Site menu:
Natural History Information for Cavity Nesting Songbirds.
Table 5. Reproductive landmarks of songbirds & House Sparrows In the Central Wisconsin area (2005 Data*)
| Bird Species |
Arrival |
1st Nest Built |
1st Egg Laid |
1st Hatch |
1st |
Last Fledge |
Length of Reproduction |
|---|---|---|---|---|---|---|---|
| EABL | 24 Mar | 1 Ap | 10 Ap | 30 Ap | 20 May | 10 Sept | 163 Days |
| BCCH | Resident | 7 Ap | 18 Ap | 5 May | 25 May | 25 July | 110 Days |
| TRES | 29 Mar | 1 May | 12 May | 8 June | 28 June | 21 July | 82 Days |
| HOWR | 20 Ap | 15 May | 23 May | 20 June | 20 July | 2 Sept | 107 Days |
| HOSP | Resident | 1 Ap | 10 Ap | DNA | DNA | DNA | 163 Days# |
* In some cases, the actual dates may be off by a few days
# Estimated only
Natural history data has been collected each year (2002-06) of the Audubon Study. Table 5 is representative of the data collected during that time. Actual dates vary somewhat, but the over- all principles are the same.
Swallows, wrens and sparrows (usually in that order but depending on the habitat) are the main competitors for nest boxes occupied by bluebirds throughout Wisconsin (individual trails may vary from these statewide trends). Chickadees are a distant 4th as a competitor but do compete for boxes on some occasions.
In late March & early April, only chickadees and sparrows compete with bluebirds for nest boxes, as all start nesting about the same time (sparrows before bluebirds before chickadees). If one places nest boxes 100+ feet in the open, away from wooded edges, occupancy by chickadees is normally not a problem. Likewise, if you place your nest boxes some distance away from cattle and other livestock (200+ yards) or do not place your boxes in suburban neighborhoods where millet and corn are fed in the spring & summer, occupancy by sparrows is minimal.
Bluebirds have a “wing up” on swallows in that they will start building nests 3-4 weeks before swallows. As our winters have shortened due to global warming, the swallow is narrowing that gap because they are migrating back from the Gulf Coast earlier. But for now, the bluebird faces less competition from the swallow for the first nesting than the 2nd nesting.
Even less is the competition from House Wrens. First of all, if one places a nest box 100’+ away from short, dense, brushy vegetation, wrens usually do not build in those boxes and if they do so, build dummy nests. Secondly, wrens migrate back to WI even later than swallows. Since they do not even start nesting until mid-May, nearly 100% of nest-seeking bluebirds have selected boxes by then. Therefore, wrens are almost never a competitor in the 1st nesting cycle, but can become a major competitor in the 2nd and/or 3rd nesting cycles for bluebirds.
What kind of nest box should I use for a bluebird trail? Read More >>