Browsing by Subject "Minneosta"

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    Small Mammal Diversity in Variable Vegetation and Land Management Types
    (2010-12-01) Goreham, Seth
    Species richness and diversity of many small mammals vary depending on the vegetation type and density. In June 2009, we trapped small mammals in six different types of forest and six different locations in the prairie using Sherman, Russian, and Longworth traps. Grids that had been burned in the past tended to yield a higher total number of animals caught in traps; however, species richness was not as heavily influenced by burning. Unburned red pine forest showed the highest number of species collected. We found that species richness and the overall number of species is greatly influenced by the forest type, vegetation, moisture and land management methods used in these areas. Over the history of northern Minnesota forests and prairies, fires have played a major role in maintaining and regulating natural ecosystems (Frissell 1973). Fires in the past were started by lightening strikes and would exterminate themselves. This pattern of burning the understory came to dictate the diversity of plants and animals residing in this area (Frissell 1973). By burning away the young growth, white and red pines prevailed and established the dominant vegetative type for this region. Since present fire prevention has halted most of the wildfires that occur, prescribed burns have been implemented to try and replicate historic ecology based on the prevalence of wildfires. Based on this, areas that have undergone prescribe would be expected to contain species that are adapted to living in and recolonizing burned habitats. These species should be a representative of historic diversity in the region. The same can be said for the prairie region which historically experienced similar events. For this project, we are looking into several different grids on burned and unburned habitats to determine if there is a significant difference in the species diversity.
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    Territoriality of Northern Crayfish (Orconectes virilis) in Itasca State Park
    (2011-02-01) McCullough, Jenna; Kindler, Mae
    In general, it has been shown that large crayfish will tend to win aggressive, territorial conflicts against small conspecific opponents (Figler et al. 1999). Size is not the only factor that can affect the outcomes of territorial interactions however. The “prior residency effect” suggests that the initial resident in a given area will have a dominance advantage over intruders (Peeke et al. 1995). This investigation explores the effects of territorial residency and size on the outcomes of territorial conflicts. We hypothesized that interactions between crayfish with large percent size asymmetries would result in higher eviction rates of the smaller resident by the larger intruder than interactions between crayfish with small size asymmetries. We tested this hypothesis by observing the outcomes of territorial conflicts between crayfish of various sizes in controlled environments. We found that average percent size asymmetries of interactions resulting in evictions of residents were statistically greater than the average percent size asymmetries of interactions resulting in non-evictions of residents by larger intruders. We determined that the level of percent size asymmetry with the highest likelihood of eviction ranged from 67 to 109%. These data support the proposed trend where the likelihood of successful evictions of smaller prior residents by larger intruders increases as the size differences between the two individuals increases.