Influence of phenology on site selection by female American black bears in coastal British Columbia

Davis, Helen; Weir, Richard D.; Hamilton, Anthony N.; Deal, John

doi:10.2192/1537-6176(2006)17[41:ioposs]2.0.co;2

Cited by 30 publications

(24 citation statements)

References 13 publications

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“…As bears track the spatial variation in fruiting phenology to consume fruit with the highest sugar content (Davis et al. , Armstrong et al. ), they deposit seed‐filled bear scats on the forest floor.…”

Section: Discussionmentioning

confidence: 99%

“…In addition to provisioning small mammals with seeds, bears can extend the period of seed availability to small mammals. As bears track the spatial variation in fruiting phenology to consume fruit with the highest sugar content (Davis et al 2006, Armstrong et al 2016, they deposit seedfilled bear scats on the forest floor. These seeds would otherwise primarily be made available to granivores following senescence of the infructescence, or in the smaller seed aggregations after primary dispersal by birds.…”

Section: Small Mammal Utilization Of Seed-filled Bear Scatsmentioning

confidence: 99%

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Salmon‐supported bears, seed dispersal, and extensive resource subsidies to granivores

2018

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In salmon‐rich environments, which once spanned much of the Northern Hemisphere, bears occur at exceptionally high densities. Salmon, by growing bear populations, have the potential to exert wide‐ranging effects on ecosystem processes. Salmon‐supported bears provide seed dispersal services to plants, and bear scats containing thousands of seeds may then be efficient nutritional resources for granivorous small mammals that also function as secondary seed dispersers while hoarding seeds for winter. We taxonomically identified and enumerated seeds in individual bear scats to characterize patterns of bear frugivory. We then combined estimates of seed abundance and digestible energy content to quantify the energy available to granivorous small mammals, and we quantified the proportion of the mouse population that could be supported by locally abundant bear populations in lowland salmon systems. We additionally monitored seed‐filled bear scats with remote cameras to quantify small mammal visitation rates, and live‐trapped small mammals seasonally to determine whether rodents visited bear scats proportional to their densities or whether some species preferentially selected for bear scats, and to assess whether seasonal variation in scat visitation was driven by density or selection. Bears were an important initial dispersal agent for 12 species of fruit, particularly devil's club (Oplopanax horridus) and blueberry (Vaccinium spp.), which occurred in 80% (5839 seeds/scat) and 50% (10,719 seeds/scat) of scats, respectively. Seeds in bear scats were intensively utilized and dispersed by small mammals, primarily scatter‐hoarding northwestern deer mice (Peromyscus keeni; 8.5 visits per day/4295 total visits) and larder‐hoarding northern red‐backed voles (Myodes rutilus; 2.2 visits per day/1099 total visits), with visitation rates proportional to the seasonal density of each species. Small mammals likely incurred significant nutritional benefits from seeds deposited in bear scats (kcal/scat, mean = 114, n = 71). In coastal Alaska riparian areas, bears are potentially capable of indirectly subsidizing the energy needs of 45–65% of local deer mouse populations. Thus, this work helps elucidate the role that salmon, by supporting abundant bears, plays in ecological communities via influencing seed dispersal and resource subsidies to the small mammals that compose the base of the food web.

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Section: Discussionmentioning

confidence: 99%

Section: Small Mammal Utilization Of Seed-filled Bear Scatsmentioning

confidence: 99%

Salmon‐supported bears, seed dispersal, and extensive resource subsidies to granivores

2018

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“…By tracking altitudinal gradients in fruit phenology, bears are able to find fruit at this optimal stage of development for an entire month (Koike et al 2008). Black bears in North America also appear to track spatial variation fruiting phenology; the phenological stage of trophic resources (composed largely of multiple berry species) was the strongest predictor of site selection for gPS-collared individuals (Davis et al 2006).…”

Section: Additional Examples Of Resource Waves For Mobile Consumersmentioning

confidence: 99%

Resource waves: phenological diversity enhances foraging opportunities for mobile consumers

Armstrong

Takimoto

Schindler

et al. 2016

Ecology

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Time can be a limiting constraint for consumers, particularly when resource phenology mediates foraging opportunity. Though a large body of research has explored how resource phenology influences trophic interactions, this work has focused on the topics of trophic mismatch or predator swamping, which typically occur over short periods, at small spatial extents or coarse resolutions. In contrast many consumers integrate across landscape heterogeneity in resource phenology, moving to track ephemeral food sources that propagate across space as resource waves. Here we provide a conceptual framework to advance the study of phenological diversity and resource waves. We define resource waves, review evidence of their importance in recent case studies, and demonstrate their broader ecological significance with a simulation model. We found that consumers ranging from fig wasps (Chalcidoidea) to grizzly bears (Ursus arctos) exploit resource waves, integrating across phenological diversity to make resource aggregates available for much longer than their component parts. In model simulations, phenological diversity was often more important to consumer energy gain than resource abundance per se. Current ecosystembased management assumes that species abundance mediates the strength of trophic interactions. Our results challenge this assumption and highlight new opportunities for conservation and management. Resource waves are an emergent property of consumerresource interactions and are broadly significant in ecology and conservation.

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“…At G1200 and G1400 only one tree was used in order to observe abscission period and ADTT, making it impossible to assess whether the period of acorn availability at those sites influenced the bears' selection of foraging location. Previous research has not adequately examined the temporal effect of plant phenology on site selection of bears (Davis et al 2006), making further research into site selection with respect to phenology necessary. Signs of bears foraging on acorns were observed only at T1200, G1200 and G1400, while the other sites were not utilized.…”

Section: Bear Foraging In Relation To Acorn Characteristics and Phenomentioning

confidence: 99%

Spatial and elevational variation in fruiting phenology of a deciduous oak (Quercus crispula) and its effect on foraging behavior of the Asiatic black bear (Ursus thibetanus)

Nakajima

Koike

Masaki

et al. 2012

Ecological Research

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In habitats with elevational gradients, differences in the fruiting phenology of a single key food resource may affect the feeding behavior of an animal. The objectives of the present study were to assess (1) whether or not fruiting phenology and characteristics of Quercus crispula acorns differed with changes in altitude (900–1,400 m asl) and area; (2) when bears foraged acorns in relation to their phenological development; and (3) where bears engaged in acorn foraging behavior with respect to acorn phenology. No difference in the fruiting phenology of acorns at various altitudes and locations was found, with the exception of changes in color and abscission period. Acorn abscission period occurred later at a site with an elevation of 1,200 m in Tochigi and at another with an elevation of 1,400 m in Gunma, making the available energy of acorns in the tree canopy (AET) greater and available for a longer time period at those two sites. Foraging of acorns by bears was observed at sites of moderate to high altitude between late September and mid‐October. A threshold date when acorns became suitable for foraging by bears could not be identified, as the size and nutritional value of acorns increased continuously. Foraging activity of bears observed at moderate and high altitude sites corresponded with locations where AET was available in greater amounts and for a longer period of time for some sites; however, the small sample size precluded accurate assessment.

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Influence of phenology on site selection by female American black bears in coastal British Columbia

Cited by 30 publications

References 13 publications

Salmon‐supported bears, seed dispersal, and extensive resource subsidies to granivores

Salmon‐supported bears, seed dispersal, and extensive resource subsidies to granivores

Resource waves: phenological diversity enhances foraging opportunities for mobile consumers

Spatial and elevational variation in fruiting phenology of a deciduous oak (Quercus crispula) and its effect on foraging behavior of the Asiatic black bear (Ursus thibetanus)

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