WILDLIFE NATURAL
HISTORY & INDENTIFICATION
Birds
Part I
LEC
University of Rio Grande
Donald P. Althoff, Ph.D.
02
Distinguishing Features of Birds
__________:
no other vertebrates have these.
Unique modification of the outer skin—clear
advancement over scales
HOLLOW BONES: extremely lightweight…
works in combination with feathers to
accommodate flight
_________: toothless and covered with a horny
sheath. More lightweight than jaws made of bone
_______________ EGGS: “richly provisioned”
external eggs. Most elaborate reproductive cells
of any animal
Distinguishing Features of Birds
WELL-DEVELOPED BRAINS:
6-11 times
larger than those of like-sized reptiles. Helpful
for processing sensory information, control of
flight muscles
HIGHLY DEVELOPED NEURAL SYSTEMS &
ACUTE SENSES: communication systems very
advanced (sight and sound to the n-th degree).
Navigation, depending on species,
accomplished by using patterns of Earth’s
magnetism, celestial cues, and maybe even
polarized light.
_______________: adaptations permit allow
metabolic demands of flight and temperature
regulation
Classification & Diversity of Birds
Aves
CLASS
29
ORDERS
FAMILIES
187
GENERA
SPECIES
> 2,050
> ______
Passeriformes (songbirds, perching birds, passerines)
• _______________ are the Order with the most:
Families 83 (next most is Charadriiformes…
shorebirds…with 19)
Genera1,161 (next most is Apodiformes…
swifts and hummingbirds…
with 128)
Species5,712 (next most is Apodiformes…
with 422)
5 types of feathers
• CONTOUR FEATHERS
• SEMIPLUMES
• DOWN FEATHERS (several kinds)
• BRISTLES
• FILOPLUMES
contour
feather
filoplume
semiplume
bristle
down
feather
Major Feather Types on the Wing
 Primaries
(___________ = wing feathers)
 Secondaries (remiges = wing feathers)
 Major _________ – leading edge of wing
 Alula—forms wing slot on leading edge (at
carpal bones
Major Feather Types on the Wing
3
2
1
1
4
2
Birds Often Can Be “sorted/classified” by
Toe Arrangements
• Most have _______ (3 toes forward, 1 toe back)
• Some have _______ connecting some toes (i.e.,
webbing…think ducks, geese)
• Some have lobes (think grebes)
• Some have “_______” = claws
Toe arrangements
2 3 4
____________
2 3 4
Syndactyl
2 & 3 fused
1
1
2
1
3
4
Pamprodactyl
2
1
3
4
____________
3
2
4
1
Heterodactyl
some ___________ BIRDS
Webbed and Lobed Feet
Partial webbing
Totipalmate
(4-toes)
cormorants
(3-toes)
ducks
Lobed
(grebes)
Power-strokeforward stroke (front) & side
views
Feeding & Digestion
• Many ______________—especially with respect
to beak & tongue designs
• Example: _______ designs include:
insect catchers
insect net
fruit plucker
generalized bill
flesh tearer
dip net
fish grasper
fish spear
mud sifter
water strainer
seed cracker
pine seed extractor
• For probing species,
ability to raise the tip
of the bill without
opening the mouth
provides opportunity
to exploit food
sources in the sand
(some shorebirds)
and/or soil
(woodcock)
• Woodcock shown
here has beak that
is 3+ inches long—
probes for
earthworms
American woodcock
Digestive System
MAIN TRACT
• Oral cavity
• Pharynx
• Esophagus
• _________
• Proventriculus
• _________
• Pylorus
• Small intestine
• Large intestine
• _________
AUXILLARY
• Liver
• Pancreas
Earthworm
small intestine
anus
mouth
pharynx
esophagus
CROP
GIZZARD
Reproduction & Mating Systems
• Wide array of “approaches” to choosing mates,
often involving elaborate displays
• Ultimately, it comes down to laying eggs…
• …and incubating those eggs
• …then parental care
Mating Systems
• Considerable variety in pair bonds for birds—
ranging from brief sexual union to sustained
mutual efforts:
Greek for…
1) monogamy – “mono” + “marriage”
2) polygamy – “many” + “marriage”
3) polygyny – “many” + “woman”
4) polyandry – “many” + “man”
5) polgynandry – “many” + “woman” + “man”
6) promiscuity – “pro” + “mix”
Monogamy
F+M
• “the” predominant avian mating system
• ______ of bird species (but % probably continuing
to drop because of DNA evidence on paternal
“contributions” to clutches…suggesting
promiscuity)
• Prolonged and essentially exclusive bond with a
single member of the opposite sex for purposes of
raising young.
• Appears common among passerines, raptors
(hawks and owls)
Polygyny..con’t
• ___________________—males are not defending
females nor are they defending a resource.
Instead, males compete for females by
establishing “dominance” or by demonstrating their
quality through displays.
Aggregations of many males in a small
area are called ________
ex.
V
prairie chickens
sage grouse
sharp-tailed grouse
https://www.youtube.com/watch?v=ut-bQn88xEc
Promiscuity
• ~6.0% of bird species
• Indiscriminant sexual relationships—usually of
_______ duration
• Examples: male hummingbirds and male
manakins (…and technically, one could classify grouse
species—lek or non-lek like the ruffed grouse found
locally as promiscuous)
Egg laying &
Nesting/Parental Care
• Nest preparation variable, ranging from…
a) no nest (just “lay” eggs) (ex. Nighthawks,
fairy tern)
b) scrap (ex. gulls)
c) scarp and line (ex. piping plovers, killdeer)
d) “build” a nest (most common)
e) “weave” a nest (ex. weaverbirds, orioles)
f) “build up” (many years, in some cases…
ex. eagles, hawks)
• Value of nest with respect to incubation of eggs:
a) _______ provided for development
b) ___________ to many predators
______________
• Considering the diversity of birds…including a wide
variety of mating strategies….all are limited to
laying eggs
• All lay a single egg laid at a time (usually 24-36
hours between eggs). Contrast this to viviparity in
lizards and snakes….multiple eggs are retained in
the oviducts of the female for extended (>24-36 hr)
periods of time. The strategy of viviparity suggest
that for this group of vertebrates, the benefit of egg
retention outweighs its cost (makes sense in “cold
climates”—eggs can start to develop sooner). Vice versa
with respect to birds…laying one egg per day, then
incubating them all must outweigh the cost.
ovary
infundibulum
1• Site of fertilization
2• Albumen and shell
3•
4•
membranes (not
shell) are secreted
Egg enclosed in
calcareous shell
Deposited
1
2
2
2
shell gland
3
4
___________
Different patterns of Laying Eggs
• Some species are _______________ layers:
a) a fixed number of eggs are laid
b) usually those species that have
1, 2, 3, 4, or 5 eggs for an average
clutch size.
c) remove and egg and they probably
won’t lay a “replacement” egg
d) example: piping plover
• Some species are ________________ layers:
a) not usually a “fixed” number of eggs
b) usually those species that have
10 or more eggs for a clutch
c) remove an egg or eggs and they just
keep laying (example: chicken)
Different patterns of Incubating Eggs
• Some species start to incubate eggs after 1-2 are
laid even if clutch ends up being 3-5 or more eggs
ex. Most raptors (hawks and owls)….results
in ________________ hatching of young
advantage? ______________________
• Some species do not start incubation until all eggs
in the clutch are laid. Common among species
with small clutches (i.e., 2-5) and large clutches
Results in ______________ hatching of young
advantage? _______________________
Clutch Size
• How many eggs should a bird produce?
• Optimal clutch size should = maximum number of
young (chicks) the parents can bring to the
fledgling size that ____________ their chances of
survival
Spectrum of Maturity of Young @ hatching
• ___________: eyes open, covered with feathers,
leave nest after one or two days
a) some are independent of parents at
hatching (megapods)
b) follow parents but find their own
food (ducks & shorebirds)
c) follow parents and are fed by
them (grebes, rails)
vs.
• _________: eyes closed, little or no down,
unable to leave nest, fed by parents (passerines)
Spectrum of Maturity of Young @ hatching
• Precocial
• Semiprecocial— eyes open, covered with
down, able to walk, remain at nest (gulls &
terns)
• Semialtricial—covered with down, unable to
leave nest, fed by parents
1. eyes open: herons and hawks
2. eyes closed: owls
• Altricial
Altricial vs. Precocial
• Eggs
Greater for _________
amount of yolk in eggs
amount of yolk remaining Greater for _________
@ hatching
• Chicks
size of eyes & brain
development of muscles
size of gut
rate of growth after
hatching
Greater for _________
Greater for _________
Greater for _________
Greater for _________
Major MIGRATION: ___________
Typically associate
flyways with
waterfowl
Pacific
Central Mississippi Atlantic
Major MIGRATION Short & Long Distance
Includes waterfowl,
passerines, even
raptors
Arctic Tern
Migration “impacts”
•
•
•
•
•
Fat reserves
Mating systems
Feeding habitat
Resting/loafing habitat
Setting of hunting seasons
Generally, only hunt
waterfowl migrating
“south”….thus, in the fall