DOI: 10.5061/dryad.sxksn03c5
title: Prey size mediates interference competition and predation dynamics in a large carnivore community

description: Direct competition for resources is especially fierce among predators,
 leading to disproportionately strong effects on fitness and functional
 roles. These competitive effects are exacerbated in complex predator
 guilds with dominance hierarchies that have clear winners and losers. The
 direct costs of losing these competitions are well understood, but the
 drivers of such interactions, and their indirect effects on prey, are not.
 We evaluate the drivers of interference competition for cougars, and how
 such competition affects cougar-prey dynamics, by leveraging 23 years of
 cougar predation data from Yellowstone National Park, USA. We show that
 the effect of prey size is context-dependent, negatively affecting how
 often cougars kill ungulate prey but positively affecting how often
 wolves/bears find and steal cougar kills. Further, cougars increasingly
 kill smaller prey as larger, primary prey density decreases. Handling time
 is shorter for smaller prey, leading to less kleptoparasitism by wolves
 and bears when primary prey density is lower. Our study counters the
 theory suggesting that interference competition should increase at kills
 when prey density declines, interspecific competitor density increases, or
 kill rates increase. We demonstrate that predator, competitor, and prey
 traits drive the strength of and even dampen interference competition,
 possibly increasing coexistence in complex communities.
description: Data was collected through predation cluster monitoring of
 GPS-collared cougars. Visited cougar kill sites to document remains, cause
 of death, scavenger/competitor presence, etc.
description: # Prey size mediates interference competition and predation dynamics in a
 large carnivore community
 [https://doi.org/10.5061/dryad.sxksn03c5](https://doi.org/10.5061/dryad.sxksn03c5) ## Description of the data and file structure Data was collected through predation cluster monitoring of GPS-collared cougars from 2016-2022. Missing data represented as "NA". Files: **1) ck.covs.ungulate.csv** Contains the following data columns related to each of the 350 individual cougars killed-ungulates included in analyses: ·      kill: unique identifier (e.g., year-nth kill of year) ·      study: one of three monitoring seasons ·      study_period: monitoring season and year ·      cougar_id: unique identifier of study cougar ·      cougar_sex: sex of study cougar ·      demographic_group: demographic group of study cougar ·      species: prey species common name ·      sex: sex of prey species ·      age_class: actual age class of prey ·      age_class_biomass: age class of prey used for biomass calculations ·      size: binned size of prey (Small = &lt;40kg, Medium = 40-105kg, Large = &gt;105kg) ·      full_biomass_kg: estimated live weight of prey in kg ·      edible_biomass_kg: estimated edible weight of prey in kg ·      acquired_biomass_kg: estimated weight of prey acquired by study cougar in kg ·      acquired_adjustment: adjustment factor from edible to acquired biomass ·      handling_time_days: handling time in days of kill by cougar ·      search_time_days: search time in days for cougar to make kill ·      search_time_ung_days: search time of kill since last ungulate kill in days ·      ground_east: easting UTM of kill ·      ground_north: northing UTM of kill ·      bear_sign_present: bear sign at kill (yes/no) ·      wolf_sign_present: wolf sign at kill (yes/no) ·      predator_sign_present_yn: either bear or wolf sign at kill (yes/no) ·      displaced: cougar displaced by bear and/or wolf from kill (yes/no) ·      displaced_wolf: cougar displaced by wolf from kill (yes/no) ·      displaced_bear: cougar displaced by bear from kill (yes/no) ·      cougar_study: combined *cougar_id*-*study_period* ·      dod: date of death for kill ·      cover_250m: average percent tree cover in 250-m buffer around kill ·      roughness_250m: average topographic roughness in 250-m buffer around kill ·      wolf_ud_1km: average wolf density (wolf use weighted by pack size) in 1-km buffer around kill ·      bb_density_buff_corrected: average black bear density in 1-km buffer around kill ·      gb_index_buff_corrected: average grizzly bear density in 1-km buffer around kill ·      bear_density_buff: average combined bear density in 1-km buffer around kill ·      predator_density_buff: average combined bear + wolf density in 1-km buffer around kill ·      dod_julian: date of death in julian day ·      displaced_prior_kill: was cougar displaced from prior kill (yes/no) ·      fmr_kcal_day: field metabolic rate of study cougar in kcal per day ·      fmr_kg_day: field metabolic rate of study cougar in kg per day **2) predseq.covs.tidy.csv** Contains following data columns related to each of the 46 individual cougar predation cluster sequences included in analyses: ·      cougar_id: unique identifier of study cougar ·      sex: sex of study cougar ·      age_class: age class of study cougar ·      reproductive_status: reproductive stage if female, NA if male ·      demographic_group: demographic group of study cougar ·      demographic_group2: demographic group of study cougar with adjusted and binned naming ·      kitten_dob: date of birth of dependant young if present ·      dob_est: is the date of birth estimated ·      no_dependents: number of dependent young with female ·      fmr_kcal_day: field metabolic rate of study cougar in kcal per day ·      fmr_kg_day: field metabolic rate of study cougar in kg per day ·      study_period: monitoring season and year ·      year: year of cougar predation sequence ·      cougar_study: combined *cougar_id*-*study_period* ·      date_start: date predation sequence started ·      time_start: time predation sequence started ·      date_time_start: combined datetime predation sequence started ·      date_end: date predation sequence ended ·      time_end: time predation sequence ended ·      date_time_end: combined datetime predation sequence ended ·      study_duration: duration in days of study period (datetime start – datetime end) ·      number_of_x: columns V-AA; number of kills made by cougar in predation sequence where *x* refers to species or species group ·      re_x_kill_rate_kills_day: columns AB-AG; ratio estimated kill rate of prey for predation sequence in kills per day where *x* refers to species or species group ·      re_x_kill_rate_kills_30_day*s*: columns AH-AM; ratio estimated kill rate of prey for predation sequence in kills per 30 days where *x* refers to species or species group ·      study: one of three monitoring seasons predation sequence was collected in ·      sum_full_x_biomass_kg: columns AO, AR, AU, AX, BA, BD; sum of live weight of prey killed by cougar during predation sequence in kg where x refers to species or species group ·      sum_edible_x_biomass_kg: columns AP, AS, AV, AY, BB, BE; sum of edible weight of prey killed by cougar during predation sequence in kg where x refers to species or species group ·      sum_acquired_x_biomass_kg: columns AQ, AT, AW, AZ, BC, BF; sum of weight of prey acquired by cougar from kills during predation sequence in kg where x refers to species or species group ·      full_x_biomass_kg_day: columns BG, BJ, BM, BP, BS, BV; live weight of prey killed by cougar during predation sequence in kg per day where x refers to species or species group ·      edible_x_biomass_kg_day: columns BH, BK, BN, BQ, BT, BW; edible weight of prey killed by cougar during predation sequence in kg per day where x refers to species or species group ·      acquired_x_biomass_kg_day: columns BI, BL, BO, BR, BU, BX; sum of weight of prey acquired by cougar from kills during predation sequence in kg per day where x refers to species or species group ·      prop_ung_displaced: proportion of ungulate kills in predation sequence that cougar was displaced from by either wolves or bears ·      prop_ung_displaced_bear: proportion of ungulate kills in predation sequence that cougar was displaced from by bears ·      prop_ung_displaced_wolf: proportion of ungulate kills in predation sequence that cougar was displaced from by wolves ·      prop_ung_predator_sign_present_yn: proportion of ungulate kills in predation sequence that either wolf or bear sign was present at ·      prop_ung_wolf_sign_present: proportion of ungulate kills in predation sequence that wolf sign was present at ·      prop_ung_bear_sign_present: proportion of ungulate kills in predation sequence that bear sign was present at ·      prey_size_ung_avg_kg: average size in kg of ungulate kill during predation sequence ·      prey_size_ung_avg_std: standardized (centered and scaled) average size of ungulate kill during predation sequence ## Code/software Data can be viewed in R, Excel, or other spreadsheet/statistical software. Code used for analysis of data can be provided upon request.