Bird nest riddle: Which shape came first?
Don’t assume simple cup-shaped architecture evolved before roofed structures
![warbling vireo in a cup nest](https://i0.wp.com/www.sciencenews.org/wp-content/uploads/2016/08/081916_sm_bird-nest_free.jpg?fit=860%2C460&ssl=1)
OPEN QUESTION A new study questions the intuitively obvious idea that simple cup nests, like this one of a warbling vireo, evolved before nests with roofs.
Gary L. Clark/Wikimedia Commons (CC BY-SA 4.0)