Morgan W Tingley - US grants

The timing and synchrony of seasonal events presents real challenges in the natural world. Migratory birds coordinate their departure from wintering grounds in Central or South America to arrive at North American breeding grounds at just the right time. Too early and they risk experiencing severe weather from late frosts or blizzards. Too late and they risk missing the peak in early spring insects that they depend on to successfully raise offspring. For their part, insects such as butterflies also benefit when their emergence coincides with the springtime flush of new plant growth. The timing of spring has been shifting earlier in recent years, and this raises the possibility of mismatches in spring timing between birds, insects, and plants. A few local scale studies have suggested that such mismatches may be responsible for long-term population declines for some species, but the extent of this problem, especially over large areas remains unknown. In this project, the research team will combine information on springtime weather, satellite imagery on plant emergence, and multiple large-scale citizen science data on birds, butterflies, and caterpillars to perform a comprehensive evaluation of mismatches in seasonal timing between interacting species. This work is critical for understanding the potential impacts of continued shifts in seasonality on living systems. The work will also engage K-college students and the public through a new citizen science program, educational units, and outreach events focused on learning about the timing of seasonal changes.
 
The proposed research will be the first attempt to examine phenological mismatch across three trophic levels at a semi-continental extent. Local-scale studies have documented specific instances of phenological mismatch but fail to inform how mismatch consequences propagate across spatial, temporal, or trophic scales. Birds and butterflies provide the most expansive, long-term and detailed macroecological data sets on distribution, diversity, and demography. The project will unite multiple large-scale citizen science datasets for these taxa with targeted field data collection, and remotely-sensed climate and vegetation data layers, to examine the cross-scale and multi-trophic interactions that connect shifting thermal environments, phenological mismatch, and fitness consequences. This will be accomplished by: (1) assembling and uniting continental and regional monitoring and citizen-science databases for Lepidoptera and birds; (2) building spatio-temporal models in order to assess drivers of phenology, calculate direct metrics of phenological mismatch across trophic levels, and evaluate fitness and population consequences of those mismatches; and (3) testing the ability of generated models to predict phenology and population trends for focal birds and Lepidoptera across eastern North America as a function of tri-trophic phenological mismatch. Taking a macro-scale perspective on phenological mismatch is critical for understanding the range-wide impacts of sustained trends in seasonal timing. In addition to answering critical research questions on phenological mismatch the team will extend the impacts of their work through both specific training opportunities and broad-based education and outreach efforts.

Many recreational and cultural events are based on the seasonal timing of natural events. For example, visitors flock to New England to enjoy fall leaf colors and birdwatchers congregate in May to welcome migrating birds. Seasonal timing also matters to plants and animals. To fuel their fall migrations, birds rely on calorie-rich wild fruits. Likewise, the plants that make those fruits rely on migrating birds to carry their seeds to places where they can grow into new plants. This mutually beneficial interaction works because the timing of wild fruit production matches the timing of bird migration. In many places, however, the seasonal timing of bird migration and fruit production has become misaligned. With not enough fruit to fuel their migratory flights, birds may suffer during migration. And, without birds to disperse their seeds, some plants could fail to produce the next generation. This research will measure how much fruit production and bird migration are misaligned. Investigators will study the environmental cues for fall migration and fruit production as well as the factors that control how many fruits are produced by wild plants. Members of the public will participate by providing observations on bird-fruit interactions and will learn about scientific research through field trips led by the investigators.

The relationships between environmental cues and fall seasonal events in birds and plants remain largely unexplored. This project will use multi-year, multi-species, publicly available datasets to estimate year-to-year differences in the timing of fall migration in birds and fruiting in fleshy-fruited shrubs. Two methods will be employed to determine relationships. First, researchers will use Bayesian survival models to regress data on yearly timing of migration and fruiting from the National Phenology Network and eBird, respectively, with data on environmental drivers. Second, a common garden experiment with five genera of shrubs will be set up to mechanistically determine for the first time how increased temperature, drought, and the interaction between the temperature and drought affect the timing and abundance of fruits. Results will be useful in predicting the ability of birds to migrate and fruiting-plants to disperse their seeds.