Parasitism

Hidden predators

Introduction

• Parasitism is a symbiotic relationship in which one organism benefits while the other is harmed

• Common Parasitic Organisms– Fleas, ticks, tapeworms, roundworms

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

Cuckoos are parasites!• Yes Birds can be parasites!

Cuckoos are a special type of parasite called

a BROOD PARASITE

Reed Warbler feeding a Common Cuckoo chick in a nest.

Notice the size difference….

One of these

things is not like the

other…

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!

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.

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.

Other Brood Parasites

• A Shiny Cowbird chick being fed by a Sparrow