Implications of maple sugarbush stand structure and composition for neotropical migrant forest bird populations in northern Vermont

Hagenbuch, Steven
Peter Palmiotto, PhD
Department of Environmental Studies
The population declines of numerous species of neotropical migrant forest birds over the past 40 years has lead to many studies that have investigated how forest management practices may impact breeding habitat. The majority of these studies have looked at bird response to vegetative conditions resulting from silvicultural treatments used for timer management; few have examined the implications of treatments used in management for non-timber forest products, such as maple syrup. This master's thesis examined neotropical migrant forest bird community composition of managed maple sugarbushes, during the breeding season and at the stand level, in northern Vermont. Across ten sugarbushes (30 sample points) stand structure and species composition did not differ significantly among sample points with high, medium, or low percent Acer Spp. Basal area categories. Correspondingly, there was no significant difference in bird species richness or abundance among sample points. A negative relationship did exist between both bird species richness and abundance and Acer Spp. Basal area, indicating that maple monocultures may provide habitat for fewer bird species and individual when compared to more diverse forest stands. Fifty-five percent of the individuals and 27% of the species were categorized as neotropical migrants of the closed-canopy deciduous assemblage. Neotropical migrants of the intermediate-canopy, closed-canopy mixed, and open-canopy assemblages were also found but in lower abundances respectively. Of the 37 total species observed, 13 (35%) are priority bird species for Bird Conservations Region (BCR) 14. Overall forest stands that are managed primarily for the production of maple syrup may have positive implications for the conservation of neotropical migrant forest birds of the closed-canopy deciduous assemblage, including a number of regional priority species.