Feeding%20III:%20Specialized%20Structures,%20Learning

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Feeding III Specialized Structures, Learning
American woodcock, Nantucket
Great Egret Immokalee, FL

• JodyLee Estrada Duek, Ph.D.
• With assistance from Dr. Gary Ritchison
• PBS Life of Birds

Willet, Nantucket
Oystercatcher, Nantucket
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Crop

• out-pocketing of the esophagus that's
  particularly well-developed in seed-eaters like
  pigeons doves (Columbiformes) and gallinaceous
  birds (grouse and pheasants)
• specialized for production of 'milk' that pigeons
  doves feed to their young. Crop milk is rich in
  proteins, fats, vitamins and is produced by
  proliferation sloughing off of epithelial cells
  that line the crop.

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Ventriculus or Gizzard
Source http//arbl.cvmbs.colostate.edu/hbooks/pat
hphys/digestion/herbivores/birds.html

• the avian equivalent of teeth
• very muscular (less in birds that eat meat,
  insects, nectar, and other 'soft' foods)
• used primarily to grind break up food (such as
  seeds)
• may, in seed-eating birds, contain grit (small
  stones ingested to help grind the food)
• lined with tough, abrasive keratin-like layer of
  koilin, known as the cutica gastrica (or
  cuticle)The cuticle is secreted by simple tubular
  glands

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Red Knots Gizzard Size

• van Gils et al. (2003) served knots that had
  large and small gizzards (as determined by
  ultrasonography) a selection of hard intact
  molluscs and soft mollusc meat
• Knots with large gizzards consumed more molluscs
  with shells than the birds with smaller gizzards
• van Gils et al. (2003) offered a shell-heavy
  diet, but even the birds with largest gizzards
  fed 16 hours a day to sustain weight
• Birds with smaller gizzards couldn't feed enough.
  By allowing them to crush more shell per
  gizzard-full, larger gizzards gave birds the edge
• Also found the knot's gizzards enlarged when the
  molluscs begin shrivelling (as their winter food
  supply dwindles)

Frequency distribution of gizzard mass of
free-living Red Knots (N920).
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Variable Gizzard Size

• adult Japanese Quail (Coturnix japonica) (a)
• Red Knots (Calidris canutus) (b).

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Burrowing owl traps beetles
Golf Links Blvd., Tucson

• Levey et al. (2004) compared what Burrowing Owls
  ate when there was a typical litter of dung at
  the entrances to their nest burrows with diet
  when the dung was removed
• The owls ate 10 times more beetles when dung
  present waste did not build up by accident.
• Burrowing Owls nest in tunnels, and place a
  variety of debris, including dung, at entrance 
• After finding Burrowing Owls had dung beetles in
  their diet, proposed owls use dung as bait
• cleared all nest entrances at two colonies of
  owls of debris
• one owl colony had a typical littering of dung
  applied
• other was left bare.
• after four days each entrance was again
  completely cleared and the situation was reversed
• when dung was present, the owls ate ten times
  more dung beetles.
• As Levey says, "this experiment demonstrates that
  tool use makes a difference". -- Peter Wood, BBC
  News Online 

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Avian geophagy purpose?

• geophagy (the intentional consumption of soil) is
  known for geese, parrots, cockatoos, pigeons,
  cracids, passeriforms, hornbills, cassuaries
• Brightsmith and Muñoz-Najar (2004) observed ten
  species of psittacids, three species of
  columbids, and two species of cracids consuming
  soil from banks of a river in Peru.
• preferred soils were deficient in particles large
  enough to aid mechanical breakdown of food
• Percent clay content and cation exchange capacity
  (CEC), both predicted to correlate with
  adsorption of toxins, did not differ between used
  and unused sites as had been found in a similar
  study
• preferred soils were more saline and had higher
  concentrations of exchangeable sodium
• This suggests that the choice of soils at their
  study site was based primarily on sodium content
• Experimental evidence has shown that soils are
  capable of adsorbing biologically relevant
  quantities of toxins in vitro and that soil
  consumption by parrots does reduce the absorption
  of toxins in vivo
• They did not find evidence that parrots choose
  soils with greater CEC or clay content, the
  characteristics that correlate with the capacity
  to adsorb toxins
• Instead, they found that birds chose soils with
  higher concentrations of sodium
• These two findings are not mutually exclusive but
  instead suggest that there may be a set of
  conditional rules for soil selection
• In situations in which sodium concentrations are
  variable, the birds appear to choose soils that
  are highest in sodium (this study)
• In areas in which sodium concentrations are
  uniformly high, birds may choose the soils that
  have the largest ability to adsorb dietary toxins

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Geophagy in Macaws, Parrots
www.pbs.org/wnet/nature/realmacaw/photoessay6.html
A group of green wing and scarlet macaws
congregate on a clay lick by a river in the
jungles of the Amazon. Clay licks are high
concentration of minerals that form in river bank
clay deposits. Below Parrots at a clay lick.
www.pbs.org/wnet/nature/realmacaw/photoessay7.html
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Bird Diet Beak Digestive System Varies
Accordingly

• Nectivore
• Frugivore
• Insectivore
• Herbivore seed-eater
• Piscivore
• Carnivore
• Scavenger
• Omnivore

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Obligate vs. Opportunistic Practice

• Make a list of 10 birds you think might be
  obligate feeders on particular resources. Look
  at their wings, feet, and beaks. Are they highly
  specialized?
• Now make a list of birds that appear
  opportunistic. HINT They are probably
  omnivores. Look at their wings, feet, and beaks.
  How are they adapted for their lifestyle.
• Be sure you consider morphological,
  physiological, and behavioral adaptations

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Food and Learning, Solothe Monarch Butterfly /
Jay story
Aposematic coloration Müllerian mimicry
By Lincoln P. Brower
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Food and Learning, SocialBlue tits
http//sunaddict86.blogspot.com/2007/11/provisioni
ng-choices-and-offspring.html

• blue tit at a bird feeder http//birdcinema.com/vi
  ew_video.php?viewkey760c8bbafb4acb29e344
• Blue tits (insectivore seed eater) and robins
  learned to drink milk from delivered bottles in
  1930s
• When foil covers were introduced, blue tits
  learned to pierce, socially passed this on
  robins never did

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Tool Use

• According to reports by Jane Goodall in Tanzania,
  vultures search as far as 50 yards from egg to
  find a proper tool
• forward jerking movement of the vultures' head
  when breaking an egg with a stone is similar to
  movement when the bird pecks to break an egg. 
• Other species of birds break eggs by throwing
  them on stones.  However, this is not considered
  tool use because the stone is not being used as
  an extension of the bird's body. 

Egyptian vultures
www.pigeon.psy.tufts.edu/psych26/birds.htm
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Vulture tool-use hypothesis

• Alcock(1975) theorized vultures originally threw
  eggs
• They evolved from throwing eggs to throwing rocks
  at eggs.  The use of rocks probably began when a
  vulture accidentally broke an egg with a rock 
• Vultures' aim is poor, hitting the target 40-60
  persist until they succeed
• C.R. Thouless (1989) supports Alcock, finding
  vultures prefer egg-shaped stones
• Assumed connection to original behavior of
  throwing an egg
• (National Geographic Society, 1972) showed that
  vultures will try to use a stone to break a green
  or red egg-shaped decoy, but do not attempt to
  break white cubes
• Observations by Thouless of young vultures reared
  without exposure to adults proved that throwing
  stones at eggs is innate, not learned
• vultures need to learn that ostrich eggs are a
  source of food before they begin cracking them
• learning occurs when a young vulture encounters
  an egg already cracked

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Tortoise tossing

• In the Dardia Mountains of Greece, eagles can be
  seen carrying tortoises up to a great height and
  dropping them on to rocks below
• The hapless Aeschylus (525-456 BC) (ES-kih-lus ),
  a father of Greek tragic drama, is said to have
  met his end this way
• A soothsayer foretold he would be killed on a
  particular day by a house falling on him he
  spent the day outdoors
• Alas, his bald head looked like a rock

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Green Herons Fish with Bait
www.pigeon.psy.tufts.edu/psych26/birds.htm
The green heron drops a small object onto the
water Fish swim to the surface, hoping the object
is prey The heron then snatches the fish

• The practice of bait-fishing is rare among green
  herons
• The fact that few herons use bait-fishing
  indicates it is not innate behavior
• infrequency suggests the behavior is not
  culturally transmitted
• The roots of using objects to attract fish are
  unclear
• One theory suggests herons imitating human
  behavior when they use bait for fishing
• Attempts to teach herons to use bait for fishing
  have failed
• Another possibility is herons learn to use bait
  through experience, i.e. the heron accidentally
  drops an object in the water and sees the object
  attract fish
• Some researchers believe making the connection
  between dropping something on the water and
  seeing the crowd of fish that results and
  intentionally dropping bait is very difficult
• According to researchers, only exceptionally
  intelligent herons bait-fish
• The intelligence requirement accounts for rarity
  of green herons who bait-fish
• Others argue that infrequency of the behavior is
  because few herons have the opportunity to
  observe the results of dropping an object into
  the water  

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Tool Use
Caledonian Crow uses a twig as a tool to extract
grubs

• The Galapagos woodpecker finch snaps off a twig,
  trims it to size and uses it to pry insects out
  of bark.
• In captivity, a cactus finch learned to do this
  by watching the woodpecker finch from its cage.
  The teacher helped the pupil by passing a
  ready-made spine across for the cactus finch to
  use.

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Woodpecker Finch
www.pigeon.psy.tufts.edu/psych26/birds.htm
A woodpecker's long barbed tongue enables it to
extract grubs from branches the woodpecker finch
compensates for its short tongue by grasping a
cactus spine in its beak and prying grubs out of
the branch with the cactus spine

• The finch then drops the cactus spine and holds
  it under its foot while eating the grub
• The cactus spine is carried from branch to branch
  for reuse
• Millikan and Bowman(1967) saw finches adjust
  posture and manipulation of tool according to its
  size and shape
• woodpecker finches were more likely to use tools
  with an increase in hunger
• the large Galapagos cactus ground finch was caged
  next to woodpecker finches acquired similar tool
  usage .  Other species of finches did not learn
  to use tools as probes
• observed a young woodpecker finch's acquisition
  of the skill of using the cactus spine.   The
  finch attempted to obtain grubs by using its
  beak.   When that failed, it used a twig to reach
  into the branch.  Another finch snapped off a
  part of a forked twig to fashion a superior tool 
  
• Millikan and Bowman(1967) also observed
  woodpecker finches shortening long cactus spines
  to form more manageable tools.   This
  manipulation of an object is impressive
• Brown(1975) posits that woodpecker finches would
  be replaced by woodpeckers or nuthatches if
  either of those species were to come to the
  Galapagos islands.  His basis for this theory is
  that woodpeckers and nuthatches have more
  effective morphological means for accomplishing
  what the woodpecker finch does with tools.

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Carrion Crows Using Cars as Tools
www.pbs.org/lifeofbirds/brain/index.html

• Seen in Japan California since 1990s to crack
  walnuts
• The crows already knew about dropping clams from
  a height on the seashore to break them open, but
  this didnt work for walnuts because of the soft
  green outer shell.