City Nature Clock

How do you know when spring has begun? You could look at a calendar, but everyone seems to have their own definition of when the seasons change: the sugarhouses are making syrup, the first person is seen in shorts, baseball games are on the radio. Nature has its own markers of the seasons, and we want your help tracking them!

From the spring (vernal) equinox on March 20th to the summer solstice on June 20th, we will track species across Burlington and Winooski to see when they reapear for the summer, are passing through, or are in full bloom. Add to the City Nature Clock this spring on iNaturalist by submitting observations of the focal species listed below. By tracking five different sets of species, we will get to see how they exhibit their spring phenology in relation to others, expanding on last year's 2020 Burlington Seasons Clock project.


Find other activities to get involved in that are part of the City Nature Celeberation on that webpage, or play Wildways Bingo! 


Henry David Thoreau marked the dates of blooming wildflowers, the arrivals of migratory birds, and the occurrence of other animals in his time at Walden Pond and Concord, MA. Researchers today are recording some of the same phenophases and using them to track climate change. A warmer climate has changed average animal and plant behavior by days or even months.

What is a phenophase?  The scientific term for nature‚Äôs calendar is Phenology. A subset of ecology, phenology is defined as the study of the timing of recurring biological events and how these events are influenced by seasonal variations in climate and other ecological factors. A phenophase is an observable stage in the annual life cycle of a plant or animal that has starting and end points. Plants are the most common focus of phenological studies because of their fixed location and suitability for repeated seasonal observation. Timing of budbreak, leafing, flowering, fruiting, and leaf coloring are the commonly observed phenophases. The timing of bird migration, the dates of salamander courtship, and mammalian hibernation cycles are examples from the animal world.

City Nature Clock Spring 2021 Species List (Burlington & Winooski, VT)

We encourage you to submit any photos or soundbites of wildlife you find to iNaturalist!

Birds (20) - Returning with spring!

  • Song Sparrow
  • Red-winged Blackbird
  • Canada Goose
  • Eastern Phoebe
  • Ruby-crowned Kinglet
  • Osprey
  • Yellow-bellied Sapsucker
  • Hermit Thrush
  • Yellow-rumped Warbler
  • Pine Warbler
  • White-throated Sparrow
  • Tree Swallow
  • Eastern Kingbird
  • Wood Duck
  • American Redstart
  • Ovenbird
  • Scarlet Tanager
  • Baltimore Oriole
  • Rose-breasted Grosbeak
  • Yellow Warbler

Trees (10) - Leafing out!

  • Boxelder
  • Sugar Maple
  • Eastern Cottonwood
  • Red Maple
  • Paper Birch
  • American Elm
  • Silver Maple
  • Basswood
  • American Beech
  • Staghorn Sumac

Wildflowers (10) - In bloom!

  • Jack-in-the-Pulpit
  • Bloodroot
  • Round-lobed Hepatica
  • Red Columbine
  • Wood Anemone
  • Large White Trillium
  • False Solomon's Seal
  • Red Trillium
  • Yellow Trout Lily
  • Largeflower Bellwort

Amphibians & Reptiles (10) - Emerging from hibernation!

  • Common Garter Snake
  • Eastern Red-backed Salamander
  • Painted Turtle
  • Northern Leopard Frog
  • American Toad
  • Wood Frog
  • Green Frog
  • Snapping Turtle
  • Gray Tree Frog
  • Spotted Salamander

Insects (10) - Back in action!

  • Red Admiral
  • Mourning Cloak
  • Eastern Forktail
  • Common Ringlet
  • Eastern Black Carpenter Ant
  • Silver Spotted Skipper
  • Common Eastern Bumble Bee
  • Six-spotted Tiger Beetle
  • Twelve-spotted Skimmer
  • Hobomok Skipper

Results of our Burlington Seasons Clock 2020 Project: