DOI: 10.5061/dryad.8sf7m0czc
title: Behavior of brown bears foraging on sockeye salmon in Lake Aleknagik, Alaska (foraging tactics and success)

description: Studies of foraging where focal animals are easily observed may miss
 common behaviours expressed under more cryptic conditions. For example,
 much of what is known about brown bears (Ursus arctos) foraging on Pacific
 salmon (Oncorhynchus spp.) comes from a few anomalous locations where
 bears congregate, leaving open the question of how bears exploit salmon in
 the small streams where most predation occurs. Here, we used
 motion-activated video recordings to study the use and success of foraging
 tactics of Alaskan brown bears preying on sockeye salmon (O. nerka) in six
 small streams over three summers. We identified eight tactics from 387
 independent foraging bouts and used multinomial models to explore drivers
 of their use and generalized linear models to examine factors influencing
 their success in capturing salmon. Cubs were far more likely to use
 sporadic foraging, a haphazard approach characterized by low success and
 high energy expenditure, than were adults, suggesting that this tactic may
 reflect inexperience. Tactics also varied with diel period and year.
 Foraging success was affected by tactic; notably, bears engaged in mixed
 and sporadic foraging were far less likely to catch a salmon than those
 using active tactics, whereas bears foraging passively were far more
 likely to catch a salmon than those foraging actively. Foraging success
 also varied among years but was not related to salmon abundance. These
 findings 1) showcase the diverse approaches brown bears use to exploit
 salmon in small streams, 2) add to our understanding of the ontogeny and
 success rates of foraging behaviours in habitats where most predation on
 salmon occurs, and 3) highlight the utility of video for overcoming
 challenges to the direct observation of bear behaviour.
description: Data were collected using camera traps deployed along streams
 where sockeye salmon spawn during the summer (mid-July-late August), and
 set to video mode, in Bristol Bay, Alaska (Lake Aleknagik). Video was
 watched and extracted to record tactics use by, and success in capturing
 salmon (proportion of captures versus attempts) of, brown bears,
 categorized by age (cub, sub-adult, adult) and sex (female/male). One
 observed did all the categorizations and extractions (lead author Natalee
 Bozzi). Data were analyzed statistically using
 multinomial models to identify drivers of use of different tactics (a
 total of 8), and negative binomial models to assess drivers of success in
 capturing salmon (including as a function of specific tactics).
description: # Behavior of brown bears foraging on sockeye salmon in Lake Aleknagik,
 Alaska (foraging tactics and success)
 [https://doi.org/10.5061/dryad.8sf7m0czc](https://doi.org/10.5061/dryad.8sf7m0czc) ## Change Log (ao 7/21/2025) Since uploading the previous version of this dataset to Dryad as part of a submission to the journal *Animal Behaviour*, we discovered that it contained a number of duplicated entries. Accordingly, this updated upload, which is the dataset used for the published version of the paper in the *Journal of Mammalogy*, contains fewer observations (460 as opposed to 528). Note that the outcome of the analysis has not changed. ## Description of the data and file structure Data were collected non-invasively using camera traps set to video mode to record foraging behavior or brown bears (targeting salmon). Recordings were watched to extract use of specific tactics, and success rates in capturing salmon of each tactic, as a function of age and sex. ### Files and variables #### File: Bozzi_et_al._Clean_Bear_Foraging_Analysis.R **Description:** This file contains all of the R code used for the analysis, with instructions as to what all the variables and response in the two analyses (multinomial, negative binomial) were and the steps we took to complete them (so that repetition of both analyses should be straight forward). #### File: Bozzi_et_al._Updated_Complete_Bear_Data.csv **Description:** This is the full data file used as the basis for both analyses. ##### Variables * Year: We collected data over 3 years (2016, 2021, 2022). In each year, data collection interval was mid-\ July through late August. * Camera: We deployed 2 cameras per stream, so this variable indeitifes which camera it was on a stream that collected the video of a particular foraging bout. * File Name: ID for each foraging bout (independent). * Stream: We collected data on 6 streams: Happy, Hansen, Eagle, Yako, Bear, Whitefish * Salmon Estimate: Salmon count for a particular stream in a particular year. * Month Collected: July or August. * Month: July or August. * Day: Day of week on which video was recorded. * Date: Calendar date on which video was recorded. * lat: position lat * lon: position long * Time: Time of day when video was recorded * Light Level: Suntime estimate (continuous measure of amount of darkness) * Time of Day: Self explanatory. * Age: Cub, Junveile, Adult * Sex: Male/Female * Adult Count: How many adults in video * Subadult Count: How many sub-adults in video * Cub Count: How many cubs in video * Foraging?: Did the video include foraging? * Tactic: Which tactic was observed in a video (of 8 options) * Tactic (simplified): For the analysis, the subset of tactics included in the two analyses (e.g., scavenging was not included in the success analysis because scavenging is always successful). * Multinom_tactics: Tactics included in the multinomial model (some were excluded because of too few observations; e.g., provisioning). * ActiveVsMixed: For multinomial, active is the reference * ActiveVsPassive: Active is the reference. * ActiveVsScavenge: Active is the reference * ActiveVsSporadic: Active is the reference * Success?: Capture or not * Outcome: Capture or not * Comments: ## Code/software R code - included. ## Access information Other publicly accessible locations of the data: * N/A Data was derived from the following sources: *  N/A