Copyright © 2010 Andrea Liberatore
I love the four seasons. Having spent my 72 years residing in the mid latitudes, I’ve learned to celebrate each of our seasons, but especially spring!
This is the rebirth flush with abundant water, new greenery, and air filled with bird song and sweet aromas as new flowers perfume the air hoping to lure in a pollinator.
With mid-April upon us and our 42 degree latitude, spring is in full swing here in northern Utah! Winter departs grudgingly slapping us with snow squalls intermingled with glorious, early summer days, a wild roller coaster ride which I truly enjoy!
I’m an avid phenology follower. Phenology is the study of how life adapts to seasonal changes. I revel in the first floral bloom, the first neotropical birds returning from Latin America with a heart full of song, and newly emerged, gaudy butterflies.
With a relatively stable climate, until recently, the timing of these events has evolved to near perfection
Let’s take a closer look at some of these phenomena. I’ll begin with our neotropical birds such as lazuli buntings, yellow warblers, and Western tanagers to mention a few. These species spend over half of their year in Mexico, Central and South America flying thousands of miles to for the breeding and nesting season in the Intermountain West. This may seem a bit extreme for these tiny flurries of life.
On closer inspection, you will find they have good reason for this daunting and dangerous task. The tropics have a relatively stable climate without the dramatic seasonal change that we experience. This results in relatively stable populations of flowers and insects, the primary food sources for most species. Further, the ratio of daylight to darkness is nearly constant with 12 hours of each. Our days lengthen as we journey toward summer solstice with nearly 16 hours of daylight! This allows a burst of energy to flow through ecosystems resulting in eruptive populations of insects and floral bloom. It also offers long hours of daylight for parents to gather food for their young which grow rapidly toward fledglings, thus reducing the possibility of predation and also preparing them for the arduous flight south as fall approaches.
Let’s examine flowers and insects. With our very warm winter and spring, I was expecting a much earlier arrival of both and was not disappointed. I counted 17 species of flowers by the second week of April! And butterflies were on a similar schedule with 9 different species during the last week of March- remarkably early! Although delighted, it occurred to me that returning birds may not be so pleased. If the flowers begin to fade, and insects begin their downward slide at the peak of birds rearing their young, trouble is afoot! A five year Audubon study revealed that 1/3 of our birds are predicted to be severely impacted by these rapid climate shifts.
On a more positive note, spring will continue as will bird song, vernal waterfalls, eruptions of wildflowers and butterflies. And spring repeats itself as we move to higher elevations. As cornices on our mountain ridges recede, up pops flowers for yet another spring bloom, and with them butterflies, bees, and birds!
Pictures: Courtesy Dr. Thomas G. Barnes, US FWS
Pictures Lilies: Copyright © 2010 Andrea Liberatore
Audio: Courtesy and Copyright Kevin Colver
Text: Jack Greene, Bridgerland Audubon Society