Foraging ecology and plant dispersal by fruit bats: the role of social, genetic and physiological factors

Status
Currently In Progress
Foraging is a pivotal animal movement process, and is governed by internal and external factors that stem from
physiological motivations and constraints, social and behavioral aspects, and resource distribution. These
factors cross through trophic levels in the case of animal‐mediated dispersal of plant seeds, where the foraging
movement of the dispersing animal affects the movement of the dispersed plant. Social behavior, genetic
associations, and energetic demand, expenditure and gain, play a key role in determining animal foraging
movements. In the proposed research framework, we take an individual‐based mechanistic approach to link
between these underlying factors, animal foraging movement paths and ensuing patterns of seed dispersal.
The Egyptian fruit bat (EFB), Rousettus aegyptiacus, is a highly social mammal, an important seed
dispersal vector for a variety of plants, an agricultural pest and a disperser of invasive plants, thus providing an
excellent model for the proposed study framework. In our previous work carried out on this system, fascinating
foraging patterns have been uncovered. Importantly, the EFB chooses specific fruiting trees to which it returns
to night after night, ignoring many other fruiting trees. However, its social life has largely remained a mystery,
and other key factors controlling its foraging patterns, such as energetic constraints, are still unknown.
In the proposed research, we aim to elucidate the complex relationships between social, genetic and
individual physiological factors, which give rise to movement patterns of free‐ranging EFBs, and in turn
influence the spatial distribution of dispersed plants. To achieve this, we aim:
(A) To quantify movements, social and genetic associations among roosting and foraging bats.
(B) To characterize the affinity to a favorite fruit tree across individuals, seasons and years.
(C) To elucidate how genetic (familial) and social (colonial) associations among foraging bats determine the
individual choice of favorite trees.
(D) To develop a predictive energy landscape model for explaining individual foraging patterns, costs, benefits
and choice of favorite tree.
(E) To examine how social and genetic associations among bats, and their physiological considerations and
constraints, jointly and separately affect bat‐generated seed dispersal patterns.
We will quantify movement using high‐resolution GPS tracking devices, and the innovative ATLAS radio
tracking tags applied to an almost entire EFB colony. We will quantify social and genetic associations by radio
tags, video cameras, DNA samples and field experiments on favorite trees. We will elucidate energetic
cost/benefit factors from empirical data on bat movement, morphology and flight metabolisms calibrated by
wind tunnel measurements, and from fruit nutritional analysis. We will estimate bat‐generated seed dispersal
kernels based on high‐resolution movement data. Finally, we will synthesize these results into an individualbased
framework to elucidate how interactions among social, genetic and physiological factors shape bat
foraging behavior and the resulting seed dispersal patterns.