First I have to say, I can't believe that this bird actually eats as many insects as it does in a day. Second I can't believe the variety that it catches, I have seen the parent birds bring, mosquitoes, gnats, butterflies, moths, flies, beetles, dragonflies, spiders and bees to the nest. Sometimes the butterflies seem way too big for the young to swallow, and sometimes they are and the Mother has to pull it from the throat of the choking baby, but sometimes the gnats are so small that it's hard to believe the bird can actually catch something so small while in flight.
Ok I've never been a bird watcher so I'm new to this, a lot of things about this bird impressed me.
It uses a lot of moss on it's nest so it is VERY soft to the touch.
It is a very small bird so it's eggs and young are very small, (I wouldn't think it could catch insects as large as it does.)
I have read that the Phoebe is pretty tame around it's nest, I have not found this too be true. It's nest is behind my house on the second story gutter, as soon as I come around the corner she flies off the nest. If I try to take pictures of the young out of the second story window close to the nest I get dive bombed by both parents while they chirp loud and aggressively. This has been the same for all the Phoebe nests I have had so far, the American Robins were a lot tamer.
I can be 20 to 30 feet away and whistle and the young will throw their heads back and open their mouths for food. They quit doing this when their eyes open and they don't see an adult.
I can take pictures, (if the parents are away) of the young when their eyes are closed, but when their eyes are open they can all really squeeze themselves down into the bottom of the nest when danger is present, so all I get is the top of their backs way below the level of the nest, not a good picture. I have tried to be extremely quiet but as soon as they see movement that is not their parents, they get way down.
When an adult shows up to feed the young, the strongest usually opens it's mouth first, I have seen the parent fake feed the first baby by just placing her bill into the first ones mouth and then giving the "real" insect to the next weaker baby. And I have also seen a parent have more than one insect in it's mouth at a time.
When the young are small and their fecal sacs are small, the parents don't take them away, they swallow them. It's days into their growth before the parents fly away with the sacs.
When the young birds get a little bigger, they will put their rear ends up to the edge of the nest when getting rid of waste, most of the time they only have to "go" right after eating so the parent is there and grabs the sac and flies away with it, I may have seen 4-5 droppings under the nest after the young left. They are extremely clean, if a sac breaks and some gets on the nest, a parent will set and eat and pick at it until it's cleaner.
I have seen what is called parasitic birds, the cowbird. My motion detector has caught a cowbird more than once checking out my Phoebe nests, so far they have not been successful. Cowbirds are larger than Phoebes and they will find an Eastern Phoebe nest with an egg or two in them and then they will lay one of their own. When the adult Phoebe comes back in the evening, she doesn't seem to notice that there is one extra egg and she will finish her eggs in the next few days and start sitting. After the eggs hatch, the cowbird baby is larger and will kick out the smaller Phoebe young or eggs and the Phoebe parent will raise the baby cowbird as it's own, not knowing what has happened.
I had one nest where the Phoebe had starting laying her eggs, after two eggs the weather turned very cold and we received eight inches of snow. She didn't sit on the eggs all day and after ten days laid a third egg, then started sitting. All three eggs hatched and all survived even though two of those eggs went through a week of daytime temperatures at close to freezing, she did sit at night when the temperature was below freezing.
The adult Phoebes will sit on a limb and wag their tails, looking around for insects. They are like tiny hawks that dive after insects they see flying around.
As they get older the young Phoebes make a snapping noise with their bills or beaks, when they feel threatened, guess that's the last thing a bug hears as it is caught.
When the young were bigger at one nest, I climbed up to get a good picture and placed my thumb right up to the nest as a guide to how small the young were. After taking the photo I looked at my thumb and it was covered with little mites or bugs of some sort, after looking at the picture closer I noticed the young were covered with these things. I found it ironic that an adult Phoebe being such an outstanding insect hunter had it's young covered in small insects that they couldn't eat.
I'm not an Ornithologist, Scientist, or a Teacher, guess you figured that out after reading my web page, I just am lucky enough to have the time and a little know how to watch a really great little bird that I had no knowledge of before, build it's nest on my house gutter. If you have any questions you can email me at proof of a a lot of the statements I made above, or I could provide witnesses :)