The North American beaver, or Castor canadensis, is a species that is known for drastically altering ecosystems; however, the impacts of their dam building behavior are unclear as experts cannot determine whether the net positives outweigh the negatives, or vice versa, which makes managing beaver populations quite difficult. This study aims to determine how beaver dams impact benthic macroinvertebrate abundance and richness, while also investigating the opinions trained professionals in the biology field have on beavers to see if their specialization influences their perception of the rodent species. To test the hypothesis that dammed waterways have a higher abundance and richness of pollution sensitive macroinvertebrates, samples of these creatures were collected using a kick-net in six waterways: three with active beaver dams and three with no beaver activity. The data was analyzed using the Mann-U Whitney test. To test the hypothesis that job specialization does not have any connection to expert’s perceptions of beavers, a survey was sent using Qualtrics software to gain a better understanding from five members of the Kalispell Fish, Wildlife, and Parks organization on their opinions of beavers. The opinions were analyzed by splitting up the members into two groups (terrestrial and aquatic focused professions) and using charts from Qualtrics to compare/contrast. The results of the aquatic invertebrate analysis showed no significant difference in abundance and richness of macroinvertebrates between the two treatment groups. It did happen to show more pollution tolerant organisms found in dammed waterways whereas in damless waterways, pollution sensitive organisms appeared much more frequently. The survey showed that there is most likely a connection between job specialty and perceptions of beavers, although it is uncertain. These results suggest that dams have a more negative impact on the surrounding ecosystem since the bioindicators found in dammed streams show up more often in streams with low water quality. The surveys for beaver perception suggest that management for this species is difficult since although experts with similar focuses agree on most opinions, groups that specialize on different aspects of the ecosystem do not share common beliefs. The suggested negative effect beavers have on stream health from this study is merely one amongst several effects’ dams have on ecosystems, and until opinions of experts can be agreed upon, there is no telling whether or not beavers are more beneficial or harmful for the surrounding area and what should be done for the management of the species. The management of North American beavers could be improved if we could find ways to generate greater consensus in perception among specialists.


Moreno, Carlo


Environmental Studies


Physical Sciences and Mathematics

Publication Date


Degree Granted

Bachelor of Arts

Document Type

Senior Independent Study Thesis



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