Signs of spring were late to arrive in Maryland this year. Still, as temperatures slowly rose and days lengthened throughout April, leaves grew on trees and plants sprouted into flower. Birds and spring peepers made their presence known through trilling song and chirping call, and insects began to take wing. Later this year, frosty mornings and honking skies of migrating geese will hint that winter is once again on its way. These familiar seasonal changes signal the passage of time for humans, but for plants and animals in nature, seasonal change is essential for survival—it triggers growth and new life stages, feeding and mating activities, migration, hibernation and other natural phenomena.
How do animals emerge from an egg, find a mate or head south for winter at the right time? And how are plants cued to unfold from the soil, send flowers into bloom, produce fruit or go dormant come autumn?
Scientists study animal physiology and behavior, plant form and function and seasonal weather patterns carefully to understand these recurring life events. This science is calledphenology, which is derived from Greek phaino, meaning to show or appear. Studying phenology provides information about the life history of a species and the systems that underlie food webs and population dynamics.
Timing is everything
When it comes to phenology, nothing is as simple as it may seem. The interconnected nature of ecosystems means that one species’ seasonal life events affect many other plants and animals. For instance, the life cycles of many pollinatorspecies in Maryland, such as native bees and butterflies, are aligned with the cycles of the plants that provide food for larvae, nectar for adults and host locations for eggs or transitional life stages.
If the life events of the host plant and insect do not align—if, for instance, butterflies emerge before host plants emerge—the butterfly may not survive to reproduce. This falling out of sync is called phenological mismatch. Biologists track the phenologies of many plant and animal species, and apply this knowledge to manage habitats and conserve at-risk species.However, current understanding of the phenology of many species is far from complete, especially as the impacts of global climate change continue to affect temperature patterns.
As average temperatures warm and weather patterns are altered, biologists are beginning to understand how some species are reacting, and possibly adapting, to the coming change.