Loading...
Relationships Between Invasive Plant Densities And Breeding Bobolink Abundance And Post-Fledging Bobolink Survival Is Positively Correlated With Mass And Fledge Date
Tolan, Kevin S.
Tolan, Kevin S.
Citations
Altmetric:
License
License
DOI
Abstract
Grasslands are among the most heavily degraded biomes, and the ground-nesting birds that depend on them for breeding are the most rapidly declining guild of bird species in North America. In Vermont, forest clearing during the 19th century and expansion of modern dairy agriculture have created a mosaic of hayfields that now support a suite of these imperiled species. Although avoiding management during the breeding season has been shown to greatly increase the reproductive productivity of ground-nesting birds, doing so also permits forbs and invasive species to rapidly inundate fields such that they no longer provide suitable nesting habitat for grassland birds. I surveyed adult Bobolinks (Dolichonyx oryzivorus) and vegetation within 13 plots in Vermont hayfields to assess how invasive plants impact the breeding abundance of Bobolink at the early stages of territory establishment, and later during peak nesting season. Reed canary grass (Phalaris arundinacea), which rapidly forms tall monocultures in wet portions of fields, but is not favored for nesting, was statistically, positively correlated with male Bobolink abundance during territory establishment, however its biological significance is uncertain.
Additionally, 46 Bobolink were tagged with VHF transmitters as nestlings and subsequently radio-tracked during the post-fledging period – the period of highest mortality in many songbird species. I tracked their daily post-fledging movements, habitat use, and survivorship in 2023 and 2024. Tracked birds remained on study fields for an average of 46.2 ± 8.5 [SD] days, using areas that were disproportionately open and far from field edges. Daily survivorship was positively correlated with mass and fledge date, and the cumulative 21-day probability of survival was ~50% for a bird of average mass and fledge date. These findings highlight the importance of incorporating post-fledging ecology into grassland habitat management as part of long-term land management.
Description
Date
2026
Journal Title
Journal ISSN
Volume Title
Publisher
Collections
Files
Loading...
Tolan_uvm_0243N_11968.pdf
Adobe PDF, 4.54 MB