Highland Endemic Diets, Disturbance, and Climate Change
Volcano Juncos (Junco vulcani) are a species of Neotropical highland endemic sparrow that occupy small, disjunct patches of montane grassland called Isthmian sub-páramo. Though locally abundant, little is known about their ecology or behavior, and they are likely susceptible, like other montane endemics, to climate-related upslope vegetation creep and eventual extirpation. My dissertation research uses stable isotope analysis, a forensic approach applied to non-lethally collected bird tissues (e.g., feathers, claws) to provide information on within-individual vs. population level variation in diet, as well as seasonal variation in diet across three Junco populations.
Volcano Juncos at Cerro de la Muerte (Buena Vista Massif) and Volcán Irazú are often baited for photo opportunities with ecotourists and have access to discarded food in trash cans, respectively. A portion of my dissertation research explores how proximity to these "supplemental feeding sites" affects the synchronicity of breeding behaviors across populations using a Bayesian modeling approach. Stay tuned for these two publications in 2023! |
Seasonal Variation in the Costa Rican Avifauna
During the COVID-19 pandemic, I joined a virtual collaboration ("the Motmots") affiliated with the Field Museum and Costa Rica Bird Observatory exploring different facets of the Costa Rican avifauna. Through a combination of stacked ecological niche models (created by Mélusine Velde in her undergraduate thesis) and a clustering algorithm, we explored spatial and temporal shifts in community cohesion using eBird community science observation data. We performed our analyses using a biogeographically neutral (i.e. Hubbell) and an informed model (including regional partitioning along likely barriers to dispersal). We found that, at large spatial scales, the concept of a cohesive community of interacting species appears to break down, suggesting that the relevance of co-occurrence to community cohesion is scale-dependent. Further, in our review of the literature, we note that inconsistent usage of the terms "community" and "assemblage," even amongst ecologists, constrains our ability to draw generalizable conclusions about the nature of these concepts. We offer a more repeatable approach, and demonstrate how these terms should be clearly defined in all community ecology research. Check out our paper (Velde et al. 2023) in Neotropical Biodiversity.
It was a privilege to participate in the Motmots working group, many members of whom also graciously contributed ideas and field work (Dr. Jacob Cooper, Mélusine Velde, M.s. and Holly Garrod, M.s.) to my dissertation research on Volcano Juncos (see above). |
Figure 3 from Velde et al. 2023. Plots from ecostructure showing results for June (left) and December (right) with K values of 2 (top), 7, (middle), and 13 (bottom). Note that plots become structured in a similar fashion and display patterns reminiscent of the richness and beta diversity plots, indicating common patterns of distribution structuring the geographic motifs.
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