The Green Heron really wanted this curved twig. It could not break it off.
Meanwhile. Literally, at the same time, another Green Heron was further up in the woods. This one was successful, snapping off a twig and then flying it back to the nest site. The first heron flew back as well, but without a twig. The birds are nest-building. As with Red-tailed Hawks, they seem to want fresh twigs, not ones already on the ground, which, I assume, could be too wet and/or carrying unwanted lifeforms.
“Green Heron” sure is a misnomer. The specific epithet, virescens, means becoming green. “Possibly it is losing its green, of which the bird has very little,” snarks Choate. Anyway, they’re nesting nearby and their hunting and gathering show is great.
Backyard and Beyond 
Marvelous series.
I think it more likely the previously detached twigs are too dry, inflexible and brittle. Making a nest is not just a laying of twigs stems and grasses. These materials are more woven into a shape with somewhat interlocking parts. As the nest material dries it becomes lesss flexible and harder to disassemble. This contributes to the durability of the nest. In some nests the mixture of mud and fibers in the bottom acts like an adobe. It is moldable when wet but strong and rigid when dry. Birds are pretty good engineers and choose their materials carefully.