Smithsonian Unlock the Mysteries of Nighthawk Migration

Posted By : The Animal Facts Editorial Team

Date: February 6, 2021 10:30 pm

A common nighthawk with a GPS transmitter which was used to map their migratory route.

Photo Credit: Smithsonian’s National Zoo

A new study led by led by Smithsonian Migratory Bird Center and University of Alberta biologists has helped to unveil the secrets of the migration of the common nighthawk. The study was published on February 2nd in Ecography.

It has created a comprehensive picture of the 10,000 kilometer migratory route used by the common nighthawk and represents the first step in tracking their decline.

“This charismatic migratory bird—known for its evening dances to catch insects—is one of many species whose name includes the word ‘common’ despite the fact that they’re disappearing from parts of their range,” said Autumn-Lynn Harrison, research ecologist at the Smithsonian Migratory Bird Center. “Our international partnership revealed the previously unknown migratory pathways of common nighthawks as an important step in planning their recovery.”

Despite being one of the most widely distributed birds in the western hemisphere the common nighthawk is one of the most poorly understood as they are nocturnal. Despite being called a hawk they are actually a ‘nightjar.’

“Like many migratory bird species, common nighthawks are declining, but the rate of those declines varies across North America,” said Elly Knight, lead author and doctoral student in the Department of Biological Sciences at the University of Alberta. “Figuring out what causes those declines can be difficult and complicated for migratory species like the nighthawk because they occupy so many different places during the year.”

This project was a collaboration bringing together researchers from the Smithsonian Migratory Bird Center, University of Alberta and Environment and Climate Change Canada in a massive collaboration across 13 locations throughout North America.

— AD —

During summer researchers would place a small GPS backpack on common nighthawks. The researchers sought to form a complete picture of common nighthawks migration connectivity, this is the degree to which the separate populations stay together during the migration.

“This is a critical start to developing conservation approaches, because it allows us to focus in on the times and places where population declines might occur,” said Knight, who completed the research under the supervision of professor Erin Bayne. “Without understanding migratory connectivity, there are a myriad of potential reasons why a migratory species might be declining. Without the full picture, we might miss times and places where population declines are occurring.”

Common nighthawks undertake breeding in North America before flying to South America in the fall. Along the way they make a number of stops with the GPS tracking helping researchers to understand where they spend their time outside of North America.

“We were surprised to find that despite being distributed across North America, common nighthawks essentially use the same migratory route to their wintering grounds in South America,” Knight said. “All breeding populations fly east or west to congregate in the midwestern United States along what we call the Mississippi migration flyway. From there, they all mix together and take a common route south across the Gulf of Mexico, down through the northern Andes and onto their wintering grounds, mostly in Brazil. That common route means that there’s little migratory connectivity for common nighthawks outside the breeding season.”

“Now that we understand common nighthawk migratory connectivity, we can take the next steps along the path to understanding what limits their populations,” Knight said. “We plan to focus on the times and places with elevated connectivity: breeding, fall migration in North America and prior to crossing the Gulf of Mexico during spring migration.”