Although Purple Martins won’t be returning to Squamish until April, planning has already begun for the 2021 monitoring season. Last week we were thrilled to learn that our application for a Club Support Grant from the BC Naturalists’ Foundation and BC Nature was approved! The grant will be used to install cameras at an active Western Purple Martin colony in the Squamish estuary, providing a non-invasive way of monitoring nest box activity and documenting nestling development. The photos and video captured will contribute to an online resource, made available to other citizen science groups who are also undertaking Purple Martin recovery projects in BC.
The Western Purple Martin (Progne subis arboricola) is considered a species of special concern in British Columbia. While they once nested in cavities in old trees and snags, their numbers have been decreasing as logging, agricultural land clearing, fire suppression and urban development has reduced their natural habitat. Introduced bird species have also out-competed Martins for natural nest sites. Now they are almost entirely dependent on artificial nest boxes.
Since 2015, SES has installed 26 Purple Martin nest boxes on marine pilings in the central channel of the Squamish Estuary. The colony started with one nesting pair in 2016 and increased to approximately 14 pairs in 2020, during which the nest boxes were monitored from the beginning of May through September. A high of 22 individuals (including fledglings) was counted. There were 8 successful nests, 6 failed nests, 6 empty boxes, and 3 boxes used by tree swallows. Although the lower nesting success in 2020 was typical for the region, due to a cool and wet breeding season, the year-on-year increase in nesting activity is encouraging.
At the end of the 2020 season, we submitted our photos and observations to Mr. Bruce Cousens, senior biologist with the BC Purple Martin Stewardship and Recovery Program, Georgia Basin Ecological Assessment and Restoration Society. Mr. Cousens commended our volunteers on their excellent documentation for the success of the colony, as well the time and effort involved. He provided detailed comments on the submitted photos and suggested that the annotated photos could form an online reference guide, for use by other citizen scientists. Mr. Cousens suggested doing something similar in 2021 and that we try to include some nestling photos as well. Our project aims to fulfill this goal, in a non-invasive manner.
We are grateful to the BC Naturalists’ Foundation and BCNature for their financial support and we look forward to the upcoming season!