The activities of many plants and animals are influenced by temperature. Rising spring temperatures trigger flowers to bloom, trees to leaf out, and insects to emerge. Many animals depend on the cycles of plants to provide food at the correct time. Migratory birds that eat insects depend on their food source to be available when they reach their destinations. The timing of insect emergence must be timed to match the arrival of the birds.
If warm spring temperatures occur earlier in the year, some animals and many plants begin their spring cycles sooner. Not all organisms respond to changes in temperature, or they do not respond in the same way. This creates an asynchronous timing of species that depend on each other as a food source.
Photo: Yellow-bellied marmots emerge from hibernation 38 days earlier today than 23 years ago due to spring temperatures arriving sooner. However, their food source has not changed its patterns. Today, when the marmot awakes there is still snow and very little food available. Yellow-Bellied Marmot
Photo: These birds have responded to warmer spring temperatures at lower altitudes by moving up the mountain slopes to their nesting ground 14 days earlier than in This means they arrive before their food source emerges, which has not changed its phenological patterns. American Robin
The duration of summer has increased in this region of the U.S. over the last 20 years. Earlier springs means summers lasts longer
Change in spring leafing out can be beneficial or harmful for trees. Beneficial: Early leaves get more sun, providing a longer growing season for the tree. Harmful: First leaves get attacked by plant-eating insects and other animals as there is no other food available. Photo:www.commons.wikimedia.org
Why Should We Study Phenology?
The study of phenology lets us predict when pollen counts will be high. Allergy season starts when certain flowers bloom. Changes in the climate influence when these flowers bloom and therefore affects the length of the season for allergy sufferers. Image:
Phenological patterns help farmers know when to plant crops. Photo:
Phenology patterns tell us when we can expect to see whales at different locations. Sighting festivals and events are planned around traditional migration dates.
The Cherry Blossom Festival in Washington D.C. is a long- time favorite. Image:
In this activity we investigate three organisms: oak trees winter over moth caterpillars Great Tit (a migratory bird) For centuries, the seasonal cycle for each of these organisms has been beneficial to the others.
These oak trees loose their leaves in the winter. Spring temperatures trigger the growth of new leaves. New leaves are edible to caterpillars of the winter over moth for about a month. Then they develop tannins which make them inedible.
Winter over moth—caterpillar and adult. These caterpillars only eat early growth oak tree leaves. Their hatching date is linked to the budburst of the oak tree leaves.
The Great Tit uses day length to trigger its spring migration to the European oak forests and their nesting sites. They depend on the abundance of winter over moth caterpillars to feed their young.
This material is based on work supported by an Environmental Literacy Grant from the National Oceanic and Atmospheric Administration’s Office of Education (NA09SEC ) and prior work supported by the National Science Foundation under Grants ANT and ESI Any opinions, findings, and conclusions or recommendations expressed in these materials are those of the authors and do not necessarily reflect the views of the National Oceanic and Atmospheric Administration or the National Science Foundation.