Over two months ago I started early daylight watches from my kitchen porcelain top table out to my nearby shoreline area to wait for the sure-to-be Woodduck and Hooded merganser interactions around and in the nesting boxes I put up.
Back in mid-March when we had about a week of temperatures around 80 degrees and cover ice melting around our lake, a female Hooded merganser eyed the cavity entrance of a cedar nesting box I had posted up near our shed off the water. I watched her come up to the edge of the lake ice over 50 yards away and look directly at the box repeatedly. I knew she was looking right at the nesting box and would attempt to fly to it soon. Not that I knew much about Hooded merganser behavior at such times, but it was rather obvious to me what was going on between her visual acuity and her intent to find a nest cavity already at this early stages of breeding.
In my leather covered journal of bird watching that I try to keep on almost a daily basis here at Hidden Lake, I started making entries about this nesting behavior and what would come to be a most rewarding written recording of the almost daily feuding and challenges facing nest box competition between female Wood ducks and female Hooded mergansers. It would take many pages of writing to cover here what I saw and learned about such behavior.
There are some key behavioral interactions between the two species I had never witnessed nor read anything about until I decided to watch them this year from the indoor comfort of my kitchen table chair.
By the end of March, the female Hooded merganser had chosen her nesting box, and yes she did actually come right over to our shoreline once the ice had melted in that far, and I watched her make an attempt to fly from the shoreline right to the box near our shed, a distance of about 25 feet. She had selected THAT box and nothing was going to deter her from using it to nest in. Once I saw this flight from water to box, I immediately moved the box into the water to the north side of our deck By the end of March she had 3 eggs in the dark mulch shavings I had put the box covering the bottom and up a couple of inches in depth.
Soon I moved the same box from dock area to a place along our shoreline closer to our large willow tree, supporting the box post in the water with some underwater blocks. I now could watch the box directly with my journal ready. In past years I would have been more interested in recording the action with a camera, but felt no compulsion now to do so. But I did miss doing so, and now wish I would have tried to capture some of what I witnessed. It would have made for some award-winning photos I think.
A number of times the female Hooded merganser had to challenge the presence of two pairs of Woodducks around the box. At times she did so by going right up to either male or female, and rising up beak to beak, attempt to drive them away from her chosen box. Sometimes she succeeded, driving away briefly both male and female that came into another nesting box I had mounted on our deck facing to try and ease this competition for nesting places, but it didn't work, I put up a third box and it was hardly used by the female Hooded, she wanted the one box she had chosen earlier, and that was it.
One early morning, while this female Hooded was in her chosen nest box along the shoreline with three eggs, a female woodduck flew up to the box cavity, and perched there for some seconds, then went right into the box and in about fifteen seconds kicked the female merganser right out. In the process, an egg was broken, and the female woodduck removed it, took it out into the middle of the lake and gently dropped it into the water. I was watching all this through my Celestron binoculars. Over two months, this female Hooded always came back every morning to this one box and attempted to get in, only to be thwarted from doing so because the female woodduck had already taken up the box at an earlier time, usually by 5:30am, but sometimes when the woodduck slipped out after laying an egg, the female merganser slipped in for up to 10 minutes before leaving again, so the box was getting filled up over a period of weeks with both woodduck and merganser eggs. At one point when the female merganser no longer seemed interested in the box, I went out to it when I knew it was empty of any female, and counted 19 eggs! Female woodducks lay up to 12 usually. This is just a short description of all the interactions I witnessed because I decided it was important to witness for future placements of nesting boxes not only here at the lake but along lakes in other areas nearby where they are needed.
In the last days of March 2011, I witnessed a woodduck pair fly up into our large willow, perch on a large limb, and look around the tree for a suitable cavity for nesting, Immediately after that, I went to a bird product store in Brighton,MI, and bought the cedar woodduck box I am using this year. Last year it wasn't used until June when both a female woodduck and a female Hooded came into it but never laid any eggs. The female woodduck would stay in the box all day, sometimes leaving for a short period but always returning and staying inside it overnight with no males around anywhere.
Interesting behavior! I have thoroughly enjoyed watching and learning about the interactions between these two waterfowl species. The pages of my leather journal contain a lot more of it, and the pages describing it all just ended June 16 with the successful hatching of around 10 eggs by the female woodduck in the shoreline box. The first dock nesting box contained 18 eggs, but female woodduck abandoned it a week before hatching, and no female returned to it, though I often spotted the female Hooded looking intently at it. You see, there were two female woodducks and two female Hooded interested in both boxes at one time, but only one succeeded in incubating any eggs until they hatched and left the box into Hidden Lake.
Thanks for following a part of the ongoing story sure to continue next year.