Lincoln Park Zoo biologists, including myself, have been monitoring the local colony of endangered black-crowned night herons since the first birds arrived at the area around Nature Boardwalk at Lincoln Park Zoo at the end of March.
The population seems to have stabilized at around 300 adult birds. On May 31 we heard nestling sounds from some of the nests for the first time in the season. Since then, we’ve been seeing more and more nestling and fledgling activity in the colony.
Most birds are still in the nestling phase, meaning they’re not yet leaving the nest and are still fully dependent on their parents for food. Once birds reach the fledgling stage, they have more developed flight feathers and wing muscles and are beginning to fly. For the most part, the offspring in the colony haven’t reached this point quite yet.
This photo shows a young black-crowned night heron stretching its wings. As you can see, the feathers need to develop a bit more before this little bird can fly, but it won’t be long now.
Learning to fly isn’t easy! Many birds will spend some time on the ground recovering after their first few flight attempts. So, if you do come across a fledgling heron (or other bird) walking on the ground, the bird is often just taking a little break as it recovers. It’s best to leave the bird alone so that it can continue the natural process of fledgling. (You can learn more about the nestlings and their colony here.)