What are Snow Geese?
What are Snow Geese?
Jun 9 2005, 05:11 PM
Group: TREC Team
Joined: 27-April 05
Member No.: 7
I’ve been doing a little research on Snow Geese so that I can be ready for our field work. I thought I’d share a little information that I’ve learned with you. The species that I will be studying is the Lesser Snow Goose. A list of all of my resources can be found at the end.
What are Lesser Snow Geese?
The scientific name of the Lesser Snow Goose is Chen caerulescens caerulescens and they are classified in the Order Anseriformes, the Family Anatidae, and the Subfamily Anserinae. They breed in the Arctic tundra in marshy areas near the coast making the northerly migration from the lower 48 states and Mexico in the spring. They winter in marshes, wetlands and cultivated fields from coast to coast in the United States and northern Mexico. For pictures of snow geese and maps of their range go to the US Fish and Wildlife Service website http://migratorybirds.fws.gov/issues/snowgse/spdesc.html.
Lesser snow geese are medium-sized geese that come in two color phases (or morphs), white and blue. Both adult morphs have a white head and neck, black wing tips, and pink legs, feet and bill. The blue phase snow goose has a pale to dark gray body and upper wings while the white phase snow goose has a white body and upper wings. To see pictures of both color phases see the USGS Snow Goose Species Description at http://www.mbr-pwrc.usgs.gov/id/framlst/i1690id.html.
You can see more pictures and hear sounds of snow geese on the Cornell Lab of Ornithology Online Bird Guide at http://www.birds.cornell.edu/programs/AllA...Snow_Goose.html.
Snow geese generally mate for life, forming pairs while still on their wintering grounds. After their migration to the nesting grounds in the far north, females lay 2 to 6 eggs in a clutch. The eggs are incubated for 23-25 days. New hatchlings leave the nest within 24 hours and begin feeding shortly after leaving the nest. The young birds fledge, or begin flying, after 40 to 49 days. Parents stay with their young through one migration cycle, separating after returning to the Arctic nesting grounds. Snow geese travel in large flocks which can be seen across North America during the annual migrations.
Lesser Snow Geese Populations
The Western Arctic population of Lesser Snow Geese is estimated to be about 200,000 and the growth rate is considered to be stable. Geese from this population use the habitat that we will be studying on the Ikpikpuk River delta. In contrast, the Canadian Arctic mid-continent population has tripled in the past 30 years and has reached nearly 6 million birds with a growth rate of 5% per year. This increase in the mid-continent region population has led to habitat degradation in some areas of Canada, especially in the Hudson and James Bay coastal areas. (See the Hudson Bay Project site for more information http://research.amnh.org/~rfr/hbp/overview.html.) The Arctic Ecosystems in Peril Working Group has come up with a report summarizing the impacts of snow geese on the mid-continent Arctic habitat, the potential for recovery, and recommendations for management strategies. (To see report, go to http://migratorybirds.fws.gov/issues/arcgoose/tblconts.html) At this time, habitat degradation on the Ikpikpuk River delta in Alaska has not been seen. However, more snow geese seem to be moving into the area. Monitoring of the populations through banding, habitat exclosures and vegetative surveys will provide insights into habitat changes.
How do Snow Geese cause devegetation and habitat degradation?
Snow geese feed on aquatic plants, grasses, sedges, and grains. The birds tend to pull up the entire root or underground part during feeding. This type of foraging is called grubbing. As the population of birds increase in a given area to the point of overcrowding, the amount of vegetation removed increases leaving behind large, denuded mudflats. The lack of vegetation causes an increase in evaporation of water from the soil, leaving salts behind and in turn causing the soil salinity (or salt content) to increase. When soils become saltier, the types of plants that snow geese eat cannot survive. New, salt-tolerant species of plants eventually come into the mudflat and begin to grow. These plants do not make good forage or food for the snow geese so the birds must move on to new habitat. This effect is called a trophic cascade. For more information and to see a slide show illustrating this effect, go to http://research.amnh.org/~rfr/hbp/kenintro.html.
Bird Counting and Migration Tracking Activity - If you are interested in birds that migrate through your area, you might want to try to do a little birdwatching! This activity will get you started. I've listed sites to go to for tips on learning how to observe birds and tracking their migration. It can be done at home as a hobby or at school as a classroom activity.
Bird_Counting_and_Migration_Tracking_Activity.doc ( 93k ) Number of downloads: 74
Geese: Wildlife Notebook Series – Alaska Department of Fish and Game
WMAC Species Status Reports: Lesser Snow Geese (Anser caerulescens) Western Arctic Population
Ducks at a Distance – Waterfowl Identification Guide – Snow Geese
USFWS Snow Goose Species Description
Cornell Lab of Ornithology Online Bird Guide
Hudson Bay Project
USFWS Arctic Ecosystems in Peril: Report of the Arctic Goose Habitat
Lesser Snow Geese and the Trophic Cascade
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