The mother Swallow is incubating six eggs. They incubate for about 14 days, beginning at the penultimate egg--so usually the fifth one, though sometimes there are seven egg clutches. When I went to take this photo, she dove at me and screeched right before she would have hit me. Defensiveness is important! Later in the season, the birds may get together in big groups to protect the nestlings from potential predators (or ASI interns).

Hatch season means banding time! The babies are so tiny, but they grow fast. In 11 days time, they are big enough for us to band (and their tarsus, or leg, has gotten thin enough for the band to fit onto). As soon as they are born, the parents' full time job is to feed them so that they can grow strong to fledge from the nest. 

The same day that the babies hatch, we catch the parents to record data on them, including either banding them or writing down their band number. Here is a photo of the mother having her wing measured. We take both a wing chord measurement, meaning the length of the wing's natural curve, and a flat wing measurement, where we gently press down to get the wing's actual length. We also take fat, culmen: beak from the nares (bird nostrils) to tip, mass, age based on plumage, and sex.

11 days have passed, time for the babies to get bands too! We cannot take a wing chord measurement for them since their wings are not grown enough for the natural curve, so only flat wing for them. In addition, we measure their culmen, mass, fat, and the length of their longest primary feather from the end of the sheath it is protruding from. We also cannot determine the birds' sexes yet because they are not old enough to have the cloacal protrusion or brood patch that adults have during breeding season. Chicks are much easier to take data on because they cannot fly away, but they still squirm. So cute and tiny! I think the way they squint at you makes them look like little grumpy old men.

The nest is empty; all the chicks have fledged. The season is winding down, and everyone from the other boxes should be fledged by the 8th of July. To fledge check, we sit a distance from the box and carefully watch for parent birds feeding chicks, or the chicks poking their heads out of the box. If after ten minutes we see nothing, we approach the box, listening for any movement or vocalizations from babies. If there is once again nothing, we carefully open the box to check for chicks. It is very important that we pay attention, because if there are nestlings in the box and we disturb them, they may fledge early. This could cause them to die. Once everyone is gone, it will be time to enter data and clean the boxes out for next year!

With nest cleanout done, the season is over! In a year, the Swallows will return to choose their nest boxes again.