1. Parasitism
Hidden predators

2. Introduction
• Parasitism is a symbiotic relationship in
which one organism benefits while the other
is harmed
• Common Parasitic Organisms
– Fleas, ticks, tapeworms, roundworms

3. Human Parasites
• When we think of a parasite we normally
think of small things that live inside or on
other organisms
– Ticks,
Ascaris – a
roundworm that can
live in the human
small intestine when
food is ingested that is
contaminated with
their eggs

4. Cuckoos are parasites!
• Yes Birds can be parasites!
Cuckoos are a special
type of parasite called
a BROOD
PARASITE

5. Reed Warbler feeding
a Common Cuckoo
chick in a nest.
Notice the size
difference….
One of
these
things is
not like the
other…

7. Murderer!
• 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!

8. Sibling Rivalry
• 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.

9. Push It!
• 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.

10. Other Brood Parasites
• A Shiny
Cowbird
chick
being fed
by a
Sparrow