Birds
Class Aves~530 Species in BC
Robin diet
Annelid worms
Steller Jay diet
Berries Nuts
Woodpecker diet
Insects
Humming Bird diet
Nectar
House Finch diet
Seeds
Ospreydiet
Fish
Peregrine diet
Birds
Barred owl diet
mice
Feathers are made of
Keratin
Keratin is-
Modified reptilian scale
Adaptive significance of feathers
Thermoregulation
Display behavior
Camouflage
Flight
Types of fethers
Flight Feathers
Contour Feathers
Down feathers and semiplumes
Filoplumes
Flight feathers
Primaries on hand
Secondaries on forarm
Tail feathers
Barbules
interlock the barbs with tiny hooklets.
Preening
Re zips hooklets onto barbules
Molting
Occurs and certain life stage
occurs seasonally
Complete Molt
All the tracts replaced within a short time
Parital molt
Parts of tracts are replaced piecemeal: tail and or primary flight feathers are often retained
Molting in late summer/ fall
Prebasic molt
Prebasic molt results in
basic plummage typically a complete molt
Pre alternate molt results in
Alternate molt (breeding or seasonal camoflage) typically partial molt
Eclipse plumage
Drakes are flightless during prebasic molt in later sumer and look like females
How are bird foremims modified for flight
Bird bones are hollow with struts for strength
Many bird bones fused, redused
Aerodynamis of flight
Both wings and individual feathers act as airfoils creating lift.
Lift
Air flowing over an airfoil creates lift
Drag
Reduces lift by clowing air moving over the airfoil
Friction
turbulence
Wing loading
Body weight / unit area of wing
high wing loading
Small wings reative to body mass: flap wings rapidly and fly fast eg Duck
Low wing loading
Larg wings relative to body mass: fly slowly for a long time eg hawk
Aspect Ratio
Ratio of wing length/width
High aspect ratio
long narrow wings- maximum lift and minimum drag (low turbulences) eg albatrosses
LoLow aspect ratio
Similar length and width good control at low speeds, maneuverability
eg. Passerines
Ellipitical wings
Low aspect ratio for high maneuverability at low speed and in tight spaces; rapid takeoff
larg wing slots and alulas to reduce drag and low speed
Generally high wing load
High speed wings
tapered wing tips and swept back angle to reduce drag at high speed.
High aspect ratio high wing load
lacki of wing slots or alulas
dynamic soaring wigs
use wind shear above ocean
high aspect ratio for high lift low wing load
lack of wing slots or alulas
High lift wings
Use thermal winds/ updrafts
Wing slots , alulas increasing lift at low speeds
low aspect ratio for maneuverability
generally low wing load
Bird circulation
4 chamberd heard
Largest hearts relative to body size
efficeint blood pumping
High blood pressure
crop
Storage chamber- food passed on for digestion or reguritated for young
Proventriculus
Enzyme production site of pellet formation in owles , hoawks and kingfihsers
Gizzard
Muscular chamber lined with rough keratin contains sandy grit
Nitrogenous waste excrectred as uric acid
Excrete uric acid into cloaca
Excess water reabsorbed in cloaca
Forms white paste, Mixes with feces
Excess salkt secreted by a special salt glands
Special salt glands above each eye secrete high concentration of salt
Salt soloution excreted via internal or external nostrils
Thermoregulation Heating (5)
Shivering Feathers Posture Thermal countercurrent Communal roosts
Shivering(thermal reg hot)
The primary means for increasing heat production for birds is shivering. The large flight muscles as well as the leg muscles play an important role in generating heat by shivering
Feathers (thermal reg hot)
number of feathers varies seasonally; more during the winter than the summer - position of feathers controlled by dermal muscles
Posture (thermo reg Hot)
Reduce heat
- withdraw feet into plyumage
- tuck head and neck under wing
Thermal counter current
Limted heat loss in cold wather because of thermal counter current in legs( arterial blood warms returning blood in veins)
Communal roosts (thermoreghot)
Burrowing
Thermoregulation (cooling)
Evaporation
Posture
Radiation
Evaporation ( thermoreg (cold)(3)
birds lack sweat glands
so evaporation can occur only via
respiratory system: - panting
- gular flutter
POsture (thermoreg)
Posture
to increase heat loss:
- extend wings
thermoregulation
can give off heat during hot weather: increased blood flow to legs in water • storks & vultures defecate on legs to increase heat loss by evaporation
Bird vision
• Vision is the dominant sense in birds – Color vision well-developed in diurnal birds - many cones – Nocturnal birds have few cones and many rods – Most birds can see UV – Some birds can see polarized light
Olfaction
Poor smell
Migration
Mass movement of individuals between breeding and wintering areas
Defining characteristics of migration
Seasonal(predictable)
Large numbers of individuals
Dispersal
Movement away from natal area
- Solitary
- New location unpredictable
Irruption
Movement away from food poor area
- not annual
- unpredictable
Migratory restlessness
Controlled by hormones activated by changing day lengths
Why do birds migrate
When benifits are higher than costs of using well seperated breeding and wintering areas
- food availbiility
- reproductive sucess
temerate zone pro/con
Abundant food and longer days for foraginf in sping/ summer
Food shortages and cold in winter
Tropics zone pro and con
High density of nest parasites and predators
Mild temperatures and food availability in winter
diurnal migrants
often depend on thermal winds or updrafts
may depend on diurnal food resourses
Nocturnal migrants
cooler less turbulant
avoid diurnal predators
Soarers
Flight concentreated in mid day when thermals occur
Powered flight
often crepuscular (start before dawn) nocturnal migrants
Natal dispersal
Fist movement away from the nest area
Breeding dispersal
Movements of adults between diffrent breeding locations.
Male reporductive system
Males
• testes small, bean shaped most of year
• testes enlarge 300 x at breeding season
• most males lack a penis
Fermale reproductive system
only left ovary and oviduct develop
• eggs fertilized at top of oviduct
• albumin, shell membrane, shell added during
passage down oviduct
Advantages of colonial breeding
favored by scarcity of sites safe from predators
favored by scarcity of sites near abundant food
- cooperative protection from predators
- enhances foraging on ephemeral food supplies
Disadvantages of colonial breeding
colony may attract predators
- increase the spread of nest parasites
- increased competition for food