DOI: 10.5061/dryad.f1vhhmh5v
title: Foraging strategies by a frugivorous primate (Eulemur rubriventer) shape spatial patterns of seed dispersal

description: The movement decisions of frugivores shape spatial patterns of seed
 deposition, with considerable impacts on plant individuals, populations,
 and communities. However, we have a limited understanding of the
 mechanisms determining the foraging strategies behind the movements of
 frugivorous animals and their interaction with the landscape. We
 investigated foraging strategies of red-bellied lemur (Eulemur
 rubriventer) groups dispersing fruits of the tropical tree Harungana
 madagascariensis. We used spatially-explicit mechanistic simulations to
 examine movements and seed dispersal generated by four theorized foraging
 strategies in an agent-based model: frugivores move directly to the 1)
 most rewarding plant in the landscape, 2) nearest fruiting plant, or
 towards the most rewarding plant in the landscape, with stops at any
 fruiting plants encountered along the way according to a local attraction
 distance of 3) 10 m and 4) 20 m. We then compared 12 metrics and data
 distributions for seed dispersal and movement patterns from these models
 to empirical observations. Simulations of foraging strategies with
 directed movement toward highly rewarding resources (strategy 1) produced
 the longest seed dispersal distances and best-matched observed patterns.
 Observed data of lemur movements and directionality best-matched results
 from three strategies, simulations toward highly rewarding resources
 without stops (strategy 1) and with either stop along the way with a 10 m
 (strategy 3) or 20 m (strategy 4) attraction distance. Collectively, our
 results supported the strategies in which lemurs moved consistently
 towards the small number of trees that produced the most fruit on the
 landscape. Because these trees were located far from each other, the
 landscape interacted with lemur foraging strategies to produce the longest
 dispersal distances compared to the strategy of moving towards the closest
 fruiting trees regardless of crop size trees that produced fewer fruits
 nearer lemur locations. Our work supports incorporating a mechanistic
 understanding of animal foraging, movement behavior, and landscape
 patterns in fruit production for the prediction of seed movement. Explicit
 considerations of these mechanisms can improve our understanding of the
 maintenance and structure of diversity in plant communities, with
 implications for the conservation of forest ecosystems relying heavily on
 animals for seed dispersal.
description: 2.1 Study Area Our study took place at
 Valohoaka camp in Ranomafana National Park, Madagascar. This park
 encompasses 41,000 hectares of mid-elevation (500-1500 m) rainforests
 (average annual rainfall 2,835 mm), set aside in 1991 to protect a
 particularly biodiverse ecosystem within a Malagasy biodiversity
 conservation hotspot (Myers et al., 2000; Wright & Andriamihaja,
 2002). Valohoaka is in a relatively intact and homogeneous portion of the
 protected primary forests of Ranomafana National Park (Razafindratsima,
 2017). Research permits for field work were provided by the Malagasy
 Ministry of Environment, Ecology, and Forests. As this was an
 observational study, involving no handling or manipulation of the animal’s
 environment, ethical approval was not necessary. 2.2
 Data Collection Movement and Dispersal
 Observations We collected data on frugivory, movement,
 and seed dispersal over three months (May - July 2018) by following two
 habituated groups of the frugivorous lemur, <em>Eulemur
 rubriventer</em>.<em> </em>This is a large-bodied (1.58
 kg – 2.63 kg) (Terranova & Coffman, 1997) species with a diet
 consisting of 80% fruit (Overdorff, 1993). Individuals live in small
 nuclear family groups that stay close to each other while they move and
 forage (average group size of 3.44 ± SD 0.55)(Razafindratsima et al.,
 2014). Daily surveys, which began at 06:30 and concluded at 15:00 hrs,
 were carried out by a dedicated team for each lemur group. Observation
 teams, which followed the lemurs on foot, were composed of three highly
 trained lemur follow technicians who recorded data and always kept the
 lemurs in sight. On each survey day, we cycled through group individuals
 to select a focal individual for a given day, then recorded every instance
 of frugivory by the focal individual. Fieldwork
 resulted in 590 hours of observation, with 431 frugivory events at 210
 individual plants. Using these data, we calculated the time, distance, and
 direction of travel between successive foraging events. Throughout the
 survey period, we also recorded any instance of seed dispersal by all
 group individuals, identified all seed species, and recorded the location
 of the event using a Garmin eTREX GPS device (Garmin, Olathe, KS, U.S.A).
 We recorded 346 dispersal events for all plant species. Gut retention time
 was calculated for <em>Harungana madagascariensis</em> from
 these data using the 25 dispersal events (423 individual seeds) which
 occurred a minimum of 5 hours past the start of the survey, and for which
 there was a single possible source plant. We selected the cut-off of five
 hours based on a previous gut retention study on this species so that we
 could eliminate the risk of incorrectly identifying the source plant
 (Razafindratsima et al., 2014). We restricted the following analysis to
 the dispersal of <em>H. madagascariensis</em> seeds (Fig 1),
 as this species represented most of the dispersal events that could be
 sourced to a single-parent plant. In previous work, lemurs have been found
 to feed primarily on this species in the dry season (Dagosto, 1995)
 (comprising ~ 25% of their frugivory events in our study), and it is
 considered a keystone resource (Overdorff, 1996). We obtained gut
 retention estimates like those calculated by Razafindratsima et al. (2014)
 for this species.
description: # Foraging strategies by a frugivorous primate (*Eulemur rubriventer*)
 shape spatial patterns of seed dispersal
 [https://doi.org/10.5061/dryad.f1vhhmh5v](https://doi.org/10.5061/dryad.f1vhhmh5v) ## Description of the data and file structure This dataset contains descriptions of the movements and seed dispersal of two groups of red-bellied lemur (*Eulemur rubriventer*) in Ranomafana National Park, in Madagascar. These data were used to inform the lemur movement parameters for agent-based models and to compare the seed dispersal outcomes of these models to empirically observed dispersal patterns by a wild population. ### Files and variables #### File: empirical\_movements.csv **Description:** These data describe the movements of lemur groups between individual trees where they consumed fruit. ##### Variables * month: the month of the year when the data was taken (numeric, 1-12) * day: the day of the month when the data was taken (numeric, 1-31) * year: the year when the data was taken (2018) * group: the name of the lemur group (Sakafo or GOT) * decimal_time: the time when the movement began with minutes translated to decimals (9:30 am = 9.5) * start_tree: The individual ID of the tree where the movement began * end_tree: The individual ID of the tree where the movement ended * movement_start_time: the time when the movement began with minutes translated to decimals (9:30 am = 9.5) * movement_end_time: the time when the movement ended with minutes translated to decimals (9:30 am = 9.5) * distance_between_points: the straight-line distance between start and end points in meters * start_y: the latitude of the start point * start_x: the longitude of the start point * end_y: the latitude of the endpoint * end_x: the longitude of the endpoint #### File: empirical\_seed\_dispersal.csv **Description:** These data describe the dispersal events. Outlining their start and end location. ##### Variables * id_seed: ID given to an individual seed * id_cluster: ID given to a cluster of co-dispersed seeds * date: variable showing which dispersal events occurred on the same day * group: the name of the lemur group (Sakafo or GOT) * tree_species: the common name of the plant species where the lemur was standing when the dispersal event occurred * scientific_name: the scientific name of the plant species where the lemur was standing when the dispersal event occurred * tag: the individual plant ID of the plant where the lemur was standing when the dispersal event occurred * fruit_seed: the common name of the dispersed seed * scientific_name_seed_fruit: the scientific name of the dispersed seed * seed_number: the number of seeds in the sample * seed_id: the id number of the seed within the cluster * seed_minimum: the minimum number of seeds in the sample * dispersal_time: the time elapsed between fruit consumption and see defecation. This is equivalent to gut retention time. in HH:MM * source_tree: the individual plant ID of the plant where consumed the seed * start_y: the latitude of the start point * start_x: the longitude of the start point * end_y: the latitude of the endpoint * end_x: the longitude of the endpoint * startdist: the dispersal distance in meters ## Code/software This data may be viewed with any text editor software