As the 2010 nesting season began, I had concerns as the water level at Hoover Reservoir was unusually low due to a significantly below average April rain total. But May and early June brought heavy rains and the water level was ideal when the birds began incubating their eggs and as the hatchlings appeared in the nests. The end result was another very successful year for the Prothonotary Warblers at Hoover Reservoir as a total of 166 territories were confirmed. The nest location breakdown was 60 nests (36%) in nest boxes and 106 nests (64%) in natural cavities.
2010 saw a significant reduction in usage of the nest boxes by Prothonotary Warblers, although their numbers were solid, with natural cavities taking preference over nest boxes. This may have been caused largely by the tree swallows and to a degree the house wrens arriving first and nesting in the boxes, but this is only a guess. Keep in mind that 2009 nest box usage was abnormally high, presumably because of damage to natural cavities by storms in the previous year.
During the 2010 nesting season there were 250 nest boxes in place. A total of 176 nest boxes (70.4%) were used and 74 nest boxes (29.6%) were not used, although some of the latter did contain “false nests” build by male Prothonotary warblers.
| Prothonotary warblers | 60 | 24% |  |
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| Tree Swallows | 70 | 28% | ||
| House Wrens | 43 | 17% | ||
| Carolina Chickadees | 1 | 0% | ||
| White-breasted Nuthatch | 1 | 0% | ||
| Eastern Bluebird | 1 | 0% | ||
| False PROW Nests | 11 | 4% | ||
| Empty (except for false PROW nests) | 63 | 25% | ||
| Total | 250 | 100% |