Whether you're a bird person or not, this is stunning!!!
to detract from the sheer magic of it, but in practical terms, how M A
NY trips would a bird have to make with that tiny little quantity of
mud/clay it could carry? (and how far from the nest is the source?)
you take the construction of a circular bowl in your stride as
instinctive how the heck does the bird come up with the
windbreak/entrance design that shields the eggs/chicks from the
elements? And at what point in fashioning the bowl do they start to
Structural engineer in action.
Even if you think you could build this? Try it without using your hands!
Cliff Swallows are even more impressive - they do this against gravity - building under eaves of buildings.