Submitted By: Natalie Marioni, Penn State Extension Educator
Have you ever noticed that wood frogs are always among the first frogs to call each spring, or that spotted jewelweed appears in bloom around the same time each summer? Perhaps you have. But have you ever wondered why these events are so predictable? This predictable timing is part of nature’s calendar, a field of study known as phenology. Plants and animals have natural cycles that occur with regularity each year, driven by various environmental cues. These predictable cycles include events such as bird and amphibian migration, spring bud break, and even fall leaf color change.
At the core of phenology is the relationship between seasonal environmental conditions and the life cycles of plants and animals. Each phase of a plant’s or animal’s life is called a phenophase. For plants, common phenophases include bud break, the presence of fruit, and fall leaf drop. For animals such as amphibians, common phenophases might include adult vocalization (e.g., frogs), mating, seasonal migration to water, or egg-laying.
Because species coevolved, many phenophases occur in synchronized ways that support the ecosystem. For example, peak caterpillar emergence often coincides with the period when trees have the most leaves available for feeding. Bird migration, nest building, and chick rearing may align with this timing to ensure adequate food for young birds. These overlapping phenophases create stable ecological relationships.
However, climate shifts are influencing the timing of these once-predictable events. Changes in temperature and seasonal patterns are causing some species to adjust their phenophases, while others respond more slowly and become out of sync. These mismatches can disrupt wildlife behavior, ecosystem health, and even economic activities that depend on seasonal timing.
Penn State Extension will explore how species interact and how a changing climate is altering phenological events and other life-history strategies in the upcoming webinar, “When Seasons Shift: New Challenges for Nature in PA.” The webinar will be held at 12:00 PM on Wednesday, April 29, 2026. Registration is $5, and registrants will have access to the webinar recording for six months.
This webinar will cover:
-What phenology is and what the common plant and animal phenophases are
-How people have used these cues in nature to guide their own behaviors
-Current and potential concerns for plants and animals as climate shifts occur
-How invasive species are better adapted to withstanding these changes
-Where to find community science projects you can join
Who is this for?
-Outdoor enthusiasts
-Anyone interested in learning more about the environment around them
-People interested in wildlife
-Anyone who wants to learn new ways to connect with nature through community science
To register, visit: https://extension.psu.edu/when-seasons-shift-new-challenges-for-nature.
To register by phone, call 877-345-0691.
For questions or more information, contact Extension Educator Natalie Marioni at nkm5342@psu.edu.
