Sampling and tracking a changing environment: persistence and reward in the foraging decisions of bumblebees

Abstract

The question of when to collect new information and how to apply that information is central to much of behaviour. Theory suggests that the value of collecting information, or sampling, depends on environmental persistence and on the relative costs of making wrong decisions. However, empirical tests of how these variables interact are lacking. We tested whether bumblebee foraging decisions are indeed influenced by these two factors. We gave bees repeated choices between a resource providing a steady, mediocre reward and a resource fluctuating between a low reward and a high reward. In this paradigm, we manipulated environmental persistence by changing how long the quality of a fluctuating resource remained stable at one reward level. We manipulated the costs of decision errors by changing the relative values of the available rewards. Bees sampled the fluctuating resource more frequently when it changed quality more frequently, indicating that they measured environmental persistence and reacted to it as predicted by theory. Bees showed surprisingly suboptimal tracking, not reliably choosing the currently best resource except when the fluctuating resource was very persistent and the potential rewards high. While bees modify their choices in response to different levels of change and potential rewards, they do not always do so according to optimality predictions.

Noisy communities and signal detection: why do foragers visit rewardless flowers?

“…For example, when floral displays are highly heterogeneous, carry-over effects (a preference for signals similar to known rewarding ones) may keep visitors foraging on flowers that resemble rewarding ones [45], as mentioned in §3a. Additionally, foragers' attempts to adjust acceptance thresholds in response to frequent changes in PDF overlap could inflict high learning costs, or require extra assessment to make adaptive choices [64]. These learning and assessment costs could prevent flower foragers from adjusting acceptance thresholds.…”

Testing Pollination Syndromes in <i>Oenothera</i> (Onagraceae)

“…Hildesheim et al 2019;Kalisz & Vogler 2003;Moreira-Hernandez & Muchhala;Opedal et al 2016) and studies have examined how reliability of floral rewards affects pollinator behavior (e.g. Austin et al 2019;Dunlap et al 2017); however, how stochasticity in the presence of pollinators affects floral evolution and the delineation of pollination systems remains a largely understudied topic. Future studies testing the pollination syndrome concept should utilize plant-pollinator data with broad spatiotemporal coverage when defining primary pollinators and consider how pollinator reliability across time and space may influence the interpretation of pollination syndromes (or the lack thereof) in their focal species.…”

Irrational risk aversion in an ant

“…The majority of studies on nectarivores have been carried out on bees. Results have, however, been unclear, possibly due to the previously described binomial interpretation of risk (Shafir 2000;Weber et al 2004): bees have been observed to be risk-indifferent (Banschbach and Waddington 1994;Perez and Waddington 1996;Fülöp and Menzel 2000), risk-averse (Waddington et al 1981;Shapiro 2000), to follow the budget rule (Cartar and Dill 1990;Cartar 1991), or a mixture of those depending on risk variability (Shafir et al 1999;Shafir 2000;Mayack and Naug 2011;Dunlap et al 2017). Bees and other eusocial insects represent a special case for risk sensitivity.…”