Collecting Phenology Data

a page from my nature journal
a page from my nature journal

Collecting phenology data helps us to understand the ways of the land we live in. This seasonal information probably fills the pages of your nature journal. All you may need to do is to look at your past nature journal pages in new ways.

When you look over your nature journal, ask yourself these questions.

  • What plants bloomed at the same time?
  • What temperature highs and lows did you record?
  • When the first migrating birds returned, what was in bloom?
  • What was the temperature like when you spotted the season’s first bumble bee?

How to Begin Collecting Phenology Data

Begin by thinking about the animals and plants you notice anyway. With me it’s always cardinals, robins and the fruiting of mulberry shrubs. Select subjects of interest and set up a routine for collecting and comparing your observations. The best observations are made from the same location year after year.

Limiting what you collect information on is probably a good idea. Too many things to observe and fatigue and frustration may stop you from observing all together.

Weather and Climate

Phenological events, which are easily observed such as buds opening or plants leafing out, can be matched with weather conditions and with other, less easily observed events like the hatching of insect eggs.

  • temperature – the daily highs and lows
  • the amount of moisture in the atmosphere – rain, humidity, snow, fog, dew, etc.
  • the day length – sunrise and sunset times
  • last snow or last frost of Spring
  • first snow or first frost of Fall
  • date a local lake or pond freezes in the Fall or opens in the Spring
  • date of the first mosquito bite of the season
  • anything else of interest to you


Plants used for phenological observations are called “indicator plants.” Good indicator plants need to be common to a wide geographical area, hardy, easy to recognize, and easy to grow. They should have short, well-defined bloom periods, with blooms and fruits recognizable from a distance.

  • bud opening
  • first leaf
  • First flower
  • 50% bloom
  • 90% bloom – full bloom
  • petal fall
  • leaf drop
  • seedling development
  • color changes


  • track first appearance
  • migration
  • courtship
  • breeding
  • flocking
  • hibernation, if the animal hibernates

For specific animals

  • Amphibians (frogs & toads) – first singing, egg laying, life stages
  • Birds – migration, courting rituals or nesting dates
  • Insects – dates of appearance/emergence or life stage cycles
  • Mammals – dates of hibernation, courting rituals, birth of young

After year of two of tracking such changes, you should have some very useful information. This data can be used for vegetable and flower gardening planting, harvesting and pest management. This is great information to put in a nature journal or to scribble on a calendar.

Or join a citizen science project and hone your data collecting skills.

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