After Humboldt, Frank went on to pursue a PhD at Mississippi State University. For his thesis, Frank investigated how shade coffee can harbor forest-associated species of birds in Kenya. Previous research has shown that coffee farms in the Neotropics can provide good habitat for birds, but it remains uncertain how well coffee supports birds strongly associated with forests, and much less work on this topic has been done in Africa. Frank compared and contrasted bird abundance and diversity between shade coffee farms in central Kenya and adjacent natural forests of Karura forest and Ngong road forest. His analysis revealed which Kenyan forest bird species are and are not able to occupy shade coffee farms. This understanding helps clarify the role of natural forests and agriculture in Kenyan bird conservation and helps inform land use planning that incorporates the management and diversification of the anthropogenic matrix in which natural areas are embedded.