An invasive insect species, the Hemlock Woolly Adelgid, has infested large portions of Eastern Hemlock-dominated stands in Southwest Nova Scotia. It takes about 5-10 years for the insect to kill a tree. There are no natural predators in this part of the world, so the outlook for hemlock-dominated forests is dire. This situation began in the eastern United States in the 1950s, and studies show a negative impact on a variety of forest bird species.
The infestation has recently spread to Kejimkujik National Park. As the Eastern Hemlock is an essential component of the forest in the park, Parks Canada is looking at ways to manage the infestation. Donna Crossland, the Hemlock Woolly Adelgid Coordinator at Keji, reports that Parks Canada-National Office has deemed our work on slowing the spread of HWA and investigating ways to maintain healthy hemlocks for future generations to be of national importance.
Also, studies in the USA have shown that the loss of hemlock negatively impacts some bird species more than others. In Nova Scotia, the species likely to be affected the greatest are Black-throated Green Warbler, Blackburnian Warbler, and Blue-headed Vireo.
The Listening Together project is conducting annual breeding bird surveys in both infested and non-infested hemlock stands throughout the province to document the effects of the adelgid on bird populations and forest structure. Point-counts conducted by participants in non-infested areas are essential for detecting changes that may not be adelgid-related as well as providing a baseline record of forest bird composition should the trees become infested in the future.
The expertise of the members of the Nova Scotia Bird Society is a great asset in making this project possible. The ability to identify a bird, hidden in the dense canopy of a hemlock stand, by their song along is a special skill possessed by these birders. Participants conduct a point-count twice per breeding season, and staff from Parks Canada do a vegetative survey of the point locations outside of the breeding season. These surveys could play a vital role in developing conservation approaches to diminish the negative impacts of the Hemlock Woolly Adelgid on our forest birds. Let me know if you are interested in participating in this project.
Resources for this project include: