The Simpsons have a chaotic couch gag and opening credits.

Marge gets a scam letter about a student book.

Marge takes the family to a go-kart arcade as a reward.

The family races go-karts, with Nelson causing trouble.

Homer fails at batting while Lisa wins a prize.

Nelson and Bart get a BB gun from prize tickets.

Marge forbids Bart from playing with Nelson.

Bart sneaks to Nelson's house to use the BB gun.

Bart accidentally kills a mother bird with the BB gun.

Marge learns Bart went to Nelson's and lies about it.

Bart imagines a bird tribunal punishing him.

Marge finds the dead bird and gives up punishing Bart.

Bart discovers the dead bird's eggs and decides to raise them.

Bart watches a nature film about blue jays and egg care.

Bart uses a light bulb to keep the eggs warm and tries regurgitation.

Marge finds Bart with the eggs and forgives him.

The eggs hatch into Bolivian Tree Lizards, not birds.

Bart takes the lizards to a bird expert who identifies them as dangerous.

The authorities order the lizards killed, but Bart refuses.

Bart is chased and the lizards are seemingly killed.

The lizards survive and begin to multiply, eating pigeons.

The town celebrates the lizards for killing pigeons.

Homer proposes a chain of predators to fix the lizard problem.

Bart realizes he killed many birds but doesn't care.