I was on a trail along Humber River West just north of where I live. I came across a pair of male Mourning Warblers, chasing each other. I took some photos and while looking at them on my computer screen I noticed that one of the males had some form of growth under its lower beak. This is probably what is called an Avian Pox - quite a common occurrence in domesticated birds; however, wild birds get them too as is the case here. This is breeding time and given that it can be transmitted from bird to bird, not sure what the impact of this male will have on its breeding partner and also on the chicks. At one point it sat on a branch for quite some time with beaks open, could be from exhaustion. However, I also have a photo of it catching an insect (last photo below) - so all is well for him now.
