Birds Of A Feather Shop Together

May 4, 2015

"Have you ever been shopping at your local retailer, heard the chirps of birds coming from the rafters, and wondered, “How did those birds get in here?”

Perhaps you assumed that the poor creatures flew in by accident, trapped forever with little chance of escape. You’re not alone; many people have noticed these urban shoppers. There have been increasing reports of birds nesting inside cafes, grocery stores and retail businesses worldwide.

For birds, gaining access to these buildings is clearly a problem. How do they get inside? At least some birds open doors by fluttering in front of the automatic door sensors. This could be a learned behavior. Once inside, these individuals have at their disposal everything a nesting bird could hope for: plenty of food, a constant climate, and protection from predators. Two very common species behave this way: house sparrows and barn swallows.

House sparrows, notorious for their individual personalities as well as their adaptations to urban sprawl, are a common sight in towns and cities. These sparrows employ a variety of tactics to gain access to buildings and a bird lifestyle of luxury. In addition to hovering directly in front of an electronic eye sensor, they’ll perch on top of the sensor itself while leaning their heads in front of the infrared beam. One observer saw sparrows open a door in this manner sixteen times in a 45-minute period. Female house sparrows seem to prefer us to open the doors for them, flying into the store close behind us – which gives new meaning to the expression, “Ladies first.”

Barn swallows once nested in caves or overhanging cliffs, but human encroachment has led them to nest mainly on buildings, under bridges, and in culverts. They’ve also learned to open automatic doors. In one Home Depot store, 2004 marked the fourth year barn swallows had taken up residence inside, building at least a dozen nests. This suggests that these birds are returning to the same nest sites each year after long winter migrations. Some of these birds even fluttered in front of the motion sensors from inside the store, opening doors for other feathered friends outside. Wildlife biologists in the area watched in astonishment as swallows flew in and out of the cavernous store with food for their young.

Nesting in a Home Depot protects swallows from bad weather, parasites and predators. And opening automatic doors suggests that being called a bird brain isn’t such a bad thing. Maybe the next feathered consumer you see is there of its own accord. It might be even smarter than the average coupon-clipper.”

(Broadcast: "Fieldnotes," 5/5/15. Listen weekly on the radio, Sundays at 12:55 p.m., Tuesdays at 4:54 p.m., or Fridays at 4:54 p.m.,  or via podcast.)