Brood patch: A bare area (larger on females) that develops in the breeding season to help keep eggs and chicks warm. Peregrines do settling-like movements so eggs and chicks are in contact with the brood patch.

Cere: The yellow, featherless skin on the upper part of the beak and (surrounding the nares (nostrils).

Cloaca: The cloaca is a single opening found underneath the tail. It is a multi-purpose opening for excretion, transfer of sperm and egg laying.

Crop: The crop is a storage organ which allows birds to quickly ingest food. When the crop is full, the chest area bulges visibly.

Crop dropping: is when food is moved from the crop to the falcon’s ‘stomach’ (proventriculus and gizzard) for digestion. They do this by lifting their heads with beak open, sometimes with a wiggle of the neck.

Eyas: is a term only used for raptor chicks and includes the period from hatching to first flight. It originated as a falconry term, but is now in wider use.

Feaking: is rubbing or wiping the beak on a surface to help clean it of prey material.

Fledge: the first flight from the nest of a young raptor.

Fledgling: a young raptor who has recently flown for the first time.

Hallux: is the hind toe.

Orbital ring: is the yellow, featherless area around the eyes.

Malar: The malar stripe is the dark grey or black patch of plumage below the eye. It is believed to reduce the amount of glare reflected into the eyes when hunting. The stripe is different on each falcon and can help in identification of individuals.

Mantling: is the spreading of wings around prey to prevent it being seen or stolen by another bird.

Moult: is the changing of one set of feathers for another. In peregrines, they are grown bilaterally and gradually so as not to interfere with flight and hunting. The process can take up to 26 weeks.

Nare: The nasal openings in the cere. They contain small, bony tubercles that break up air flow during stoops, enabling the falcon to breathe easily.

Nictating membrane: is the peregrine’s third eyelid. It is translucent and moistens and cleans the eye via blinking in a side-to-side motion. It can be closed to protect the eye during flight at high speed.

Pellet: Indigestible material (feathers and bones) forms into a solid oval shape called a pellet. This is cast (regurgitated) sometime after a meal.

Pin feathers (blood feathers): New feathers growing from the feather follicle look like feather shafts or pins. They are encased in a keratin sheath and have a blood supply which recedes back into the follicle as the feather grows. The sheath is removed via preening and the feather emerges and the blood supply is lost once the feather is fully grown.

Preening: is grooming of the feathers with the beak to straighten and position them.

Preen gland: is located at the base of the tail and produces an oil used to coat the feathers by preening to keep them waterproof.

Primary feathers: are the longest and largest of the feathers and the ones most necessary for flight. They are also known as primaries.

Rouse: is the action of erecting and shaking the feathers as part of grooming.

Secondary feathers: are the inner flight feathers and the second largest of the falcon’s feathers. They are also known as secondaries.

Scrape: is the name of a peregrine nest but is also the action of scraping gravel to create an indentation and wall for future egg laying.

Stoop: is the action of a falcon flying to a height, folding back the wings and dropping at very high speed (300kph) in order to make a kill.

Sub-adult: a juvenile peregrine in the process of transitioning from juvenile to adult plumage.

Talon: is a raptor’s toenail or claw.

Tarsus (plural is tarsi): is the area of the falcon’s leg between the talons and the next joint which is actually the ankle even though it bends backwards. Chicks rest on their tarsi until they have the strength to stand, and will still occasionally rest on them in the juvenile stage.

Tiercel: is a term sometimes used for the male peregrine. As with eyas and ‘falcon’ for the female, these terms originated in the falconry world, but are now more widely used.

Tomial tooth: Peregrines have a triangular notch on the upper beak known as the tomial tooth. It is used to sever the spinal column of prey at the base of the skull, resulting in a quick kill.

Warble: is the action of stretching both wings overhead.