Presentation Title

P-28 Seasonal Variation in Diet of Thirteen-lined Ground Squirrels in Southwestern Michigan

Presenter Status

PhD student, Plant Sciences

Second Presenter Status

Professor, Biology

Preferred Session

Poster Session

Start Date

25-10-2019 2:00 PM

Presentation Abstract

Thirteen-lined ground squirrels (Ictidomys tridecemlineatus) are omnivorous rodents known to eat a variety of plant and animal matter. Prior work on a population of these ground squirrels in southwestern Michigan hypothesized a sharp shift in diet in late summer, from a diet rich in C3 plants to one rich in C4 plants. This hypothesis was based on an abrupt shift in the carbon isotope composition of teeth from squirrels collected in the region but has not been directly confirmed. Here, we present more direct data on diet, based on isotopic evidence and microhistological analysis of fecal samples collected from squirrels. These data confirm that squirrels in a local colony shifted diets during the study season. From June to mid-July, squirrels ate abundant arthropods and C3 vegetation. In August and later, squirrels ate few arthropods and abundant C4 vegetation. The latter observation supports the hypothesis originally developed to account for a carbon isotope shift in teeth.

Acknowledgments

Andrews University supported the senior author with a Grants-in-aid-of-research grant and the junior author with a Faculty Research Grant; both are gratefully acknowledged.

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Oct 25th, 2:00 PM

P-28 Seasonal Variation in Diet of Thirteen-lined Ground Squirrels in Southwestern Michigan

Thirteen-lined ground squirrels (Ictidomys tridecemlineatus) are omnivorous rodents known to eat a variety of plant and animal matter. Prior work on a population of these ground squirrels in southwestern Michigan hypothesized a sharp shift in diet in late summer, from a diet rich in C3 plants to one rich in C4 plants. This hypothesis was based on an abrupt shift in the carbon isotope composition of teeth from squirrels collected in the region but has not been directly confirmed. Here, we present more direct data on diet, based on isotopic evidence and microhistological analysis of fecal samples collected from squirrels. These data confirm that squirrels in a local colony shifted diets during the study season. From June to mid-July, squirrels ate abundant arthropods and C3 vegetation. In August and later, squirrels ate few arthropods and abundant C4 vegetation. The latter observation supports the hypothesis originally developed to account for a carbon isotope shift in teeth.