Sprint Nextel Corp. is racing to build a complicated new coast-to-coast cellphone network. The carrier could move faster if it weren't for the birds.

It turns out the same towers Sprint is rigging with high-speed wireless technology to compete with Verizon Wireless and AT&T Inc. are a favorite nesting spot for ospreys. The big fish-eating raptors favor high perches with a clear approach—exactly what network engineers look for when putting up cellular sites.

The nests, basically just big piles of sticks, can be large enough to house a full-grown person and weigh up to half a ton. And once they have settled on a spot, ospreys are tough to evict.