The Science of the Seasons


By Jessica Steiner

While the first day of spring was officially March 20, the weather has remained unpredictable in many parts of Canada.  In southern Ontario, where I live, it has been hard to decide what clothes to put on in the morning.  I look longingly at my spring-summer wardrobe as near freezing rain pounds against the window.  But so goes spring in the Great White North.

Now, finally, I am starting to see spring arrive – the bulbs in my garden have flowered, a queen bee was spotted high up foraging for pollen from the neighbour’s maple tree, and toads are calling from the wetlands on the grounds of our head office.  Sunlight still peeps around the curtains when I put my children to bed in the evening. My Facebook feed is full of information on how to assist turtles safely across the roadas they emerge from hibernation and travel to their summer digs. The video below is one that I like to share with friends each spring.

Prairie Smoke blooms on the Carden Alvar in Ontario

Phenology is the study of plant and animal life cycles, and how these are influenced by the seasons. Many of the “firsts” that you associate with spring – the first flower, the first bird nest – are all examples of phenology.  What drives these life cycle events is still relatively unknown.  Plants and animals may move from one life cycle stage to the next due to cues from temperature, rainfall, day length, or some combination of these. Understanding when different seasonal events occur is useful for timing when to plant or harvest crops, when to hit those birding hotspots, or when to start your allergy medication!

By tracking when “firsts” of the season occur annually, we can start to understand how these seasonal events may be changing over time.  Are the toads starting to call earlier than they were 20 years ago? One study of frog species in Eastern Ontario found that increasing spring and summer temperatures had caused three frog species to start calling up to 37 days earlier.

Even less is known about how much flexibility plants and animals have in their responses to the environmental cues that drive their life cycle events. As species experience climate change, habitat loss, and other changes to their environment, can they respond and adapt?  Some species might be able to change when they arrive on breeding grounds, or emerge from their cocoons, but not all will be so lucky, or at least cannot change quickly enough to avoid the negative consequences.  Many birds time their nesting for when insects are plentiful to feed their young.

A newly emerged taylor’s checkerspot butterfly. This species overwinters as a larvae and completes development in the early spring. Photo: P Karsten

Butterfly emergence is often synchronized to leaf out in host plants and flowering nectar sources.  But observed shifts in phonological events, such as spring events occurring earlier, often lead to mismatches, e.g. nests hatch after the peak in insects has passed. How plants and animals respond to a changing climate can help scientists predict whether their populations will grow or shrink – making phenology a “leading indicator” of climate change impacts.  Including climate change considerations is now an important component of many species-at-risk recovery programs.

It may now be obvious that another sign of spring for me is that I start thinking about species phenology.  When will our first loggerhead shrike return to Ontario breeding grounds? When will our first massassauga rattlesnake be spotted in Ojibway?  When will our first queen yellow-banded bumble bee be collected?  It’s always an exciting time getting these “first” reports from our field staff.


How do you know when spring arrives? Tell us your stories below!


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Jessica Steiner

Jessica Steiner

Conservation Programs Director

Jessica joined Wildlife Preservation Canada in 2006 as a shrike field biologist in the Carden Area. The following year she began managing all aspects of the Loggerhead Shrike Recovery Program in Ontario as a Species Recovery Biologist. In 2014, Jessica became the Conservation Programs Director, overseeing all of our species recovery projects. Jessica lives in Brampton with her partner, and two energetic boys, and various furry family members. She loves experiencing the marvels of nature renewed through her children’s eyes, whether it be flipping rocks in the garden, chance animal encounters, or deciphering tracks in the snow.