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> De-vegetation of Snow Goose Habitat, Did we see any?
post Jul 28 2005, 10:16 PM
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De-vegetation of Snow Goose Habitat
Did we see any?

So, what did we discover on the Ikpikpuk River delta? Data analysis will not be completed until early winter, but did we see any habitat degradation while we were out there? Are the snow geese eating themselves out of house and home like they are in parts of Canada? (see the entry on Snow Geese) We did see areas that had been grubbed, grazed, and turned to mud. The approximate percentages of those areas will come out of Brianís research. The extent of degradation is very small as compared to the Hudson Bay area in Canada, but as the lesser snow goose population increases on the North Slope, the habitat will continue to be monitored.

One factor that affects the habitat use by snow geese on the delta is spring flooding. When the geese arrive in May the only ground available for nesting is the high, dry ground (what Brian calls dry graminoid habitat) and those areas show a high degree of habitat degradation. The other factor that Brian mentioned is that in May when the snow geese arrive the vegetation has not greened up yet. The only available food is in underground shoots and roots. So, most grubbing of these plant structures occurs in the early season near the nesting grounds.

As the snow melts, the lower ground is temporarily flooded until Smith Bay opens up to drain the delta. Brian thinks that in the years which flooding occurs, those low-lying habitat types are essentially protected from grubbing by snow geese. Grubbing is first noticed as plugs of moss are discarded on the ground. It looks like a lawn aerator has been run over the tundra. The snow geese must not prefer to eat the moss as they grub up the vegetation.

There are plugs of moss left on top of the ground near these grubbed holes.
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Other areas were seen with sparse graminoid vegetation (grass or sedge) and no moss, but mud with holes that the grubbing gooseís beak left behind. Sometimes grasses or sedges would be growing out of these holes, looking like hair plugs on a dollís head.

Holes left in ground from the snow goose beaks.
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Some intermediately grubbed areas had some vegetation left, but the willows were dying. The willows had been denuded of their leaves and did not look like they would recover.

Intermediate grubbed area
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Grubbed area with dead willows
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Eventually, the nesting grounds are surrounded by muddy, devegetated areas.

Muddy area
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As the flooding subsides, and the eggs hatch, the snow geese move off to newly exposed areas with good foraging habitat. The tundra has greened up and the sedge and grass shoots are available for grazing. Grazing is the process of clipping the vegetation off aboveground. This type of foraging tends to leave large areas of short grass, like Puccinella phryganoides, or sedge, like Carex subspathacea. These grazing lawns are able to maintain plant growth because there are some leaves left above ground to photosynthesize.

Grazing lawns
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It will be interesting to see what Brian finds from his analysis and aerial photo transects of the delta.

More Grubbed areas
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