Human Disturbance and Shorebird Decline in the Victoria Harbour Migratory Bird Sanctuary

On several occasions this past month, I visited two locations within the Victoria Harbour Migratory Bird Sanctuary on southern Vancouver Island, Willow’s Beach and Clover Point. On each visit, the shorelines were alive with human activity with people walking, children playing, and dogs running off-leash across the sand flats and rocky coastline. Amid the movement, I expected to see small flocks of migrating shorebirds, such as Dunlin (Calidris alpina), Western Sandpipers (Calidris mauri), Black-bellied Plovers (Pluvialis squatarola), and Black Turnstones (Arenaria melanocephala). These shorebirds travel thousands of kilometres along the Pacific Flyway from their Arctic breeding grounds to their Central or South American overwintering habitats. Intertidal flats along coastal British Columbia provide critical foraging habitat rich in invertebrate prey. The shallow sandy and rocky substrate at Willow’s Beach and Clover Point have historically provided these food sources, allowing large flocks to rest and refuel (Warnock, 2010). However, with each visit, I noticed these once reliably seen species were found less often and in fewer numbers. Rather than settling in to forage, they frequently flushed fearfully into the air, flying hard and fast away from the approach of dogs or even distant walkers. Their flocks seemed smaller than I remember from previous years, having been a birdwatcher for over twenty years. I also note more adult birds than juveniles, possibly an indicator of poor summer breeding. I come here because these shorelines are part of a federally protected migratory bird sanctuary, an important resting stop habitat for birds arriving exhausted from long flights, and yet birds seem unable to rest (Hentze et al., 2022). Human recreation pressures, such as off-leash dogs and shoreline tourism, is likely exacerbating the disturbances, causing repeated flushing events and energy loss during critical refuelling stopovers. These local disturbances may compound with regional stressors such as habitat degradation and changing prey availability due to climate warming (Weiser et al.). Checking recent citizen-science data from eBird, I can see that several shorebird species are being reported less frequently and in lower numbers here by other observers (eBird, 2025a; eBird, 2025b). While this represents only one stop for birds on their long journeys, every disrupted foraging opportunity matters. As human activity fragments stopover sites along the globally important Pacific Flyway, migration becomes more energetically costly and dangerous. Climate-driven shifts in prey availability and the loss of intact coastal ecosystems compound this stress, leading to lower chick survival and fewer juveniles returning the following year (Galbraith et al., 2014). What I am witnessing here is the breakdown of a global process, one that sees significant biomass transfers to fragile Arctic ecosystems and is a window into the biodiversity crisis that is unfolding. These declines reflect larger patterns of global biodiversity loss. According to UNEP’s sixth Global Environment Outlook (2019) and Richardson et al. (2023), human pressures are pushing biodiversity beyond its planetary boundary, eroding the resilience of ecosystems. My observations of shrinking flocks could be an indicator of a positive-feedback loop of habitat loss and declining migratory bird population resilience (Hentze et al., 2022). In coastal British Columbia, much of this habitat loss stems from urban sprawl, shoreline modification, and recreational infrastructure development. Sea level rise and coastal erosion compound the loss of intertidal feeding areas further, reducing the availability of safe stopover sites for migratory birds (Finlayson et al., 2022; Murray et al., 2019). This makes me question how effective current conservation efforts and protections really are, especially for urban biodiversity. Shorebirds are known as sensitive bioindicators of global change (Piersma & Lindström, 2004), so their decline means action must be made. Adaptive management approaches could help strengthen this and other sanctuaries’ resilience by emphasizing continuous monitoring, feedback loops, and flexible decision-making changing to the needs of the present ecology (Holling, 1986). By tracking shorebird numbers, human activity, and habitat conditions in real time, accessibility or restoration efforts can dynamically adapt to the needs of sensitive species. It is important to acknowledge the care that Songhees and Esquimalt Nations have for these coastal areas, holding deep place-based knowledge of local ecological patterns (Buscher, 2019). Incorporating their traditional knowledge and collaborating with these Nations to guide management decisions would reframe conservation in long-term ecological relationships and cultural stewardship values, enhancing scientific monitoring (Woodbury, 2023). Migratory shorebirds play vital ecological roles in coastal food webs and global nutrient cycling (Bauer & Hoye, 2014). Feeding on benthic invertebrates and translocating nutrients through their guano, they regulate invertebrate populations and facilitate nutrient cycling between ecosystems, linking Arctic breeding ecosystems with more bio-productive southern nonbreeding habitats. The loss of these species therefore weakens ecosystem connectivity and resilience, emphasising the need for their conservation and protection (Bauer & Hoye, 2014). While my observation only encapsulates changes in one small area, it connects to the global biodiversity crisis. The 2024 State of Canada's Birds attributes shorebird declines to habitat loss, climate change, and human disturbances breaking down the global flyway network they depend on (Birds Canada, & Environment and Climate Change Canada, 2024). This local decline feels like a window into the wider unravelling of life across our planet, one I find myself personally bearing witness to.

Expert Consults I have compiled the following potential consults, with Dr. David Bradley as my preferred expert consult: • Dr. David Bradley – BC Program Manager, Birds Canada; specialist in shorebird migration and population monitoring. Contact: dbradley@birdscanada.org • Rocky Point Bird Observatory (Victoria, BC) – Rosa Munzer, RPBO President - Local monitoring organization with long-term bird count data. Contact: https://rpbo.org/contact/ • Dr. Jennifer Provencher – Environment and Climate Change Canada, expert in marine bird health and contaminants. Contact: jennifer.provencher@ec.gc.ca

  References

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