Biodiversity Research on the Sunshine Coast

Birds on the move up Tetrahedron

As temperatures rise, mountain species are generally expected to move to higher, cooler elevations to survive, and many are already doing exactly that. Scientists have proposed three main ideas for how this plays out. The "escalator to extinction" suggests a species' range gradually creeps upslope until they simply run out of mountain. The "upslope lean" idea suggests species don't shift their whole range, but instead become more concentrated toward the upper end of where they already live. The "persist-in-place" idea suggests many species simply stay put and adapt.

These ideas are usually tested by tracking whether a species is present or absent in a given area over time. But this misses something important: how many individuals are there? Counting actual numbers gives a clearer picture of whether a population is truly healthy or quietly declining before it disappears from an area entirely. A species that still shows up in surveys could already be in serious trouble if its numbers are falling fast.

Here is a recent local study of birds on the move, including in Tetrahedron Provincial Park, that considered both presence/absence and abundance.

This study, led by Ben Freeman, looked at breeding birds in the old-growth forests of the Pacific Northwest over three decades of warming. Ben was a post-doc at UBC at the time he conducted the study. He had come across some mountain bird surveys conducted by F. Louise Waterhouse in the early 1990s, and recognized that he could build on these to test the reigning hypotheses for climate change effects on mountain species.

Basically, surveys were conducted by walking trails, stopping at a series of set stations, and listening to calls to estimate species' presence and abundance. With these data you can estimate elevational range and abundances within those ranges for each species. This is roughly what Waterhouse did in the early 1990s, and Ben and his team repeated in 2023. Contrasting these datasets and comparing them to temperature records allows one to test hypotheses about range shifts associated with climate change, including the escalator to extinction idea.

The species included in the study were Brown Creeper, Chestnut-backed Chickadee, Hairy Woodpecker, Olive-sided Flycatcher, Pacific-slope Flycatcher, Red-breasted Nuthatch, Red-breasted Sapsucker, Sooty Grouse, American Robin, Pine Siskin, Townsend's Warbler, Red Crossbill, Steller's Jay, Vaux's Swift, Hermit Thrush, Varied Thrush, Canada Jay, American Three-toed Woodpecker, Golden-crowned Kinglet, Pacific Wren, Dark-eyed Junco, and Swainson's Thrush. The surveys were conducted at several sites on mountains north and west of Vancouver.

Here is a figure from their 2025 paper in Ecology illustrating some key hypotheses and their results:

Freeman, B.G. et al. 2025. Pacific Northwest birds have shifted their abundances upslope in response to 30 years of warming temperatures. Ecology, 106:e70193.

Shining a Light on Dungeness Crab Larvae

The Sentinels of Change light trap network tracks the arrival of Dungeness crab larvae along the coast. Launched in 2022, this cross-border program connects scientists, resource managers, and coastal communities from Haida Gwaii down to Puget Sound in Washington. Sentinels of Change and Hakai have just released their 2025 Light Trap Network Report, which demonstrates the value of biomonitoring programs on the Coast.

Dungeness crab matter a lot. They've been a cornerstone of coastal Indigenous life for thousands of years and are one of the most valuable fisheries in both Canada and the US. Understanding how their larvae disperse and survive is key to helping managers keep crab populations healthy as oceans change.

Two local sites, Pender Harbour and Gibsons, are included in this study courtesy of local biomonitoring programs.

2025 was the network's fourth year, with 29 sites participating overall. From mid-April through early fall 2025, community partners checked traps every two days, counting and photographing any Dungeness larvae they caught to track size and abundance. Beyond tracking larvae, the network is also exploring how climate change affects young crabs, how crab populations are connected across the coast, and whether light traps can help detect invasive European green crab. While these studies are ongoing and the analyses just ramping up, the scale of the data collected so far is impressive.

https://sentinels.hakai.org/

Seabirds on the Move Along BC's Coast

As oceans warm and ecosystems shift, the birds that depend on them are quietly redistributing and a sweeping 20-year study of coastal waterbirds by de Zwaan et al. document dramatic shifts in distribution along BC's Pacific coast.

Researchers have recently tracked the winter occupancy of 57 waterbird species between 1999 and 2019. The picture that emerged is one of widespread decline, but with important regional twists.

The study rests on a remarkable foundation of volunteer effort. Since 1999, dozens of volunteers in BC, including a number within biomonitoring programs on the Sunshine Coast, have conducted monthly counts along 368 standardized shoreline routes from the Salish Sea to BC's northern coast. This citizen science program, the BC Coastal Waterbird Survey, has accumulated one of the richer long-term bird datasets on Canada's Pacific coast, and it's now paying scientific dividends.

The news was worst for the Salish Sea. Declines there were steep and broad, cutting across most feeding groups (diving ducks, fish-eaters, shellfish-eaters). The cause likely include both warming waters and a suite of impacts associated with human activities including pollution from urban runoff, nutrient loading from rivers, and dense coastal development combine to degrade habitat for species that depend on cold, productive waters.

However, on BC's North-Central coast the story appears quite different. Several species are actually holding steady or increasing there. The likely reason is that this area has maintained cold, less salty water that supports the prey species these birds depend on. In a warming world, these places may function as cold-water refugia.

The clearest signal from the data is directional movement. On average, waterbirds are wintering farther north than they did 20 years ago. Cold-tolerant species are retreating poleward or pulling back into fjord habitats. Meanwhile, herbivores and warm-tolerant species appear to be expanding northward into the Salish Sea from farther south, taking advantage of milder winter conditions there.

The study also tackled an important conservation question: do protected areas actually help? They found evidence that newer marine protected areas show genuine benefits because birds colonize them more readily and disappear from them less often.

de Zwaan et al. 2024. Occupancy trends of overwintering coastal waterbird communities reveal guild-specific patterns of redistribution and shifting reliance on existing protected areas. Global Change Biology 2024;30:e17178.

How did Sunfish get into Trout and Colvin Lakes?

Many may have read the 2023 Coast Reporter story "Go fish: How fishers and scientists are racing to protect a world-famous species from invasives." The piece tells the story of the discovery of invasive pumpkinseed sunfish in Trout Lake, which are threatening and may have even led to the extinction of Trout Lake's population of the world-famous threespine stickleback. There will be more on this little fish, the stickleback, that has contributed so much to our understanding of the origin of species (Charles Darwin's "mystery of mysteries") later on this page.

The question does arise: how did the invasive sunfish get into Trout Lake? The answer suggested in the piece is that they were likely introduced deliberately around 2021. Perhaps they were accidentally introduced from a fisher's bait bucket, or perhaps intentionally for sport fishing. However, the piece also notes that sunfish have recently been found in the unconnected Colvin Lake at Sargeant Bay, where the presence of fishers seems unlikely.

One commonly invoked explanation for the movement of invasive fish across long distances to remote lakes is that fish eggs get stuck on the feathers or feet of waterbirds, which then transport them long distances. Even Darwin wrote about this potential phenomenon. However, recent surveys of the scientific literature have found no evidence directly supporting this idea. So how did the sunfish get into Colvin Lake?

Sargeant Bay Society streamkeeper, Dave Spicer, suggested that perhaps eggs of sunfish were consumed by birds in Trout Lake and then deposited in their faeces into Colvin Lake. At first pass, this seems even less likely than their being stuck to feet or feathers — delicate fish eggs (think caviar) passing through the gut of a vertebrate and surviving? However, a recent paper shows this is indeed possible.

Hungarian researchers, led by Ádám Lovas-Kiss, fed fertilized eggs of nine fish species to mallards and recovered viable embryos of several species from their droppings, with two species successfully hatching into larvae. The findings establish waterbird gut passage as a rare but plausible natural dispersal mechanism for fish eggs across isolated water bodies, independent of human introduction. Among the species whose eggs survived passage through the gut were pumpkinseed sunfish, though in this very small sample, none developed into larvae.

Lovas-Kiss et al. 2024. Bird-mediated endozoochory as a potential dispersal mechanism of bony fishes. Ecography 2024: e07124

Stickleback and the Origin of Species on the Sunshine Coast

Local populations of this widespread little fish have transformed our understanding of the formation of new species. In the lakes and streams of the Coast, this small spiny fish barely the length of your finger has become one of science's most important windows into how new species come to be. And decades of research on the Coast plays a prominent role in these discoveries.

Speciation, the process by which one species splits into two descendant species, is notoriously difficult to study. It typically unfolds over a few million years, leaving scientists trying to reconstruct ancient events from fossils and genetic clues. Moreover, it is typically thought that a geographic barrier is necessary to isolate the populations and allow them to diverge and speciate. But in some lakes on the Coast sticklebacks appear to have speciated without a complete barrier and in a remarkably short period of time.

After the last Ice Age, freed from the immense weight of ice sheets, rising land isolated populations of marine sticklebacks into lakes. In several of these lakes (Paxton, Priest, Enos and Hadley) something remarkable occurred. Rather than resulting in a single freshwater adapted form in each lake, two distinct types evolved from a single ancestor: an inshore form known as the benthic, and an open-water form known as the limnetic. These two species found living side by side in the same lake, have become so specialised in their body shapes, behaviours, and resource use that they rarely interbreed. Similar divergence in body form, behaviour, resource use and even genetics, appears repeatedly across separate lakes. This and the recency of the divergence has allowed researchers to study, both by observation and experiment, the processes that underlie speciation itself. These insights are shedding light on what Darwin referred to as "the mystery of mysteries".

One of the main goals of these studies is to understand what is special about these few post-glacial lakes that have facilitated the evolution of two types, rather than one, which is more typical in nearby lakes. It turns out that rather precise ecological conditions are required, an understanding of which helps researchers to understand the process of speciation itself. However, it also means that ecological disturbance can lead to the collapse of the species pair into just one. This is exactly what happened to the Enos Lake populations on Vancouver Island with the introduction of signal crayfish. At Hadley Lake on Lasqueti Island, the introduction of brown bullhead catfish resulted in the extinction of both populations.

This left just two known populations, Paxton Lake and Priest Lake (a chain of 3 lakes) on Texada Island, putting at risk one of evolution's great stories. Thankfully, in 2007, a new species pair was found in the previously unexplored Little Quarry Lake on nearby Nelson Island. Involved in that important discovery, and the resulting publication, was Michael Jackson, the long serving past Executive Director of the Loon Foundation.

Gow et al., 2008. Ecological predictions lead to the discovery of a benthic–limnetic sympatric species pair of threespine stickleback in Little Quarry Lake, British Columbia. Can J. Zool. 86: 564–571.

Mapping the Nurseries of the Salish Sea: Pacific Sand Lance Spawning Habitat

Beneath the surface of the Salish Sea, a small, slender fish quietly contributes much to the marine food web. Pacific sand lance rarely make headlines, but they are everywhere in the diets of the animals that do: salmon, seabirds, humpback whales, and the critically endangered southern resident killer whales. Between spring and fall, sand lance make up a large portion of prey consumed by the Chinook salmon, which in turn are relied upon by resident killer whales. Yet until recently, scientists had a surprisingly incomplete picture of where these fish actually breed here in the Pacific northwest.

Sand lance are unusual fish. Lacking a swim bladder, they bury headfirst into coarse, silt-free sand to rest, hide from predators, and ride out winter in a kind of dormancy. In the colder months, they come to the intertidal zone to spawn, laying sticky eggs that attach to individual sand grains and incubate for one to three months before hatching. The beaches where this happens are specific and rare, and identifying them has been one of the more pressing gaps in coastal conservation science.

Community Science Meets Habitat Modelling

A recent study has gone a long way toward filling that gap. Over nearly two decades, community scientists, First Nations members, independent biologists, and Fisheries and Oceans Canada conducted more than 1,000 intertidal surveys along beaches across the Canadian Salish Sea, searching for sand lance eggs in sand samples examined under dissecting microscopes. By 2020, eggs had been detected on more than 90 beaches. Using this dataset and a modelling approach called MaxEnt, which is well suited to the kind of presence-only data that community science generates, researchers identified the environmental conditions that best predict where suitable spawning habitat is likely to occur.

A Rare and Patchy Habitat

Suitable intertidal spawning habitat turns out to be genuinely scarce. The model estimates that only about 5.4% of the intertidal zone in the Canadian Salish Sea has a moderate to high likelihood of providing the conditions sand lance need. Proximity to estuaries was the strongest predictor, not because estuaries themselves are suitable, but because they supply the coarse sand that waves and currents sort into the grain sizes sand lance require. Beach slope came second, with slopes between roughly 4° and 10° hitting a sweet spot where energy is sufficient to flush out fine silts without washing suitable sand away entirely.

Critically, only about 8.5% of this predicted habitat currently falls within a protected area. Sand lance show strong site fidelity, returning year after year to the same patches of sediment, which makes them especially vulnerable to habitat loss from shoreline armouring, dock installation, and coastal development. Current Canadian law permits armouring up to the mean high-tide line, leaving intertidal spawning habitat with limited legal protection.

The authors describe the model as a "living process," intended to be refined as survey coverage expands and new approaches like environmental DNA become available. The next steps will continue to depend upon people willing to walk beaches in winter and peer through microscopes looking for eggs the size of a grain of rice. Here on the Coast, this will include a number of non-profits and their volunteers engaged in biomonitoring of these forage fish.

Huard, J.R. et al. 2022. Predictive habitat modelling of Pacific sand lance (Ammodytes personatus) spawning habitat in the Canadian Salish Sea.

Two Roads South: The Divided Migration of Swainson's Thrushes

The Swainson's Thrush is a small, spotted songbird that breeds across the boreal forests of North America and winters in Central and South America. Along the coast mountains of British Columbia, a coastal form and an inland form meet and interbreed in a narrow hybrid zone. The coastal form breeds on the Sunshine Coast. Scientists suspected that these neighbouring populations diverge sharply in their migration routes, but the evidence had rested mainly on band recovery records and genetics rather than direct observation of individual birds.

To put the idea to a more rigorous test, Kira Delmore (UBC) and colleagues attached light-level geolocators to thrushes caught on both sides of the hybrid zone. Among these tagged coastal birds were 10 from the Sunshine Coast. These small devices record daily light patterns that can be translated into approximate locations, making it possible to follow individual birds through a complete annual cycle. The approach offered a far more direct window onto migration than banding records alone, and what it revealed was striking.

Coastal Swainson's Thrushes flew south along the Pacific corridor, wintering in Mexico, Guatemala, and Honduras. Many of these birds did not settle in one location for the non-breeding season but moved between two or more wintering sites, suggesting that their winter behaviour is more flexible and complex than previously appreciated.

Inland birds followed an entirely different path. They crossed the Rocky Mountains, moved through central North America, and continued south all the way to Colombia and Venezuela — a considerably longer journey. Their routes often formed a loop: crossing the Gulf of Mexico heading south in autumn, then returning by a different path in spring. This loop migration means the two groups not only winter in different regions but travel through different parts of the continent in each season.

The findings also shed light on how migratory behaviour may contribute to keeping the two groups separate. Neighbouring populations that travel in opposite directions and spend the winter thousands of kilometres apart have few opportunities to interact outside the breeding season. Different ecological pressures along those contrasting routes may reinforce the biological differences between groups over time, even where no sharp physical barrier divides their breeding ranges.

Perhaps the most practical implication is for conservation. Protecting the forests where these birds nest is not enough on its own. A Swainson's Thrush depends on a chain of stopover sites and wintering areas spread across several countries, and disrupting any link in that chain could affect populations far to the north. For migratory songbirds crossing multiple borders, effective conservation must span the full annual cycle.

Updates: More recent work has shown that, remarkably, some hybrids tend to take an intermediate migratory route to the coastal and inland forms. And in another recent study by the same group, they have been able to identify genetic differences between the two forms that are clustered on a single chromosome and suggest a gene package for migration.

Delmore et al., 2012. Dramatic intraspecific differences in migratory routes, stopover sites and wintering areas, revealed using light-level geolocators. Proc. R. Soc. B 279: 4582–4589

Delmore and Irwin, 2014. Hybrid songbirds employ intermediate routes in a migratory divide. Ecology Letters 17: 1211–1218.

Delmore et al., 2016. The genetics of seasonal migration and plumage color. Current Biology 26: 2167–2173.