First, per my yard list records, birds are migrating very early this year. I am seeing things 2-4 weeks earlier than in previous years.
Second, I have a mountain ash tree that I keep, mainly as a way to observe thrushes, despite the fact that my spouse hates the tree and wants to axe it. It provides a real bounty to thrushes in the fall. However, last year to some extent and even more so this year, we have been completely overrun with immature robins. They are finishing off the berries way earlier than in previous years. Thus altho I have seen a few Swainson's thrushes this year (early as per first thought), there will be nothing left for hermit, wood and gray-cheeked who are still to come through. My theory is that West Nile has eliminated crows in our neighbourhood (they were very common a few years ago), and reduced blue jays, resulting in much higher nest success for robins. I'm assuming the young robins are coming from nearby, but I really don't know if that's true.
