C. Lee Gass


How do animals use information about themselves and their environments? How intelligent are they in using it? What kinds of memory are important, and what constrains the use of it? How does cognition function in the economy of nature? We explore these and other questions in laboratory, field, and computer simulation studies of hummingbird foraging.
In our computerized laboratory, we evaluate hummingbirds' energetic performance as they forage. By manipulating the complexity and geometric structure of habitats, we've learned that hummingbirds learn static environments whole, as spatial maps. Spatial memory is less important in changing situations, where itis more useful to associate features of the environment with risk and opportunity. Both in the laboratory and in remote mountain meadows, predictions from optimal foraging theory guide our studies of how hummingbirds live in a complex, changing world.

Also, in the laboratory, we manipulate the size, shape, orientation, and distribution of feeders (and how these things change) to explore the energetic significance of hummingbird morphology in foraging. For example, with their longer bills and tongues, females can remove nectar faster than males from all but the shortest of flowers. We are now exploring the possibility that with their shorter wings, males may negotiate 3-D 'obstacle courses' of flowers faster than females, compensating their disadvantage at flowers.

Learning and remembering of spatial patterns by hummingbirds
Anim. Behav. 50:1273-1286
Sutherland, G.D. & C.L. Gass
Spatial association learning by hummingbirds
Anim. Behav. 46:487-497
Brown, G.S. & C.L. Gass
The problem of temporal scale in optimization: three contrasting views of hummingbird foraging
The American Naturalist 140: 829-853
Gass, C.L. & W.M. Roberts
Importance of energy costs in central place foraging by hummingbirds
Ecol. 70: 195-205
Tamm, S
Responses of territorial hummingbirds to experimentally enriched patches of flowers: energetic profitability and learning
Can. J. Zool. 63: 2125-2173
Gass, C.L. & G.D. Sutherland