Sight of Finches

 We noticed that there are Finches around the building recently.  

From August, they randomly pop in and dropped by.  They leave quickly if they see us.

I can't figure out if they are House Finch, Purple Finch or Cassin's Finch.

I only caught the picture from the back as he or she is leaving.

From this angle, it looks brown, but I think the front is red or pink.

I will leave some seeds or sunflower seeds to see if they come more often.