The Bewick's Wren is a pretty little bird, active and often breaking into song. Unfortunately, Bewick's Wren populations has declined dramatically. The North American Breeding Bird Survey estimated that it has dropped by about 39% between 1966 and 2015. It has just about disappeared east of the Mississippi River, and appears to be declining in the West too. That is a shame because I love to see and photograph them.
According to 'All About Birds' - "The House Wren is a likely culprit. Drawn to the same nesting sites as Bewick’s, this widespread wren doesn’t hesitate to appropriate the other birds’ real estate, ejecting eggs and destroying nests..... Bewick’s Wren populations may also be falling prey to agricultural pesticide use, and to competition with the European Starling, House Sparrow, Carolina Wren, and Song Sparrow." https://www.allaboutbirds.org/guide/Bewicks_Wren/lifehistory