Joseph LaManna - Ph.D. Candidate - Wildlife Biology
Advisor - Tom Martin
Natural Science Building - Room 311
Bachelor's in Art at University of Michigan 2003
Master's of Science at Humboldt State University 2010
Effects of aspen forest restoration on songbird diversity, habitat selection, and reproductive strategies and success
Understanding features that enhance bird diversity and determine reproductive strategies and success is of great interest to science and conservation, especially in Aspen because these forests are declining across western North America. Aspen forests are biodiversity hotspots in North America, and declining area of aspen may be associated with population declines of a variety of organisms dependent on this community type, including many species of birds. Conifer trees are being removed from some aspen stands as one management treatment that can increase aspen survival and recruitment, and similar treatments are being planned and executed across western North America. However, the effects of such forest treatments on wildlife populations, such as breeding birds, are unknown. Conifer removal greatly alters vegetation structure, which may strongly affect bird populations within the treated aspen stands. Therefore, I am interested in understanding how bird communities utilize aspen forests before and after treatments to improve management decisions and to test hypotheses regarding habitat selection and reproductive strategies. More specifically, we want to know how changes in predator and plant community assemblages influence songbird diversity, habitat selection, and reproductive strategies and success.
Progress and Status:
The third season of fieldwork was completed August 2011. Bird diversity, predator abundance, various measurements of reproductive success, and vegetation structure were surveyed during the 2009, 2010, and 2011 songbird breeding seasons. Bird diversity was measured using intensive point counts in all study plots for all seasons, and separate point count plots were added in pure conifer stands adjacent to our aspen study plots to measure the difference in diversity and density among the two vegetation types. A total of 38 nesting songbird and woodpecker species were surveyed across all study plots. Predators were surveyed during point counts and also throughout the season during daily nest searches. Red Squirrels, chipmunks, Gray Jays, and Common Ravens are common nest predators. Initial results show that bird diversity and squirrel abundance increase with the amount of conifer trees present in and around aspen stands, as well as with aspen stand size. However, whereas 37 species were detected within aspen and aspen-conifer mix, only 20 species were detected in pure conifer. A total of 1,230 nests were found and monitored during the three field seasons. Reproductive success data will be used in conjunction with vegetation surveys and the conifer removal treatment to examine the bird community and reproductive response to changing habitat conditions. Systematic vegetation survey points in each aspen stand will be used to answer questions about habitat preferences for nest placement, availability of nest sites, and overall aspen stand structure. Data analyses and proposal writing are underway and a complete dissertation proposal will be completed and defended during the spring 2012 semester.