Oct 10

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.

Honey bee photo

Come spring time, honey bees rely on blooming plants for food, while the plants rely upon the bees for pollination

 

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.

North Atlantic right whale photo

Conservation measures to protect the North Atlantic right whale include regulations in the US to restrict the use of certain types of fishing gear in specific areas at times when the whales are present

 

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.

Caspian seal photo

The Caspian seal relies on change in ice formation to jump-start its migration

Black-eared mantella photo

The black-eared mantella begins breeding at the arrival of the seasonal rains

 

 

 

 

 

 

 

 

 

 

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.

Loggerhead turtle photo

Climate change could cause this young loggerhead turtle to hatch too early or too late in the season

Butterflies and blooms education resource

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

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