4/20: Bluebirds have started a nest at the winery!
4/30: 5 bluebird eggs. Since incubation began when the last egg was laid on 4/29, these should hatch around May 11-13. The nestlings then stay in the nestbox for another 16-21 days.
HOSP are an introduced, invasive species that will attack and destroy the eggs, young and adults of bluebird and other native birds. In addition to being aggressive, they are extremely prolific. Successful bluebird landlords do not let HOSP breed in their boxes. Because they are non-native, they are not protected by the Migratory Bird Treaty Act.
Bluebirds are nesting nearby, and the owners, Linda and Dick Auger, are interested in hosting native birds such as bluebirds, tree swallows or chickadees. Since I have several bluebird trails in the area, I offered to get involved in a House Sparrow management program in 2008. Note that there are a number of other boxes on surrounding properties (and possibly bluebirds nesting next door.)
The first step was plugging up two decorative boxes that can not be opened for monitoring, cleaning or trapping.
The second step was removing all existing HOSP nests the week of 3/31. The bulky nests filled a large garbage bag. The owner commented that within 3 hours of removing the nests, the HOSP were furiously rebuilding.
The third step was starting a trapping program on 4/6 to remove HOSP that are nesting in the area. The HOSP will be donated to a local raptor recovery center. If the HOSP are not removed, they are likely to go next door to attack nesting bluebirds, and will not allow native birds to use the nestboxes.
After local HOSP are trapped, the next step will be to put up some HOSP resistant boxes (Gilbertson/Slot) and to outfit existing boxes with monofilament to attempt to deter HOSP. IF a native bird is able to get to the point of laying an egg, the box will be outfitted with a sparrow spooker.
Results:
As of 5/3: Number of HOSP trapped: 8 males, 8 females (in live ground and inbox traps.) All trapped birds are donated to a local raptor recovery center.
Log:
4/5: All boxes have HOSP nests, removed. Trapped 2 males (one in ground trap, one in nestbox.
4/13: Saw a bluebird perching on the sign out in front. All boxes still have HOSP nests, no eggs yet. Saw at least 8 pairs of HOSP on house roof. Trapped 4 male HOSP.
4/19: The owner saw a bluebird starting a nest.
4/20: There is a partial bluebird nest in a small box that faces west. Monofilament was added to the box. No HOSP eggs yet, but nests in all other boxes, which were removed. A slot box (which is a style that some HOSP do not prefer) was added out in front. Bluebirds were checking out that box later in the day. Linda said that in the past, bluebirds used to come and check out the boxes but were always chased off by HOSP.
4/22: It appears that the bluebird pair have abandoned their first choice and have moved over to the new slot box. Linda said the sparrows didn't miss a beat, noticed another box available, and have taken that one back. Actually this is good! It slows them down a bit (see timetable), but they will probably be safer over there - the new box is deeper (harder for predators to reach into), has more room for growing babies, and the entrance is wider, so if a House Sparrow gets inside, the bluebird can escape more readily (if they can break away from the killer beak.) Also, HOSP are less likely to be interested in that style box, and it is on the other side of the house where most are currently nesting. In addition, the slot box is easier to open for monitoring.
4/26: Two bluebird eggs in the slot box! A sparrow spooker was installed to protect the precious contents of the box 24/7 from HOSP attack.
4/28: Four eggs.
4/30: 5 eggs, she is done laying.
5/3: Heard male singing nearby, female is incubating. Five HOSP nests, seven eggs and 2 female HOSP removed. Another 7 adults seen in the area. Linda reported seeing the male bluebird chasing off a single investing House Sparrow.
5/11: Bluebird eggs are find, Linda indicated Tree Swallows (TRES) were investigating other boxes. Trapped on in box in back. 2 full HOSP nests with 3 eggs each, removed, partial HOSP nests in 2 other boxes.
Who does not welcome the beloved Bluebird and all that his coming implies? His cheery warble, heard at first as a mere wandering voice in the sky, heralds returning spring .... Snow may still lie in patches or drift in flurries; but when the Bluebird comes we know that spring is near.
- John B. May, abridgement to A Natural History of American Birds of Eastern and Central North America, 1930's
