Date Approved


Graduate Degree Type


Degree Name

Biology (M.S.)

Degree Program


First Advisor

Dr. Paul Keenlance

Second Advisor

Dr. Joseph Jacquot

Third Advisor

Eric Clark


Female American marten (Martes americana) produce litters of 1-5 kits between late March and early May. Kits remain with their mother for the duration of their first summer in a series of den structures. We located these den structures using radio-telemetry and placed remotetriggered cameras at the entrances to capture information on litter size, female activity patterns, and den visits by males and potential predators. From the summer of 2012 to the summer of 2014 we tracked 13 individual female marten (8 in the Lower Peninsula, 5 in the Upper Peninsula) with 17 litters to 75 unique den sites (60 in the Lower Peninsula, 15 in the Upper Peninsula). We found 58 dens in live trees, 11 in snags, 5 in hollow logs, and 1 subterranean. Of the tracked marten we were able to collect camera activity data for 14 litters produced by 11 female marten at 59 dens. We found that den trees in both the Lower and Upper Peninsulas were significantly larger than the trees surrounding them in a 30-m diameter circular plot. In the Lower Peninsula we found that den trees were in areas with a higher basal area than was found in randomly selected areas. Average litter size was 2.5 ± 0.25 kits (range 1-4, n=14). We recorded 858 activity periods, 68 occurrences of the female delivering prey to kits, 72 instances of males visiting dens, and two instances of potential predators at dens. We found no relationship between litter size and den relocation patterns, documented den reuse four times, and found a range of distances between successive dens (5–3382m, median 407m, n=60 relocations). These findings indicate that den-switching behavior is very complex and is likely due to a combination of outgrowing den space, pest buildup at the den, predator avoidance, and relocation to areas of higher prey density. The retention of large structures that are hollow or contain cavities is essential to maintaining suitable denning habitat for marten.

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