• Currency
– What is to be maximized
• Strategy set (decision)
– What the animal can do
• Constraints
– The limits of the model

• Currency
– Net energy intake per time
• Strategy set
– Add another prey type to diet or don’t
• Key constraints
– Searching and handling are mutually exclusive
– Prey are encountered sequentially
– Animal has perfect information
– Prey of a given type are identical

• E = Energy
• T = Time
• λ = Encounter frequency
• h = Handling time
• Math Time

• All-or-nothing rule
• The inclusion of a less profitable item depends only on the absolute abundance of the more profitable prey types
– Increased overall abundance will lead to diet narrowing

• Absolute abundance of large prey matters
• Birds do not abide by “all-ornothing” rule
– Why not?
• Error
• Sampling

• Currency
– Net energy intake per time
• Strategy set
– Stay or leave
• Key constraints
– Density of prey in a patch decreases exponentially because predator searches at random
• Energy gain decreases over time in patch
– Predator has complete knowledge of landscape

• The expected travel time correlates positively with the time spent in each patch and the level at which each patch is exploited
• The effect of patch richness depends on the shape of the exploitation function

• Central place foraging
– Travel time
• Predictions
– Load time and load size increase with distance to patch

• Conclusions
– Animals make subtle distinctions to optimize behavior
• But why isn’t the fit better?
– Predation risk
– Sampling
• Why don’t we just add more terms?

• Animals can learn about patch quality
• Animals are
Bayesians

• Ecological risk
• The fitness value of a food item depends on one’s energetic state
• Predicts risk-sensitivity when foraging