The climes are a-changin’

Tim Iverson

(1/2016) April showers bring May flowers. Geese are spotted flying south for the winter. Leaves on trees turn brilliant colors and fall to the ground as the trees become dormant for winter. The arrival of the Cherry Blossom trees in D.C. signal spring has finally arrived. How do these plants and animals know when to do this? That’s where a type of ecology, known as phenology, comes in. Phenology is the study of changes in seasonal timing, it literally means the study of appearance. Anyone can observe examples of these appearances or changes as birds migrating, flowers blooming, or animals hibernating. Plants and animals have developed some unique and resourceful ways to adapt for survival, but can they adjust to climatic changes that are growing ever more present? There are implications for some animals and others will hardly notice. As always, when the die is cast there are always winners and losers, but can those who suffer as a result of the phenological changes keep up the pace?

With seasonal changes organisms have evolved different ways to survive. Animals have three options when confronting this prospect: hibernate, migrate, or adapt. The Wood Frog (which is native to Maryland) survives for months at a time frozen solid! The glucose in its blood essentially acts as anti-freeze and will surround vital organs while the rest of the frog remains frozen solid. Then when warmer temperatures return in the spring it thaws out and keeps on hopping. Wooly Bear Caterpillars have a similar adaptation. Once the wooly bear caterpillar hatches from an egg laid by an adult moth it will start life in the spring voraciously munching on plants like dandelions and nettles. It will continue to do this all through spring and summer. Once the warm air moves out, and the chill of fall settles in the wooly bear makes its way from feeding grounds to overwintering sites. They usually set out for places underneath logs, rocks, or dense brush that will provide protection from any unwanted disturbance. The cool turns to cold and this is where the fur kicks in. The caterpillar begins to hibernate. Once this begins their bodies produce a natural "anti-freeze" called glycerol, and they begin to freeze almost solid. They will freeze until everything but the inside of their cells is frozen. The setae (their "fur") will actually begin the freezing process on the outside of the body, away from the internal cells. This is less damaging to their bodies, and energy reserves aren’t taxed on healing as much when it’s time to thaw out and wake up. It will spend just a few more weeks in spring eating some more before it spins a cocoon and grows up into a moth.

When the weather turns mIgratory animals pack up shop and relocate to more suitable environments for a few months. Birds and insects, like the Monarch Butterfly, can travel thousands of miles to find suitable wintering grounds. Year after year these critters find the same locations. Scientists believe this is done by navigating with the sun, moon, and stars. They also seem to have the amazing ability to sense the magnetic field of the earth, which they use like a compass. It’s not just birds or insects who migrate south though. Fish, whales, elk, and some species of bats also migrate south. Instead of migrating south earthworms migrate deeper. They can go down to as far as 6 feet under the top soil, where the temperature is much more regular and habitable for them.

Animals take their cues from the food availability, sun, and weather pattern changes. This is the mechanism that tells them what to do and when. Other animals like hibernators and long distance migrators are on a cyclical clock that cues them into when it’s time to wake up or move along. In either instance, decades long research indicates that these annual events are occurring earlier and earlier every year. The UN’s Intergovernmental Panel on Climate Change (IPCC) released a report in 2007 showing that spring is arriving by about 2.3 to 5.2 days earlier per decade in the last 30 years. The findings show that seasonal timing that ushers in plants and animals is accelerating across the globe. These new arrival times for plants and animals aren’t always syncing up potentially leading to complex problems down the road.

Hypothetically, warming temperatures can indicate to plants that it’s time to sprout and bloom. These temperatures also indicate to insect species like butterflies it’s time to migrate north. These butterflies fly north and begin to lay eggs, but because it’s still so early in the season a frost settles in destroying the plants and leaving the eggs nothing to eat should they survive the frost. Migratory hummingbirds could also face similar issues with food scarcity caused by frosts destroying plants and their nectar. Other birds having exhausted food supplies in the south and being signaled that it’s time to move north due to increasing temperatures might find that the warming pace hasn’t ushered in the required prey species. The issue is that these aren’t hypothetical situations. These are documented cases involving the Mormon Fritillary Butterfly and the Red Knot (a migratory bird that stops mid trip in Delaware to feast on horseshoe crab eggs). Breaking any link in these chains can be critical for these species survival and overall productivity.

The bottom line is that ecologists and climate scientists don’t know an awful lot. Predictive models often fail to grasp the complexity and intricacies of macro and micro ecosystems and the affected species. Whether or not the long-term sustainability or extinction rates of species is affected ultimately depends on their evolutionary adaptability and whether or not these climatic shifts can be slowed. We have seen the fingerprints of these changes around the globe and many species can change behaviors to adapt. Within a few generations of fast reproducing species genetic changes may even occur to make them better suited for new and changing environments. The recent climate summit in Paris has the potential to help curtail rapid environmental degradation (assuming all parties stick to the agreements made). This, however, is not a panacea, but a start. Between curbing emissions and responsible development with both conservation and economics in mind we can strike a balance.

Everyone has heard worst-case scenarios including but not limited to mass extinctions, oceans swallowing islands, heat waves that melt all the ice cream, and more supercell storms terribly named by meteorologists. Ultimately at the end of the day we don’t know what we don’t. When we can acknowledge that fact and the fact that we, for better or worse, are a part of a changing world that we can affect we can begin our own adaptative evolution. By observing appearances of these cyclical events we can get a pretty clear picture of what’s going on in the world around us. Phenology can help researchers, policy makers, and people be better decision makers and agents of positive change.