DOI: 10.5061/dryad.d51c5b0fd
title: The diel niche of brown bears: constraints on adaptive capacity in human-modified landscapes

description: Diel activity rhythms, representing the behavioral pattern of the
 sleep-wake cycle, may be adjusted by wildlife in response to changes in
 environmental conditions. An increase in nocturnality is typically
 recognized as an adaptive strategy to segregate from humans and mitigate
 heat stress. Numerous studies have investigated spatial patterns and
 habitat use of large carnivores in human-modified landscapes, but little
 research has examined their activity rhythms. We compiled Global
 Positioning System data (2004–2022) for 139 brown bears (Ursus arctos)
 from 6 populations across Europe, representing a human-modified landscape,
 and the Greater Yellowstone Ecosystem, U.S.A., representing a landscape
 with limited human impact, which we used to calculate hourly movement
 rates as an activity proxy. Using a Bayesian approach to model the
 temporal autocorrelation of activity data, we tested if the extent of
 nocturnality in brown bears is modulated by the intensity of human
 encroachment, accounting for primary productivity and maximum ambient
 temperature. All bear populations exhibited a predominantly bimodal,
 crepuscular pattern of activity, although Yellowstone bears were
 proportionally more crepuscular and diurnal. Whereas the effect of primary
 productivity was variable, all European populations became more nocturnal
 in response to higher human encroachment and reduced diurnal and
 crepuscular activity at higher summer temperatures, decreasing overall
 diel activity levels. Yellowstone bears displayed the greatest shift
 towards nocturnality among all populations in response to increasing human
 encroachment, and increased nocturnal activity to compensate for lower
 diurnal and crepuscular activity at higher summer temperatures. Our
 research indicates that European bears in human-modified landscapes may be
 reaching a limit in the behavioral plasticity they can manifest in their
 activity patterns, being already constrained into increased nocturnality.
 Our findings enhance the understanding of brown bears adaptive capacity to
 accommodate future changes, such as urbanization and increasing
 temperatures, to the ecosystems they inhabit.
description: # The diel niche of brown bears: constraints on adaptive capacity in
 human-modified landscapes Dataset DOI:
 [10.5061/dryad.d51c5b0fd](10.5061/dryad.d51c5b0fd) ## Description of the
 data and file structure We compiled Global Positioning System (GPS) data
 from six brown bear populations (i.e., Apennine, Karelian, Scandinavian,
 Yellowstone, and Dinaric Pindos bears from Croatia and Serbia), spanning
 11 countries. Scandinavian and Karelian bears were included to represent
 bears residing in landscapes featuring relatively low human development,
 but experiencing intense hunting practices. The other European bear
 populations were chosen along a latitudinal gradient, different management
 systems, and ecological conditions, including bears from Croatia, Serbia,
 and central Italy. European bear populations were contrasted with bears in
 Yellowstone, which represent a protected population living in a largely
 unaltered environment. Overall, the final dataset comprised 379,676 GPS
 locations collected from 139 bears, for an equivalent of 235 bear-years,
 from 2004–2022. None of the individuals were collared in response to
 human-bear conflicts, as activity patterns of these bears may reflect
 human-related bear behaviors (e.g., habituation, food-conditioning). ###
 Files and variables #### File: dataset.csv **Description:** This is the
 dataset we used for analyses in the corresponding article. We used hourly
 movement rates as the response variable in our models, and GHM, maximum
 temperature, and NDVI as independent variables. Missing values, when
 present, are indicated with "NA". Please see the corresponding
 article for details on how each variable was obtained. ##### Variables *
 id: unique bear ID * Sex: 1=female, 2=male * age: 1=subadult (3/4 years
 old), 2=adult (&gt;= 5 years old) * movem_60: movement rate (km/h) *
 timestamp: date and time of fix registration * season: 1=spring, 2=summer,
 3=fall * reprod: 1=lone female, 2=male, 3=female accompanied by young *
 move_status: indicates if the bear is a resident or migrant *
 cor_hour: rounded hour from timestamp * altitude_dg: altitude of the Sun
 on the horizon (degrees) * t_period: classification of the diel period
 based on Sun altitude * index: global human modification of terrestrial
 systems (GHM) index * tmx: maximum daily ambient temperature (°C) *
 dayle: day length (hours) * study: bear population 1=Apennine, 2=Dinaric
 Pindos (Croatia), 3=Dinaric Pindos (Serbia), 4=Scandinavian, 5=Karelian,
 6=Yellowstone * year: numeric value representing the year nested in the
 population * ndvi: Normalized Difference Vegetation Index (NDVI)