Reserve Laguna Nimez is a must see in El Calafate.  The Reserve is easily accessible from center of town via foot.  There is a well marked trail and self guided leaflet that the park ranger will provide at the entrance.  There are over 10 species of birds including flamingos.  More flamingos are in Laguna Nimez than the Lake Argentina viewing spot from the edge of town.  If you are a bird watcher, you will want to spend several hours camped out in Laguna Nimez in one of the hidden shelters.