An Investigation into Marmot Migration in Grand Teton National Park

Authors(s): G. Montopoli, H. Harlow and N. Visser

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Publication Date: 0000-00-00

Type: annual report

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Abstract: Objectives In 1994, and then again in 1995, while investigating melanism(black fur coloration) in the yellow-bellied marmot (Marmota flaviventris) of Grand Teton National Park, we observed that abundant winter snowfall at higher elevations suggested that marmots migrated substantial distances over snow to lower elevations where food was more available. As the snow melted and food became abundant, the marmots appeared to once again move up to higher altitudes. We therefore decided to conduct an experiment to investigate if significantly different numbers of marmots were observed at locations prior to, and after, snow melt, thus suggesting migrational movements by marmots. Three locations where migrational movements were previously observed were selected (Lower Garnet Trail, Lower Death Canyon, and North Fork of Cascade Canyon). Marmots were surveyed previous to snow melt just below snow line, and then several weeks after snow melt. Based on data presented in Table 1 below, we conducted a simple proportion z-test that resulted in a value of 5.33 (P < 0.0000), indicating that a proportionately greater number of marmots were observed previous to snow melt just below snow line (where food was available). Table 1. Frequencies of Marmots in Areas Just Previous to Snow Melt and Several Weeks After Snow Melt Lower Garnet Lower Death NF Cascade Total Trail Canyon Canyon Before Melt 16 20 33 69 After Melt 4 8 7 19 Total 20 28 40 88 To further investigate this "potential" migrational activity, and to document specific movements, we decided to capture and place intraperitoneal tracking transmitters within marmots that were located in areas just below snow line early in the summer season, 1997. We felt that this was necessary to eliminate any other possible reasons for the discrepancy in marmot numbers prior to and after snow melt. Findings and Status On June 20, 1996, the first potential area was realized low in the North Fork of Cascade Canyon, approximately 1 km above the Cascade Canyon Forks. On June 22, two marmots (L1 and L2) were captured and equipped with intraperitoneal Telonix tracking transmitters. On June 23 and 29, two other marmots (L3 and L4) were captured and equipped with transmitters. On July 21, four marmots were captured and equipped with intraperitoneal Telonix tracking transmitters in the vicinity of Solitude Lake. Two trap sites were utilized. The first three marmots (U1, U2, and U3) were captured at the first trap site, located at the Surprise Lake outlet, about 100m from the shore at the south end of the lake. The last marmot (U4) was trapped at the second trap site, located at the northeast corner. Through September, all marmots at the Solitude Lake area and in the lower canyon were located on a (minimal) weekly basis and their movements were observed. We decided a priori to consider distances in excess of 400m from the initial trap site to indicate a significant migratory movement. However, we did expect to commonly observe movements in excess of 1 kilometer. Of eight marmots that were equipped with intraperitoneal transmitters, six (L2, L4, U1, U2, U3, and U4) demonstrated significant migratory movements, one (L1) did not, and one (L3) most likely succumbed to predation before any movement could be observed. Of the six that demonstrated significant migratory movements, only one (U4) exhibited movements involving distances that we expected (1 km or more). Based on our documented observations, we feel that marmots, after emerging from hibernation, do communally congregate in snowfree areas as they become available. As the snow melts, most marmots move upward to higher elevations, but not to the extent that we originally hypothesized. Instead, they move to the first available habitat where food is available, and any other (dominant) marmots accept their presence. This movement is exhibited in both males and females, yearlings and adults, and melanistic and normal colored marmots. Although an abundance of literature has investigated the social structure of marmot colonies, where gender, social status, age, and other considerations physically define the marmot colony and any satellite borders, our results suggest that early in the season this structure is limited, if it exists at all. Marmots do congregate in snowfree areas, and as the snow melts, they move into snowfree areas where the social structure may emerge. This activity may explain how genetic traits such as melanism may originate in a single location and yet be dispersed throughout an entire range. Two of the eight marmots succumbed to predation. This fact suggests that marmots do form an important food base for many predators, including hawks and eagles, mustelids (such as the pine marten), coyotes, bears, and other mammals. Although marmot predation is not generally observed, it nevertheless is common (personal observations, and personal communications with Daniel Blumstein, University of Kansas). We acknowledge the fact that our study was limited in size. Eight marmots do not constitute a valid sample for inference about the marmot population in general. However, the fact that six of eight marmots exhibited substantial movements does suggest that marmots do travel over snow as a survival strategy. Certainly, future studies should beconducted to verify this claim. Finally, in May, 1997, hibernation sites will be located, and movements from these locations will be monitored after the marmots emerge from hibernation, until the transmitter cease to function. These additional movements early in the year should further validate our findings from 1996.

Keywords: Grand Teton National Park, habitat, migration, food , forage, radio collar, predation, population, mortality, behavior, animal, mammal, marmot, yellow-bellied marmot, Marmota flaviventris, bird, ornithology, Aves, raptor, hawk, eagle, Buteo, Mustelidae, pine marten, Martes martes, mammal, coyote, bear, Canidae, Ursidae, Canis latrans