By Breanne Massey
The Great Blue Heron populations are declining in the Upper Columbia Valley, according to Marlene Machmer, Pandion Ecological Research Ltd. Nelson-based spokesperson and Inventory for Breeding Sightings project lead.
She will be collecting information about heron nest sites, active breeding colonies or any large groups of herons that frequent the area in the East and West Kootenay regions as well as the North Columbia region, which is a sponsored breeding inventory and habitat assessment of Great Blue Herons with funding from the Columbia Basin Trust and the Fish and Wildlife Compensation Program (FWCP).
We need to come up with some effective tools to deal with the predation and encroachment of bald eagles on breeding herons and we need to identify wintering areas that herons are using in the Columbia Basin because we dont have a good handle on those, said Ms. Machmer. During the winter months, when herons are feeding up and trying to regain their energy resources to breed, we need to allow them to do this without being disturbed so that they can feed up and put themselves into a better condition for breeding.
She has been visiting the Columbia Valley since 2002 to conduct surveys for a wide variety of species and has noticed both the advantages and challenges for herons in the surrounding area.
Wetlands are a very rich feeding site so the (environment) supports very abundant, dense aggregations of fish, amphibians, reptiles, birds and even invertebrates, explained Ms. Machmer. Herons eat all of those things and because the wetlands generally have still-water, its easy for the herons to hunt in that still-water because the prey are easier to see. The other thing about wetlands is youve got all these emergent vegetation communities, which conceal the herons. Their legs are kind of like sticks if you see them from up close and when theyre standing in the wetlands, theyre well-concealed in the vegetation because their legs almost look like reeds.
Great Blue Herons can stand quietly in a wetland area, wait for their prey and effectively strike due to these condirtions.
Wetlands are great areas for herons to aggregate because many herons, large groups, can be supported by those wetlands, she concluded.
However, Ms. Machmer reported approximately 17 active sites and 350 nests for herons in the East and West Kootenay region during 2002; which has dropped to about nine or 10 sites and roughly 180 nests.
Thats a huge decline in numbers of active nests, and its a concern, she added. There are a number of factors that are related to that decline (such as) development in wetland and riparian areas; human disturbance around the breeding sites; bald eagle harassment and predation; and Ive been doing some separate monitoring on the bald eagle populations which are definitely increasing.
She explained that bald eagles are competing with herons for prey, while simultaneously attacking heron nests to eat their eggs as well as adult herons being killed.
In addition, the heron habitat is also impacted significantly by the construction and operation of dams; human inhabitants; extensive land developments; as well as other competing species such as ravens and crows.
Bald eagles are a very opportunistic species, she added. They eat things like roadkill. They congregate in areas where theres human habitations to take advantage of the opportunistic prey thats available bald eagles are very good at capitalizing on human impacts.
Ms. Machmer believes herons are more sensitive as a species to the presence of humans than bald eagles, which is why their habitat is shrinking.
Were definitely going to have to do the best job that we can in terms of protecting the existing habitat that herons are using or that is suitable for herons; that includes a number of wetland and riparian areas which is on private land that is not protected, she said. Theres a need to improve stewardship on private land through conservation covenants, landowner agreements, and Crown land needs to have protective buffers we need to do a better job of protecting areas outside of Crown land, and there are lots of opportunities to do that.
To report a heron sighting, call Ms. Machmer at 250-505-9978 or email her at firstname.lastname@example.org. She will be following up with people who report heron sightings from across the Basin with observations and updates about the species to help with conservation efforts.
Alternatively, submissions for the inventory can be made online at www.fwcp.ca.