Boldly Invisible

A continuation of the discussion in the last post of why black accent or coloration is so widespread, especially in small birds…there are still more questions to answer.

For example, you would think that a boldly striped, black and white animal would be an easy target to spot against the homogeneous green or gold African savanna.

zebra-

But how many zebra do you actually see here?

Disruptive patterns of black and white break up the outline of an animal’s body, making it difficult to detect them in a complex background.  Maybe this is why a herd of zebra can be referred to as a “dazzle”?

Looking at a single chickadee against a plain white or tan or gray background makes them standout because of their bold black and white markings.

Black-capped chickadee-

But finding them in their more typical, complex background of myriad tree branchlets and leaves is much more difficult.

chickadee family-no highlights-

How many chickadees hiding in the bushes?  They blend in well with highlights of snow on branches or in the background, deep shade on unlit branches, and the tan of leaves and bark.

chickadee family-with highlights-

Here they are!  Highlighted with a little illumination in Lightroom photo editor.

Birds that live in complex environments like the dappled shade of a forest, or the complex vegetation of a wetland or grassland, often have complex feather patterns (especially dark and light) that more or less blend with their background, or at the least, make them difficult to detect until they move.  Some of the boldest black and white patterns, like the stripes on a Kildeer’s breast, actually distract one’s eye from the outline of the bird’s body.

kildeer-defending-chicks-

Until she moves, mama Kildeer isn’t obvious in this marshy wetland. I didn’t even notice her chick standing silently on her right until I was editing the photo for a blog post.

Some birds emphasize camouflage even more by combining spots of white or bands of dark and light on their feathers.

barred-owl-camouflage

A sleeping Barred Owl has pretty good camouflage in this leafless Amur Maple forest.

barred-owl-close-up

Stripes down its breast and spots on the wings and back of the Barred Owl help break up the solid outline of its body.

brown creeper-

The blotchy brown and white plumage of Brown Creepers lets them hide in plain sight on the rough bark of mature trees where they forage in crevices for prey.

So, one of the answers to why so many birds, especially those residents that live in the northern temperate forests all year, adopt splotchy patterns of black or brown and white plumage is that they maximize their ability to hide in plain sight by being boldly invisible.

the distraction lure

Some bird mothers go to great lengths to distract predators away from their nest and/or fledgling chicks.  They feign injury, flapping like they are wounded but can’t fly, chirping loudly to attract attention to themselves and away from their chicks.  I’ve seen Kildeer do this many times, as they lead me on a merry chase away from their nest.  For example…

But I’ve never heard of small songbirds using this strategy, until I saw it in action today when a female Indigo Bunting led me all over the backyard as I tried to find her nest and her chirping chicks.

indigo bunting-female feigning injury

Here I am, look at me, I’m helpless with my broken wings.”

Wings fluttering, hopping sort of helplessly through the grass, chirping continuously, and flying weakly from spot to spot, this female Indigo Bunting put on quite a show.

Moving around in the underbrush of the wildflower garden, I discovered two of her chicks, also chirping loudly, but hidden from view until one of them tried to cross a patch of grass.

indigo bunting-fledgling

Bunting chicks may fledge (leave the nest) after only 8 days, and can hardly fly more than 10 feet, so they tend to stay hidden in low, dense vegetation.

indigo bunting fledgling-

Not a very adept flyer yet…

indigo bunting-fledgling

The chick is not even fully feathered yet, has short stubby wing feathers, and no tail. It would be easy prey for a wandering cat…

Meanwhile, its mother is still chirping away at me, from all over the garden.

indigo bunting-female

first here…

indigo bunting-female

then here… (see that faint tinge of blue on her shoulder?)

indigo bunting-female

and finally right out in front of me.  Older females may be much bluer than this, with streaky blue patches on their shoulders, back, and tail.  But their overall drab plumage helps camouflage them while they care for the chicks.

indigo-bunting-male

A brightly colored male Indigo Bunting would attract way too much attention if he were feeding chicks in the nest.

Fun facts:

  • although Indigo Buntings are about the size of a Goldfinch and the female sort of resembles a female Goldfinch (but lacks those distinctive wingbars), they are actually members of the Cardinal family.
  • the blue color (especially evident in males) does not come from a blue pigment, but is due to special reflective particles in the feathers that scatter light and reflect blue wavelengths.  Read more about blue coloration in animals by clicking here.

on the river

A bright, sunny day above freezing requires a long walk, and what better place to go walking than by the river where the birds are supposed to hang out.  Suddenly there seem to be many more migrants around:  Red-winged Blackbirds, Song Sparrows, and Chipping Sparrows added their musical calls to those of the resident Cardinals, Chickadees, etc.

By the water’s edge, a couple of surprises awaited  us.

A pair of Kildeer were foraging (?) in the muddy grass.

A pair of Kildeer were foraging (?) in the muddy grass.  

A pair of immature Bald Eagles obviously didn't read the "Thin Ice" sign before stepping out on the icy edge.

A pair of immature Bald Eagles obviously didn’t read the “Thin Ice” sign before stepping out on the icy edge of the river.  Another pair of adult Bald Eagles soared overhead.

A lone kayaker braved the chilly water of the Minnesota River.  But what a great way to sneak up on the ducks!

A lone kayaker braved the chilly water of the Minnesota River to float downstream toward the Mississippi.  But what a great way to sneak up on the ducks!

It’s great to be able to walk around outdoors again!  Hooray for spring.