The zoo announced on its Facebook page that the Pritzker Family Children's Zoo's outdoor area will be closing temporarily to accommodate breeding season for the black-crowned night herons. The animals, which are endangered in Illinois, call Lincoln Park Zoo home and tend to nest in the children's zoo (I remember the zoo closed off the viewing window for the red wolves once because the birds kept defecating, I'm assuming on guests, as their nests were right over the window). It should reopen after breeding season is over.