Climate and species traits give rise to complex phenological dynamics

Area of Science:

• Ecology
• Climate Change Biology
• Entomology

Background:

• Climate change is causing widespread phenological shifts in organisms.
• The drivers and complexity of these shifts, especially across different aspects of an organism's activity period, are not fully understood.
• Butterfly phenology is sensitive to environmental changes, making them valuable indicators.

Purpose of the Study:

• To investigate how climate variables influence various aspects of butterfly flight periods (timing, duration, abundance).
• To determine the relative importance of local climate and species' natural history traits in shaping phenological responses.
• To assess the differential impacts of climate on distinct phenological phases.

Main Methods:

• Utilized multidecadal butterfly survey data from five montane sites across an elevational gradient.
• Employed a hierarchical Bayesian framework to model annual probability of occurrence distributions for 135 butterfly species.
• Incorporated polynomial models to capture changes in abundance, timing, and flight length, correlating with climate data.

Main Results:

• Spring maximum and minimum temperatures and winter precipitation were key predictors of phenological variation.
• Winter precipitation delayed phenology, while warmer spring maximum temperatures advanced it; increased spring minimum temperatures had strong effects.
• Climate impacts varied significantly across sites, species, and even populations, with local climate explaining more variation than natural history traits.

Conclusions:

• Winter precipitation and nighttime temperatures are critical, often overlooked, drivers of phenological shifts.
• Considering the entire flight period, rather than isolated aspects, is essential for accurate predictions of species' responses to climate change.
• Both natural history traits (voltinism, overwintering stage) and local climate modulate how different phenological aspects respond to climate change.