DOI: 10.5061/dryad.kwh70rzcz
title: Does sentinel presence improve foraging success? A study in a cooperative breeder

description: In various cooperative breeding species, a group member often sentinels
 from a prominent position that enables early detection of approaching
 predators and then utters alarm calls to which the other group members
 react immediately. We tested in the cooperatively breeding Arabian babbler
 (Argya squamiceps), whether in the presence of a sentinel the other group
 members forage for longer or more effectively. In natural observations, at
 different distances from the shelter and in different group sizes, we
 found no effect of sentinel presence on foraging time. Likewise, in a
 giving-up density (GUD) experiment with artificial food patches containing
 mealworms at each of three different distances from the shelter, fewer
 mealworms were consumed further from the shelter, irrespective of whether
 a sentinel was present or not during foraging. While foragers react to a
 sentinel’s alarm calls when a predator approaches, our findings indicate
 that Arabian babbler foragers do not improve their foraging efficiency due
 to the sentinel's presence. Combined with previous studies on the
 Arabian babbler, these findings reinforce the conclusion that in this
 species the sentinel is 'selfish' and benefits from early
 detection of predators. These results contrast with those from other
 cooperative breeders in which sentinels utter calming calls and foraging
 efficiency increases when sentinels are present. We, therefore, suggest
 that similar sentinel behaviour may serve different sentinel systems and
 functions in different cooperative breeders.
description: Data were collected in field observations as well as throughout
 an experiment. The raw data are presented in two files: one for the
 natural observations and the second for the experiment. Data were analyzed
 by R, and R codes were presented.  
description: # Does sentinel presence improve foraging success? A study in a
 cooperative breeder by Roni Ostreiher, Roger Mundry & Aviad Heifetz ##
 Files: * experiment_data.txt and nat_obs_data.txt are tab-separated text
 files (i.e., plain asci) * nat_obs_data.txt contains the data collected
 during the natural observations * experiment_data.txt contains the data
 collected during the experiment * code_natural_observations.r and
 code_experiment.r contains the R code for the analysis ## Columns in
 nat\_obs\_data.txt: * row.id: consecutive integers with row numbers; *
 subject: ID of an individual (nested in the group, i.e., the same ID in
 different group means different individual); * obs.id.within.group: ID of
 the trial within a group; * date: the date at which a trial was conducted
 [day, month, year; year with 2 or 4 digits]; *
 foraging_within_sentinel_yes: total time foraging within the shelter when
 sentinel was present [seconds]; * foraging_within_sentinel_no: total time
 foraging within the shelter when sentinel was absent [seconds]; *
 foraging_near_sentinel_yes: total time foraging near the shelter when
 sentinel was present [seconds]; * foraging_near_sentinel_no: total time
 foraging near the shelter when sentinel was absent [seconds]; *
 foraging_far_sentinel_yes: total time foraging far from the shelter when
 sentinel was present [seconds]; * foraging_far_sentinel_no: total time
 foraging far from the shelter when sentinel was absent [seconds]; *
 preening_sentinel_yes: total time preening when sentinel was present
 [seconds]; * preening_sentinel_no: total time preening when sentinel was
 absent [seconds]; * interactions_sentinel_yes: total time spent with
 social interactions when sentinel was present [seconds]; *
 interactions_sentinel_no: total time spent with social interactions when
 sentinel was absent [seconds]; * moving_sentinel_yes: total time moving
 when sentinel was present [seconds]; * moving_sentinel_no: total time
 moving when sentinel was absent [seconds]; * resting_sentinel_yes: total
 time resting when sentinel was present [seconds]; * resting_sentinel_no:
 total time resting when sentinel was absent [seconds]; *
 total_time_sentinel: total time a sentinel was present (obsolete and not
 used); * total_time_foraging: total time foraging (obsolete and not used)
 [seconds]; * total_time_other_behavs: total time spent with other
 behaviours (obsolete and not used) [seconds]; * obs_dur: total observation
 duration (obsolete and not used) [seconds]; * group: ID of the group; *
 tot.time.sentinel.yes: total time a sentinel was present [seconds]; *
 tot.time.sentinel.no: total time a sentinel was absent [seconds]. ##
 Columns in experiment\_data.txt: * group: ID of the group; * repetition:
 index number of the experiment (i.e., order of experiments, per group)
 [consecutive integer per group]; * date: the date at which the experiment
 was conducted [D.M.YYYY, DD.M.YYYY, D.MM.YYYY, or DD.MM.YYYY]; * seconds:
 duration of feeding [seconds]; * mealworms: number mealworms eaten
 [count]; * distance: distance from the shelter in which the tray with the
 mealworms was placed [factor with levels close, middle, and far]; *
 context: dominance (dominant or subordinate) and sex of the sentinel if
 there was one present and otherwise 'Without sentinel'; *
 r.date: date in nr. days elapsed since 1970-01-01 [integer]; * group.size:
 size of the group [nr. individuals]; * winterID: ID of the testing winter
 (extends over the change of years); * day.in.season: nr. days elapsed
 since the first experiment of a given testing winter [days];sentinel:
 sentinel status (absent or present).