Tree Swallow Nest Update

Both of my tree swallow nests are showing signs that chicks have hatched. 

As I watched, a swallow arrived and perched. 

Jumped in and stayed for a few moments. 

Then popped up again, carrying evidence of chicks. 

The bird has a fecal sac in its beak. Tree swallow chicks produce waste in little, easily carried packages that the parents remove from the nest. It keeps the nest clean and helps avoid odors that might attract predators. Click to enlarge. 

The same thing was happening at the second nest I monitor. 

Tree swallow parents catch insects in the air and form balls of them called boluses to feed to the chicks. In with a meal. Out with a fecal sac.  

A hardworking bird on its way back out to dispose of a sac and catch more food. 

Impressive.