NATUREWISE: Phenology — arrival of birds and blooms

Many people jot down the dates of the first migratory birds and the first wild flower blooms.

On March 31, neighbours emailed to say their first hummingbird had arrived at 7:15 a.m. looking for its feeder.

This was the earliest date of arrival they had ever recorded. The earliest records for the South Okanagan I found for calliope and rufous hummingbirds were April 7 and April 16, respectively.

Many people jot down the dates of the first migratory birds, especially robins, red-winged blackbirds and bluebirds, and the first wild flower blooms. Two of the earliest wild flower blooms in the Okanagan are sagebrush buttercup and yellow bells, one of the lilies. The buttercups usually start blooming en masse the second week of March but this year the first bloom was spotted on Feb. 18. The yellow bells were out on March 11; they usually start blooming March 19. Orchardists have observed that fruit bloom is about two weeks ahead of schedule this spring.

Recording the dates of bird arrival and flower bloom is part of the science of phenology which Webster’s dictionary defines as “the study of natural phenomena that recur periodically as migration, blossoming etc. and of their relations to climate and changes of season.”

Factors influencing time of bloom include precipitation (including rainfall the previous autumn), sunshine, temperature, elevation and wind.

The warm, windy weather in late February and March probably triggered premature flowering. If the mild weather continues the effect of early flowering will result in fruit and seeds, but if a weather system brings in a killing frost the blooms may be killed with the result being a reduction in fruit or seed yields.

The point is that phenology is the analysis of a variety of interrelated factors and understanding their effect will determine, for example, whether a farmer plants a frost resistant variety or not.

Since 1998 we have recorded the dates when we first noticed certain wild flowers in bloom here in the Penticton area. In fact, people have been recording flowering and ripening of crops for ages. Viticultural records of grape harvest in Europe, have been used to reconstruct summer growing season temperatures from 1370 to 2003.

Horticulturists have been using signals from plants to determine the best times to prune or sow seed. Advice from Okanagan gardeners suggests that the best time to prune roses is when forsythia is in bloom.

We have found that the indicator plant for hummingbird return is the native wax currant.  This year they were in full bloom on March 30.

As we get deeper into climate change it will be interesting to have these records.

The South Okanagan Naturalists’ Club’s monthly meeting is April 23 in the United Church, 696 Main St., Penticton at 7 p.m.

Biologist Jared Maida will describe the snake research program at the Nk’mip Desert Cultural Centre. All are welcome.

Jim Ginns is a member of South Okanagan Naturalists’ Club, BC Field Ornithologists and the Native Plant Society of BC but the views expressed here are his own.



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