Blue Bird Update
| Eastern Bluebird | 2010 | 2011 |
| Number of Nesting Attempts | 130 | 97 |
| Number of Eggs | 534 | 397 |
| Percent of Hatch Rate | 82% | 84% |
| Number of Live Young | 439 | 334 |
| Percent of Fledge Rate | 92% | 91% |
| Number of Fledged | 406 | 305 |
| Percent of All Eggs Resulting in Fledging | 76% | 77% |
| Tree Swallow | 2010 | 2011 |
| Number of Nesting Attempts | 98 | 97 |
| Number of Eggs | 474 | 487 |
| Percent of Hatch Rate | 80% | 82% |
| Number of Live Young | 378 | 398 |
| Percent of Fledge Rate | 78% | 75% |
| Number of Fledged | 296 | 300 |
| Percent of All Eggs Resulting in Fledging | 62% | 62% |
| House Wren | 2010 | 2011 |
| Number of Nesting Attempts | 23 | 14 |
| Number of Eggs | 128 | 67 |
| Percent of Hatch Rate | 84% | 78% |
| Number of Live Young | 107 | 52 |
| Percent of Fledge Rate | 85% | 83% |
| Number of Fledged | 91 | 43 |
| Percent of All Eggs Resulting in Fledging | 71% | 64% |
| Black-capped Chickadee | 2010 | 2011 |
| Number of Nesting Attempts | 2 | 1 |
| Number of Eggs | 13 | 7 |
| Percent of Hatch Rate | 54% | 86% |
| Number of Live Young | 7 | 6 |
| Percent of Fledge Rate | 100% | 100% |
| Number of Fledged | 7 | 6 |
| Percent of All Eggs Resulting in Fledging | 54% | 86% |
| House Sparrow | 2010 | 2011 |
| Number of Nesting Attempts | 14 | 11 |
| Number of Eggs | 57 | 45 |
| Percent of Hatch Rate | 0% | 0% |
| Number of Live Young | 0 | 0 |
| Percent of Fledge Rate | 0% | 0% |
| Number of Fledged | 0 | 0 |
| % of all eggs resulted in fledging | 0% | 0% |
Despite the cold and wet, wet, wet weather this year, our bluebirds had a pretty good season.
The final fledgling count is 305, which ranks as 11th in the 47 year history of the program. Compared to 2010, our fledgling count is down a lot – 406 fledged in 2010 – but overall nest success is up slightly, 76 percent in 2010, 77 percent in 2011.
The date of the first bluebird egg this year was April 13, nine days later than the past year. This late start meant that we had fewer bluebird nests in April, but more in May than what we normally see. We also had fewer nesting attempts in June and July, perhaps because the late start didn't allow enough time for some nesting pairs to have a second brood.
The Tree Swallows were a real shock to Holden conservational, who saw a lot of nestling mortality in June and July due to weather. Based on this, the expectation was that the final number count would be low. Surprisingly, the final fledgling count was 300, which makes 2011 the third best year on record! Nestling mortality meant that our fledgling rate was 3 percent lower this year than last – 78percent in 2010, 75 percent in 2011. However, overall nest success was the same – 62 percent – due to a higher number of eggs laid and higher hatching rates than last year.
Conservation biologist Mike Watson thinks the fact that the high fledgling count despite the nestling mortality shows just how successful Holden's program has been; we've built and supported a strong swallow population that was able to tolerate high nestling mortality without a substantial shock to the overall population.
In addition to the blue birds and tree swallows, volunteers also noted the number of house wrens, black-capped chickadees and house sparrows fledged at Holden. The data is included in the chart to the right.
Thank you to all of our volunteers who helped build and install the new nestboxes, monitor the trails, and enter data.
For more details on the volunteer bluebird monitoring program contact Mike Watson at 440.946.4400 or mwatson@holdenarb.org.
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