Hummingbirds choose not to rely on good taste: information use during foraging

Abstract

To increase their chances of survival and reproduction, animals must detect changes in food quality and then decide if, and how quickly, to adjust their behavior. How quickly an animal responds to change will depend on the information available (cognitive, sensory, or physiological) and how it weights those types of information. Surrogate measures of meal size suggest that sensory information is used to make initial choices about how much to eat following changes in resource quality, choices are subsequently altered and refined as further information becomes available. Using direct measures, we investigated the amount of food consumed, the time taken to feed, and the interbout intervals between visits to a feeder of rufous hummingbirds, before and after changes in sucrose concentration. The hummingbirds did not change how much they drank at first experience of a new concentration but then rapidly adjusted meal sizes toward optimal for that concentration over a few feeding visits. Thus, it seems the hummingbirds used both cognitive and physiological information to decide how much to drink but appeared to ignore sensory information, such as taste. The early responses animals make to changed resources enable us to determine the types of information on which they rely most in their decision making.

The dynamics of hummingbird dominance and foraging strategies during the winter season in a highland community in Western Mexico

“…The partition of resources among hummingbird species has been explained by different mechanisms related to: differences in nectar resource use (Lyon, 1976;Justino, Maruyama & Oliveira, 2012), variations in foraging behavior (Feinsinger & Colwell, 1978;Stiles, 1985;Sandlin, 2000a;Lara, Lumbreras & Gonz alez, 2009), population movements at the landscape scale following plant blooming (Des Granges, 1979;Guti errez-Zamora & Rojas, 2001), microhabitat differences (Guti errez-Zamora & Rojas, 2001;Ritchie, 2002), interspecific morphological variations in traits such as weight, beak length and curvature (Stiles, 1975;Lyon, 1976;Snow & Snow, 1980;Rodr ıguez-Flores & Stiles, 2005;Maglianesi, B€ ohning-Gaese & Schleuning, 2015), spatial and temporal segregation in floral use patterns (Ornelas et al, 2002;Lara, 2006;Lara et al, 2009) and phylogenetic relationships among species (Martin & Ghalambor, 2014). Several of these mechanisms are based on the hummingbird's abilities and movement capabilities, all of which allow them to use a heterogeneous distribution of nectar resources at a given time, and take appropriate decisions on the basis of their morphological and physiological characteristics (Ritchie, 2002;Bacon, Hurly & Healy, 2011).…”

The psychophysics of sugar concentration discrimination and contrast evaluation in bumblebees

“…probability of reward, amount of reward: Markowitz 1952; Kahneman and Tversky 1979; Wedell 1991; Kacelnik and Brito e Abreu 1998; Bateson et al 2003; Cnaani et al 2006; Bacon et al 2011). Theoretical analyses of choice assume that different reward dimensions are integrated into some common currency, that is, “utility” (Chib et al 2009; Kenrick et al 2009).…”

From a sequential pattern, temporal adjustments emerge in hummingbird traplining

“…For our experimental birds, however, depleting the available resources may have been worth the cost of flying with a half full crop after having ingested more sucrose per visit than these birds usually drink in a single bout. Although we did not measure the frequency of intruders or how often the birds revisited a patch after they had chased away an intruder, modifying the value of a male's territory does change his behavior: when the concentration of the sucrose in their feeder was increased from 14% sucrose solution to 25%, territorial males fed less often (Bacon et al 2011).…”