From the field: Tree swallows

A male tree swallow sits near his nest box during breeding season in central Alaska. (Photo by Dan Doak.)
A tree swallow chick at one of the Alaskan sites used for a CU Boulder-led study looking at how wind, rain play a role in breeding cycles. (Photo by Meredyth Duncan.)
Eggs and a newly hatched tree swallow chick at one of the Alaskan sites used for a CU Boulder-led study looking at how wind, rain play a role in breeding cycles. (Photo by Meredyth Duncan.)
Young tree swallow chicks are nearly naked and require parental warmth as well as feeding to survive. (Photo by Meredyth Duncan.)
UAA Professor Audrey Taylor examines female tree swallow wing for signs of wear. (Photo by Lindsay Hermanns.)
Rachel Irons measures an adult tree swallow. (Photo by Lindsay Hermanns.)
A male tree swallow enters his nest box. (Photo by Lindsay Hermanns.)
Rachel Irons checks a tree swallow nest box. (Photo by Lindsay Hermanns.)
A canoe loaded with nest boxes, ready to be installed in the field to create a new study site. (Photo by Tess Forstner.)
A tree swallow perches on a wire. (Photo by Dan Doak.)