Who Are We to Judge?

Exploring the Big Beauty in Little Beauties and Ugly Pests Alike  -- May 15, 2011

Beauty is in the eye of the beholder.  What harm can come in a little beauty? Why do we feel intent on destroying the things that don’t fit our own definition of beauty?  Today’s exploration is a visit to the skewed perceptions of beauty and ugly.

Exhibit 1: The Brewster’s Warbler

First, let me introduce you to a fairly rare hybrid.  It is a mix of two species, the Blue-winged Warbler and the Golden-winged Warbler.  It is called the Brewster's Warbler, and its lovely expression of these combined genes is a veil of beauty concealing a grim reality. Every Brewster's Warbler hybrid is a small genetic step closer to the loss of the Golden-winged Warbler.  Is it beautiful? Perhaps it is.

I have lived 42 years, most of it within a stone’s throw of the Mississippi and Saint Croix Rivers.  I am a lifelong birder and a lifelong “river rat,” so I have long been well aware of the magical nature of rivers in their ability to transport a recharge of nutrients to ecosystems downstream.  At the same time, those rivers that flow from North to South have another, even more magical ability to transport the population ranges of birds in quite the opposite direction.  It is the Saint Croix River’s corridor of habitat that pulls the Blue-winged Warbler northward into the realm of the Golden-winged Warbler.

Blue-winged Warbler

Both warblers are of the same genus, Vermivora, and both warblers have a nearly identical Type-2 song, a staccato buzzing trill that exclaims extremely strong feelings about territory and mate. Both warblers, recently diverged species, seem to find the other species occasionally suitable as a mate.  Hybrids are regular where the two species overlap, and one bird-bander from eastern Wisconsin explained to me that “pure” Golden-winged Warblers with gray feathers of the rump are never banded anymore.  It would seem that all Golden-winged Warblers have a touch of Blue-winged, a firmly embedded chunk of DNA in Golden-winged’s gene pool that results in just a few yellow rump feathers. 

Brewster’s Warbler hybrid preening

Wisconsin holds about 25% of the world’s breeding population of this bird.  In Northwest Wisconsin, where habitat is naturally very good, Golden-winged Warblers are a common sight for the experienced birder.   In marginal habitats, Blue-winged Warblers are quickly replacing them.  The sad anxiety in this situation is that range expansion by Blue-winged Warblers, loss of good breeding habitat for Golden-winged Warblers (alder swamp, young aspen or clearcut in necessarily close proximity to older, mature forest), and loss of productive, species-nurturing reproduction to cross-species hybridization may result in the extinction of the Golden-winged Warbler.  Without proper protections, the Golden-winged Warbler will be in big trouble soon.  Indeed it is already a candidate for Threatened Species status.  While a spectacular comeback story has been written for so many species by the good work of the Endangered Species Act, short-sighted politicians are gunning for the Act just as the Golden-winged Warbler needs it most.

Golden-winged Warbler

So, here it is in all its beauty…the Brewster’s Warbler.  It is proof that beauty has an ugly side.  I waited most of my years and all of my adult life to set eyes upon this wondrous plumage.  I focused my passion on making good images but had to “come up for air” occasionally to tremble and marvel at the spectacular, soft, lemony hues.   I enjoyed every lasting moment with this bird.  And I knew that I was seeing evidence for the destruction of a beloved species of bird all the while.   Paradox is a big part of nature.

Brewster’s Hybrid with Blue-winged Warbler

Exhibit 2: What So Many Fail to See

What is that mouse-like squeak in the trees?  Do you hear it?  I ask the question, intending it to be rhetorical.  But, to my surprise, most people still hadn’t noticed it.   I point their attention to the sound, “squeeeek squeeeeek squeeeeeeek eeeeeeeek” up in the trees.  It is chalky, rasping, high, and quiet.  The mousey squeak in the canopy of a forest… Listen for it, and you will find it.

Blue-gray Gnatcatcher calling with a mouse-like "Squeeeeek"

The sound is found where oaks abound, where some trees are standing, dead snags with some branches, and where lichens grow freely in big, blue-gray scales on knotholes and branches.  It is the sound of the Blue-gray Gnatcatcher.  This bird, so closely related to kinglets, is a tiny bird, an insect-eater, and a hyperactive dweller of the upper forest canopy.  It takes a forest of complexity to keep a gnatcatcher happy.

Blue-gray Gnatcatcher

In Northwest Wisconsin, it is another year of Forest Tent Caterpillar outbreak.  This year, the cabins along Balsam Lake are covered with writhing forms.  Families report using wasp spray, gasoline and even blow-torches to sizzle, pop, poison and destroy the fuzzy baby-blue and yellow-spotted caterpillars.  It is another example of humanity at war with something with little perceived value.  It is also an example of something so small and unassuming as to be unknown and poorly understood by almost everyone…until the outbreak year.  Suddenly, trees are defoliated, and students and parents alike visit my classroom with bags of caterpillars, individual caterpillars, and iPhone images of “tents” in tree branches.  What ARE these things?  They are EVERYWHERE?  How do I get RID of them? 

Forest Tent Caterpillar

While I sympathize greatly (I also try to keep my home in order), I also see the forest tent caterpillar in a very different light.  To me, they are beautiful.   Here are some things that may make them more beautiful to you.

Black-billed Cuckoos follow outbreaks and dine upon the caterpillars.  To cuckoos, forest tent caterpillars mean nesting success!  The forest tent caterpillar is a long-standing partner in a predator-prey relationship.

A parasitoid fly, know by many northerners as the “Friend Fly” will control the populations by laying eggs upon the caterpillars.  The maggots will feast on caterpillars and will likely kill them. The forest tent caterpillar is a long-standing partner in a parasitic co-evolution.

I have seen chickadees eating overwintering (or dead) caterpillars during bitter cold days in January.

…And, oh yes, the Blue-gray Gnatcatcher uses forest tent caterpillar silk in building its nest. This fact alone is enough to bring love of forest tent caterpillars deeply into my heart.  Beautiful birds need ugly pests.  Rachel Carson was right, you know.

Blue-gray Gnatcatcher with forest tent caterpillar silk: An example of Interdependence

May 15, 2011 was a memorable day in nature.  In just a few hours, I had crossed paths with more than a hundred species of birds, insects, and wildflowers.  I had taken the time to notice things, to make some sense of the ecological connections around me.  One of the most important themes in the study of biology is that of interdependence.  Human cultures were once more connected to the urgency of interdependence.  Our lives once depended upon being good students of nature.  Today, we lie to ourselves.  We have found too much importance in things of our own invention and, as we strive for economic improvement, we often forget that our true wealth is in a sustainable ecology.  We cannot continue to expect an economy based on natural resources to grow infinitely.  We must realize the limitations of a planet faced with human population growth and increased appetites among human inhabitants.  True wealth is in finding beauty in nature…even in those things that may be “ugly” to us but life-giving to all.

Yellow Warbler: An insectivore dependent upon healthy populations of aquatic insects

Broad-winged Hawk: A forest hawk that depends upon snakes, mice, and other things “ugly.”

Yellow-bellied Sapsucker, a beautiful bird often persecuted for destruction of trees, drills sap wells that spur on entire food chains (and food webs).

These images were captured using Canon 30D Digital SLR and Canon 300mm, F4 IS lens. A 1.4X Converter was used some of the time.  All images were captured between 7 and 10 AM on May 15, 2011 when the light was pleasing.  It was a very lucky, good day! Lots of images!