Installation of Predator Deterrents on Swallow Nest Boxes in Corn Creek Marsh: Update
By Jacob Ewashen; Wildlife Habitat and Operations Technician
My one-year milestone of working for the Management Authority has come and gone, and summer is fading. There will always be something new to learn, but I am feeling more settled into my role here at the CVWMA. The following is an update on a previous e-news publication that spoke about a project I undertook. The purpose of said project was to mitigate the high rates of predation on the swallows making use of the constructed nest boxes in Corn Creek Marsh.
There are approximately 115 swallow nest boxes that line the Marsh Trail, Beaver Boulevard, and the Corn Creek Marsh to Summit Creek Trail, which are all located in the Corn Creek Marsh management unit. The nest boxes are primarily used by tree swallows (Tachycineta bicolor) and occasionally by violet-green swallows (Tachycineta thalassina). In summer, 81 of these nest boxes are monitored on a weekly basis by the wetland naturalists at the Kootenay Columbia Discovery Centre. While their primary purpose is to provide habitat for swallows to rear their young, the nest boxes are also used for educational purposes. They give the fledgling biologists enrolled in summer programs, put on by the Discovery Centre, an opportunity to get an up-close look at some of the wildlife in the wetlands.
In summer 2022, the wetland naturalists reported a higher-than-normal number of occurrences of predation on both eggs and swallow chicks in the nest boxes. Seventy-four of the nest boxes were occupied by swallows at some point throughout the summer, during which there were at least 24 occurrences of predation. This meant that 30% of the active nest boxes were predated upon. There are several possible culprits, but the naturalists did report seeing a weasel poking it’s head out of a box during a survey, making it a prime suspect!
To give the swallows a better chance at survival, 15 predator deterrents were installed on nest boxes that still contained eggs or chicks. Early data suggested that the predator deterrents were working, as there was only one possible case of predation on the nest boxes with predator deterrents installed throughout the remainder of the season.
The results of this experiment were encouraging. Throughout the winter of 2022/2023, I constructed 66 more predator deterrents and installed them on the nest boxes. All 81 of the nest boxes monitored by the wetland naturalists now had a predator deterrent. While winter conditions made the installation process a little time consuming, as the boxes were not accessible by vehicle, they were simple to make and relatively easy to install.
Fast forward to present day; the results of installing the deterrents appeared to be successful! This year, the wetland naturalists reported zero instances of predation on the nest boxes throughout the 2023 season. This winter, I will be installing predator deterrents on the final 24 nest boxes, all located on the Corn Creek Marsh to Summit Creek Trail. Hopefully we will see continued success for our tree and violet-green swallows for many years to come! | 
