Here in the Northern Hemisphere autumn has well and truly hit us and we are moving fast heading towards winter. As leaves change colour and fall from the trees, many creatures are beginning their preparation for hibernation and birds are embarking on their seasonal migrations to warmer climes. Across the globe many species rely on seasonal changes in weather to signal the next stage in their life cycle, such as hibernation, migration, blooming or molting. Although all organisms go through natural lifecycles, the study of seasonal cycling is unique and scientists refer to it as phenology.
What is phenology?
By definition, phenology is the study of how seasonal and climatic changes influence natural cycles. Not only can phenology provide valuable clues to the lifecycles of individual species, it can also highlight the importance of relationships between species. For example, insects such as honey bees must carefully time their spring emergence with the blooming of flowers, which they rely upon to provide nectar and pollen.
Why study phenology?
Although phenology seems like something that is just observed and not studied, it is actually very valuable to research phenological patterns. Understanding phenology can allow scientists to make comparisons to see if a community is healthy and following normal cycles. Phenology can also aid conservation efforts, for example by calculating the timing and migration routes of the North Atlantic right whale, the species can be protected appropriately throughout its range at different times of year.
What triggers seasonal changes in nature?
One well-known sign that the seasons are changing is the difference in temperature throughout the year, but there are other indicators that may not be as well known. For example, the Caspian seal relies on the presence of ice formations in the Caspian Sea to trigger its seasonal migration to different locations, while the Critically Endangered black-eared mantella gets its signal to start the breeding season from seasonal fluctuations in rainfall.
How can climate change affect phenology?
Climate change can have a negative effect on species that follow phenological patterns. For example, unusual seasonal droughts in the Namib Desert in southern Africa were followed by large declines in quiver tree numbers, which scientists believe to be the result of drought stress. Climate change can also effect species’ reproductive cycles, for example the loggerhead turtle comes ashore to lay its eggs in the summer when the odds of the young surviving are at their highest. Changes in climate patterns are likely to shift this cycle, putting the eggs and young at risk.
Related education resource
Learn more about phenology with our creative Butterflies and Blooms education resource. Check it out on the ARKive Education pages, and help your students to discover the relationship between the butterflies of Wisconsin’s Northwoods and the springtime flowers they depend upon.
Christin Knesel, Intern, Wildscreen USA