Peter Repetti

Such a favorite and iconic pose!

A Great Egret wading in shallow water with its long neck curved into an S-shape, yellow bill poised just above the surface. A near-perfect mirror reflection fills the bottom half of the frame. Dense green and brown vegetation lines the bank behind. Sandy Creek Park, Durham, NC. August 14, 2025.

A Great Egret and its consultant, agreeing on the next move. Sandy Creek Park, Durham, NC. #BirdOfTheDay #StandingInWater #GREG

That looks purely paradisic!

Brrrrrr!

Thank you @robcrank68.bsky.social and @alan678.bsky.social for #BirdOfTheDay! I love the fun challenge of quickly having to think through my photo catalog to dig up shots that fit the theme. 📷 🐦

That iridescence!

A Boat-tailed Grackle photographed head-on at ground level, mid-stride on a sandy beach. Iridescent blue-black plumage, piercing yellow eyes, and long legs caught in a confident strut. Its shadow stretches to the right on the sand. Sunset Beach, NC. November 9, 2024.

Boat-tailed Grackle serving iridescent blue-black on the shoreline runway. No stylist. No agent. Just fierce main character energy, a beach and that swishy tail. Werk it! Sunset Beach, NC. #BirdOfTheDay #SteppingOut #BTGR

Journal of Field Ornithology: Nest usurpation and adult mortality in a secondary cavity-nesting songbird Competition for limited nest sites among secondary cavity-nesting bird species is intense and may result in loss of nests, physical conflict, injury, and occasionally death. The Prothonotary Warbler (...

Cavity life has a cost. Scerbicke et al. (2024) found House Wrens usurped 38% of PROW nests; puncturing eggs and removing nestlings. Limited real estate, fierce competition. In our yard, when I hear them sing, I think, "oh, the murdurous House Wren is here for my bluebirds and chickadees"

Female prothonotary Warbler clinging to a moss-covered tree trunk with a bill full of green moss for nesting material. Golden-yellow body with olive-tinged darker wings visible. The bird is perched vertically on the trunk, looking slightly upward. The trunk is draped in moss and small vines. Soft green, out-of-focus swamp forest background. April 30, 2022. Great Dismal Swamp.

Female Prothonotary Warbler, bill stuffed with moss destined for a cozy old woodpecker hole. Most eastern warblers weave open nest cups, but the PROW is the only one that chooses already-excavated cavities, preferably over standing water. #PROW #NestBuilders #BirdOfTheDay alt.

Behavioral, Morphological and Physiological Correlates of Diurnal and Nocturnal Vision in Selected Wading Bird Species Abstract. We examined in selected wading bird species if diurnal or nocturnal foraging and the use of visual or tactile feeding strategies could be correlated with retinal structure and function. The ...

Rojas et al. (1999) measured rod:cone ratios across six wading bird species. Rods detect dim light; cones handle color and detail. Yellow-crowned Night-Heron: 2.3:1 — the only one where rods outnumber cones. Cattle Egret? 0.3:1. Same family, very different eyes.

Close-up side profile of a Yellow-crowned Night-Heron head against a soft green background. The large orange-red eye is sharply focused, surrounded by slate-blue facial feathers. Buffy-gold crown plumes sweep back from the forehead. The heavy dark bill shows texture and wear. Fine white filoplumes extend from the nape. Warm light catches the crown and lore area. Sandy Creek Park, Durham, NC. July 22, 2025.

A face built for the night shift. Yellow-crowned Night-Herons have rod-dense retinas tuned for low light, a bill heavy enough to crack crab carapaces, and the patience to stand motionless until something moves. #YCNH #BirdOfTheDay #SideView

Does solar irradiation drive community assembly of vulture plumage microbiotas? - Animal Microbiome Background Stereotyped sunning behaviour in birds has been hypothesized to inhibit keratin-degrading bacteria but there is little evidence that solar irradiation affects community assembly and abundan...

Graves et al. (2020) found vulture plumage is dominated by Deinococcus, a bacterium famous for surviving extreme radiation. Dark, melanized feathers had the most. Feather-degrading microbes were nearly absent. Sun exposure doesn't just clean; it curates!

Turkey Vulture perched atop a broken tree snag with wings fully spread in the horaltic pose, backlit by warm morning light. Dark brown-black plumage with lighter brown feather edges visible across the wings and tail. Small red featherless head in profile, including sharp hooked beak. Dark, blurred foliage behind. September 9, 2025 @ 8:37 AM. Durham, North Carolina.

This isn't just a power pose. Turkey Vultures drop body temp overnight to save energy, then spread their wings in the AM to reboot: solar-heating flight muscles, UV-killing feather bacteria, baking off parasites. This "horaltic" pose is maintenance and power. #TUVU #PowerPose #BirdOfTheDay

Biophysical optimality of the golden angle in phyllotaxis - Scientific Reports Scientific Reports - Biophysical optimality of the golden angle in phyllotaxis

Why 137.5°? The golden angle ensures each new leaf or primordium is maximally displaced from all previous ones — optimal packing, minimal self-shading. Sunflower heads show it most dramatically: 34 spirals one way, 55 the other. Both Fibonacci numbers. This geometry is everywhere in plants.

Fig. 6: 3D model. 3 rules explain the spiral: (1) divide along the shortest wall, (2) new wall must pass through the outer face, (3) displace the division point away from the oldest neighbor walls. Rules 1+3 are sufficient. The model tolerates substantial noise and works across starting shapes.

Fig. 1: Time-lapse confocal imaging of the moss apical cell dividing over 48 hours. Each division produces a new daughter cell (future phyllid) and a new apical cell. The divisions rotate in a spiral; average divergence angle 126.9°, close to the golden angle. All from one tetrahedral cell.

Vascular plants and mosses both produce Fibonacci-like spiral phyllotaxis, but diverged 450MYA. One uses auxin transport across a multicellular meristem to get the shape, the other does so via a single cell dividing such that new walls avoid oldest neighbors. Convergent evolution or deep homology?

Female Northern Cardinal perched on a bare branch in falling snow, facing the camera. Plumage puffed for warmth, showing warm buff-orange body, red-tinged crest dusted with snow, red-orange bill, and dark face mask. Snowflakes fill a soft gray background. February 19, 2025. Durham, NC.

She's not migrating. Cardinals don't use torpor; they depress nighttime body temp ~1.3°C, saving an estimated 10-16% on energy. In winter, diet shifts from insects to seeds. Fat reserves hit 3x summer levels. Puffed plumage traps warm air. Brrrrr.
#NOCA #WinterSurvivors #BirdOfTheDay

My shorebird/duck knowledge is severely lacking. I've heard of the BBWD, but never seen one in person! I'm making up for my deficit thought this morning at Barnegat Light State Park in NJ. It's been amazing. Many lifer birds!

The first time I saw ducks sitting a tree: 🤯

10 Fun Facts About the Barred Owl Maniacal laughter. Pink wings. Tree climbing. This bird has a lot going on.

See #5!

Barred Owl perched in a lichen-covered tree, facing the camera with dark eyes and a pale facial disc. Its breast and belly feathers are visibly soaked and disheveled from hunting crayfish, with one wing draped loosely around a branch. Talons visible. Overcast sky behind. September 7, 2025. Sandy Creek Park, Durham, NC.

This Barred Owl is still drying off after a successful crayfish hunt. Some apparently eat so many that their underwing feathers can turn pink (!) from the carotenoids, like a flamingo. The most opportunistic owl in North America; 85+ prey taxa documented. #BAOW #portrait #birdOfTheDay

What a talented beast!!

Amazing capture!

Two male Hooded Mergansers on still water, facing each other with crests fully raised, displaying the striking fan-shaped white patch bordered by black. Both birds show golden-brown flanks, black backs with white striping, and bright yellow eyes. Their reflections ripple in the water below. January 26, 2025. Durham, NC

Hooded Mergansers can change the refractive properties of their eyes to hunt underwater by sight. Built-in goggles via their transparent nictitating membrane. These two males are sizing each other up topside, but the real action is below the surface. #HOME #DivingForFood #BirdOfTheDay

My #BirdOfTheDay offering is this male bluebird feeding his mate, a mating ritual seen regularly in the spring in middle Tennessee.

#birds #canonbirdphotography #wildlife #BirdOfTheDay #bluebird

American Robin perched on a thick tree branch with its beak packed full of insects and invertebrates. The bird displays the species' characteristic dark gray-brown upperparts, brick-orange breast, and broken white eye ring. Soft green foliage fills the background, out of focus. The robin is in profile, facing left. April 23, 2025. Durham, NC

Beak crammed with every squishy invertebrate it could find. Maximizing prey per trip, minimizing flight time to the nest. The bill-loading strategy: efficiency over elegance. Parents of all sorts will recognize this energy math. #AMRO #Birds&Bugs #BirdOfTheDay

SLQ1 operates at ER–plasma membrane contact sites, running a pathway that opposes the LAZY auxin gradient. Wild-type gravitropism integrates both; their relative strengths set the growth angle! S149F breaks SLQ1 oligomerization, flipping the balance. Yoshihara & Spalding, PNAS 2025.

How do you find a gravity-sensing system nobody knew existed? First, knock out all 4 Arabidopsis LAZY genes so the plants can't stand up. Then, mutagenize thousands of those plants, and look for the one that pops back up! One aa change (S149F in SLQ1), and a whole new pathway emerges. #gravitropism