Bluebird Research

Test shows Gilbertson Nestboxes help deter House Sparrows

By Michael Jaramillo & Joshua Luisto
tree swallon on Gilbertson box
Tree Swallows nested in 15 of 26 Gilbertson nestboxes that replaced the traditional style. Last year we had 21 House Sparrow pairs attempting to nest in these 26 locations. The Gilbertson boxes reduced that number to just 3, proving a great deterrent for House Sparrows. However, we still did not increase the number of Eastern Bluebirds. None chose the Gilbertson box. Maybe with the reduced House Sparrow population, they try the box next year.

White Plains High School Students in the Authentic Science Research Program

We have been conducting an experiment with the Gilbertson Box (PVC Box) to see if the design of the box helps ward off House Sparrows from nesting inside the box. House Sparrows have been a huge problem for Eastern Bluebirds by attacking them in their nestbox and killing them, and then taking over the nestbox. In order to see if the Gilbertson Box will prevent any House Sparrows from nesting, the boxes were placed in the most heavily infested areas containing House Sparrows.

After three months of observing the Gilbertson boxes and writing down our observations, we have noted that the three species of birds that nested inside the boxes were the Tree Swallow, House Wren, and House Sparrow. The bird that nested in most of the boxes was the Tree Swallow.

It should also be noted that out of the 26 nestboxes that were placed in the selected locations, 15 boxes contained Tree Swallows, 9 boxes were left empty, 2 boxes contained House Wrens, and 3 House Sparrows attempted to nest.

The locations where the House Sparrows attempted to nest had a certain factor that could have contributed to their nesting there. The location at the Westchester Community College had only 1 Gilbertson box and even though Maple Moor Golf Course had 5 boxes placed, they were all spread out from one another. It is speculated that the House Sparrow will attempt to nest there if there are no other boxes or areas for them to nest in. What we also observed from the results gathered is that Tree Swallows are the most likely inhabitants of the Gilbertson box.

But what still needs to be tested is if the Eastern Bluebirds will decide to nest inside the Gilbertson box. If this is tested as true, then the Bluebirds will have a new home where they will not have to worry about any ongoing attack from the House Sparrows.

We would like to thank the Bronx River Sound Shore Audubon Society for their donation to allow us to purchase the Gilbertson boxes for our experiment. We would also like to thank the people that allowed us to place the boxes in the locations to be monitored and we would like to thank our mentor, Mrs. Morrissey, for helping us in our project.

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