Are Lesser Snow Geese, <em>Chen caerulescens caerulescens</em>, Exceeding the Carrying Capacity of the Fraser River Delta's Brackish Marshes?

Brackish marshes of the Fraser River delta provide important habitats for such high-profile animals as White Sturgeon (Acipenser transmontanus), Pacific Eulachon (Thaleichthys pacificus), Pacific salmon (Oncorhynchus spp.), Western Sandpiper (Calidris mauri), and Lesser Snow Goose (Chen caerulescens caerulescens), the latter comprising the “Fraser-Skagit” segment of the Wrangel Island (Russia) population. This study assessed whether the current numbers of Snow Geese are exceeding the carrying capacity of brackish marshes in the Fraser River delta. Simulation modelling predicts that those marshes are presently capable of supporting ~17,500 Snow Geese—a value that is greatly exceeded by the numbers of geese that have over-wintered there in recent years (~80,000 in 2004-2005). The Pacific Flyway Council’s target 3-y average population and segment sizes of 120,000 and 50,000 - 70,000, respectively, were set without considering the carrying capacity of natural wintering habitats, the potential impacts of too many geese on upland agriculture, or implications for hazards to civilian aircraft at Vancouver International Airport. The modelled results of the present study suggest that the Fraser River delta can sustain the current numbers of Snow Geese that stage or winter there only if those birds also forage in agricultural and refuge fields—a relatively recent phenomenon that likely bolstered the Snow Goose population. Over-use by Snow Geese can degrade the productivity and habitat quality of marshes. There is documented evidence that some key plant species (e.g., Scirpus americanus) of the brackish marshes of the Fraser River delta are well below their biomass potential (~15%), primarily because of grubbing by Snow Geese. Other species that depend on this brackish environment as well as human interests in the Fraser River delta may be adversely affected by an overabundance of Snow Geese. The future effectiveness of hunting as a primary means of population regulation is questioned.

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Hybridization and Population Subdivision Within and Between Ross's Geese and Lesser Snow Geese: A Molecular Perspective

The Condor ◽

10.1093/condor/104.2.432 ◽

2002 ◽

Vol 104 (2) ◽

pp. 432-436 ◽

Cited By ~ 1

Author(s):

Jason D. Weckstein ◽

Alan D. Afton ◽

Robert M. Zink ◽

Ray T. Alisauskas

Keyword(s):

Control Region ◽

Mtdna Control Region ◽

Data Set ◽

Snow Goose ◽

Chen Caerulescens ◽

Snow Geese ◽

Lesser Snow Geese ◽

Lesser Snow Goose ◽

Chen Caerulescens Caerulescens ◽

Ross's Geese

AbstractWe reanalyzed Quinn's (1992) mtDNA control region data set including new sequences from nine Lesser Snow Geese (Chen caerulescens caerulescens) and 10 Ross's Geese (Chen rossi) and found the same divergent lineages that Quinn (1992) attributed to vicariant separation of Lesser Snow Goose populations during the Pleistocene. However, peculiar patterns of mtDNA control region sequence variation, including a multimodal mismatch distribution of mtDNA sequences with two levels of population structuring and the sharing of two divergent haplotype lineages, are consistent with two hybridization episodes in Chen geese. Comparisons of mtDNA variation with historical and allozyme data sets compiled by Cooke et al. (1988) are consistent with the hypothesis that sharing of two mtDNA haplotype lineages between Ross's Goose and Lesser Snow Goose resulted from hybridization (Avise et al. 1992). Furthermore, population structure found within one haplotype cluster is consistent with Cooke et al.‘s (1988) hypothesis of past allopatry between blue and white Lesser Snow Geese.Hibridización y Subdivisión dentro y entre Poblaciones de Chen rossi y Chen caerulescens caerulescens: Una Perspectiva MolecularResumen. Reanalizamos los datos de la región de control del ADN mitocondrial (ADNmt) de Quinn (1992), junto con nuevas secuencias de nueve individuos de la especie Chen caerulescens caerulescens y 10 de Chen rossi. Encontramos los mismos linajes divergentes que Quinn (1992) atribuyó a la separación vicariante de las poblaciones de C. c. caerulescens durante el Pleistoceno. Sin embargo, encontramos que las dos especies comparten dos linajes de haplotipos divergentes, y la distribución de “mismatch” en secuencias del ADNmt mostró multimodalidad con dos niveles de estructuración de la población. Estos patrones peculiares están de acuerdo con la hipótesis de que hubo dos episodios de hibridización en gansos del género Chen. Los datos históricos y de aloenzimas compilados por Cooke et al. (1988) también apoyan esta hipótesis (Avise et al. 1992). Además, la estructura de la población dentro de un grupo de haplotipos es consistente con la hipótesis de Cooke et al. (1988) acerca de la pasada alopatría entre los morfos azul y blanco de C. c. caerulescens.

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Lesser Snow Geese, Chen caerulescens caerulescens, and Ross's Geese, Chen rossii, of Jenny Lind Island, Nunavut

The Canadian Field-Naturalist ◽

10.22621/cfn.v122i1.540 ◽

2008 ◽

Vol 122 (1) ◽

pp. 34

Author(s):

Richard H. Kerbes ◽

Katherine M. Meeres ◽

James E. Hines ◽

David G. Kay

Keyword(s):

Habitat Degradation ◽

Population Decline ◽

Snow Goose ◽

Chen Caerulescens ◽

Snow Geese ◽

Lesser Snow Geese ◽

Limited Food ◽

Chen Caerulescens Caerulescens ◽

Chen Rossii ◽

Ross's Geese

We surveyed the Lesser Snow (Chen caerulescens caerulescens) and Ross’s geese (Chen rossii) of Jenny Lind Island, Nunavut, using aerial photography in June 1988, 1998, and 2006, and a visual helicopter transect survey in July 1990. The estimated number of nesting geese was 39 154 ± SE 2238 in 1988, 19 253 ± 2323 in 1998, and 21 572 ± 1898 in 2006. In 1988 an estimated 2.7% of the nesting geese were Ross’s. The July 1990 population of adult-plumaged birds was 25 020 ± 3114. The estimated percentage blue morph among Snow and Ross’s geese was 19.0% in 1988, 25.1% in 1989, 23.0% in 1990 and 21.1% in 2006. Estimated pre-fledged Snow Goose productivity was 47% young in 1989 and 46% in 1990. Combined numbers of Snow and Ross’s geese on Jenny Lind Island grew over 250 fold, from 210 adults in 1962-1966 to 54 100 adults in 1985. Numbers subsequently declined, to 42 200 in 1988, 25 000 in 1990, 20 300 in 1998, and 26 400 in 2006. Population decline between 1985 and 1990 was consistent with anecdotal reports by others that die-offs of Snow Geese occurred in 1984, 1985 and 1989, and with our August 1989 fieldwork which found evidence of habitat degradation and malnourishment of young geese. In spite of limited food resources on Jenny Lind Island, the colony continued to exist in 2006 at near its 1990 and 1998 levels. Further studies there could provide insights for management of the overabundant mid-continent Snow Goose population and its arctic habitats.

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Rapid Growth of a Nesting Colony of Lesser Snow Geese (Chen caerulescens caerulescens) on the Ikpikpuk River Delta, North Slope, Alaska, USA

Waterbirds ◽

10.1675/063.040.0103 ◽

2017 ◽

Vol 40 (1) ◽

pp. 11-23 ◽

Cited By ~ 4

Author(s):

Robert M. Burgess ◽

Robert J. Ritchie ◽

Brian T. Person ◽

Robert S. Suydam ◽

John E. Shook ◽

...

Keyword(s):

Rapid Growth ◽

River Delta ◽

North Slope ◽

Chen Caerulescens ◽

Snow Geese ◽

Lesser Snow Geese ◽

Chen Caerulescens Caerulescens

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Snow goose primaries as indicators of age and sex

Canadian Journal of Zoology ◽

10.1139/z74-105 ◽

1974 ◽

Vol 52 (6) ◽

pp. 791-794

Author(s):

John P. Kelsall

Keyword(s):

River Delta ◽

Or Management ◽

Snow Goose ◽

Chen Caerulescens ◽

Snow Geese ◽

Lesser Snow Geese ◽

Age And Sex ◽

Mackenzie River

Significant differences were found, by age and sex, in mean vane length and mean weight of the fourth primary flight feathers of lesser snow geese (Chen caerulescens) collected in the Mackenzie River delta in September, 1971. Such differences might have research or management applications.

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The prevalence and pathogenicity of gizzard nematodes of the genera Amidostomum and Epomidiostomum (Trichostrongylidae) in the lesser snow goose (Chen caerulescens caerulescens)

Canadian Journal of Zoology ◽

10.1139/z84-269 ◽

1984 ◽

Vol 62 (9) ◽

pp. 1849-1852 ◽

Cited By ~ 10

Author(s):

Benjamin N. Tuggle ◽

John L. Crites

Keyword(s):

Snow Goose ◽

Mean Intensity ◽

Chen Caerulescens ◽

Progressive Degeneration ◽

Snow Geese ◽

Lesser Snow Geese ◽

Lesser Snow Goose ◽

Mucosal Lining ◽

Chen Caerulescens Caerulescens ◽

Amidostomum Anseris

Three species of trichostrongylid nematodes were removed from the gizzards of 25 lesser snow geese, Chen caerulescens caerulescens, collected at Winisk, Ont. A 100% prevalence of infection was noted in the sampled population with each bird harboring two or more of the following species: Epomidiostomum crami (prevalence, 92%; mean intensity, 18.7 ± 13.3), Amidostomum anseris (prevalence, 84%; mean intensity, 9.6 ± 9.8), and Amidostomum spatulatum (prevalence, 84%; mean intensity, 11.2 ± 9.8). When large burdens (>30) of both A. anseris and A. spatulatum were present in the mucosal lining of the gizzard, progressive degeneration of the epithilium and koilin linings was noted in 16% of the geese examined. Severe necrotic granulomata observed in the gizzard muscle of 36% of the geese were associated with sizable burdens (>25) of E. crami which were found burrowed in the gizzard muscle.

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Seismic site response in the greater Vancouver, British Columbia, area: spectral ratios from moderate earthquakes

Canadian Geotechnical Journal ◽

10.1139/t98-096 ◽

1999 ◽

Vol 36 (2) ◽

pp. 195-209 ◽

Cited By ~ 11

Author(s):

John F Cassidy ◽

Garry C Rogers

Keyword(s):

Site Response ◽

Strong Motion ◽

River Delta ◽

Data Sets ◽

Fraser River ◽

Spectral Ratios ◽

Data Set ◽

Seismic Site Response ◽

Fraser River Delta ◽

S Period

Three-component, digital recordings of two recent moderate earthquakes provide valuable new insight into the response to seismic shaking in the greater Vancouver area, particularly on the Fraser River delta. The 1996 M = 5.1 Duvall, Washington, earthquake (180 km southeast of Vancouver) triggered strong-motion seismographs at seven sites and the 1997 M = 4.3 Georgia Strait earthquake (37 km west of Vancouver) triggered instruments at 13 sites in the greater Vancouver area. The latter data set is especially important because it contains the first three-component recordings made on bedrock in greater Vancouver. Both data sets represent weak ground motion, with peak horizontal accelerations of 0.5-1.5% gravity (g) for the Duvall earthquake, and 0.2-2.4% g for the Georgia Strait earthquake. Using the method of spectral ratios, we estimate the site response for each of the strong-motion instrument soil sites. On the Fraser River delta amplification is observed over a relatively narrow frequency range of 1.5-4 Hz (0.25-0.67 s period), with peak amplification of 4-10 (relative to competent bedrock) for the thick soil delta centre sites, and about 7-11 for the delta edge sites. Relative to firm soil, the peak amplification ranges from 2 to 5 for the thick soil delta centre sites, and 2 to 6 for the delta edge sites. At higher frequencies, little or no amplification, and in many cases slight attenuation, is observed.Key words: seismic site response, Fraser delta, earthquakes.

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