Grazing, Trampling, & Fecal Deposition

“The geese make up a really important force on the landscape.” – Kathy Kelsey

Grazing, Trampling, & Fecal Deposition

Pacific black brant geese create grazing lawns as they feed on Hoppner’s sedge (Carex subspathacea) in the Yukon-Kuskokwim Delta, Alaska. Plants that have been chomped short work to grow. Plants’ new photosynthetic tissue is high in nitrogen, proving extremely nutritious for geese and growing goslings.

The birds absorb some but not all of the nitrogen in plants they digest. They defecate (poop out) the rest. Ryan Choi reported “A lot of that nitrogen still passes through, and through that process a lot of cellulose is broken down into a more digestible form. Once it passes through and is deposited on the soil [it] likely becomes a much more accessible form of nitrogen and material for plants to utilize and take up in the roots and turn into new plant material.”

Ryan Choi: “By continually grazing on the subspath lawns they are able to increase both the abundance and the quality of forage necessary for them to thrive out here. And it’s this feedback—this positive feedback by geese grazing on vegetation, the vegetation responding, becoming tastier and more nutritious for the birds that created this really dynamic feedback system. One of the things that we are looking at is what happens if the timing of that grazing and the response of the vegetation to warming is discoupled or is altered in some way, and how does that change the abundance and quality of forage for the birds.”

Grazing trampling fecal deposition geese vegetation carbon nitrogen ratio

Thomas DeMasters, Ryan Choi, Kathy Kelsey

Grazing trampling fecal deposition geese vegetation carbon nitrogen ratio
Simulated geese feet help researchers perform an experiment in the Y-K Delta / Frontier Scientists

Grazing, Trampling, & Fecal Deposition video | Frontier Scientists YouTube

(Grazing trampling fecal deposition geese vegetation carbon nitrogen ratio)

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Project Summary

Climate Change and Brant Geese in the Y-K Delta

Climate Change and Brant Geese in the Y-K Delta

Climate Change and Brant Geese in the Y-K Delta Warming temperatures create a mismatch in the timing of plant growth and the arrival of migratory birds. Researchers explore the implications of this mismatch in Alaska's Yukon Delta National... Read More >