Through phenological research, scientists have shed light on how ecosystem services have been impacted by climate change. With warmer dates progressively occurring earlier in the spring season, environmental time sensitive events such as bud burst from trees and songbird migration have been shifting to occur at earlier dates than previously observed. Because these events are not independent from one another, studying the phenological interspecific relationships provides valuable insight to truly understanding the health of our ecosystems.
This case study investigates the usefulness of a unique long-term dataset of songbird first arrival dates collected from 1940 to 2016 on the Mohonk Preserve, NY. Phenology observations over this long time period were collected in a consistent manner along pre-determined routes and at specific locations. The goal for this study was to test the usefulness of the database by determining if certain songbird species first arrival dates in spring had shifted to earlier dates over time in a localized area. To perform over-time change analyses arrival dates were separated into three time period categories (1940-1974, 1975-1994, 1995-2016). Preliminary analyses using Kruskal-Wallis analyses of variance were used to determine significance of change in arrival date for each selected songbird species.
All records prior to 1989 were carefully digitized from notecard observations into a database containing the other subsequent phenological observations. Species chosen for analyzation (number of observations) include the Red-winged blackbird (63), Brown-headed cowbird (71), Eastern towhee (76), Eastern phoebe (77), Louisiana waterthrush (66), Red-eyed vireo (74), and American redstart (75). As expected, a shift to earlier arrival dates was seen over the three time periods, with the Red-winged blackbird and Eastern phoebe showing significant shifts from the earliest time period to the most recent. Although, these preliminary analyses show promise that our dataset can be valuable at determining local phenological changes, more robust analyses with other variables are necessary to fully understand complete impacts on regional phenological events.
We have just started to scratch the surface of the importance of Mohonk Preserve’s long-term dataset. This vast long-term dataset provides not only multiple bird species first arrival dates but also daily temperature/precipitation, and first bud/ leaf-out for trees/shrubs. Next analyzation steps include comparing the differences in timing response in short vs. long distance songbird migrants, and correlating songbird mean first arrival dates with first bud of dominant forest canopy trees and annual average spring (March-May) temperatures.