|The Drums of Spring
"A red fox was dancing on the woodpile," my friend said. "Cavorting around, enjoying himself." A more dramatic sign of spring than the first robin I just saw, fat and sassy on my porch.
Out in the garden, I get ambushed on the way to the compost pile by the sight of fresh, deep green shoots of chives. Although I haven't been able to eat any of the lily (onion) family for years, my food allergies are getting better: I just might try a few chives. The temptation makes me feel like one of those cartoon characters whose body stretches, pulled into the air toward the animated floating musical notes of a siren call....
Even in the house I can't get away from this restlessness. On the eaves, snow is melting, dripping water onto the porch roof. It makes a different sound than rain, a more irregular drumming. It's getting under my skin: saying "Spring. S-spring. S-s-spring.
Animals and plants both respond to the warming weather. Recently it's warming sooner, and in different patterns. The robin on my porch was fat, but in the Rocky mountains, robins are in trouble. They winter in lower altitudes, which are warming faster than the higher breeding grounds they migrate to in Spring. Cued by the temperatures at their departure point, the robins have been arriving two weeks earlier in the Rockies ... where snow still covers the ground, making it hard to find worms.
Around the globe, scientists say we will see increasing species extinctions due to failure of ecosystem synchrony. Already insects are hatching or migrating out of synch with plants that depend them for pollination. Most at risk are plants whose pollinators also depend on them for their only food, like figs and yucca. Several species of butterfly were already endangered from loss of habitat due to human encroachment; increasing warmth further reduces the extent of suitable environment.
For many annuals and perennials, light determines flowering. But it's heat that triggers most spring-flowering trees and shrubs (and some perennials). In general, phenology (biological events triggered by natural rhythms) responds less to photoperiod in spring than in fall.
Larvae of the threatened Monarch butterfly can only eat milkweed (Asclepias species). Up the street from me, a neighbor has planted common milkweed (Asclepias syriaca) all over his garden. It's not so pretty as A. incarnata, but the larvae prefer it.