Among many bird-watchers, there is an obsession with listing. Species one has seen anywhere, species one has seen in Ontario, species one has seen in Ontario in October, species one has seen through a particular window while sitting on the toilet and so on. I once had a colleague point his binoculars up at the sky for a few seconds, and say, "Awesome, I've never seen a Red-Throated Loon on the southward migration over Lake Eire before. Another tic for my list."
I keep a few place specific lists, "birds I've seen in the El Cerrito Hillside Natural Area," or, "birds of Mahopac, NY," and used to keep a life list (e.g. all the wild birds I've ever seen anywhere) but I've never really gotten into listing for listing's sake. Hard-core listers (commonly referred to as twitchers for their inability to hold still if someone suggests a bird they don't yet have on a particular list is nearby) are often far more interested in adding birds to lists than in actually looking at the birds, and will often travel long distances to find a bird, look at it for just long enough to confidently add it to their list, then begin the long journey home. Those of us who are not twitchers, but know people who are, enjoy the game of making up new types of lists and mentioning them to twitchers so that they will feel compelled to rush out and start building a bigger, longer more impressive list with more rare species. So, in that spirit, I have started to compile a copulation list, of all the bird species I have ever observed copulating. This list is necessarily incomplete, as I am only including those species which I know a particular time and place when I witnessed a copulation in the wild, but excluding all the other species that I forget where or when. This list was inspired by the activity of two house-sparrows this fine June morning.
In no particular order: