Nesting birds are protected during construction

Typically, we’re asked about driver licenses, project timelines, vehicle registration and even ramp meters, but we hardly ever get questions about bird nests.

So, when we found out that someone had in fact submitted a bird nest question to ADOT’s constituent services officer, we knew we had to share the answer on this blog.

The inquiry concerned nests built by cliff and barn swallows (you’ve likely seen them before – they’re mostly made out of mud and are found under eaves or bridges). Someone who regularly jogs near the Loop 101 widening project wanted to know why the nests under the freeway bridges had been removed.

ADOT biologists were able to explain that the birds are protected by the Migratory Bird Treaty Act and that ADOT’s Environmental Planning Group reviews all projects before assigning measures to protect nesting birds from harm during construction.

In many instances, ADOT goes in to remove old, EMPTY nests from a project site before work begins, but after the birds have gone south for the year (they only nest here during the spring and summer months). This was the case on the Loop 101.

Cliff Swallow Nesting Stages

If work is happening during nesting season, the birds will often try to rebuild, even on a bridge structure that’s under construction.

When that happens, the nesting mud must be removed by contractors on a daily basis to prevent nest completion.

“We can remove the nests as they’re building them without harming the birds,” said ADOT Biologist Joshua Fife, adding that contractors are given training on what to look for and are instructed to not remove nests that are farther along and may contain eggs or nestlings.

On some projects, the team may also install exclusionary measures such as netting or plastic to prevent the birds from building nests.

After construction is complete, the birds are free to build their nests again and ADOT stays out of their way because the mud doesn’t impact our structures.

If you’re interested in birds, you might like this post that explains how ADOT keeps birds away from project site water sources near airports.