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John
A. Litvaitis: Research Projects |
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Detailed Description of Research Projects
| Effects of contemporary land uses on wildlife populations, especially species that are hampered by habitat fragmentation |
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I continue to direct some of my research activity toward understanding how terrestrial vertebrates can persist in human-dominated landscapes. Much of this activity has used New England cottontails as a model organism. The distribution and abundance of this rabbit have declined substantially in recent decades.
My students and I have addressed a number of specific questions on the influence of landscape composition and interactions of rabbits and their predators in human-dominated landscapes.
Most recently, Dr. Adrienne Kovach and I have initiated an effort to understand how habitat fragmentation and population isolation are affecting gene flow among remnant populations of New England cottontails. |
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Reptiles also are responding to land use changes. Our recent study on black racers in southeastern New Hampshire indicated that this species is dependent on large patches of early-successional habitat. Current land-use patterns are resulting in a dramatic decline of these habitats, threatening the long-term survival of racers and other species that rely on shrublands and young forests. |
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| Influences of historic land uses on present-day wildlife populations and their habitats |
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Perhaps a less obvious influence on wildllife habitats is the role of historic land use, especially agriculture. In New England, much of the land was cleared by early European settlers and subsequently abandoned from the mid 1880s to early 1900s.
Northern New England is now the most forested region in the United States. However, much of the region is dominated by second-growth forests that lack age and structural diversity. |
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The successional wave that is passing through many of the forests of the region has had a substantial influence on wildlife. Species dependent on young forests initially became very abundant and then their populations declined rapidly. Bobcats are one example of this “rise and fall”. Efforts to understand such patterns will help place current levels of wildlife abundance into proper perspective. |
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| Understanding and limiting the effects of invasive shrubs on forest wildlife |
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Worldwide, non-native plants have invaded a variety of habitats where they are having substantial influences on native plant and animal communities. The successful invasion by alien (non-native) plants is probably a consequence of many factors that operate at several spatial scales. Results of our preliminary investigations indicate that local features (soil fertility and historic land use), as well as landscape characteristics (abundance of roads) affect the initial colonization and subsequent establishment of alien plants. |
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| Identifying factors that contribute to wildlife-vehicle collisions |
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Roads are probably the most conspicuous human-made feature that wild animals encounter. I am initiating a project to investigate what factors can be used to predict the likelihood that several species (such as turtles, bobcats, and moose) will suffer road mortalities. Our initial efforts are examining the effects of road density, traffic volume, and the rate of animal movement on the probability of vehicle collisions with these species. |
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Additional Info... |
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