R. I. Guy Morrison

• BSc (St. Andrews), PhD (Cambridge)
• Researcher at Government of Canada

Seasonally abundant arthropods are a crucial food source for many migratory birds that breed in the Arctic. In cold environments, the growth and emergence of arthropods are particularly tied to temperature. Thus, the phenology of arthropods is anticipated to undergo a rapid change in response to a warming climate, potentially leading to a trophic m...

Shorebirds are declining to a greater extent than many other avian taxa around the world. In North America, shorebirds, along with aerial insectivores and grassland birds, have some of the highest proportions of declining species of any group. Here, we apply a new hierarchical Bayesian model to analyze shorebird migration monitoring data from acros...

Genetic data are useful for detecting sudden population declines in species that are difficult to study in the field. Yet this indirect approach has its own drawbacks, including population structure, mutation patterns, and generation overlap. The ivory gull (Pagophila eburnea), a long-lived Arctic seabird, is currently suffering from rapid alterati...

In seasonal environments subject to climate change, organisms typically show phenological changes. As these changes are usually stronger in organisms at lower trophic levels than those at higher trophic levels, mismatches between consumers and their prey may occur during the consumers’ reproduction period. While in some species a trophic mismatch i...

Droughts can affect invertebrate communities in wetlands, which can have bottom-up effects on the condition and survival of top predators. Shorebirds, key predators at coastal wetlands, have experienced widespread population declines and could be negatively affected by droughts. We explored, in detail, the effects of drought on multiple aspects of...

Ocean acidification (OA) is increasing predictably in the global ocean as rising levels of atmospheric carbon dioxide lead to higher oceanic concentrations of inorganic carbon. The Gulf of Maine (GOM) is a seasonally varying region of confluence for many processes that further affect the carbonate system including freshwater influences and high pro...

Lemmings are a key component of tundra food webs and changes in their dynamics can affect the whole ecosystem. We present a comprehensive overview of lemming monitoring and research activities, and assess recent trends in lemming abundance across the circumpolar Arctic. Since 2000, lemmings have been monitored at 49 sites of which 38 are still acti...

In the original published article, some of the symbols in figure 1A were modified incorrectly during the typesetting and publication process. The correct version of the figure is provided in this correction.

A recent study demonstrated that semipalmated sandpiper (Calidris pusilla) wing lengths have shortened from the 1980s to the present-day. We examined alternative and untested hypotheses for this change at an important stopover site, James Bay, Ontario, Canada. We evaluated morphometric patterns in wing length and bill length by age and sex, when po...

Measurement error results from within-year historical recaptures by different banders along James Bay, Ontario, Canada (1974–1982). (DOCX)

Wing photo and caliper measurement calibration. Methods, model results, and calibration equations comparing shorebird wing photos to wing measurements taken with calipers. (DOCX)

Results from size constrained correspondence analysis (SCCA) of semipalmated sandpiper primary feathers. (DOCX)

In the original publication of the article, the linear discriminate Eq. (1) was mistyped. We provide below the correct equation to use to discriminate male and female in Ivory Gull Pagophila eburnea (Phipps, 1774).

We compiled a >50-year record of morphometrics for semipalmated sandpipers (Calidris pusilla), a shorebird species with a Nearctic breeding distribution and intercontinental migration to South America. Our data included >57,000 individuals captured 1972–2015 at five breeding locations and three major stopover sites, plus 139 museum specimens collec...

Sex identification of birds is relevant to studies of evolutionary biology and ecology and is often a central issue for the management and conservation of populations. The Ivory Gull Pagophila eburnea (Phipps, 1774) is a rare high-Arctic species whose main habitat is sea ice throughout the year. This species is currently listed Near Threatened by t...

Species may cope with rapid habitat changes by distribution shifts or adaptation to new conditions. A common feature of these responses is that they depend on how the process of dispersal connects populations, both demographically and genetically. We analyzed the genetic structure of a near-threatened high-Arctic seabird, the ivory gull (Pagophila...

Long-distance migratory shorebirds are vulnerable to stressors throughout their annual cycle, including during migration when they must rely on a limited set of stopover sites to refuel. The rufa subspecies of Red Knot Calidris canutus has shown drastic population declines in recent decades and is listed as Endangered in Canada and Threatened in th...

Modified Malaise traps are used to capture surface active and low-flying arthropods. Two 5-trap transects are established in two dominant shorebird foraging habitats that are used during the brood rearing period, i.e. marsh and dry tundra (2 transect/habitat), and run continuously from late June to early August. Traps are emptied every 48 hrs. Arth...

We are monitoring the nesting activity of shorebirds. We find nests through systematic search of 12-ha plots established in a variety of habitats used by shorebirds (tundra terraces, graminoid marshes, barren ground). Some nests are also found opportunistically during other routine work. Nest locations are recorded with a GPS and revisited periodic...

Numbers of all species occurring during daily activities are recorded. Counts occur regularly at some locations (e.g., sewage outfall stream), and are also recorded during visits to other locations in the Alert area. Numbers of each species as well as start and end times of observations are recorded to enable relative abundance of species to be cal...

We monitor lemming abundance using snap-traps at 2 sites; we accumulate at least 50 trap-nights at each site annually by trapping during 3 days.

We sampled the production of plants (forbs, grasses and shrubs) at 4 sites (2 in damp, marshy areas and 2 in drier, poorly vegetated habitats) in 2007 and 2008. We sample plant biomass at the end of the growing season in late July to early August by removing 8 quadrats of 20 x 50 cm at each site. All live above-ground biomass is cut, sorted out by...

We are monitoring the nesting activity of Long-tailed Jaegers. We find nests through either systematic searches or opportunistically. All nests found are positioned with a GPS and revisited during the breeding period to determine laying date, clutch size, hatching date and fledging success.

Foxe Basin is a down-faulted arctic basin floored by Palaeozoic carbonates, surrounded by metamorphic Precambrian terrains. Quaternary deposits consist of Pleistocene–Holocene glacial drift, and frost-shattered bedrock-clasts mostly reworked by sea waves during post-glacial emergence during the last 5000–6000 yr. The shallow, primarily micro- to me...

Migratory birds are sometimes known to make reverse movements to seek better fuelling sites before undertaking long-distance migratory flights across ecological barriers. Red knots Calidris canutus rufa regularly make prodigious migratory flights of ~ 8,000 km from southern South America to North America; these flights depend critically on the bird...

Significant progress has been made in our understanding of species-level responses to climate change, but upscaling to entire ecosystems remains a challenge. This task is particularly urgent in the Arctic, where global warming is most pronounced. Here we report the results of an international collaboration on the direct and indirect effects of clim...

2014. Conservation assessment and ecology of the Magellanic Oystercatcher Haematopus leucopodus. International Wader Studies 20: 173-181. The Magellanic Oystercatcher Haematopus leucopodus is a monotypic species endemic to southern Patagonia. Breeding (from September to January−February), it occurs along the coast on the Falklands/Malvinas and to s...

Allochthonous input of resources (i.e., originating from a place other than where they are found) can have a significant impact on food availability for consumers. We assessed the impact of an allochthonous source of food (the sewage outfall stream of a military base) on an avian predator breeding in a low-productivity, high-arctic site (Alert, 83°...

In long-lived animals, survival rate is a key demographic parameter affecting population dynamics. The objective of this study was to estimate the apparent survival rate of adult Long-tailed Jaegers (Stercorarius longicaudus) breeding at one of the most northerly sites on earth, northern Ellesmere Island, Canada. Because of the large temporal fluct...

Arctic arthropods are essential prey for many vertebrates, including birds, but arthropod populations and phenology are susceptible to climate change. The objective of this research was to model the relationship between seasonal changes in arthropod abundance and weather variables using data from a collaborative pan-Canadian (Southampton, Herschel,...

We re-assessed the population size and trend of 52 species and 75 taxa of shorebirds that occur in North America by reviewing published papers, soliciting unpublished data, and seeking the opinions of experts. New information resulted in changing population estimates for 35 of the 71 taxa that could be compared directly to the estimates published i...

In the 1980's, aerial surveys in South America established that the main wintering areas of Semipalmated Sandpipers (Calidris pusilla) were found on the north coast of the continent, especially in the Guianas (Suriname, French Guiana and Guyana). Although population trend analyses have consistently shown declines in numbers of Semipalmated Sandpipe...

The Semipalmated Sandpiper (Calidris pusilla) is a small, abundant shorebird that breeds primarily in sub-Arctic to mid-Arctic habitats across the Nearctic and winters principally along the northern and central coasts of South America. No subspecies have been described and little is known concerning their genetics. However, birds show a cline in bi...

Although Semipalmated Sandpipers are one of the most common shorebirds in North America, analyses of migration trends using data from the Maritimes, International and Ontario Shorebird Surveys, as well as the Quebec Checklist, collected between 1974-1998, consistently showed negative trends. An additional eleven years of data was assessed to determ...

1. Seasonal carry‐over effects may be important structuring components of avian life‐history cycles. However, little is known on physiological transitions between stages and on phenotypic compromises that may be made at such time to improve fitness. 2. We studied postmigratory body remodelling in red knots ( Calidris canutus islandica ) arriving on...

Shorebirds are thought to be declining across North America but trend analyses for migrant shore-birds at interior sites in eastern North America have not been updated since the late 1990s. Data from a volunteer-based survey at stopover sites throughout Ontario were used to assess population trends of shorebirds over the period 1974-2009. Surveyors...

Snow cover is visually estimated every two days from an elevated vantage point that allows estimation of cover over a variety of flat and sloped terrain. The monitoring starts on the date of our arrival at the study site until the end of snowmelt. Descriptive notes are kept on daily weather conditions to complement the full set of climatic variable...

Earlier studies have indicated that the diet of egg-laying female birds which eat only terrestrial arthropods has to be supplemented with calcium if they are to produce high-quality eggshells without interruption. During egg laying, females of tundra-breeding shorebird species may supplement their diet with fragments of mammalian skeletons, but as...

Approximately 100 pairs of Semipalmated Sandpipers (Calidris pusilla) nested in a 2-km2 area at La Pérouse Bay, Manitoba, each year from 1980 to 1982. The proportion of nesting yearlings in the population varied from 3 to 10% in different years. Some aspects of the breeding biology of pairs containing at least one yearling were compared with those...

Arctic predatory birds are a diverse group that includes raptors (falcons, hawks, eagles and owls) and tundra seabirds (jaegers and gulls). Many species show irruptive behaviour, which makes it difficult to assess population trends and possible range expansion or contraction. A few species such as the peregrine falcon in North America and Russia, t...

Superinfection strategy 56 Histone partitioning Beguiled by the unwild COMMENTARY Response YAKSH, EISENACH, AND SHAFER RAISE AN important issue associated with off-label drug use. As they point out, many IRB-approved studies do not take into account populations or route of administration when assessing disclosure adequacy and informed consent. Basi...

Predator Avoidance Strategy Selective pressures influencing bird migration can include availability of food, pressure from parasites and pathogens, and predation risk. The importance of the last of these is revealed by McKinnon et al. (p. 326 ; see the Perspective by Gilg and Yoccoz ), who present an experimental analysis of the benefits of long-di...

A large proportion of the Hudsonian Godwits (Limosa haemastica) spending the boreal winter along the eastern Pacific Ocean coast are known to occur in the vicinity of Chiloé Island, Chile, but the importance of the region to Whimbrels (Numenius phaeopus) is less known. Ground counts conducted in 2007 and 2008 increased published estimates, at a min...

Each May, red knots (Calidris canutus rufa) congregate in Delaware Bay during their northward migration to feed on horseshoe crab eggs (Limulus polyphemus) and refuel for breeding in the Arctic. During the 1990s, the Delaware Bay harvest of horseshoe crabs for bait increased 10-fold, leading to a more than 90% decline in the availability of their e...

Stable-isotope analyses of egg components can illuminate the contributions of endogenous and exogenous nutrients to egg formation in cases where birds move from one isotopic biome to another just before egg-laying, as in Red Knots (Calidris canutus islandica) and Ruddy Turnstones (Arenaria interpres interpres) nesting in the northeastern Canadian H...

We describe a simple and robust method for estimating trends in population size. The method may be used with Breeding Bird Survey data, aerial surveys, point counts, or any other program of repeated surveys at permanent locations. Surveys need not be made at each location during each survey period. The method differs from most existing methods in b...

Surveys of the North American race of the Red Knot (Calidris canutus rufa) on its main wintering areas on the coasts of Patagonia and Tierra del Fuego (Argentina and Chile) showed a dramatic decline in the wintering population: totals in 2003 were about 30 000 compared to 67 500 in the mid-1980s. Numbers at the principal wintering site, Bahia Lomas...

The autumn moult pattern of adult Purple Sandpipers Calidris maritima in Iceland is described. The duration of the moult was estimated to be c. 5½-7 weeks (c. 40–50 days). Females generally started moult before males and moult did not appear to overlap breeding. Information from other areas is reviewed. A mechanism by which the duration of moult is...

The Sanderlings Calidris alba that breed in NE Greenland and W Siberia mix on the wintering grounds along almost every available sandy beach between the British Isles and South Africa (Lyngs 2003, Myers et al. 1987, Underhill et al. 1999). In these areas, birds of Siberian and Greenlandic origin cannot be distinguished by morphology, appearance, or...

The population of the rufa subspecies of the Red Knot (Calidris canutus), which breeds in the central Canadian Arctic and mainly winters in Tierra del Fuego, has declined dramatically over the past 20 yr. Previously estimated at 100,000-150,000, the population now numbers 18,000-33,000 (18,000 if just the Tierra del Fuego birds are C. c. rufa, more...

Severe summer weather in Greenland and Arctic Canada in 1972 and 1974 caused very poor breeding success and elevated adult mortality in red knots Calidris canutus islandica. We show that those individual knots that are known to have survived these summers were in better than average nutritional condition shortly before departure from their late spr...

Previous studies have shown that preen wax composition in some sandpipers shifts from the usual monoesters to diesters during the breeding season, possibly to reduce the ability of mammalian predators to find nests using olfactory cues. To investigate further the relationship between incubation and wax secretion, we examined seven sandpiper species...

We analyzed data from two surveys of fall migrating shorebirds in central and eastern North America to estimate annual trends in means per survey and to determine whether trends indicate a change in population size or might have been caused by other factors. The analysis showed a broad decline in means per survey in Atlantic Canada and the northeas...

About 50 species of shorebirds breed in the Arctic, where they constitute the most characteristic component of the tundra avifauna. Here, we review the impact of weather and climate on the breeding cycle of shorebirds based on extensive studies conducted across the Arctic. Conditions for breeding shorebirds are highly variable among species, sites...

Using information from many sources, but especially data collated for the third edition of Wetlands International’s Waterbird Population Estimates, we review the status of the world’s waders in the late 1990s. There are widespread declines in most regions and biotopes caused principally by loss and degradation of wetland (and other) habitats. On di...

Using information from many sources, but especially data collated for the third edition of Wetlands International’s Waterbird Population Estimates, we review the status of the world’s waders in the late 1990s. There are widespread declines in most regions and biotopes caused principally by loss and degradation of wetland (and other) habitats. On di...

This paper reviews the nutrient storage dynamics and body changes of Red Knots Calidris canutus islandica during migration through their final spring stopover area in Iceland and after arrival on the breeding grounds in the northeastern Canadian High Arctic at Alert. In Iceland, Red Knots not only accumulate large stores of fat and protein, but als...

We examined changes in body composition of Red Knots (Calidris canutus islandica) following arrival on their High Arctic breeding grounds at Alert, Ellesmere Island, Canada. Knots arrived in late May and early June with large fat and muscle stores. In the next two weeks, fat and protein stores (pectoral muscles) declined, while increases occurred i...

We examined changes in body composition of Red Knots (Calidris canutus islandica) following arrival on their High Arctic breeding grounds at Alert, Ellesmere Island, Canada. Knots arrived in late May and early June with large fat and muscle stores. In the next two weeks, fat and protein stores (pectoral muscles) declined, while increases occurred i...

Aim We test the hypothesis that tarsus length in all shorebirds breeding in the Canadian arctic shows an evolutionary response to average metabolic stress encountered across the breeding range, such that birds nesting in metabolically stressful environments have relatively shorter legs. Longer-legged birds living in colder environments will experie...

Sauer et al. (2004) advocate the use of trend estimation models that adjust counts for differences among observers. We agree that such adjustments are sometimes needed, and we noted (Bart et al. 2003) that they may readily be carried out prior to using the estimation method we described. Including observer covariates, however, is not always necessa...

Sauer et al. (2004) advocate the use of trend estimation models that adjust counts for differences among observers. We agree that such adjustments are sometimes needed, and we noted (Bart et al. 2003) that they may readily be carried out prior to using the estimation method we described. Including observer covariates, however, is not always necessa...

Stable-isotope analyses of egg components can illuminate the contributions of endogenous and exogenous nutrients to egg formation in cases where birds move from one isotopic biome to another just before egg-laying, as in Red Knots (Calidris canutus islandica) and Ruddy Turnstones (Arenaria interpres interpres) nesting in the northeastern Canadian H...

Stable-isotope analyses of egg components can illuminate the contributions of endogenous and exogenous nutrients to egg formation in cases where birds move from one isotopic biome to another just before egg-laying, as in Red Knots (Calidris canutus islandica) and Ruddy Turnstones (Arenaria interpres interpres) nesting in the northeastern Canadian H...

Surveys of the North American race of the Red Knot (Calidris canutus rufa) on its main wintering areas on the coasts of Patagonia and Tierra del Fuego (Argentina and Chile) showed a dramatic decline in the wintering population: totals in 2003 were about 30 000 compared to 67 500 in the mid-1980s. Numbers at the principal wintering site, Bahia Lomas...

Given the allometric scaling of thermoregulatory capacity in birds, and the cold and exposed Arctic environment, it was predicted that Arctic‐breeding shorebirds should incur high costs during incubation. Using doubly labelled water (DLW), daily energy expenditure (DEE) during incubation was measured in eight shorebird species weighing between 29 a...

We describe a simple and robust method for estimating trends in population size. The method may be used with Breeding Bird Survey data, aerial surveys, point counts, or any other program of repeated surveys at permanent locations. Surveys need not be made at each location during each survey period. The method differs from most existing methods in b...

2003. Monitoring the shorebirds of North America: towards a unified approach. Wader Study Group Bull. 100: 102-104. The Program for Regional and International Shorebird Monitoring (PRISM) has recently developed a single blueprint for monitoring shorebirds in Canada and the United States in response to needs identified by recent shorebird conservati...

After a migratory flight of several thousand kilometers to their high arctic breeding grounds, red knots (Calidris canutus islandica, Scolopacidae) showed high baseline concentrations of plasma corticosterone (58 ng/mL). Such high baseline corticosterone levels may be conditional for the right behavioral and metabolic adjustments to environmental a...

The median density of shorebirds during their non-breeding season on the coast of South America was significantly greater in coastal zones with high primary productivity than in zones with moderate and low primary productivity. A world-wide review showed that sites harboring large numbers of wintering and migratory shorebirds corresponded significa...

Estimates are presented for the population sizes of 53 species of Nearctic shorebirds occurring regularly in North America, plus four species that breed occasionally. Population estimates range from a few tens to several millions. Overall, population estimates most commonly fall in the range of hundreds of thousands, particularly the low hundreds o...

Estimates are presented for the population sizes of 53 species of Nearctic shorebirds occurring regularly in North America, plus four species that breed occasionally. Shorebird population sizes were derived from data obtained by a variety of methods from breeding, migration and wintering areas, and formal assessments of accuracy of counts or estima...

Landsat-5 Thematic Mapper imagery was used to produce a 17-habitat classification of Prince Charles Island, Foxe Basin, Northwest Territories, through a combination of supervised and unsupervised approaches. Breeding shorebirds and habitats were surveyed at 35 study plots in July 1989. Habitat-specific breeding densities calculated from these obser...

It is often desirable to estimate the metabolic costs incurred by homeothermic organisms of differing morphology living in different real or hypothetical environmental conditions. To address this problem, we describe a method, based on previously published empirical allometric and heat-transfer equations, that allows a rough estimate to be made of...

We compared the distribution of shorebirds, wading birds, and seabirds in coastal habitats along the entire Pacific and Atlantic coasts of Panama in January 1993. For all birds combined, the greatest densities occurred on mudflats with mangrove swamps adjacent to ocean-upwelling zones in the Bay of Panama. Median densities on mudflats with mangrove...

To investigate whether shorebirds breeding in the High Arctic have relatively high rates of energy expenditure due to the harsh climatic conditions that prevail even in summer, we measured daily energy expenditure (DEE) and water turnover of Ruddy Turnstones (Arenaria interpres) during the incubation phase on Rowley Island in Foxe Basin, N.W.T., Ca...