As it’s Sunday, we have a themed batch of bird photos from John Avise. Today’s theme, like last week’s, is about bird eyes. John’s notes and IDs are indented, and you can enlarge the photos by clicking on them.
Don’t miss the leg-banded female woody at the end!
Eye-Rings
Eye adornments must be important in avian behavioral signaling and non-verbal communication. I say this because the eyes of many bird species have evolved colorful irises (see last Sunday’s WEIT post) or are otherwise exaggerated in appearance, much as people’s eyes vary with iris color or eyelid mascara.
Another way that avian eyes may draw attention is via the presence of eye-surrounding circles known as “eye-rings” that give the birds a spectacled look (much like large-rimmed eye-glasses on people). This week’s post shows several examples of North American avian species with notable eye-rings, which are a useful aide in species’ identification by birdwatchers. Because eye-rings have evolved independently many times in different avian taxa, we can speculate that they probably serve some adaptive role, perhaps in inter-bird communication or species recognition. But precisely what that adaptive role is remains uncertain. Readers are welcome to suggest potential roles for eye-rings, or how any such hypotheses potentially might be tested.
American Robin (Turdus migratorius):
Blue-gray Gnatcatcher (Polioptila caerulea):
Blue-headed Vireo (Vireo solitarius):
Hermit Thrush (Catharus guttatus):
Ovenbird (Seiurus aurocapilla):
Pacific-Slope Flycatcher (Empidonax difficilis):
Ruby-crowned Kinglet (Corthylio calendula):
Rufous-crowned Sparrow (Aimophila ruficeps):
Yellow-throated Vireo (Vireo flavifrons):
Townsend’s Solitaire (Myadestes townsendi):
Solitary Sandpiper (Tringa solitaria):
Laughing Gull (Leucophaeus atricilla):
Ring-necked Duck hen (Aythya collaris):
Wood Duck hen (Aix sponsa):
“Eye-rings”
Interesting theme!
Fascinating! One thing that eye rings universally do is make the eyes look larger. I’ve never thought about this before, but my guess is that at least 6.023 x 10E23 other people have noticed this as well. Thank you for posting these pictures.
Beautiful photos, as always, John! Thanks for sharing these.
You always open new worlds. Thank you.
Is there any correlation between white eye rings and distance of annual migration? Could it aid in low-light flight? Today’s birds seem like serious, working-class birds, not the silly sex-obsessed types.
Augmenting low-light vision during flight is a very interesting hypothesis that hadn’t occurred to me. Conversely, I have wondered whether eye-rings might help to alleviate the glare from bright sunlight (much as do human eyebrows, or the black cheek blotches that some baseball and football players use).
Kathy, upon further reflection, I really like your hypothesis about eye-rings helping vision in low-light environments. Indeed, several of the pictured species (including the vireos, ovenbird, thrush, flycatcher, and kinglet) usually reside in dense forests, often near the ground, where light may especially be at a premium.
Silvereyes/waxeyes have a conspicuous white eye, and are migratory and widespread in Australasia/Pacific region. https://ebird.org/species/silver3
I wonder if a pattern can be seen in diurnal animals that contrasts with nocturnal.
“Pattern” and “contrast” meaning if a whole set of animals were all compared – dark rings, light rings, nocturnal/diurnal…
This is an interesting idea, and made me also think of the athletes that use black paint to reduce glare as Prof. Avise says below….
Excellent as always!
Ovenbird! Must be good eatin’. 🙂
I’ll have to pay more attention to eye rings. I like the “low-light” explanation above, but I’m leaning more towards fitness. A bright white eye-ring may allow prospective mates to know the potential partner is healthy. Do the chicks of adults with eye rings have eye rings? Though I don’t think that adds any clarity to the matter.
Anyway, thanks again for another brilliant Sunday RWP.
For most of the pictured species, the juveniles do have an eye-ring, at least to some extent. Of course the “low-light” and ‘”health-signaling” hypotheses are not mutually exclusive, so both (and/or others) could be at play.
Interesting, thanks. And indeed, the eye-ring, I’m sure, has multiple functions, and thanks for pointing that out.
Super cool and thought-provoking post! Sorry to have missed it until now (I was rafting 🙂 )