Influence of maternal body size, condition, and age on recruitment of four brown bear populations

Hilderbrand, Grant V.; Gustine, David D.; Joly, Kyle; Mangipane, Buck A.; Leacock, William B.; Cameron, Matthew D.; Sorum, Mathew S.; Mangipane, Lindsey S.; Erlenbach, Joy A.

doi:10.2192/ursus-d-18-00008.1

Cited by 7 publications

(8 citation statements)

References 27 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Bear body size and productivity were generally higher in this subarea as well (Hilderbrand et al 2019b), suggesting that greater access to food resources (e.g., large spawning concentrations of chum salmon (Oncorhynchus keta) in the lower portions of the Noatak River [Menard et al 2020], beached marine mammals, and a suite of ungulate prey species) may afford a partial explanation. Estimates from the other 3 subareas were similar to those reported for other interior Alaska populations, possibly a function of ≥1 factors, including limited food resources (i.e., limited salmon and lower ungulate densities in the Upper Noatak and Gates of the Arctic; Miller et al 1997, Westing 2012, Rattenbury et al 2018, limited reproductive output in Gates of the Arctic (Hilderbrand et al 2019a, b), shorter growing seasons, and higher harvest in the case of the Seward Peninsula.…”

Section: Discussionsupporting

confidence: 65%

Brown Bear Density and Estimated Harvest Rates in Northwestern Alaska

et al. 2021

View full text Add to dashboard Cite

Human‐caused mortality in general, and unregulated hunting in particular, have been implicated in reductions in brown bear (Ursus arctos) populations throughout much of their range. In northwestern Alaska, USA, bear densities have not been assessed in 20 years while harvest regulations have been liberalized, raising concerns that broad undetected population declines might occur. We used a modified mark‐resight approach to estimate brown bear density during 2005–2018 in 4 subareas throughout the region. We also summarized harvest information for each subarea and used our survey results to estimate harvest rates. We estimated densities for independent bears assuming constant or heterogeneous probabilities of detection and occurrence. We present the results of the constant model for more direct comparison with past work and the heterogeneity model results to provide estimates of density that are less likely to be negatively biased. Using the constant model, we estimated the density of independent bears was 17.0, 49.2, 24.9, and 19.4/1,000 km2 on portions of the Seward Peninsula, the lower Noatak River, the upper Noatak River, and Gates of the Arctic National Park and Preserve, respectively. These estimates are broadly similar to those from past work in interior and northwestern Alaska, with the exception of the lower Noatak River subarea where our estimates are the highest reported for a bear population in northern Alaska. We estimated that the harvest rate on the Seward Peninsula was approximately 5.2% or 7.7% on average, depending upon the model used. In the remaining areas, we estimated annual harvest rates were <2.5%, well within sustainability guidelines from past work. Overall, our results suggest that brown bear densities are similar or somewhat higher than in the past in much of northwestern Alaska and that current harvest rates are sustainable in most areas, except perhaps the Seward Peninsula. Ongoing survey work will be useful for further evaluating the assumptions of the modified mark‐resight survey approach, assessing population trajectory, and determining the effect of harvest on brown bear populations. © 2021 The Wildlife Society.

show abstract

Section: Discussionsupporting

confidence: 65%

Brown Bear Density and Estimated Harvest Rates in Northwestern Alaska

et al. 2021

View full text Add to dashboard Cite

show abstract

“…Within an otherwise low-productivity Arctic environment, there are spatiotemporally limited patches of high-quality habitat (i.e., salmon streams). Males are (>1.5 times) larger than females and rely upon salmon intake more than females do in this region (McDonough and Christ 2012;Hilderbrand et al 2018bHilderbrand et al , 2019bMangipane et al 2020). Salmon intake is known to affect the growth and productivity of bears (Hilderbrand et al 1999) and, our results indicate, also their movements and annual home range sizes.…”

Section: Discussionsupporting

confidence: 49%

“…Adult brown bears were located and anesthetized using Telazol (Fort Dodge Laboratories, Fort Dodge, Iowa, USA) via helicopter darting operations during spring (27 Apr-23 Jun) from 2014 to 2017 (Hilderbrand et al 2018a). Capture and handling procedures followed Animal Care and Use approved protocols ("AKR_GAAR_Gustine_GrizzlyBear_2014").…”

Section: Methodsmentioning

confidence: 99%

See 1 more Smart Citation

Factors influencing Arctic brown bear annual home range sizes and limitations of home range analyses

Joly

Cameron

Sorum

et al. 2022

Ursus

Self Cite

View full text Add to dashboard Cite

Home range size is a basic ecological index related to individual's realized niche. Its size can be influenced by body size, sex, maternal status, population density, habitat productivity, spatiotemporal variation of resources, climate, predation risk, and disturbance. Home range estimation can also be greatly affected by methodology and sampling regime. We used Global Positioning System collar data to assess what factors influenced the size of annual home ranges (space use during a single active season) of 28 female and 8 male brown bears (Ursus arctos) that denned in the Brooks Range of northcentral Alaska, USA, from 2014 to 2017. We used 2 methods to estimate annual home ranges, the Kernel Density Estimate (KDE) and the dynamic Brownian Bridge Movement Model (dBBMM). Contrary to expectations, we did not find that larger bodied bears of the same sex had larger annual home ranges. Annual home ranges of male bears (mean [standard deviation]; 504 [312] km 2 and 3,886 [4,279] km 2 , using dBBMM and KDE, respectively) were 3.7-9.4 times larger than that of females (135 [86] km 2 and 411 [738] km 2 , respectively). We found that greater chum salmon (Oncorhynchus keta) consumption was associated with larger annual home ranges for both sexes. In contrast, coastal brown bear populations that consume high levels of salmon often have small annual home ranges. We suggest that the relatively long distance (up to 100 km) between salmon streams and another key resource, denning habitat, is a reason for the positive association between salmon consumption and annual home range size. Although age was not in our top model for annual home range size, younger bears tended to have larger annual home ranges. We documented the fact that individuals of both sexes had the largest annual home ranges of any we could find for brown bears worldwide, using a traditional measure of space use (KDE). However, very large annual home ranges were associated with nonlocalized movements and the alternative method (dBBMM) to delineate these ranges provided more realistic range estimates. We discuss options and limitations of estimating space use and recommend caution when comparing space use between studies. With large-scale industrial infrastructure approved for development in this previously undeveloped region, the size and drivers of bear annual home ranges have numerous management implications. Brown bears with large annual home ranges in northcentral Alaska, where primary productivity is relatively low and denning habitat often far from salmon-bearing streams, are likely to move outside conservation units and encounter more risks as they interact with human infrastructure.

show abstract

“…Bear managers often consider the importance of various food resources and access to these resources relative to macronutrients and caloric needs to meet the demands of survival, reproduction, cub rearing, and denning [78]. By investigating the role that diet plays in observed GMB variation, our research provides a framework for highlighting an additional way food resources may impact fitness: through the acquisition of both necessary and potentially harmful GMB contributors.…”

Section: Conservation Implicationsmentioning

confidence: 99%

Intrinsic and extrinsic factors influence on an omnivore’s gut microbiome

et al. 2022

Self Cite

View full text Add to dashboard Cite

Gut microbiomes (GMBs), complex communities of microorganisms inhabiting the gastrointestinal tracts of their hosts, perform countless micro-ecosystem services such as facilitating energy uptake and modulating immune responses. While scientists increasingly recognize the role GMBs play in host health, the role of GMBs in wildlife ecology and conservation has yet to be realized fully. Here, we use brown bears (Ursus arctos) as an ecological model to (1) characterize GMB community composition associated with location, season, and reproductive condition of a large omnivore; (2) investigate how both extrinsic and intrinsic factors influence GMB community membership and structure; and (3) quantify differences in GMB communities among different locations, seasons, sex, and reproductive conditions. To achieve these aims, we subsampled brown bear fecal samples collected during United States National Park Service research activities at three National Parks and Preserves (Katmai, Lake Clark, and Gates of the Arctic) and extracted microbial DNA for 16S rRNA amplicon sequencing and microbial taxonomic classification. We analyzed GMB communities using alpha and beta diversity indices, subsequently using linear mixed models to examine relationships between alpha diversity and extrinsic and intrinsic factors. Katmai brown bears hosted the greatest alpha diversity, whereas Gates brown bears hosted the least alpha diversity. Our results indicate that location and diet drive GMB variation, with bears hosting less phylogenetic diversity as park distance inland increases. Monitoring brown bear GMBs could enable managers to quickly detect and assess the impact of environmental perturbations on brown bear health. By integrating macro and micro-ecological perspectives we aim to inform local and landscape-level management decisions to promote long-term brown bear conservation and management.

show abstract

Influence of maternal body size, condition, and age on recruitment of four brown bear populations

Abstract: BioOne Complete (complete.BioOne.org) is a full-text database of 200 subscribed and open-access titles in the biological, ecological, and environmental sciences published by nonprofit societies, associations, museums, institutions, and presses.

Cited by 7 publications

References 27 publications

Brown Bear Density and Estimated Harvest Rates in Northwestern Alaska

Brown Bear Density and Estimated Harvest Rates in Northwestern Alaska

Factors influencing Arctic brown bear annual home range sizes and limitations of home range analyses

Intrinsic and extrinsic factors influence on an omnivore’s gut microbiome

Contact Info

Product

Resources

About