scholarly journals Hybrids between Bar-headed Goose Anser indicus and Snow Goose Anser caerulescens

Ornis Svecica ◽  
2014 ◽  
Vol 24 (3–4) ◽  
pp. 147-163
Author(s):  
Jörn Lehmhus ◽  
C G Gustavsson
Keyword(s):  
Intermediate Phase ◽  
Morphological Description ◽  
Snow Goose ◽  
Snow Geese ◽  
Actual Increase ◽  
Anser Caerulescens ◽  
Anser Indicus ◽  
Number Of Individuals ◽  
Distinguishing Features ◽  
Over Time

Very few hybrids between Bar-headed Goose Anser indicus and Snow Goose Anser caerulescens have been described in the literature. In this article we give a morphological description of such hybrids, based on 35 individuals which we either observed ourselves or found pictures of on the Internet. Some hybrids were rather similar to Bar-headed Geese and others more closely resembled intermediate phase Snow Geese. General colouration, details and distinguishing features are described in the text together with photos. The yearly numbers of hybrids increased over time. This may be due to an actual increase in number of individuals, but may also reflect an increased interest in observing and reporting hybrids. Many hybrids were initially reported as something else, and there is therefore presumably under-reporting also in registers without photographs. We hope the information in this article will facilitate correct reporting.

Snow Goose (Anser caerulescens)

2020 ◽  
Author(s):  
Thomas B. Mowbray ◽  
Fred Cooke ◽  
Barbara Ganter
Keyword(s):  
Snow Goose ◽  
Anser Caerulescens

Temporal Changes in Habitat Selection and Nest Spacing in a Colony of Ross' and Lesser Snow Geese

The Auk ◽  
1983 ◽  
Vol 100 (2) ◽  
pp. 335-343 ◽  
Author(s):  
M. Robert McLandress
Keyword(s):  
Nearest Neighbor ◽  
Average Distance ◽  
Habitat Preferences ◽  
Nearest Neighbors ◽  
Nest Density ◽  
Snow Goose ◽  
Snow Geese ◽  
Lesser Snow Geese ◽  
Average Size ◽  
Island Habitats

Abstract I studied the nesting colony of Ross' Geese (Chen rossii) and Lesser Snow Geese (C. caerulescens caerulescens) at Karrak Lake in the central Arctic of Canada in the summer of 1976. Related studies indicated that this colony had grown from 18,000 birds in 1966-1968 to 54,500 birds in 1976. In 1976, geese nested on islands that were used in the late 1960's and on an island and mainland sites that were previously unoccupied. Average nest density in 1976 was three-fold greater than in the late 1960's. Consequently, the average distance to nearest neighbors of Ross' Geese in 1976 was half the average distance determined 10 yr earlier. The mean clutch size of Ross' Geese was greater in island habitats where nest densities were high than in less populated island or mainland habitats. The average size of Snow Goose clutches did not differ significantly among island habitats but was larger at island than at mainland sites. Large clutches were most likely attributable to older and/or earlier nesting females. Habitat preferences apparently differed between species. Small clutches presumably indicated that young geese nested in areas where nest densities were low. The establishment of mainland nesting at Karrak Lake probably began with young Snow Geese using peripheral areas of the colony. Young Ross' Geese nested in sparsely populated habitats on islands to a greater extent than did Snow Geese. Ross' Geese also nested on the mainland but in lower densities than Ross' Geese nesting in similar island habitats. Successful nests with the larger clutches had closer conspecific neighbors than did successful nests with smaller clutches. The species composition of nearest neighbors changed significantly with distance from Snow Goose nests but not Ross' Goose nests. Nesting success was not affected by the species of nearest neighbor, however. Because they have complementary antipredator adaptations, Ross' and Snow geese may benefit by nesting together.

First pairing in Snow Geese Anser caerulescens: at what age and at what time of year does it occur?

Ibis ◽  
2004 ◽  
Vol 147 (1) ◽  
pp. 57-66 ◽  
Author(s):  
BARBARA GANTER ◽  
W. SEAN BOYD ◽  
VASILY V. BARANYUK ◽  
FRED COOKE
Keyword(s):  
Snow Geese ◽  
Anser Caerulescens ◽  
Time Of Year

scholarly journals Influenza A virus surveillance, infection and antibody persistence in snow geese ( Anser caerulescens )

2021 ◽  
Author(s):  
Susan A. Shriner ◽  
J. Jeffrey Root ◽  
Jeremy W. Ellis ◽  
Kevin T. Bentler ◽  
Kaci K. VanDalen ◽  
...  
Keyword(s):  
Influenza A Virus ◽  
Influenza A ◽  
Antibody Persistence ◽  
Virus Surveillance ◽  
Snow Geese ◽  
Anser Caerulescens

Long-term vegetation changes in a Snow Goose nesting habitat

1996 ◽  
Vol 74 (5) ◽  
pp. 965-969 ◽  
Author(s):  
Barbara Ganter ◽  
Fred Cooke ◽  
Pierre Mineau
Keyword(s):  
Salt Marsh ◽  
Ground Cover ◽  
Habitat Destruction ◽  
Food Plants ◽  
Nesting Habitat ◽  
Snow Goose ◽  
Brood Rearing ◽  
Nest Sites ◽  
Bare Sediment ◽  
Snow Geese

Vegetation in a small section of nesting habitat in a Lesser Snow Goose colony was mapped in 1976 and again in 1993. During the 17-year period, ground cover changed dramatically from being dominated by salt-marsh graminoids and short grasses to being dominated by willows and areas of bare sediment. Lyme grass, Elymus arenarius, a plant strongly favoured by Snow Geese when selecting their nest sites, which covered 15% of the ground in 1976, had completely disappeared by 1993. Although the area had contained 79 Snow Goose nests in 1976, no nests remained in 1993. Degradation of the nesting habitat is caused by foraging activities of the geese themselves during the prenesting and nesting phase: salt-marsh graminoids and short grasses are removed by grubbing and the sediment is exposed; E. arenarius plants are removed by shoot pulling. Both clutch size and hatching success can be negatively affected by the decline in available food plants, and, presumably as a consequence, the area was abandoned by breeding geese. This habitat destruction and subsequent abandonment of nesting areas by breeding geese is a process similar to that documented for brood-rearing areas of Lesser Snow Geese.

Snow Goose (Anser caerulescens)

2000 ◽  
Author(s):  
Thomas B. Mowbray ◽  
Fred Cooke ◽  
Barbara Ganter
Keyword(s):  
Snow Goose ◽  
Anser Caerulescens

1. Ageing, a brief history

2016 ◽  
pp. 1-21
Author(s):  
Nancy A. Pachana
Keyword(s):  
Life Expectancy ◽  
Developing World ◽  
Ancient World ◽  
Human Beings ◽  
Historical Trends ◽  
Factors Influencing ◽  
Number Of Individuals ◽  
Over Time

How has the construct of ageing, and attitudes towards it, changed over time? How have human beings from various historical epochs, cultures, and perspectives viewed ageing? What impact have these views about ageing had on individuals and our broader society? ‘Ageing, a brief history’ considers these questions and shows that from the ancient world to the modern there have been conflicting views on ageing. It examines historical trends in longevity and lifespan, and factors influencing life expectancy and ageing. We are now at a point in history where the number of individuals over the age of 65 will surpass those aged 5 and under, across the developed and developing world.

scholarly journals A comparison of drone imagery and ground-based methods for estimating the extent of habitat destruction by lesser snow geese (Anser caerulescens caerulescens) in La Pérouse Bay

PLoS ONE ◽  
2019 ◽  
Vol 14 (8) ◽  
pp. e0217049 ◽  
Author(s):  
Andrew F. Barnas ◽  
Brian J. Darby ◽  
Gregory S. Vandeberg ◽  
Robert F. Rockwell ◽  
Susan N. Ellis-Felege
Keyword(s):  
Habitat Destruction ◽  
Snow Geese ◽  
Lesser Snow Geese ◽  
Anser Caerulescens Caerulescens ◽  
Anser Caerulescens

Urban pigeon populations: stability, home range, and the effect of removing individuals

1995 ◽  
Vol 73 (6) ◽  
pp. 1154-1160 ◽  
Author(s):  
Daniel Sol ◽  
Joan Carles Senar
Keyword(s):  
Home Range ◽  
Small Area ◽  
Columba Livia ◽  
Home Ranges ◽  
Population Stability ◽  
External Perturbations ◽  
Removal Experiments ◽  
Alternative Sites ◽  
Number Of Individuals ◽  
Over Time

The population stability and home ranges of rock doves (Columba livia var.) were investigated by means of surveys and monitoring of marked individuals. We also studied the population response to removal of animals. Pigeons used small home ranges, and there was very little exchange between adjacent populations despite their proximity. Individual day attendance at the home range was not bimodal, so individuals cannot be divided into regular and sporadic visitors. The number of individuals remained very stable during the 5 months of the study. Pigeons did not show any group cohesion, but individuals simply used the same small area. The consequence of the removal experiments was a rapid immigration of individuals from areas where no control was exerted, supporting the hypothesis that compensatory changes in dispersal are probably the main mechanism of pigeons' response to external perturbations. The rapid response after control and the disappearance of marked pigeons over time indicate the existence of some sampling movements of individuals between alternative sites. Redistribution of pigeons after the creation of a population vacuum would be in accordance with current models of habitat selection.

scholarly journals Are Lesser Snow Geese, Chen caerulescens caerulescens, Exceeding the Carrying Capacity of the Fraser River Delta's Brackish Marshes?

2006 ◽  
Vol 120 (2) ◽  
pp. 213 ◽  
Author(s):  
Mike W. Demarchi
Keyword(s):  
Carrying Capacity ◽  
Pacific Salmon ◽  
River Delta ◽  
Fraser River ◽  
Snow Goose ◽  
Chen Caerulescens ◽  
Snow Geese ◽  
Brackish Marshes ◽  
Fraser River Delta ◽  
Chen Caerulescens Caerulescens

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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