• Parasitism is a symbiotic relationship in
which one organism benefits while the other
• Common Parasitic Organisms
– Fleas, ticks, tapeworms, roundworms
• When we think of a parasite we normally
think of small things that live inside or on
Ascaris – a
roundworm that can
live in the human
small intestine when
food is ingested that is
Cuckoos are parasites!
• Yes Birds can be parasites!
Cuckoos are a special
type of parasite called
Reed Warbler feeding
a Common Cuckoo
chick in a nest.
Notice the size
not like the
• Female Cuckoos watch the behavior of the
Reed Warblers as they build their nests and
start their broods.
• At the appropriate moment the mamma
Cuckoo flies down to the reed warblers'
nest, pushes one Reed Warbler egg out of
the nest, lays an egg and flies off!
• Cuckoo chicks methodically evict all host
progeny from host nests. It is a much larger bird
than its hosts, and needs to monopolize the food
supplied by the parents.
• The Cuckoo chick will roll the other eggs out of the
nest by pushing them with its back over the edge.
• If the Reed Warbler's eggs hatch before the
Cuckoo's egg, the Cuckoo chick will push the other
chicks out of the nest in a similar way.
• Once the Reed Warbler chicks are out of the nest,
the parents completely ignore them.
Other Brood Parasites
• A Shiny
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