Birds and Mammals Flashcards
(31 cards)
What characteristic links birds with modern-day reptiles rather than mammals?
A diapsid skull - two openings for muscle attachment - helps widen mouth.
What was Darwin’s missing link?
Archaeopteryx - had feathers similar to modern day birds but had long, bony tail, teeth, and clawed fingers.
What’s the evolutionary origins of birds?
Theropods.
What’s the difference between paleognathus and neongathus birds?
Neognathus birds are common birds, paleognathus birds are larger and flightless - e.g. Kiwi and Moa.
What’s the evolution hypothesis for paleognathae?
Originated in Northern hemisphere and dispersed into the Southern hemisphere (where the evolved to become flightless convergently).
How do birds maximise thrust and lift and reduce drag and weight?
By being lightweight, streamlined, having efficient respiratory, circulatory, and digestive systems, and by having powerful flight muscles.
How are birds lightweight?
Pneumatised - hollow bones.
What are the key parts of feathers?
Vane (flattened surface), shaft (supporting structure down middle of feather), quill (hollow end of shaft), barb (lateral struts extending outward from shaft), and barbule (hooked filaments from barb - latch onto one another - strengthens feather).
What are the main types of feathers?
Wing feather (classic), down feather (soft feathers - warmth under wing feathers), tail feathers, and contour feathers (vaned feathers that help streamline shape).
Define aposematism, and Batesian vs. Mullerian mimicry.
Aposematism - warning colouration.
Batesian - copy of aposematism without being dangerous.
Mullerian - copy of aposematism while being dangerous.
What’s the key anatomy in bird wings?
Wing slots between primaries (feathers attach to arm), secondaries (on arm), Carpometacarpus - fused carpals and metacarpals promotes wing rigidity. Fused clavicle - wishbone - stores elastic energy in wing beats. Pygostyle - fused tail vertebrate - produce rigidity for flight. Sternum with keel - attachment site for wing muscles.
How do flight muscles in birds work?
Bird muscles act as a ‘pully’ system, where the contraction of pectoralis muscle pulls the wing downward while the contraction of supracoracoideus muscle pulls the wing upward.
What are the two main kinds of wings?
Active soaring - long and narrow gliding more than flying. No wing slots. Elliptical wings - broad wings, large wing slots - made for bursts of fast, controlled flight - high maneuverability. (Albatross vs. Pīwakawaka.)
What does wing aspect ratio refer to/mean?
The ratio of wing length to width - high aspect ratio = less maneuverability - more speed. low aspect ratio = more maneuverability - less speed.
How do birds in cold climates withstand standing in snow/cold?
They warm the blood that’s been cooled by the environment before returning the blood to the heart.
How does the perching mechanism of a bird work?
When birds perch, as they bend their legs before they land, outer tendons automatically tighten and cause the toes of the bird to close around the perch - more energy efficent.
Why are toucan bills the way they are?
They have veins in their bill - can direct blood flow to the bill to release excess heat and maintain stable temperatures in tropical environments.
What are crossbills, how do they work?
Bills where the lower mandible is curved to the side. These crossbills + ability to shift lower mandible to the side = can pry open conifer cones and extract seeds with tongues - leverage.
What’s the process of digestion in birds?
Esophagus - crop (stores food) - proventriculus (digestion) - gizzard (grinds food) - small intestine - large intestine - cloaca (single opening for waste excretion).
Why may rocks be found in bird gizzards?
Some birds have been seen to swallow rocks to store in the gizzard to assist in grinding up food.
How do birds excrete nitrogenous wastes, how does this differ from mammals?
Birds excrete nirtrogenous waste as uric acid rather than urea (mammals). Uric acid requires significantly less water than urea and proves to be more efficient.
What is the pattern of food requirements and bird size?
As bird size increases, their food requirements (in relation to their body weight) decreases (e.g. 3g hummingbird eats 100% of its body weight per day, 11g bluetit eats 30%).
How does avian respiration work?
Air travels to the trachea - mesobranchii (bronchus) - some air enters lungs for gas exchange, some fills prosterior air sacs. Fresh air sac air then enters lungs and used air exits body via exhalation. During inhalation spent air from lungs is pushed into anterior sacs - exits during second exhalation.
