By Charlona Ingram, Houston Audubon Volunteer
In 2016, Houston Audubon began surveying birds on Glenbrook Golf Course next to the Raptor and Education Center. The bird surveys continued even as the property was turned over to the Houston Botanic Garden in 2018. Beginning the surveys while the property was still in use as a golf course allowed Houston Audubon to assess bird populations over the years as the property was converted into a botanic garden.
During the early surveys, participants noticed that the property had a large number of Eastern Bluebirds. Although Eastern Bluebirds can be located in urban areas, they are not usually seen in the middle of a city the size of Houston. However, the golf course property was good bluebird habitat: open fields with scattered trees and low fences for the birds to perch on, with short mowed grass allowing the birds to easily forage for insects.
As Eastern Bluebirds are a species of concern due to habitat loss and competition from introduced European Starlings and House Sparrows for nesting cavities, survey participants wanted to encourage the bluebirds to remain on the property. Mary Anne Morris, Houston Audubon Education Director, and Charlona Ingram, Houston Audubon Volunteer, proposed that we install a “Bluebird Trail” for the birds. A Bluebird Trail is a series of manmade nest boxes for the bluebirds to use as nesting cavities. A proposal was submitted to Claudia Gee Vassar, President and General Counsel of Houston Botanic Garden, along with Joy Columbus, Vice President Horticulture, and Brent Moon, Horticulture Manager, in December of 2018 to install the trail on the garden’s property.
In March of 2019, Houston Botanic Garden generously agreed to fund the purchase of the bluebird boxes for the new Bluebird Trail. Jeff Glattly of Wild Birds Unlimited Nature Shop in Pearland partnered with us on the project by supplying bluebird nest boxes made of recycled plastic milk jugs, which won’t rot and helps keep milk jugs out of landfills. He also supplied us with box installation poles and predator guards which made for the perfect set-up for the boxes. Jeff and Mary Anne installed three bluebird boxes on the south side of the garden property in May 2019.
I began weekly monitoring of the nest boxes in February 2020 at the beginning of Eastern Bluebird nesting season. Unfortunately, in March 2020, I was unable to continue to access the property due to COVID restrictions. I started monitoring again in June 2020 when access was again granted. Due to this, there is a 3-month gap in data collection, but we were still able to collect some results. In our first year of monitoring, every box was utilized. We had 9 confirmed fledglings, although there may have been more. I entered all bluebird monitoring data into the Cornell Lab of Ornithology NestWatch nest monitoring program, which is designed to track trends in reproduction of birds.
Our second year of nest box monitoring consisted of my weekly visits to the trail from February 2021 to the end of August 2021. Each nest box was utilized with more than one nesting attempt with varying degrees of success. By the end of nesting season, we had a total of 24 bluebird fledglings! This many successful fledglings shows that the birds have adapted to using these manmade nest boxes, and that the Botanic garden property has the proper habitat and food supply for nesting success. Just recently, bluebird boxes were also installed at Houston Audubon’s neighboring Raptor and Education Center across Sims Bayou. The bluebirds have been regular on the center’s property and we hope some will find the new nest boxes available there.
In the future, we hope to be able to put up more nest boxes for Eastern Bluebirds, with the potential for use by other cavity-nesting birds such as Tree Swallows, Carolina Chickadees, and House Wrens. With 132 acres, the Houston Botanic Garden has potential for many species of birds to successfully inhabit this piece of vital habitat in the middle of the fourth largest city in the country.