NBS Blog

Springing Into Action for 2024 Nest Box Season

Read Conservation Manager, Jay Manning's account of the impressive and speedy installation of nest boxes to accommodate the early migration of tree swallows this spring. Thanks to the hard work of Conservation Crew volunteers, NBS staff, and Met School interns, 65 were erected on March 14th! Read on to learn how it all went down.

Don’t you hate it when company shows up early? Last Tuesday morning, NBS Science Coordinator Sara Poirier and I drew up a schedule to install the nest boxes that will be used by the tree swallows when they return to the Sanctuary from heir wintering grounds in South America. The Conservation Crew would put up the boxes in one field on March 27th, NBS staff would do another field on the 28th, and Professor Jameson Chase’s Bio 255 class would finish up on April 4th. The nest box monitoring program would begin on April 1st.

Well, that was the plan. The next day, while the Con Crew was demolishing an old shed next to the Cabana, I noticed three tree swallows flying over the North Field. The following day more swallows were flying over the field. Two plans had to be scrapped now. First the nest box installation schedule had to be sped up, and the Conservation Crew’s plan to remove privet at the end of the Valley Trail was dropped. Crew members Bob DeMagistris and Kitty Rok pivoted with aplomb. They were joined by Met School interns Lucie Stubler and Ian Marchand, along with NBS Gardens Program Assistant Sophie Cleland, in an emergency swallow housing project. A total of 65 boxes were erected that morning.

The swallows were happy to see the nest boxes. Some landed on a box almost as soon as it was installed. Others started peering inside, checking to see if it was THE place to raise a family. Unfortunately, the swallows weren’t the only house hunters. The non-native house sparrows, who are year-round residents, were as opportunistic in checking out the new listings. And it didn’t take long for them to display their aggressive behavior. Any nest box that a tree swallow was interested in, a house sparrow quickly claimed for itself. Soon males were fighting on the ground while an awaiting female house sparrow looked out from the nest hole. There goes the neighborhood!

It’s going to be interesting to see what the nest box monitoring data reveals. Normally, an entire field gets its boxes installed at once. Previous data tells us that the boxes that tree swallows and house sparrows use are randomly spread throughout a field. (Fun fact: house wrens, the other species that uses our nest boxes, will set up in the boxes only located on the perimeter of a field). Because we had to unexpectedly raise some nest boxes, will the aggressive house sparrows that those boxes, leaving the boxes in the rest of the North Field, once they are installed, to the tree swallows? Stay tuned.