Final answer:
Scientists can determine if two bird species are related by examining homologous structures and genetic sequences, then visualize their evolutionary relationships with a phylogenetic tree.
Step-by-step explanation:
Two methods that a scientist could use to determine if two species of birds are related to each other involve examining their physical features and their genetic sequences. Firstly, by comparing homologous structures, which are physical features that are similar due to common ancestry, scientists can deduce a relationship. For example, the wings' bone structure in different bird species can provide evidence of a common evolution path. Secondly, by analyzing DNA and gene sequences, scientists can measure how closely related two species are, with more similar genetic codes suggesting a closer relationship. A phylogenetic tree, or a diagram that outlines evolutionary relationships, can help visualize these connections among birds and other organisms.