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One for the Books:
Bluebird Trio Share Nest and Are Cooperatively Raising 8 Chicks
BRAW member and long-time bluebirder Mary Roen of River Falls, Wisconsin is witnessing and documenting a fascinating case of cooperative nest sharing and rearing behaviors on her bluebird trail in western Wisconsin.
Mary's Account
On May 31, when I monitored, box #11 had 3 EABL eggs in it, and box #12 had 2 nestlings with 2 unhatched eggs. When I monitored my trail again on 6/7/08, the nestlings in box #12 and the eggs in box #11 were gone. I have stovepipe baffles on both boxes and they are mounted on electrical conduit over rebar. I have no idea what happened to both boxes, there was no sign of predation. It almost had to be avian. I removed both nests and when I monitored my trail again on 6/15, there were 5 EABL eggs in box #12.
I was on vacation, so couldn't monitor again until 6/27, when I found 9 eggs in box #12! The only thing I could think of was that 2 females were laying eggs in the same nest box. Maybe a mother and last year's daughter? That could explain why there was no rivalry between the two. On July 4 there were 8 nestlings about 2-3 days old. I set up my video camera and documented 2 females and one male feeding the nestlings. I could see that the Gilwood box they were in was not going to be big enough for 8 nestlings, so on July 8th, I moved them to a bigger box that I built with two 1.5 inch holes in the front. I am sure that the parents would have fed the nestlings just fine with one hole. I just thought it would be interesting to see what they would do with a 2 holer. I thought maybe 2 would feed at the same time more often, but I have caught that on tape only once. As the nestlings come to the hole to be fed, it will be interesting to see if there is one at each hole, and if 2 would fledge at once. I probably won't be lucky enough to get that on tape. If the nest were closer to the house, it would be easier to monitor more closely.
I hinged the roof so I could take pictures more easily. I set up my video camera to be sure the parents accepted the new box and emailed those results to Bluebird-L. I checked the nest box the next day and all 8 nestlings are doing well and have plenty of room in the new box. Even without supplementation of mealworms due to the unavailablility of mealies, the 3 parents are doing a great job of feeding and taking care of the 8 nestlings. At this point, the chicks don't even occupy half of the nest box, so there is going to be plenty of room for them to exercise their wings and hopefully all will fledge.
July 20, 2008
I am so excited to report that all 8 nestlings have fledged! There were 2 left in the nest box yesterday, and I went out to check this morning and the nest box was empty! The pictures I got yesterday of the nestlings in the holes, was of them ready to fledge. I feel like they were saying good-bye in those pictures. I am having a serious "empty nest syndrome". I have been checking these nestlings daily since July 12 and now they are fledged and out it the big world. I hope they survive the next stage of their lives and will be
back next year to start over with a new generation of Bluebirds. I love happy endings!
View a slide show of Mary Roen's photographs documenting this unfolding story
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Check back for Mary's photo updates to the slide gallery. She will be writing a formal article about her Eastern Bluebird ménage à trois for BRAW's Fall 2008 edition of Wisconsin Bluebird.