Conversion of tundra to exposed peat habitat by snow geese (Chen caerulescens caerulescens) and Ross’s geese (C. rossii) in the central Canadian Arctic

Polar Biology ◽  
2016 ◽  
Vol 40 (3) ◽  
pp. 563-576 ◽  
Author(s):  
John Conkin ◽  
Ray T. Alisauskas
The Condor ◽  
2002 ◽  
Vol 104 (2) ◽  
pp. 432-436 ◽  
Author(s):  
Jason D. Weckstein ◽  
Alan D. Afton ◽  
Robert M. Zink ◽  
Ray T. Alisauskas

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.


2006 ◽  
Vol 176 (5) ◽  
pp. 453-462 ◽  
Author(s):  
Jón Einar Jónsson ◽  
Alan D. Afton ◽  
Dominique G. Homberger ◽  
William G. Henk ◽  
Ray T. Alisauskas

2008 ◽  
Vol 122 (1) ◽  
pp. 34
Author(s):  
Richard H. Kerbes ◽  
Katherine M. Meeres ◽  
James E. Hines ◽  
David G. Kay

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.


The Auk ◽  
2006 ◽  
Vol 123 (2) ◽  
pp. 405-418 ◽  
Author(s):  
Jón Einar Jónsson ◽  
Alan D. Afton ◽  
Ray T. Alisauskas ◽  
Cynthia K. Bluhm ◽  
Mohamed E. El Halawani

AbstractWe investigated effects of ecological and physiological factors on brood patch area and prolactin levels in free-ranging Lesser Snow Geese (Chen caerulescens caerulescens; hereafter “Snow Geese”) and Ross's Geese (C. rossii). On the basis of the body-size hypothesis, we predicted that the relationships between prolactin levels, brood patch area, and body condition would be stronger in Ross's Geese than in the larger Snow Geese. We found that brood patch area was positively related to clutch volume and inversely related to prolactin levels in Ross's Geese, but not in Snow Geese. Nest size, nest habitat, and first egg date did not affect brood patch area in either species. Prolactin levels increased as incubation progressed in female Snow Geese, but this relationship was not significant in Ross's Geese. Prolactin levels and body condition (as indexed by size-adjusted body mass) were inversely related in Ross's Geese, but not in Snow Geese. Our findings are consistent with the prediction that relationships between prolactin levels, brood patch area, and body condition are relatively stronger in Ross's Geese, because they mobilize endogenous reserves at faster rates than Snow Geese.Factores Ecológicos y Fisiológicos que Afectan el Área del Parche de Incubación y los Niveles de Prolactina en Gansos Nidificantes del Ártico


10.2307/4924 ◽  
1988 ◽  
Vol 57 (2) ◽  
pp. 553 ◽  
Author(s):  
Laurene Ratcliffe ◽  
R. F. Rockwell ◽  
F. Cooke

2006 ◽  
Vol 120 (2) ◽  
pp. 213 ◽  
Author(s):  
Mike W. Demarchi

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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