[1] Gillespie's main area of research is in determining the patterns of species richness within a given geography, specifically native Hawaiian flora and tropical dry forests in biodiversity hotspot such as Hawaii, Sundaland, Indo-Burma, New Caledonia and the Caribbean, through remote sensing and GIS.
"[4] In 2009, Gillespie, along with UCLA geography professor John A. Agnew and several undergraduates, published the paper "Finding Osama bin Laden: An Application of Biogeographic Theories and Satellite Imagery" in the MIT International Review.
The results suggested that bin Laden would be based in a tall building with several rooms, electricity, and coverage in a large city.
Although the paper did not specify a specific city, Abbottabad, Pakistan, where bin Laden was eventually killed, was within the allotted range at 268 km.
[2][11] Gillespie heads the restoration efforts at Sage Hill, a four-acre lot with native shrubbery located on the UCLA campus.