Behavior of brown bears foraging on sockeye salmon in Lake Aleknagik, Alaska (foraging tactics and success)

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 tacti..., 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)., , # 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)

## 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 f...