Why are the birds discussed in this lab called darwin's finches?

The birds called "Darwin's Finches" are not really related to the finches but they share similarities to mainland finches. However, their beaks differ from other birds.

Darwin believes that the development of their beaks are due to their feeding habits and the type of food they eat in the Galapagos islands.

Their isolation in the Galapagos islands prompted the species there, like the birds, to undergo speciation in order to survive.