Often, they would break into a ritual we-are-partners display. Sometimes they'd mate.
They seemed to delight in each other's company. They seemed to be having fun. It looked like a honeymoon time.
Later, when nesting began, it was suddenly different. They could rarely be together. They had to schedule. One would be on the nest, and the other would race around solo until it was time to trade places. (Father and mother sheathbill each brood the eggs.)
There's a webcam at one nest that allowed us to see an interesting thing. Sometimes when they switch off at the nest, they just switch off. Other times, they start doing the partner display, and then run excitedly out of the nest together. Fifteen or twenty seconds later, one races back into the nest chamber at top speed, only braking to lower itself tenderly on the eggs. They spend a little intense time together, but no more, because the eggs mustn't get too cold. A flash date night.
Chicks will probably hatch very soon. That will keep them even busier.
We have to leave before the austral winter. Reports are that sheathbills aren't seen in pairs in the winter.
Sheathbills haven't been studied to see if the same birds pair up every spring/mate for life. My guess is that they usually do, like other birds who seriously bond and raise chicks together.
Birds like that are interesting. Like many human couples, they fall in love, they have a time of double happiness, then a time of family togetherness.... And again next year, if both live.
If it's true they aren't together in winter, then it's interesting to imagine them going through the romantic cycle many times. Falling in love again, being a cute couple going dancing again, setting up house again, dancing attendance on the chicks again.... I could watch these birds all year.