They are part of the family of birds called woodcreepers and lay eggs in empty woodpecker holes or other small cavity on trees. Both mother and father help in the incubation of the eggs and feeding of the newborns.
Scythebills are songbirds that live in Central and South America, sometimes joining with other types of songbirds.
It was hard to find much information on these birds, but you can find a little more at Wikipedia and Neotropical Birds.
This is Day 19 of the A to Z Challenge.