In one round trip, traveling to and from the building materials location, one bird covers 2*200= <<2*200=400>>400 miles.
If in one round trip one bird covers 400 miles, in 10 round trips, it covers 400*10 = <<400*10=4000>>4000 miles.
Since there were two birds collecting the materials, they covered a combined 4000+4000 = <<4000+4000=8000>>8000 miles collecting the building materials in 10 round trips.
#### 8000