I Know Why the Common Yellowthroat Sings

The other day in the willow scrub where I was observing the Brewster's warbler and his friend the blue-winged, there was also a pair of common yellowthroats. The Brewster's et al. were foraging and carrying food, the common yellowthroats were chucking. I never saw them pick up anything. I went back the next day to see if the Brewster's and friend were still there (they were not--it must have been fledglings not a nest that I was hearing being fed that first day), and met up once again with the c. yellowthroats. Once again the birds were chucking, and while the female centred herself around the willow clump, the male would follow me for 30 or more metres in all directions, never letting me out of his sight, and never shutting up.

Then, as we travelled south, he had to pause in his scolding of me to chase another male common yellowthroat. A few moments later, as we moved back towards the centre (where there must be a nest or a clutch of fledglings), the other bird began to sing.

This morning I ran into a common yellowthroat on the far side of the far field (a female), and shortly afterward heard a male singing there. Meantime, as I headed back towards the area held by the first pair, I was met by the male, again, some distance from the presumed nesting site, and was thoroughly "chucked" out, the female only joining in as I approached the willows.

I used to think that male birds sang until mated, then got to down to the business of nesting, feeding young, etc. with their partners (at least I thought this about the species where the male is an active partner in raising the family). And that does seem to be true of many--my Brewster's has not sung for some time now, for example. The black and white warblers have just started to sing again in the last few days after a long silence, the chestnut-sided also stopped singing quite a while ago, and the list goes on. On the other hand, the robins and wrens never shut up.

The common yellowthroat really is a common bird. Its not as often seen as the house wren or the robin. It rarely nests in people's yards, though the one from the marshy wood across the street occasionally drops by the front yard. But it does seem that there is a pair of common yellowthroats occupying every suitable half hectare available--and the singing is required to keep the neighbours from encroaching, just as in the case of the robins and house wrens. The robins and wrens live here so openly it is obvious that their nesting territories were cheek by jowl--and those boundaries must be maintained, just, as it turns out, as in the case of the common yellowthroat.

The question then is why is this bird so common, when other warblers with apparently pretty similar lifestyles in terms of habitat and food requirements are in trouble.