[cobirds] House Wrens increasing in Denver

Hi all

The House Wren has always been an infrequent spring and fall migrant in our neighborhood in Denver. Last summer a few House Wrens were noted in our backyard. This summer the House Wren has blanketed not only our backyard but the whole neighborhood's backyards, to where the wren the now is the most common breeding bird species.

It is curious what environmental factors have triggered this increase. We rightfully take note of birds decreasing in populations but rarely take note of bird population increasing, except those that are considered pest species.

Could there could be common environmental reasons  for populations both increasing and decreasing? Perhaps knowing the reasons why some birds are increasing could help explain why some birds are decreasing? 

Bob Righter

Denver CO