Cassin’s Auklet (Ptychoramphus aleuticus): management plan proposed 2025

Official title: Management Plan for the Cassin’s Auklet (Ptychoramphus aleuticus) in Canada proposed 2025

Species at Risk Act
Management Plan Series

Preface

The federal, provincial, and territorial government signatories under the Accord for the Protection of Species at Risk (1996)^{Footnote 2} agreed to establish complementary legislation and programs that provide for effective protection of species at risk throughout Canada^{Footnote 3}. Under the Species at Risk Act (S.C. 2002, c.29)^{Footnote 4} (SARA), the federal competent ministers are responsible for the preparation of management plans for listed species of special concern and are required to report on progress within five years after the publication of the final document on the Species at Risk Public Registry.

The Minister of Environment and Climate Change and the Minister responsible for the Parks Canada is the competent minister under SARA for the Cassin’s Auklet and has prepared this management plan, as per section 65 of SARA. To the extent possible, it has been prepared in cooperation with: other federal departments, the Province of British Columbia, Indigenous governments and organizations and others as per section 66(1) of SARA.

Success in the conservation of this species depends on the commitment and cooperation of many different constituencies that will be involved in implementing the directions set out in this plan and will not be achieved by Environment and Climate Change Canada, Parks Canada or any other jurisdiction alone. All Canadians are invited to join in supporting and implementing this plan for the benefit of the Cassin’s Auklet and Canadian society as a whole. Implementation of this management plan is subject to appropriations, priorities, and budgetary constraints of the participating jurisdictions and organizations.

Acknowledgments

Louise Blight wrote this Management Plan, and with Alan Burger performed the Threats Assessment. Ross Vennesland and Linda Takahashi (Canadian Wildlife Service, Environment and Climate Change Canada) oversaw the production of the report and developed the Management Objective. Adam Lee, Ross Vennesland, and Linda Takahashi produced the distribution maps. Thanks to Kerry Woo for providing information on current and planned conservation actions for Cassin’s Auklet at their Canadian colonies, to Michael Rodway for providing current data on colony populations, to Laurie Wilson for information on H5N1 biosecurity measures and updated trend data for monitored colonies, and to David Bradley for information on invasive species monitoring. Comments from Doug Bertram, Diane Casimir, Eric Gross, Mark Hipfner, Praveen Jayarajan, Peter Sinkins, Emily Upham-Mills, Ross Vennesland, Megan Willie, and Laurie Wilson helped to improve the report.

Executive summary

Cassin’s Auklet (Ptychoramphus aleuticus) is a small, greyish-brown member of the Alcidae, or auk family. About three-quarters of the world’s population breeds in British Columbia, where there are an estimated 62 extant colonies. These are found on the north and central mainland coast, on Haida Gwaii, and on the west coast of Vancouver Island. Most individuals nest at a few very large colonies along the outer British Columbia coast, on the Scott Islands and islands along the west coast of Haida Gwaii, where they have ready access to the waters of the continental shelf break. Other colonies are small. About 70% of the Canadian breeding population nests at a single remote colony – Triangle Island in the Scott Islands archipelago.

Cassin’s Auklet spends most of its life at sea in productive nearshore and offshore waters, coming ashore only in the breeding season. Birds are largely defenceless against terrestrial predators and thus require nesting islands that are free of introduced mammals such as rats (Rattus spp.) and Raccoons (Procyon lotor).

The species was designated as Special Concern by the Committee on the Status of Endangered Wildlife in Canada (COSEWIC) in 2014. The population is thought to be declining but population monitoring at time of designation was insufficient to determine trends. Apart from mammalian predators introduced to island colonies, the key threats to this species are primarily found at sea. These include risks from chronic (ongoing lower-volume release) and acute (catastrophic) oil spills, and the effects of increasing warm-water events on their zooplankton prey. The latter impact both productivity and adult survival. As it only produces a single egg per year, Cassin’s Auklet is particularly vulnerable to any adult mortality removing active breeders from the population.

The Management Objective for Cassin’s Auklet in Canada is to stabilize the declining population across its current distribution. The broad strategies that will be used to achieve this objective are:

1. reduce negative impacts of offshore oil and gas activities within Cassin’s Auklet marine habitat
2. reduce impacts of introduced mammalian species at colonies
3. reduce risk of infectious disease outbreaks at breeding colonies
4. manage and reduce oil spill risk within the marine range of Cassin’s Auklet
5. increase protection of Cassin’s Auklet marine habitat
6. conduct population surveys at nesting colonies

Twelve conservation measures are recommended as approaches that will help to implement these broad strategies and attain the Management Objective; these measures are outlined in Section 6 of this Management Plan.

1. COSEWIC Species assessment information

Date of assessment: November 2014

Common name (population): Cassin’s Auklet

Scientific name: Ptychoramphus aleuticus

COSEWIC status: Special Concern

Reason for designation: About 75% of the world population of this ground-nesting seabird occurs in British Columbia. Overall, the Canadian population is thought to be declining, but population monitoring has been insufficient to determine size and trends. The species faces threats from mammalian predators that have been introduced to its breeding islands. While predators have been removed from some breeding colonies, it is likely that ongoing predator management is going to be needed to maintain the species. The species also faces other threats when it forages at sea, including large-scale climate change effects on its oceanic prey, and risks from oiling.

Canadian occurrence: BC, Pacific Ocean

COSEWIC status history: Designated Special Concern in November 2014 (new)

* COSEWIC (Committee on the Status of Endangered Wildlife in Canada)

2. Species status information

Globally, Cassin’s Auklet is listed by the IUCN as Near Threatened under criteria A2abce+3bce+4abce^{Footnote 5} (2020; Birdlife International 2022). In Canada, the species is listed on Schedule 1 of the Species at Risk Act as Special Concern (22 May 2019). In Mexico it is categorized as a species “Sujetas a Protección Especial” (equivalent to Special Concern; SEMARNAT 2010).

Conservation status ranks for Cassin’s Auklet are provided in Table 1.

It is estimated that about 75-80% of the global population of Cassin’s Auklet breeds in Canada (COSEWIC 2014; NatureServe 2022).

Natureserve rank definitions: SX - Presumed Extirpated. SH - Possibly Extirpated. S1 - Critically Imperiled. S2 ‑ Imperiled. S3 - Vulnerable. S4 - Apparently Secure. S5 - Secure. SNR/SU/SNA - no status rank. B – Breeding. N ‑ Nonbreeding. If two ranks are provided (for example, S2S4), this represents uncertainty (a range) in the rank.

3. Species information

3.1. Species description

Cassin’s Auklet is a small (150-200 g; 23 cm; Ainley et al. 2020) alcid^{Footnote 6} with a round head and short neck, body, and tail that give it a plump appearance. Plumage is slate grey to brownish-grey above; lower breast, belly, and undertail are whiteish in colour. Iris is pale (adults) or brown (immature) and there is a small white crescent immediately above the eye. Feet and legs are pale blue. General information on the species’ natural history and biology can be found in the COSEWIC status report (2014) and various online accounts (for example, Hipfner 2015; Audubon 2022). Ainley et al. (2020) provide a full account of the species in Birds of the World, although that text has not been updated since the Birds of North America version (2011; D.G. Ainley, pers. comm.).

3.2. Species population and distribution

The centre of the Cassin’s Auklet breeding distribution is in Canada (Fig 1; Fig 2). Globally it breeds on coastal and offshore islands from Baja California, Mexico to the western Aleutians in Alaska, and occasionally into Siberia and Japan (Kurile Islands; COSEWIC 2014; Drew et al. 2005; Ainley et al. 2020; Fig 1). In Canada, it currently nests at an estimated 62 colonies in British Columbia (BC Conservation Data Centre 2018; Fig. 2; Appendix B). Historically, the species has been known from 73 colonies in British Columbia (Rodway et al. 2016, 2020, 2022, in prep.; M. Rodway pers. comm.). Most individuals nest at a few very large colonies along the outer British Columbia coast, on the Scott Islands and islands along the west coast of Haida Gwaii, where they have ready access to the waters of the continental shelf break. Other colonies are small. The majority of the Canadian population (~70%, or about 55% of the global population; COSEWIC 2014; BC Conservation Data Centre 2018) occurs at only one locality — Triangle Island in the remote Scott Islands archipelago off the northwestern tip of Vancouver Island. About 22% of the Canadian population breeds in Haida Gwaii (Rodway et al. 1991).

Cassin’s Auklet only comes ashore to breed; its marine range is depicted in Fig. 1 and Fig. 2. Marine distribution appears to vary within the breeding season (with birds at Triangle Island moving from the continental shelf to waters seaward of it as the breeding season progresses; Hipfner et al. 2014; Bertram et al. 2017) and among years (Adams et al. 2004; Boyd et al. 2008; Bertram et al. 2017a; Domalik et al. 2018). In years of adequate prey availability (that is, prey abundance sufficient for chick rearing) at Triangle Island, most breeding birds foraged 30 to 50 km beyond the shelf break in deep-water zones (1200 to 2000 m). In contrast, in a poor food year, birds mostly foraged ~80 km north of the colony near the mouth of an offshore canyon in waters of about 725 m depth (Boyd et al. 2008, Bertram et al. 2017a). In Haida Gwaii, breeders primarily foraged at the shelf break, but also over seamounts (Vermeer et al. 1985). In the non-breeding season, Cassin’s Auklet occurs in nearshore waters from southeast Alaska to Baja California, with birds mostly using waters around the shelf break (200 m isobath) and further offshore (COSEWIC 2014; Studholme et al. 2019).

Figure 1. Global range of Cassin’s Auklet (Ptychoramphus aleuticus), showing the mean number of birds observed within 50 km grid squares from 1973 to 2019. Source: North Pacific Pelagic Seabird Database (Drew et al. 2005).

Figure 2. Canadian range of Cassin’s Auklet (Ptychoramphus aleuticus). The map shows the mean number of birds observed within 25 km grid squares from 1973 to 2019, eBird observation locations and known colony locations. Sources: North Pacific Pelagic Seabird Database (Drew et al. 2005), eBird (https://ebird.org/home), and L. Wilson, (pers. comm.).

Based on the most recent full surveys at each colony (per-colony dates from 1977 to 2011), the latest status report gave the Canadian Cassin’s Auklet population as 2.69 million mature individuals and stated that the Canadian population was likely still somewhere between 1 and 3 million individuals (COSEWIC 2014). At time of writing this Management Plan, the most recent colony estimates totaled 2.64 million birds (albeit with >90% of counts still no more recent than the 1970s, ’80s or ‘90s; Appendix B). Based on population declines in the California Current system since the dates of the original surveys, the BC Conservation Data Centre estimated the 2018 Canadian population at from 1.5 to 2.5 million birds, including non-breeders (BC Conservation Data Centre 2018). It should be noted that the BC Conservation Data Centre (2018) erroneously cites COSEWIC (2014) as reporting a 40% decline in number of occupied burrows in permanent monitoring plots at Triangle Island. In actuality, there was a reported 40% decrease in number of burrows in permanent plots there over 20 years (1989-2009; -2.5% per year; no information on occupancy), with the decline beginning in about 1990 (Rodway and Lemon 2011). More recent data (L. Wilson, pers. comm.) show that the average number of Cassin’s Auklet burrows in the permanent plots at all monitored colonies in British Columbia^{Footnote 7} has shown a statistically non-significant annual decline of -0.05% per year (95% CIs: -0.5%, 0.5%; 1984 to 2019), resulting in an apparent long-term decrease in the monitored population of approximately 2% (95% CIs: -17%, 19%). The more recent short-term trends (2009 to 2019) have shown increases of 1.1% per year (95% CIs: -0.6%, 2.8%), resulting in a statistically non‑significant short-term increase in the monitored population of approximately 11% (95% CIs: -6%, 31%). However, the Cassin’s Auklet colony at Triangle Island is so large compared to all others that its influence dominates the region; there, the long-term trend to 2019 is -0.3% per year (CIs: -0.9%, 0.5%) for an overall decrease of 8.6% (CIs: ‑27%, 17%) and the more recent short term trend for 2009-2019 is 1.1% (-0.4%, 2.6%) for a statistically non-significant short-term increase of 11.3% (-4%, 29%) over the past decade (L. Wilson, pers. comm.). Looking only at the more recent 2009-2019 data, the trends show statistically non-significant increases. It should be noted that the permanent monitoring plot program was designed as to warn of potential declines, rather than to estimate quantitative population changes (Rodway and Lemon 2011; M. Rodway, pers. comm.), and the fact that many of these plots were placed in high-density nesting areas (Rodway and Lemon 2011) may mean that changes are occurring more slowly there than in more marginal areas of the colonies.

The relatively recent extirpation of the Seabird Rocks colony (SW Vancouver Island; >500 pairs estimated in 1988; Appendix B) to possible depredation by Northern River Otter (Lontra canadensis; Carter et al. 2012), and the appearance of rats (Rattus sp.) at the large Cassin’s Auklet colony at Ramsay Island (>25,000 pairs; Parks Canada 2021; L. Wilson pers. comm.; Appendix B) shows the ongoing vulnerability of entire colonies to native and non-native predators.

3.3. Needs of the Cassin’s Auklet

As a marine bird, Cassin’s Auklet requires terrestrial habitat for breeding and marine habitat with adequate prey for foraging, migration, and wintering (Table 1). The terrestrial habitat requirements of the species have been extensively studied and are well-described throughout its range (Ainley et al. 2020), as is its marine habitat use during the breeding season around major colonies (for example, Adams et al. 2004; Boyd et al. 2008; Bertram et al. 2017a; Domalik et al. 2018; Ainley et al. 2020). Details of its marine habitat use outside the breeding season are less well understood and have primarily been based on vessel transect surveys; however, recent studies using geo-tagged birds have provided more information on Cassin’s Auklet wintering range (Studholme et al. 2019; Johns et al. 2020).

Terrestrial habitat needs

Cassin’s Auklet is described as “opportunistic” in its choice of nest site locations (Ainley et al. 2020). Across its range, the species nests on offshore islands in cavities such as rock crevices or excavated burrows, on bare ground under plants, rocks or driftwood, or even in artificial nest boxes. Any type of island habitat may be used, from flat areas to cliffs, and treed to bare areas (Ainley et al 2020). In Canada, Cassin’s Auklet primarily nests in burrows, which are dug in a range of habitats. In Haida Gwaii, 75% of nests were under tree cover while 25% were without tree cover (Vermeer and Lemon 1986). The burrows of most birds were under trees, stumps, roots, or fallen logs (55%) or in grass tussocks (33%). Eight percent of burrows were excavated in bare ground or moss tussocks, and 4% of birds nested in rock crevices. Nesting in rock crevices is more common in the US portion of its range, for example, SE Farallon Islands, California, where 49% of nests were in this habitat (Ainley et al. 2020). At treeless Triangle and Sartine Islands in Canada’s Scott Islands archipelago, where the world’s largest populations of Cassin’s Auklet occur, nesting birds favour open, generally steep, burrow sites dominated by tussocks of Tufted Hairgrass (Deschampsia cespitosa), and avoid areas dominated by tall shrubs of Salmonberry (Rubus spectabilis). Some nest burrows are found in areas of short Salmonberry, albeit at much lower densities (Hipfner et al. 2010, Rodway et al. 2017).

On Frederick Island, Haida Gwaii, most birds nest within 100 m of the shoreline (Vermeer and Lemon 1986); elsewhere in the species’ range burrows may be excavated up to several hundred metres from the coast (Johnsgard 1987). On Triangle Island they nest at all elevations (to the island’s central plateau at approx. 200 m; Vermeer et al. 1979). Burrows are of varying form and length, depending on the substrate, and show no specific orientation to the sun or the prevailing winds (Ainley et al. 2020). Use of terrestrial (nesting) habitat outside of the breeding season has not been recorded in Canada, although further south in their range, on the Farallon Islands, paired and unpaired birds use burrows and rock crevices for roosting and socializing in the non-breeding season (Ainley et al. 2020).

Local population declines and extirpations have followed introduction of mammalian predators — primarily rats, American mink (Neovison vison), and Raccoon (Procyon lotor) — to remote island colonies; thus, Cassin’s Auklet needs islands free of such predators (cf. Regehr et al. 2007). Eruptions or recoveries of native mammals can also leave island habitats unsuitable for Cassin’s Auklet: persistent depredation by Northern River Otter may have resulted in the extirpation of Cassin’s Auklet at Seabird Rocks, British Columbia, at some time between 2002 and 2011 (Carter et al. 2012). However, ongoing egg depredation by native mice (Peromyscus keeni) has not rendered Triangle Island unsuitable for auklets (Ronconi and Hipfner 2009).

Marine habitat needs

During the breeding season, Cassin’s Auklet is associated with the mesoscale^{Footnote 8}, oceanographic features that aggregate their zooplankton prey within foraging range^{Footnote 9} of the colony (Boyd et al. 2008; Bertram et al. 2017a; Domalik et al. 2018; Ainley et al. 2020). These include both the upwelling and downwelling domains of the California Current and Alaska Current, respectively (Bertram et al. 2005). Specific features of suitable oceanographic conditions vary based on broader-scale oceanographic and atmospheric phenomena (Bertram et al. 2017a; Hipfner et al. 2020). Predominant prey are copepods (Neocalanus cristatus), euphausiids (Thysanoessa spp. and Euphausia pacifica), and larval fish (Hipfner 2008; Hipfner et al. 2014). Overall reproductive success of Cassin’s Auklet is linked to the cooler sea surface temperatures (SSTs; mean April temps of ~7 ºC; Bertram et al. 2009) that are associated with timing of availability of lipid-rich N. cristatus (with this copepod species more abundant and showing more prolonged availability in cooler years; Bertram et al. 2001, 2009; Hedd et al. 2002; Hipfner 2008). Warmer years (mean April SSTs of ~9 ºC; Bertram et al. 2009) negatively affect prey populations and result in lower reproductive success and fledgling mass (Bertram et al. 2001, 2017b; Hipfner 2008).

Until recently, marine habitat use in the non-breeding season was not well defined. Recent tagging studies suggest that Cassin’s Auklet targets distinct areas of good‑quality habitat at sea, including oceanic fronts and areas of cooler water over meso-scale areas and avoids areas of higher SSTs (Studholme et al. 2019; Johns et al. 2020). Details of the geographical areas used by ‘Canadian’ Cassin’s Auklet in the non‑breeding season are provided by Studholme et al. (2019). In warm water years, overwinter survival can be poor, as seen during a recent widespread marine heatwave (‘the Blob’, 2014-2015; Kintisch 2015) that resulted in zooplankton community composition favouring lower-quality (that is, lipid-poor) and/or smaller prey, and led to a Cassin’s Auklet mass mortality event (Jones et al. 2018).

3.3.1 Limiting factors

Cassin’s Auklet begins breeding at 3.4 years on average (range 2-10 years; mode and median 3 years) and lays only a single egg each year (Pyle 2001; Ainley et al. 2020). Like other long-lived marine birds, the species is limited by its slow rate of reproduction and is particularly vulnerable to adult mortality. Its generation time estimated at 7 years, and annual adult survival is 0.8-0.9 (Gaston 1992; COSEWIC 2014). As Cassin’s Auklet colonies grow, the nutrient subsidies to their terrestrial habitat increases, potentially increasing the growth and percent cover of Salmonberry, and in turn decreasing habitat suitability for auklets (Ydenberg et al. 2021).

4. Threats

4.1. Threat assessment

The Cassin’s Auklet threat assessment is based on the IUCN-CMP (International Union for Conservation of Nature–Conservation Measures Partnership) unified threats classification system (Salafsky et al. 2008). Threats are defined as the proximate activities or processes that have caused, are causing, or may cause in the future, the destruction, degradation, and/or impairment of the entity being assessed (population, species, community, or ecosystem) in the area of interest (global, national, or subnational). Limiting factors are not considered during this assessment process. For purposes of threat assessment, only present and future threats are considered. Historical, negligible or non-applicable threats, indirect or cumulative effects of the threats, or any other relevant information that would help understand the nature of the threats are presented in the Description of Threats section.

4.2. Description of threats

The overall threat impact for this species is Very high to High. This overall impact considers the cumulative impacts of all threats identified for each population (Salafsky et al. 2008). The higher end of this impact range captures the emerging potential threat of introduced diseases, that is, Highly Pathogenic Avian Influenza (HPAI) H5N1. Temperature extremes (in the marine environment), oil spills, and invasive and other problematic species and genes are the most significant present threats to Cassin’s Auklet. Energy production and mining in the form of future offshore oil and gas exploration and wind turbines, and pollution, are additional threats. Details are discussed below, first for threats that are identified as Low impact or greater (Table 2), in consecutive order, then other notable threats.

Threat 8. Invasive and other problematic species and genes

Threat 8.1 - Invasive non-native/alien species/diseases (Medium - Low impact)

Predation from introduced rats, raccoons and mink is a threat on at least 16 colonies and has caused extirpations at nine colonies (COSEWIC 2014; B.C. Conservation Data Centre 2018). Rats have been eradicated at three of these colonies (Langara, St. James, and Murchison Islands), but they have recently (2017) returned to Murchison Island (Parks Canada 2021) and there is a risk of rat re-introduction at Langara Island from human and vessel presence at fishing lodges. Ongoing monitoring has detected rat migrations to a series of new islands in Haida Gwaii south of Lyell Island (Agglomerate Island, House Island, Kawas Islets, Tar Islands and Ramsay Island; the latter locality being occupied by an estimated 12,900 pairs of auklets), and in some cases allowed for their eradication, including Arichika, the Bischofs, Murchison, and Faraday (Parks Canada 2021).

As good swimmers, raccoons — a species native to mainland North America, but introduced to Haida Gwaii for the fur trade — may readily access many of the offshore Haida Gwaii colonies, and this threat is realized at some islands at present. Raccoons and mink were also introduced to Lanz and Cox Islands (Scott Islands archipelago) by fur farmers in the 1930s; significant colonies of breeding seabirds, including those of Cassin’s Auklet, were extirpated there by the 1980s, although a single feather pile found on a survey in 2006 suggests that individuals may still be visiting the colony (Hipfner et al. 2010).

Impacts of introduced Sitka Black-tailed Deer (Odocoileus hemionus sitkensis; Haida Gwaii) and European Rabbits (Oryctolagus cuniculus; Triangle Island) are poorly understood but only a portion of the Triangle colony is occupied by rabbits and there are no obvious impacts reported for them (Hipfner et al. 2010).

Threat 8.5 - Viral/prion-induced diseases (High - Low impact)

Avian influenza (AI) is a viral infection that is highly contagious among birds and is found in domestic poultry and wild birds including raptors, gulls, terns, shorebirds, waterfowl, and cranes. There are many AI virus strains, which are usually classified into two categories: low pathogenic (LPAI) strains, which usually cause mild or no clinical signs in poultry and highly pathogenic (HPAI) strains, which can cause severe disease. Highly Pathogenic Avian Influenza (HPAI) is believed to have originated in domestic poultry (Kuiken and Cromie 2022; Ramey et al. 2022) and is thus not a naturally-occurring disease in seabirds. The current strain of HPAI (H5N1) virus circulating around the globe poses an emerging threat to Cassin’s Auklet. In 2022, outbreaks negatively impacted populations of breeding seabirds in eastern Canada and Europe, with cases showing very high adult mortality. As of 18 March 2024 HPAI had been detected in British Columbia in >370 individual birds (primarily waterfowl and raptors), including two seabird species (Glaucous-winged Gull Larus glaucescens and American White Pelican Pelecanus erythrorhynchos; CFIA (Canadian Food Inspection Agency) 2024). This pathogen is spread by infected wild birds, so is not containable; it is entirely plausible it will reach some North Pacific seabird colonies. The timing of this threat is assessed as Moderate (possibly in the short-term, <10 years/3 generations).

Threat 9. Pollution

Threat 9.2 - Industrial and military effluents (High - Low impact)

Chronic ship-source oil pollution is continuing in British Columbia waters, although decreasing (Serra-Sogas et al. 2008; O’Hara et al. 2013). Because Cassin’s Auklet generally feeds seaward of its breeding colonies it has been assessed as having moderate vulnerability to chronic spills, which tend to be nearshore and along shipping routes (Fox et al. 2016). However, King and Sanger's (1979) Oil Vulnerability Index for Cassin’s Auklet is 84 (ranked second out of the 19 groups considered by Fox et al. 2016). Acute spills are less predictable; hence their Scope and Severity is uncertain. A catastrophic oil spill near colonies would have serious impacts, though the actual degree of threat would depend on timing and location of spill (cf. Bertazzon et al. 2014). Number and tonnage of commercial vessels plying Canada’s Pacific waters are projected to increase over the coming years (cf. Port of Vancouver 2023).

Levels of some organochlorines, mercury and fire-retardants in marine organisms off the west coasts of North America are sufficiently high to affect marine birds (for example, Miller et al. 2015). However, the planktivorous Cassin’s Auklet, feeding low on the food chain, generally has lower levels of industrial pollutants than more piscivorous seabirds (Hipfner et al. 2011; COSEWIC 2014).

Threat 11. Climate change and severe weather

Threat 11.3 - Temperature extremes (High impact)

Cassin's Auklet has been shown in several studies to be highly vulnerable to effects of climate change (warming oceans, increased frequency of El Niño and marine heatwaves, that is, large-scale SST anomalies) affecting the quantity, quality, and timing of occurrence of preferred prey. These effects impact both breeding productivity and the survival of breeding and non-breeding birds (summarized in COSEWIC 2014; more recently: Bertram et al. 2017b, Jones et al. 2018, Ainley et al. 2020, Hipfner et al. 2020, Crossin et al. 2022). Intense marine storms linked to climate change are known to exacerbate effects of heat-driven food shortages as starving birds are less able to weather extreme events, a combination resulting in at least one mass mortality event (Jones et al. 2018). At any given time some part of the Cassin’s Auklet population is likely to be in areas less affected by oceanic heating (cf. Drew and Piatt 2013), but evidence from recent heatwaves indicated close to range-wide effects for the marine areas occupied by the BC population (Wolf et al. 2009, 2010; Morrison et al. 2011; Jones et al. 2018; Hipfner et al. 2020).

Other threats

Tourism and recreation areas (Threat 1.3) are of Negligible impact because of limited scope and severity. Recreational infrastructure (for example, lights at fishing lodges) currently is rare in Cassin’s Auklet habitat.

Marine and freshwater aquaculture (Threat 2.4) is of Negligible impact because of limited scope and severity. Cassin's Auklets tend not to aggregate on the sea close to colonies and are therefore less vulnerable to nearshore developments than some other seabirds. Future expansion of fish-pen aquaculture within the Cassin’s Auklet range seems unlikely but could potentially have a negative effect if close to breeding sites (displacing birds and disturbance from boats). Aquaculture will not occur in Gwaii Haanas National Park Reserve, National Marine Conservation Area and Haida Heritage Site (hereafter Gwaii Haanas) and is not supported by the Haida Nation.

Oil and gas drilling (Threat 3.1) is of Unknown impact due to uncertainties in scope and severity. Currently no offshore drilling and exploration is occurring or anticipated along the coast of British Columbia, and in February of 2024 all remaining exploration permits were relinquished (Canadian Press 2024). This threat is therefore no longer apparent within Canadian waters. However, some Canadian birds winter in California where they will be still exposed to this threat. The timing of this threat in California is considered to be High (that is, current and continuing), but the scope and severity are unknown because it is not known how many birds winter in California, so this threat cannot be estimated.

Renewable energy (Threat 3.3) is of Negligible impact due to limited scope currently. A 100-turbine 2,000 MW wind turbine farm (Naikun) is being planned for Hecate Strait, reportedly to be commissioned in 2025 (Power Technology 2021). This is likely to cause flight disruptions, avoidance of possible foraging habitat, and some collision mortality if constructed, based on research at large European marine wind farms. Hecate Strait is heavily used by Cassin’s Auklet from several colonies (Studholme et al. 2019).

Shipping lanes (Threat 4.3) have a widespread scope, but are of Negligible impact because of limited severity for this species. This excludes threats from marine oil pollution from shipping (Threat 9), but includes the effects of ships and vessel lights disrupting behaviour at foraging or staging areas near colonies. Shipping is expected to increase near BC colonies and in wintering areas (for example, off southern BC and Washington to California) so monitoring should continue. Flight paths (Threat 4.4) are of Negligible impact due to limited scope and severity. Helicopter and floatplane traffic are the most likely threats and might increase with increasing tourism and commercial activity on Haida Gwaii. Scope is likely at the low end of 1-10%, but not negligible.

Hunting and collecting terrestrial animals (Threat 5.1) is of Negligible impact because of limited scope and severity. Hunting or egg collecting is currently rare, but egg collecting might occur as part of traditional Indigenous practices. Hunting of deer or bear on breeding colony islands, which might damage burrows, is uncommon. Logging and wood harvesting (Threat 5.3) is of Negligible impact because of limited scope and severity. All forested colony sites are protected. Log-salvage operations may destroy nests of the small percentage of Cassin’s Auklets that nest in piles of driftwood (COSEWIC 2014). Fishing and harvesting aquatic resources (Threat 5.4) is of Negligible impact because of limited scope and severity. Analyses of bycatch in nearshore and offshore fisheries found very few Cassin's Auklets (for example, 0.35% of 852 birds killed in salmon gillnets covering <2% of the fishing effort: Bertram et al. 2021). Gillnet fisheries have declined significantly in B.C. waters (Bertram et al. 2021), so this is not considered a serious threat at this time (COSEWIC 2014).

Recreational activities (Threat 6.1) are of Negligible impact because of limited scope and severity. Camping and trampling on breeding colonies in Haida Gwaii by recreational visitors can lead to collapse of burrows and risks of attraction to campfires (COSEWIC 2014). Although recreational visits to Gwaii Haanas are increasing (Archipelago Management Board 2018), most Cassin's Auklet colonies are closed to visitors under a Parks Canada Superintendent's Order (that is, no one sets foot on the islands) and the closures are enforced by park wardens. Fishing resorts (for example, Langara island) pose a high risk of human disturbance (via boat traffic, etc.) and re-introduction of rats, but are limited in scope. Recreational boating is likely to displace birds staging near a few breeding colonies and recreational boating is expected to increase around Haida Gwaii, but the severity of this is limited. Work and other activities (Threat 6.3) are of Negligible impact because of limited severity. Visiting researchers on breeding colonies probably have some restricted effects, such as burrow collapse, and nest abandonment following handling and the effects of tagging of adults (COSEWIC 2014; McFarlane Tranquilla et al. 2020), but the impact is expected to be minor. Maintenance of navigational beacons by the Coast Guard might result in very localised disturbance (from trampling and helicopter landings) at only a few colonies.

Fire and fire suppression (Threat 7.1) are of Negligible impact because of limited scope and severity. Escaped campfires are the only minor threat identified, but with climate change, naturally-occurring fires might occur at some forested colonies.

Problematic native species/diseases (Threat 8.2) are of Negligible impact due to limited scope. Harmful algal blooms are increasing as oceans warm and bloom byproducts (for example, toxic domoic acid) are known to kill seabirds and reduce waterproofing of plumage. Toxic algae are known to kill or disable seabirds but to date no impacts on Cassin's Auklets have been reported (Jones et al. 2017). This might become a greater risk with warming oceans in the Cassin's Auklet's breeding and wintering ranges. Mass mortality of Rhinoceros Auklets in British Columbia and Washington in 2016 was linked to bacterial septicaemia (Bisgaard taxa; Pasteurella-like bacteria) but it is not known if, and under what conditions, these bacteria might affect Cassin's Auklets. River Otters were potentially linked to extermination of one small colony (Seabird Rocks: Carter et al. 2012) and could potentially affect other nearshore colonies.

Garbage and solid waste (Threat 9.4) are of Negligible impact because of limited severity. Marine organisms, including zooplankton likely to be eaten by auklets, are increasingly contaminated with microplastics from consumer products (for example, 100% of Cassin's Auklets in one study were found to contain plastics; Floren and Shugart 2017), but the population-level impacts on birds are not well known at this time (O'Hara et al. 2018). O'Hara et al (2018) showed that because of their offshore distribution, breeding Cassin's Auklets typically do not occupy waters with high plastic concentrations. However, winter distribution shifts toward the coast where plastic concentrations are higher.

Earthquakes/tsunamis (Threat 10.2) are of Negligible impact because of limited scope and severity. A major tsunami would devastate low-lying parts of colonies if it occurred in the nesting season. However, there is great uncertainty in predicting timing of such geological events. Avalanches/landslides (Threat 10.3) are of Negligible impact because of limited scope and severity. Landslides could severely damage portions of colonies on steep islands (for example, Triangle Island). However, there is great uncertainty in predicting timing of such geological events.

Storms and flooding (Threat 11.4) are of Negligible impact because of limited scope and severity. The additive impacts of climate change related storms are not considered here (see section 11.3). At breeding colonies blowdown of forest trees and subsequent regeneration is considered to have negative impacts, but these have not been quantified (Gaston et al. 2009).

5. Management objective

The Management Objective for Cassin’s Auklet in Canada is to stabilize the declining population across its current distribution.

Rationale for management objective and short-term statements

The primary management concern for Cassin’s Auklet is “stability”^{Footnote 11} given that its Special Concern status is due to a declining population (COSEWIC 2014). For this reason, the management objective concentrates on bringing stability to the population, that is, ceasing the current inferred population decline. Primary threats to this species (that is, causes of current and potential future declines) are introduced mammalian predators at colonies, the risk of oiling at sea during breeding and non-breeding seasons, the potential impact of H5N1 avian influenza, and effects of warming oceans on preferred prey. As no actions at the national scale will directly address the latter threat in the shorter term, none are proposed here (though see 6.4, Narrative to Support Conservation Measures and Implementation Schedule, below). If future data confirms a continued decline, Cassin’s Auklet could potentially be assessed as more ‘at-risk’. Management actions should take place in the next 5 to 7 years, with a goal of completion by 2030 for key conservation measures (Table 3). To understand trends it will be important to update colony counts for this species, which for most localities are decades out of date (see 3.2, Species Population and Distribution, and Appendix B). Recovery for this species is deemed feasible.

Short-term statements towards meeting the management objective

• restore breeding habitat by eliminating introduced mammalian predators on nesting islands
• reduce the potential for human transmission of H5N1 to Cassin’s Auklet colonies
• reduce the threat of oiling in marine habitats
• update population estimates at colonies

6. Broad strategies and conservation measures

6.1. Actions already completed or currently underway

Invasive species management and biosecurity

In Haida Gwaii, rats were eradicated from Cassin’s Auklet colonies at Langara and St. James Island in the 1990s, and from Murchison Island in 2013 (COSEWIC 2014; Parks Canada 2021). Cassin’s Auklet has reestablished a small colony on Langara Island (Regehr et al. 2007), but rats were again detected on Murchison in 2017 (Parks Canada 2021). Ongoing monitoring has detected rat migrations to new islands in Haida Gwaii, and in some cases allowed for their eradication (Parks Canada 2021). A regional genetics study was recently conducted to understand the origins of recolonizing rats and increase likelihood of success for future eradication efforts in Haida Gwaii (Sjodin et al. 2019; Parks Canada 2021). Gwaii Haanas provides free “Rat Aware Kits” to all boaters to the park (Parks Canada 2021).

Raccoons have been removed from three islands within Haida Gwaii (Helgeson, Saunders and East Limestone), and there is intermittent monitoring for and control of raccoons recolonizing from nearby source populations (for example, Bradley and Stefanyk 2016; Laskeek Bay Conservation Society 2021).

Eradication of introduced mammals and maintaining biosecurity to prevent re-introductions are priorities within Gwaii Haanas, and on Haida Gwaii more broadly (Marine Planning Partnership Initiative 2015; Parks Canada 2016; Archipelago Management Board 2018). Parks Canada is developing an invasive species management plan to improve understanding of invasive species and how best to manage them (Parks Canada 2021). Birds Canada is working with the Coastal First Nations Great Bear Initiative and Haida Guardians to provide training and camera equipment over the next two to three years to detect invasive mammals at key seabird breeding islands (D. Bradley, pers. comm.)

A feasibility plan has also been conducted for eradication of introduced raccoons and mink at the historical Cassin’s Auklet colonies of Lanz and Cox Islands in the Scott Islands (Howald and Gill 2010), and Environment and Climate Change Canada, in partnership with the Quatsino First Nation, the Tlatlasikwala First Nation and the Province of British Columbia, is working on a draft Management Plan for the marine National Wildlife Area (K. Woo, pers. comm.). The existing management plan for Lanz and Cox Provincial Park includes the goal of developing a program to eradicate introduced species and protect seabirds (BC Parks 2003). Biosecurity plans have recently been developed for the Scott Islands, and specifically for Lanz and Cox Islands (Gill et al. 2020; Gill and Howald 2021). These focus on rats, but they may be applied to additional species (K. Woo, pers. comm.). Research has been conducted on potential impacts of introduced rabbits at Triangle Island (Hipfner et al. 2010; Rodway et al. 2017).

Monitoring of cases of HPAI in Canadian wildlife and poultry is being carried out, and results reported in real time (CFIA 2022). In response to the current H5N1 pandemic, Environment and Climate Change Canada has also developed biosecurity guidance for holders of scientific permits (L. Wilson, pers. comm.).

Pollution management

Canada surveys for chronic and catastrophic oil spills (cf. Berry et al. 2018) within its Exclusive Economic Zone (EEZ) via the National Aerial Surveillance Program (NASP). Surveys are designed both to monitor spills and deter polluters (Transport Canada 2021). Within the Scott Islands marine National Wildlife Area, it is prohibited to “dump or discharge any waste material or substance that is likely to harm wildlife or degrade the quality of wildlife habitat in the Protected Marine Area” (Government of Canada 2022). Within Canada’s Pacific waters, the 2019 Oil Tanker Moratorium Act “prohibits oil tankers that are carrying more than 12,500 metric tons of crude oil or persistent oil as cargo from stopping, or unloading crude oil or persistent oil [defined in the Act], at ports or marine installations located along British Columbia’s north coast from the northern tip of Vancouver Island to the Alaska border” (Government of Canada 2023a). Under the Oceans Protection Plan (Government of Canada 2023b), the Government of Canada is increasing preparedness for pollution events through increased response capacity in the form of personnel, equipment, and training; increased surveillance of protected areas; expanded research on pollutants’ fate, behaviours, and effects; and modernizing federal marine safety regulations and enforcement (M. Willie, pers. comm.).

Habitat protection

Areas identified as foraging habitat for Cassin’s Auklet during the breeding season have been used to inform establishment of the Scott Islands mNWA (Boyd et al. 2008; Bertram et al. 2017a; Bertram 2019). The Scott Islands Protected Marine Area Regulation imposes certain restrictions on activities, vessels, and aircraft within the protected area (Government of Canada 2022).

Of Canada’s extant Cassin’s Auklet colonies, all but one minor site (Egg Island, est. 10 nests) are protected within national park reserves, provincial parks or ecological reserve, or Haida Gwaii heritage site or conservancy (COSEWIC 2014).

6.2. Broad strategies

The following broad strategies will be used to achieve the Management Objective for Cassin’s Auklet (listed in order of threats from Section 4.2, above):

1. reduce negative impacts of offshore oil and gas activities within Cassin’s Auklet marine habitat
2. reduce impacts of introduced mammalian species at colonies
3. reduce risk of infectious disease outbreaks at breeding colonies
4. manage and reduce oil spill risk within the marine range of Cassin’s Auklet
5. increase protection of Cassin’s Auklet marine habitat
6. conduct population surveys at nesting colonies

6.3. Conservation measures

6.4. Narrative to support conservation measures and implementation schedule

The most tractable conservation measures for advancing recovery of Cassin’s Auklet in Canada are eradication of introduced mammals at island colonies, prevention of further introductions of non-native species, and stewarding and protecting foraging areas at sea within the Canadian EEZ.

Eradication of introduced mammals on islands is an action that has been demonstrably successful at seabird colonies worldwide (Williams et al. 2020) and has seen improvements as approaches have matured. Introduced mammalian predators have extirpated or reduced populations of Cassin’s Auklet at important colonies (for example, Hipfner et al. 2010). Removal of introduced raccoons and mink from Lanz and Cox Islands has good potential to result in recolonization of these sites by auklets as there has been past evidence of prospecting by would-be nesters (Hipfner et al. 2010). Biosecurity measures for infectious diseases like HPAI must be implemented and sustained to prevent human-to-bird transmission at colonies.

Virtually all Cassin’s Auklet nesting colonies have some form of legal protection and measures to regulate visitors (COSEWIC 2014). The threat of human disturbance at colonies is identified as having only a Negligible impact and so is not addressed here. Nonetheless, protected areas do receive low numbers of human visitors and recreational boating activity is projected to increase, at least in Haida Gwaii. Thus, public outreach and enforcement of regulations designed to protect colonies from human disturbance will be important into the future (COSEWIC 2014).

One of the most important threats to Cassin’s Auklet is the impact of warming SSTs, and an increased incidence of marine heat wave events, on prey abundance and availability. Addressing global climate change is beyond the scope of this Management Plan, but the above conservation measures will help to create the resiliency in nesting populations that may allow them to buffer climate-related mortality.

7. Measuring progress

The performance indicators presented below provide a way to measure progress towards achieving the Management Objective and monitoring the implementation of the management plan.

• Leases for offshore oil and gas exploration in Pacific Canada cancelled (number of leases)
• Moratoriums on oil and gas exploration and/or transport expanded or formalized (number or length of moratoriums)
• Completed list of priority colonies for introduced mammal eradication/management
• Progress made on predator eradication and management (number of colonies with eradication completed/management plans in place)
• Biosecurity measures in place to address rat “spills” at priority colonies (number of priority colonies with plan in place)
• Biosecurity measures in place to address potential for human spread of infectious disease to seabird colonies (number of colonies with biosecurity measures in place)
• Declining number of oil spill events recorded by NASP (effective deterrence)
• mNWA expanded to incorporate breeding season foraging range of Cassin’s Auklets at Scott Island (area of mNWA)
• Increased marine pollution response capacity in British Columbia and coastal communities near Cassin’s Auklet breeding colonies
• Increased number of marine protection strategies in place in or near habitats occupied by Cassin’s Auklet
• Surveys implemented to measure distribution and significant declines or increases in Canada’s population of Cassin’s Auklet (adequate plans and support in place for complete colony surveys and subsequent monitoring) for population monitoring and to inform responses to marine pollution risks

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Appendix A: Effects on the environment and other species

A strategic environmental assessment (SEA) is conducted on all SARA recovery planning documents, in accordance with the Cabinet Directive on the Environmental Assessment of Policy, Plan and Program Proposals^{Footnote 12}. The purpose of a SEA is to incorporate environmental considerations into the development of public policies, plans, and program proposals to support environmentally sound decision-making and to evaluate whether the outcomes of a recovery planning document could affect any component of the environment or any of the Federal Sustainable Development Strategy’s^{Footnote 13} (FSDS) goals and targets.

Conservation planning is intended to benefit species at risk and biodiversity in general. However, it is recognized that implementation of management plans may also inadvertently lead to environmental effects beyond the intended benefits. The planning process based on national guidelines directly incorporates consideration of all environmental effects, with a particular focus on possible impacts upon non-target species or habitats. The results of the SEA are incorporated directly into the management plan itself, but are also summarized below in this statement.

Conservation and management of Cassin’s Auklet colonies and marine habitat across the range of the species will benefit a number of other seabirds that use the same colonies and occupy the same marine habitat for all or part of their lifecycles. Examples of at-risk seabirds in these habitats in Canada include Ancient Murrelet (Synthliboramphus antiquus), Black-footed Albatross (Phoebastria nigripes), and Pink‑footed Shearwater (Ardenna creatopus). Similarly, protection and stewardship of marine habitats will have positive effects on other co-occurring species, such as marine mammals and sea turtles. The potential for the plan to inadvertently lead to adverse effects on other native species was considered. The SEA concluded that this plan will clearly benefit the environment and will not entail any significant adverse effects.

Appendix B: Population estimates table

Population estimates for breeding Cassin’s Auklets Ptychoramphus aleuticus at colonies in British Columbia, Canada. Note that most estimates are >35 years old. Environment and Climate Change Canada - Canadian Wildlife Service (ECCC-CWS) has conducted repeated surveys of permanent plots on five of the largest Cassin’s Auklet colonies in British Columbia, representing an estimated 50% of the Canadian population and 59% of the total area (190 of 321 ha). The average abundance of Cassin’s Auklet burrows at the monitored colonies in BC has decreased from 1984 to 2019 (see 3.2, Species Population and Distribution, for details). These trends have not been applied here to generate updated colony estimates as monitoring plots were not designed to estimate colony-wide trends. Sources: COSEWIC 2014; Rodway et al. 2016, 2020, 2022, in prep.; M. Rodway, pers. comm., L. Wilson, pers. comm.).