A violet-green swallow outside of a tree-home nest.

Swallows are prolific insectivores. A single bird consumes roughly 60 insects per hour, or 850 to more than 1,000 insects per day. Their diet is composed primarily of insects they catch in flight, including mosquitoes, gnats, flies, beetles, ants, moths, bees, wasps, damselflies, and even grasshoppers and crickets. Berries and seeds make up their non-insect foods.

In June, I featured six swallows found in Denver. Here are examples of nests in which they raise their young. Barn and cliff swallows build cup-shaped nests of mud under eaves, rafters, and bridges. Tree and violet-green swallows occupy tree-hole nests or man-made nest boxes. Northern rough-winged swallows nest in pre-existing burrows along vertical dirt banks along streams and river bluffs. Bank swallows nest in similar excavated burrows.

Bird Walks:  July 4 and August 1. Two start times: 7:30am and 8am. Walks are free, but you must RSVP at blufflake.org/birdwatching. All are welcome. Bring your own binoculars or borrow a pair from your guide. 11255 MLK Jr. Blvd.

August 1 from 10am–12pm: George Ho begins Armchair Birding at Bluff Lake Nature Center, an accessible and approachable indoor lecture series. These events are open to anyone who would like to learn more about the world of birds, including those who cannot access outdoor birding opportunities or are new to the hobby of birding.

Left: A barn swallow nest. Middle: Cliff swallow nests. Right: A tree swallow leaving a man-made nest box.