?Maximization of energy or nutrient balancing:he interplay between fruit chemical content and foraging behaviour in fruit-eating birds?

BLENDINGER, PEDRO G.; IRENE BENDER; LOMÁSCOLO, SILVIA B.; JULIETA MAGRO; ORDANO, MARIANO; NUÑEZ MONTELLANO, GABRIELA; ANDRÈS RAMIREZ-MEJÌA; ROMAN RUGGERA; VALOY, MARIANA

Simposio; 7th Frugivores and Seed Dispersal Symposium; 2020

ABSTRACT. The fruit diet of frugivores is driven by foraging strategies of energy maximizationor nutrient balancing. However, frugivores face a changing fruit market when they makeforaging decisions. It is well known that the amount of available fruits and phenotypic traitmatching impose filters on the fruit diet, but lesser is known about the role on foragingdecisions of the fruit chemical content. The differences between fruit species in pulp quantityand chemical quality can interact with behavioural, morphological and physiological traits ofthe consumers, determining the contribution of the fruit species to the provision of nutrientsand energy. We use extensive field and laboratory data and modelling to explore whether afruit-based diet can provide energy and nutrients necessary for frugivores, as well as itsvariation between functional types of frugivores. Using Resource Provisioning Effectiveness(RPE) framework we investigate the effectiveness of consumed fruit species to provide dailyrequirements of energy to Andean birds, and compare them with the composition of fielddiets. Similarly, we use Nutritional Geometry (NG) framework to assess the adjustment of fieldfruit diets to a theoretical diet balanced in macronutrients. We use diet data of ca.35 birdspecies from different sites and seasons, chemical data of ca.40 species of fruits; we model thedaily ingestion rate of each fruit species for each frugivore, and estimate their energyassimilation and macronutrient balancing in the diets. Then, we assess how fruit RPEs andbalances depend on the bird´s fruit handling behaviour, body size and specialization, and theadjustment of the diet to energy maximization (in terms of RPE) and nutrient balancing (interms of NG) strategies. We provide valuable information on how fruit chemical compositioninteracts with the ability of the frugivores to acquire pulp, determining the foraging decisionsand the composition of the fruit diet.