In a copy of a letter sent to Wood Duck Society President, Roger Strand, Al Rice of Neotsu, Oregon, recently shared his observations using the BHSC Night Owl Cam.
Exerpts of Al's letter:
"I have taken the liberty of including some preliminary thoughts and comments from a real novice in this confusing field (of animal behavior).
It is interesting to note that two pair of Wood ducks were often observed inspecting this site apparently together. Question: could it be that this shared nesting was pre-planned? Perhaps by siblings or by mother/daughter? Ant it might be of further interest that on at least one occasion, after a major altercation, that minutes after the second hen left the box, the first hen joined her on the water for an apparent normal and tranquil swim together.
In All the shared nesting I've observed there have been many such visits that, beginning with the egg laying, are very peaceful, becoming more tense at the number of eggs increases. It seems be become downright violent as incubation proceeds. This has led me to surmise that the second hens and their egg contributions are basically tolerated and even welcomed during the egg laying period, but that the host hen totally rejects the second hen (and more eggs) after incubation has begun, knowing that additional eggs after that time cannot hatch and will only add to the burden of the host hen.
After all the above, the attack on the second hens eggs was amazing! On the original tape it was obviously the "intruder's" eggs -- but after the host hen tried, but couldn't, break it she tucked it under her wing and it became one of the family. I wonder what would have happened if she had, indeed, broken it.
After a particularly violent fight at the beginning of one incubation, blood was found on three of the eggs, and also on the roof of the same nest box where the expelled hen rested upon leaving. That was the only instance where I have seen blood resulting from their actions, and again (I can only surmise) it might have been from sharp claws against the brood patch. I have never seen any eggs damaged in any of the altercations.
Except for perhaps the first three or four days, we don't recall ever recognizing the second hen being present as the incubation period progressed. We were really floored when she suddenly showed up about 15 minutes before the jump. And, it appears that she was almost welcomed (by gentle preening) on the part of the host hen. I can't help but think she was there checking on "her" contributions, as perhaps she also did from time to time (unobserved) during the incubation. We also noticed that when the host hen finally jumped, she milled around in the water for perhaps a full minute before calling the ducklings out. Was she looking for the second hen? My be is that she was.
Note: Although I have had relatively little experience at this, I have not as yet observed any prolonged "shared incubation" but rather, have observed "shared nesting" during the egg-laying period with the host hen only doing the actual incubation. I realize this might conflict with reports from some of your other observations, but his type of camera work is quite new and more experience might clarify this activity. And then again, "different strokes for different folks" might prove to be the order for this unique animal.
The final porting of the video shows the same jump from the outside, and seems to highlight the hesitancy of the host hen to leave the area. This jump of 15 ducklings took one minute and 20 seconds, which is somewhat longer than we have averaged for a jump of this size.