Blog #277 Feather Game—Part ll

 Two weeks ago the Osprey chicks reminded me of small fuzzy dinosaurs with bandit masked faces. Now, Hope at day 25 and Lucky at day 22 display flight feathers resembling their parents with three notable differences: their wings have more white on  them, their eyes are red-orange, and they have a tinge of chestnut on the napes of their  necks. It is still too early to discern their genders. 

Hope (L, 25 days) and Lucky (R, 22 days) under Ophelia’s shade. Note Hope’s adult back and tail  feathers in dark brown tipped with buff and the chestnut nape of the neck. 

The egg that failed to hatch is readily seen. Salt Point Osprey Cam screenshot. 

Their second set of grayish downy feathers to keep them warm as seen in the close-up  above grew in at about 11 days. By day 22, the feather shafts of Lucky’s sub-adult  plumage is beginning to develop. Lucky’s at about stage 4 (see below) in feather  development on the body and wings and at stage 6 on their heads. Hope is further  along at stage 5 and 6 all over.

Stages of feather development including breaking out of the sheath and unfurling,  courtesy of the Cornell Lab of Ornithology. 

By 42 days old, Hope should have a full set of sub-adult feathers and will later molt into  adult plumage by the age of 18 months. 

Fledging 

The process of growing flight feathers is called fledging. Many changes in appearance  and behavioral transformations take place during the fledging process. Before Ospreys  begin to fly, the young birds or fledglings must exercise their wing muscles and learn to  

coordinate them by flapping in the nest. After ≈8 weeks of practicing and learning  control the fledglings are ready to fly. Fledglings are great fun to watch as they practice  flight, furiously beating their wings and then looking surprised when they float above the  nest aided by a lucky gust of wind. In less than a week from the first flight, the fledglings will become competent flyers. 

But learning to fly is only half the challenge of reaching adulthood. The fledgling must  also learn to hunt effectively on its own and that will take the rest of the season. It is  only when the fledgling becomes an independent hunter, no longer dependent on its  parents, that it is called a juvenile. 

Keeping Feathers Neat 

Ospreys, regardless of age, have to preen their feathers. To keep their feathers in top  shape and waterproof, Ospreys spend hours spreading waterproofing preen oil  (uropygial oil) on their feathers and grooming them. Preen oil is a thick, transparent oil  consisting primarily of fatty acid diester waxes (uropygiols), fats, and fatty acids. The 

gland that excretes it is located at the base of the tail, on the lower back, just in front of  the tail feathers. This area is largely featherless except for a tuft of down at the tip called  the uropygial wick. This two-lobed gland secretes oil through small papilla or nipple-like  projections.  

Nipple-shaped uropreen gland of Osprey (left); close up of chicken (right), courtesy of Osprey Tales. 

When preening, the Osprey gently smooths each feather into its place, adjusting them  for flight and insulation and oiling them for water-proofing. Whenever the barbs are  disturbed, the Osprey uses its beak to carefully guide or zip them back into place one by  one, much like Velcro strips coming together. The bird rubs its bill and head over its oil secreting uropygial gland and then spreads this oil over its feathered body, wings, legs,  and feet to keep the skin and feathers conditioned. 

Orpheus preening. 

Anatomy of a feather, courtesy of Encyclopedia Britannica. 

Researchers have found feathers have a structural water proofing in addition to the  preen oil. Water droplets bead on a feather surface like a water repellant raincoat.  Feather surfaces are covered with miniscule nanosized grooves, which trap air around  the feather, preventing liquids from attaching to the wing surface.  

Water droplet on top of the nano-sized grooves in a feather, courtesy Jenssen Lab.

Furthermore, Ospreys prevent their feathers from becoming water-logged after diving by  giving a rapid doggie-shake, shedding most of the water. When an Osprey forcibly  shakes, their moving skin and feathers produce energy that physically breaks the weak  

Orpheus giving a quick shake after the rain to dry off. 

attractive forces holding the water molecules. This act of physically cleaving these weak  hydrogen bonds, called “mechanochemistry,” propels the water off the feather surface.  In addition, Osprey feathers’ lack aftershafts (see anatomy of a feather above), the  small extra feathers at the base of larger feathers on most birds. Without them, water  slides off Osprey feathers easily.  

Finally, scratching with their long, curved talons looks dangerous, but it is an important  part of the Osprey preening process. It removes ectoparasites, dead skin, and caked on  feces when bathing is not an option. Scratching also relieves itchy insect bites,  especially from the mosquitos, which plague Ospreys at night. Ospreys close their  white-feathered eyelids while scratching and preening to protect their delicate yet  powerful eyes. 

Eyes to the sky! Candace  

Candace E. Cornell 

Friends of Salt Point 

Lansing, NY  

cec222@gmail.com  

To Fledge or not to fledge, that is the question!

To fledge typically misused and misunderstood. To remedy this, I offer four relevant  meanings to our discussion from the Merriam Webster Dictionary. 

A. intransitive verb to fledge: (a verb not having or containing a direct object) 1) to acquire the feathers necessary for flight or independent 

2) to leave the nest after acquiring such feathers 

B. transitive verb to fledge: (a verb having or containing a direct object) 3) to rear until ready for flight or independent activity 

4) to cover with feathers or down 

ALL EYES ON OSPREYS 

WATCH! 

Salt Point Osprey Nest Cam 

READ! 

On Osprey Time 

Ospreys of Salt Point 

VISIT! 

Cayuga Lake Osprey Trail