Gregory J. Robertson

Gregory J. Robertson
Environment Canada | EC · Wildlife Research Division

Doctor of Philosophy

About

372
Publications
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5,737
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Publications

Publications (372)
Article
Species and populations with greater cognitive performance are more successful at adapting to changing habitats. Accordingly, urban species and populations often outperform their rural counterparts on problem-solving tests. Paradoxically, urban foraging also might be detrimental to the development and integrity of animals' brains because anthropoge...
Article
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Conservation of mobile organisms is difficult in the absence of detailed information about movement and habitat use. While the miniaturization of tracking devices has eased the collection of such information, it remains logistically and financially difficult to track a wide range of species across a large geographic scale. Predictive distribution m...
Article
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Highly pathogenic avian influenza (HPAI) viruses of the A/Goose/Guangdong/1/1996 lineage (GsGd), which threaten the health of poultry, wildlife and humans, are spreading across Asia, Europe, Africa and North America but are currently absent from South America and Oceania. In December 2021, H5N1 HPAI viruses were detected in poultry and a free-livin...
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Reproduction in procellariiform birds is characterized by a single egg clutch, slow development, a long breeding season and obligate biparental care. Female Leach’s Storm Petrels Hydrobates leucorhous, nearly monomorphic members of this order, produce eggs that are between 20 and 25% of adult body weight. We tested whether female foraging behaviour...
Article
Bycatch in fisheries remains one of the biggest conservation threats to seabirds globally, but there has been limited attention given to bycatch in the Arctic. Here, we worked with Inuit commercial fishers in the Cambridge Bay region of Nunavut to record bycatch of birds, as part of a fish bycatch reporting initiative, in weir and gillnet fisheries...
Article
Seabirds are important biovectors of contaminants, like mercury, moving them from marine to terrestrial environments around breeding colonies. This transfer of materials can have marked impacts on receiving environments and biota. Less is known about biotransport of contaminants by generalist seabirds that exploit anthropogenic wastes compared to o...
Article
Seabird population size is intimately linked to the physical, chemical, and biological processes of the oceans. Yet, the overall effects of long‐term changes in ocean dynamics on seabird colonies are difficult to quantify. Here, we used dated lake sediments to reconstruct ~10,000‐years of seabird dynamics in the Northwest Atlantic to determine the...
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Starvation is a ubiquitous process in nature as all animals depend on finite resources to survive. Limited food resources can lead to starvation-induced mortality and, depending on the scale of the limitation, population-level consequences may emerge. However, attempts to model starvation-induced mortality are rare as it is difficult to isolate the...
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Common eiders Somateria mollissima have been a focus of conservation and management efforts in eastern North American for over a century; however, the complex population structure and multiple subspecies make assessing the status of populations challenging. The coastlines of Nova Scotia, Canada, are an important wintering area for common eiders, an...
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The addition of eggs to a nest by a conspecific is known for approximately 250 bird species. Understanding the evolution of conspecific brood parasitism (CBP) requires assessment of fitness consequences to the egg recipient (host). We addressed host traits and the effects of CBP on future reproduction (i.e., annual survival) and hatching success of...
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American black ducks, native to eastern North America, have been the focus of significant international conservation and management programs. The combined USA and Canadian population has traditionally been managed as a single population; however black duck demographics may vary by region. To help understand potential regional differences in black d...
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Oil spills most visibly affect waterbirds and often the number of birds affected, a key measure of environmental damage from an incident, is required for public communication, population management, and legal reasons. We review and outline steps that can be taken to improve accuracy in the estimation of the number of birds affected in each of three...
Article
Ingestion of plastic pollution by pelagic seabirds is well-documented globally, but increasingly, researchers are investigating plastic ingestion in generalist predators and scavengers like gulls. We studied the gut contents of two sympatric gull species, American herring gulls (Larus smithsoniansus) and great black-backed gulls (L. marinus), colle...
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The lack of long-term monitoring data for many wildlife populations is a limiting factor in establishing meaningful and achievable conservation goals. Even for well-monitored species, time series are often very short relative to the timescales required to understand a population's baseline conditions before the contemporary period of increased huma...
Poster
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Performing microbiological assays on environmental samples in field settings poses several logistical challenges, including the availability of suitable field-based equipment and the timely arrival of samples to a testing laboratory. Due to the importance of assessing microbiological water quality, but with a lack of methodologies to perform these...
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This study examines the occurrence and underlying factors of onshore strandings of two species of seabirds breeding in Newfoundland and Labrador, Canada. Atlantic Puffins (Fratercula arctica) are found stranded in coastal communities bordering the Witless Bay Ecological Reserve in artificially lit areas. Between 2011 and 2020, 3845 recently fledged...
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After successful conservation and management efforts throughout much of the twentieth century that led to the recovery of common eiders (Somateria mollissima) breeding in several jurisdictions in eastern North America, their abundance has declined in recent years, probably linked to various environmental stressors. To evaluate where to focus future...
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In the eastern North Atlantic, declines in the volume of Atlantic Puffin (Fratercula arctica Linnaeus, 1758) eggs have been associated with shifts in the marine ecosystem, such as changes in the abundance of forage fishes and increasing sea-surface temperatures. In the western North Atlantic, where similar shifts in oceanographic conditions and cha...
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Incidental mortality of marine birds in fisheries is an international conservation concern, including in Canada where globally significant populations of vulnerable diving species overlap with coastal gillnet fisheries. In British Columbia (BC), commercial salmon gillnet fishing effort was historically very high (>200,000 days fished annually in th...
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Parvoviruses are small single-stranded DNA viruses that can infect both vertebrates and invertebrates. We report here the full characterization of novel viruses we identified in ducks, including two viral species within the subfamily Hamaparvovirinae (duck-associated chapparvovirus, DAC) and a novel species within the subfamily Densovirinae (duck-a...
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Consuming omega-3 fatty acids (n3-LCPUFAs) during development improves cognition in mammals, but the effect remains untested in other taxa. In aquatic ecosystems, n3-LCPUFAs are produced by phytoplankton and bioaccumulate in the food web. Alarmingly, the warming and acidification of aquatic systems caused by climate change impair n3-LCPUFA producti...
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https://arctox.cnrs.fr/en/home/ Mercury (Hg) is a natural trace element found in high concentrations in top predators, including Arctic seabirds. Most current knowledge about Hg concentrations in Arctic seabirds relates to exposure during the summer breeding period when researchers can easily access seabirds at colonies. However, the few studies f...
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Recent estimates indicate that ∼70% of the world’s seabird populations have declined since the 1950s due to human activities. However, for almost all bird populations, there is insufficient long-term monitoring to understand baseline (i.e., preindustrial) conditions, which are required to distinguish natural versus anthropogenically driven changes....
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Seabirds that form large colonies often act as biovectors that transport and concentrate large amounts of nutrients, metals, and contaminants from marine feeding areas to inland breeding grounds. This enrichment can potentially transform and structure primary productivity, vegetation communities, and species richness. In a previous paleolimnologica...
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Highly migratory species pose unique conservation and management challenges, especially when significant mortality occurs away from breeding concentrations. Population genetics and genomics may help with the appropriate management of these species by (1) determining the population genetic structure of a species across its range, and (2) allowing th...
Article
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Performing microbiological assays on environmental samples in field settings poses logistical challenges with respect to the availability of suitable equipment or the ability to get samples to the laboratory in a timely fashion. For example, the viability of some bacteria can decrease greatly between sampling and arrival to the laboratory for proce...
Article
Full-text available
Many seabird species in the North Atlantic region have shown considerable declines in their populations during recent decades. One such species is the Arctic tern (Sterna paradisaea), a small seabird which migrates farther than any other seabird each year and whose global population is thought to be in decline. We used banding data of chicks and ad...
Article
In this investigation, we used a combination of field- and laboratory-based approaches to assess if influenza A viruses (IAVs) shed by ducks could remain viable for extended periods in surface water within three wetland complexes of North America. In a field experiment, replicate filtered surface water samples inoculated with duck swabs were tested...
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The black-legged kittiwake (Rissa tridactyla, hereafter kittiwake) is a small pelagic seabird and is the most numerous gull species in the world. It has a circumpolar distribution, and breeds in the arctic and boreal zones of the Northern Hemisphere. It’s breeding distribution is widespread and ranges across the North Atlantic from the west coast t...
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Background: Recent studies have proposed that birds migrating short distances migrate at an overall slower pace, minimizing energy expenditure, while birds migrating long distances minimize time spent on migration to cope with seasonal changes in environmental conditions. Methods: We evaluated variability in the migration strategies of Herring G...
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Scientists across many fields are faced with the challenge of synthesizing and communicating information from large and complex data sets. The field of stock assessment is no exception as the volume and variety of the data has grown alongside the computational methods used to integrate them. While this growth in data and model complexity has improv...
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Sympatric communities of organisms may exploit different ecological niches to avoid intra- and interspecific competition. We examined the isotopic niches of American black ducks (Anas rubripes) and mallards (A. platyrhynchos) wintering in coastal and urban areas of Atlantic Canada and compared isotopic niche with digestive tract morphologies and bl...
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Populations often show complex spatial and temporal dynamics, creating challenges in designing and implementing effective surveys. Inappropriate sampling designs can potentially lead to both under-sampling (reducing precision) and over-sampling (through the extensive and potentially expensive sampling of correlated metrics). These issues can be dif...
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Many animal populations are under stress and declining. For numerous marine bird species, only recent or sparse monitoring data are available, lacking the appropriate temporal perspective needed to consider natural, long-term population dynamics when developing conservation strategies. Here, we use a combination of established palaeoenvironmental a...
Article
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Many seabird species in the North Atlantic region have shown considerable declines in their populations during recent decades. One such species is the Arctic tern (Sterna paradisaea), a small seabird which migrates farther than any other seabird each year and whose global population is thought to be in decline. We used banding data of chicks and ad...
Article
We present the first records of fungi associated with feathers from seabirds and sea ducks in the Canadian Arctic and sub-Arctic. Birds sampled in Nunavut and Newfoundland (Canada) included the Common Eider (Somateria mollissima), King Eider (S. spectabilis), Black-legged Kittiwake (Rissa tridactyla), Northern Fulmar (Fulmarus glacialis), Glaucous...
Poster
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Leach’s storm-petrel (Oceanodroma leucorhoa = Hydrobates leucorhous) is a small seabird species that was listed as globally vulnerable on the IUCN’s Red List of Threatened Species in 2016. Breeding populations have declined more than 30% over the last three generations in Atlantic Canada. Elevated mercury exposure may be contributing to this specie...
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Wild birds are recognized viral reservoirs but our understanding about avian viral diversity is limited. We describe here three novel RNA viruses that we identified in oropharyngeal/cloacal swabs collected from wild birds. The complete genome of a novel gull metapneumovirus (GuMPV B29) was determined. Phylogenetic analyses indicated that this virus...
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Brünnich's guillemot (Uria lomvia), or thick-billed murre, is an abundant pan-Arctic seabird, but several Atlantic breeding populations are declining. The species is subject to traditional harvest in the important wintering areas off west Greenland and Newfoundland, and has been subject to chronic oil pollution on the east coast of Canada. Until re...
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The timing of annual events such as reproduction is a critical component of how free‐living organisms respond to ongoing climate change. This may be especially true in the Arctic, which is disproportionally impacted by climate warming. Here, we show that Arctic seabirds responded to climate change by moving the start of their reproduction earlier,...
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Despite the global significance of the Leach’s Storm-petrel Hydrobates leucorhous colony on Baccalieu Island, Newfoundland and Labrador, Canada, the estimate of 3.36 million breeding pairs reported for 1984 by Sklepkovych and Montevecchi stands as the single published population estimate for the world’s largest colony. This study increases knowledg...
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The occurrence of Borrelia garinii in seabird ticks, Ixodes uriae, associated with different species of colonial seabirds has been studied since the early 1990s. Research on the population structure of this bacterium in ticks from seabird colonies in the northeastern Atlantic Ocean has revealed admixture between marine and terrestrial tick populati...
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In birds, parasites cause detrimental effects to the individual host, including reduced survival and reproductive output. The level of parasitic infection can vary with a range of factors, including migratory status, body size, sex, and age of hosts, or season. Understanding this baseline variation is important in order to identify the effects of e...
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In group-living species with parental care, the accurate recognition of one's own young is critical to fitness. Because discriminating offspring within a large colonial group may be challenging, progeny of colonial breeders often display familial or individual identity signals to elicit and receive parental provisions from their own parents. For in...
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Viruses in the family Papillomaviridae have circular dsDNA genomes of approximately 5.7–8.6 kb that are packaged within non-enveloped, icosahedral capsids. The known papillomavirus (PV) representatives infect vertebrates, and there are currently more than 130 recognized PV species in more than 50 genera. We identified 12 novel avian papillomavirus...
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Following publication of the original article [1], the authors reported that one of the authors’ names was spelled incorrectly. In this Correction the incorrect and correct author name are shown. The original publication of this article has been corrected.
Technical Report
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Foreword This series documents the scientific basis for the evaluation of aquatic resources and ecosystems in Canada. As such, it addresses the issues of the day in the time frames required and the documents it contains are not intended as definitive statements on the subjects addressed but rather as progress reports on ongoing investigations.
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The genomes of influenza A viruses (IAVs) comprise eight negative-sense single-stranded RNA segments. In addition to the protein-coding region, each segment possesses 5′ and 3′ non-coding regions (NCR) that are important for transcription, replication and packaging. The NCRs contain both conserved and segment-specific sequences, and the impacts of...
Article
Mercury (Hg) is a toxic element which has increased in marine environments for more than a century, due largely to anthropogenic activities, and biomagnifies in food chains to harmful levels in some top predators like waterfowl and seabirds. We analysed total mercury (THg) concentrations in blood, brain and muscle tissue from healthy specimens of 1...
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Extreme climate can negatively affect survival through increased physiological demands or by reducing prey availability. This can have significant population-level consequences for organisms with low reproductive rates, such as seabirds. As an Arctic-breeding trans-equatorial migrant, Sabine’s gull (Xema sabini) is exposed to a profound variety of...
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Body condition is commonly used in ecology to assess the physiological health of an organism or population and can be used to predict individual survival or breeding success. Waterfowl have been the focus of much research on body condition, and we studied body condition via carcass composition and using a scaled mass index (SMI) in American Black D...