Hummingbirds modify their routes to avoid a poor location

Area of Science:

• Behavioral Ecology
• Foraging Behavior
• Animal Navigation

Background:

• Traplining, the repeated sequential visiting of locations by animals, is common across species.
• Factors influencing traplining routes, especially in response to changing resource availability, are poorly understood.
• Foragers are expected to adapt routes to prioritize profitable sites and avoid depleted ones.

Purpose of the Study:

• To investigate how wild hummingbirds modify their traplining routes in response to changes in floral reward concentration.
• To determine if hummingbirds prioritize increased rewards or avoid decreased rewards within their traplines.

Main Methods:

• Wild hummingbirds were observed foraging on established traplines with manipulated sucrose concentrations in specific flowers.
• Changes in the order of flower visitation and overall route structure were recorded.
• Responses to both increased and decreased sucrose concentrations were analyzed.

Main Results:

• Hummingbirds did not alter their traplines to visit flowers with increased rewards first.
• Birds actively avoided flowers with decreased sucrose concentrations by modifying their traplining routes.
• Route modifications included changing the trapline's origin or direction, depending on the location of the depleted flower.

Conclusions:

• Hummingbirds exhibit asymmetric adjustments to their traplining behavior, prioritizing avoidance of negative changes over pursuit of positive ones.
• This risk-averse foraging strategy may be linked to the territorial nature of hummingbirds.
• Understanding route modification in response to resource variability is crucial for comprehending animal foraging strategies.