first neotropical migrants this year earlier than normal

I was surprised to step outside my house on Saturday, April 4, 2015, and hear a white eyed vireo calling from the hedge in our front yard. Later that day I heard a northern parula in the yard. It was a week before I heard them again. It was at this time that I also was hearing the first american toads trilling. As far as the white eyed vireo goes, it is a about 3 weeks earlier than the year before.