeping fairly accurate notes on dates for first nest material, first eggs, and first hatching dates in my bird boxes since about 2004, and reporting the data to Cornell Labs as part of their Citizen Science program - The Birdhouse Network.

So my wife and I did the first survey of the year May 1, just as a baseline for information. Most years only a White-breasted Nuthatch or two has seriously started anything by May 1, so no problem, right?

Oops.

May 1, 2012 - of the 85 boxes, 22 had active nests with eggs already! 5 White-breasted Nuthatch nests, 4 Pygmy Nuthatch nests, and 13 Western Bluebird nests. I tried to extrapolate back to the latest possible first egg date by counting backwards the number of days by the number of eggs present May 1, and checked today May 6 for a little more data to figure this out.

Oops again. Today I already had 12 bluebird hatchlings!


So breaking down my early date data for those 3 species I get these comparisons.

Western Bluebird - earliest previous egg, 2004-2011 - April 25; Average- May 4; 2012- April 20.
earliest hatching - May 19; Average - May 23; 2012 - May 4

White-breasted Nuthatch (a regular early nester) earliest egg - April 19; Average - May 1; 2012 - April 25

Pygmy Nuthatch - earliest egg - April 27; Average - May 4; 2012 - April 27.


Also - for other early nesting species - but no eggs seen yet:

House Wren - earliest egg 2004-2011 - May 5; Average May 15
Violet-green Swallow - earliest egg - May 15; Average June 4

Now - more on the Pygmy Nuthatches. On May 1 one nest already had 8 eggs in it and was being incubated. Three other nests had 1, 2, and 2 eggs.
Today - First nest, still 8 eggs, 2nd - went from 1 to 6 eggs (in 5 days), 3rd went from 2 to 8 eggs, and 4th went from 2 to 8 eggs.

As I've mentioned in previous springs, I suspect that more than one female is depositing eggs in each of these nests, but I've only been able to see one adult around at any one time for any of the boxes. In 25 years of walking around the woods at the Academy (around Air Academy HS) I never identified more than one flock of up to about 15 birds at any one time. I'm probably wrong about that, but how many birds are responsible for these 4 nests and 30 eggs??? Guess I need to sit and watch more!

Cool, huh?

Happy Migration,

Steve Brown
Colorado Springs



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