Connectivity among subpopulations of louisiana black bears as estimated by a step selection function

Clark, Joseph D.; Laufenberg, Jared S.; Davidson, Maria; Murrow, Jennifer L.

doi:10.1002/jwmg.955

Cited by 57 publications

(21 citation statements)

References 46 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Total distances of predicted paths in the central region range from approximately 135 to 210 km, whereas paths in the western periphery may exceed 350 km. In fact, results of a first attempt to model movement between the populations support this notion: Based on the SSF we reported here, we initially used a correlated random-walk method similar to Clark et al (2015). To date, the most remote verified observations of grizzly bears within the region between the populations were located~110 km from the GYE and~95 km from the NCDE (locations 9, 10, 11, and 17), confirming that movements within this distance range are possible (Table 3).…”

Section: Discussionmentioning

confidence: 78%

“…The randomized shortest path (RSP) algorithm, introduced to the field of movement ecology by Panzacchi et al (2016), is a new methodological approach to predict the location of paths between functional areas based on step-selection functions (SSF) derived from individual-based movement data. By modulating the degree of randomness in simulated movements, the algorithm has the potential to better capture the movement ecology of species compared with optimal least-cost path (Walker andCraighead 1997, Cushman et al 2009) or random-walk approaches (Clark et al 2015). This approach was particularly appropriate for our objective to delineate potential paths for gene flow between the GYE and NCDE populations.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Potential paths for male‐mediated gene flow to and from an isolated grizzly bear population

et al. 2017

View full text Add to dashboard Cite

For several decades, grizzly bear populations in the Greater Yellowstone Ecosystem (GYE) and the Northern Continental Divide Ecosystem (NCDE) have increased in numbers and range extent. The GYE population remains isolated and although effective population size has increased since the early 1980s, genetic connectivity between these populations remains a long-term management goal. With onlỹ 110 km distance separating current estimates of occupied range for these populations, the potential for gene flow is likely greater now than it has been for many decades. We sought to delineate potential paths that would provide the opportunity for male-mediated gene flow between the two populations. We first developed step-selection functions to generate conductance layers using ecological, physical, and anthropogenic landscape features associated with non-stationary GPS locations of 124 male grizzly bears (199 bear-years). We then used a randomized shortest path (RSP) algorithm to estimate the average number of net passages for all grid cells in the study region, when moving from an origin to a destination node. Given habitat characteristics that were the basis for the conductance layer, movements follow certain grid cell sequences more than others and the resulting RSP values thus provide a measure of movement potential. Repeating this process for 100 pairs of random origin and destination nodes, we identified paths for three levels of random deviation (h) from the least-cost path. We observed broad-scale concordance between model predictions for paths originating in the NCDE and those originating in the GYE for all three levels of movement exploration. Model predictions indicated that male grizzly bear movement between the ecosystems could involve a variety of routes, and verified observations of grizzly bears outside occupied range supported this finding. Where landscape features concentrated paths into corridors (e.g., because of anthropogenic influence), they typically followed neighboring mountain ranges, of which several could serve as pivotal stepping stones. The RSP layers provide detailed, spatially explicit information for land managers and organizations working with land owners to identify and prioritize conservation measures that maintain or enhance the integrity of potential areas conducive to male grizzly bear dispersal.

show abstract

Section: Discussionmentioning

confidence: 78%

Section: Introductionmentioning

confidence: 99%

Potential paths for male‐mediated gene flow to and from an isolated grizzly bear population

et al. 2017

View full text Add to dashboard Cite

show abstract

“…Most recently, Hooker (), Lowe (), and Troxler () estimated bear abundances at the Tensas River Basin (TRB), Upper Atchafalaya River Basin (UARB), and Lower Atchafalaya River Basin (LARB), respectively. Additionally, O'Connell‐Goode et al () updated population estimates and evaluated the effects of flooding the Morganza Spillway on bear demographics at UARB and Clark et al () assessed movement characteristics within and connectivity among Louisiana black bear subpopulations in Louisiana.…”

Section: Introductionmentioning

confidence: 99%

Demographic rates and population viability of black bears in Louisiana

Laufenberg

Clark

Hooker

et al. 2016

Wildlife Monographs

Self Cite

View full text Add to dashboard Cite

The Louisiana black bear (Ursus americanus luteolus) was reduced to a few small, fragmented, and isolated subpopulations in the Lower Mississippi Alluvial Valley by the mid‐twentieth century resulting from loss and fragmentation of habitat. In 1992, the United States Fish and Wildlife Service (USFWS) granted the Louisiana black bear threatened status under the United States Endangered Species Act of 1973. Since that time, a recovery plan was developed, a reintroduced population was established, and habitat recovery has occurred. The Recovery Plan states that a minimum of 2 populations must be viable (i.e., persistence probabilities over 100 years >0.95), 1 in the Tensas River Basin and 1 in the Atchafalaya River Basin. Consequently, our objectives were to 1) estimate demographic rates of Louisiana black bear subpopulations, 2) develop data‐driven stochastic population projection models, and 3) determine how different projection model assumptions affect population trajectories and predictions about long‐term persistence. Our overall goal was to assess long‐term persistence of the bear subpopulations in Louisiana, individually and as a whole. We collected data using varying combinations of non‐invasive DNA sampling, live capture, winter den visits, and radio monitoring from 2002 to 2012 in the 4 areas currently supporting breeding subpopulations in Louisiana: Tensas River Basin (TRB), Upper Atchafalaya River Basin (UARB), Lower Atchafalaya River Basin (LARB), and a recently reintroduced population at the Three Rivers Complex (TRC). From 2002 to 2012, we radio monitored fates of 86 adult females within the TRB and 43 in the TRC. Mean estimates of annual adult survival for the TRB and TRC were 0.997 and 0.990, respectively, when unknown fates were assumed alive and 0.970 and 0.926 when unknown fates were assumed dead. From 2003 to 2013, we observed 130 cub litters from 74 females in the TRB, and 74 cub litters from 45 females in the TRC. During the same period, we observed 43 yearling litters for 33 females in the TRB and 21 yearling litters for 19 females in the TRC. The estimated number of cubs and number of yearlings produced per breeding adult female was 0.47 and 0.20, respectively, in the TRB and 0.32 and 0.18 in the TRC. On the basis of matrix projection models, asymptotic growth rates ranged from 1.053 to 1.078 for the TRB and from 1.005 to 1.062 for the TRC, depending on how we treated unresolved fates of adult females. Persistence probabilities estimated from stochastic population models based on telemetry data ranged from 0.997 to 0.998 for the TRC subpopulation depending on model assumptions and were >0.999 for the TRB regardless of model assumptions. We extracted DNA from hair collected at baited, barbed‐wire enclosures in the TRB, UARB, and LARB to determine individual identities for capture‐mark‐recapture (CMR) analysis. We used those detection histories to estimate apparent survival (φ), per‐capita recruitment (f), abundance (N), realized growth rate (λ), and long‐term viability, based on Baye...

show abstract

“…A population genetic structure analysis indicated that no immigration into the Spillway from the other 3 Louisiana black bear populations has occurred (S. M. Murphy, Louisiana Department of Wildlife and Fisheries, unpublished data). Furthermore, a step‐selection function analysis of global positioning system (GPS) telemetry data on bears in Louisiana indicates that the potential for such movement is low (Clark et al ). Therefore, we conclude that most of the estimated f are likely from births that occurred within the Upper Atchafalaya population.…”

Section: Discussionmentioning

confidence: 99%

“…O'Connell-Goode et al (2014) reported that w was unaffected by the flood; to test that Table 1. Results from robust-design Pradel models using noninvasive capture-mark-recapture hair trapping data of Louisiana black bears in the Spillway portion of the Upper Atchafalaya River Basin, Louisiana, USA, 2007-2015 We modeled apparent survival (w) as constant (.) and as a function of a sex and year interaction (sex Â yr); per capita recruitment (f) by year, sex, and the lack of recruitment of yearlings and 2-year-olds following the 2011 flood event whereby f(6) and f(7) ¼ f for 2012-2013 and 2013-2014, respectively; proportion of the population belonging to 1 of 2 heterogeneity mixtures (p); probability of capture (p) as a function of flood, sex, year, and mixture (mix); and probability of recapture (c) as a behavioral response (add) or independent.…”

Section: Discussionmentioning

confidence: 99%

No flood effect on recruitment in a Louisiana black bear population

et al. 2017

Self Cite

View full text Add to dashboard Cite

A flood event in 2011 had minor impacts on apparent survival and movement probabilities of a small, isolated population of Louisiana black bears (Ursus americanus luteolus) in the Upper Atchafalaya River Basin, Louisiana, USA. However, the potential effects of the flood on recruitment of juveniles into the population, then listed as threatened under the United States Endangered Species Act, were not evaluated. We used hair trapping data collected from 2007 to 2015 and Pradel temporal symmetry models in a robust‐design framework to investigate changes in per capita recruitment that could have resulted from the flood. We detected 91 bears (37 M:54 F) within the flooded area during our study period, ranging from 21 to 44 individuals/year. Models that tested for reduced recruitment resulting from the flood were not supported more than models with constant recruitment, and the population growth rate did not decline. Although we documented marginally lower recruitment following the 2011 flood, lag effects and detectability biases complicated our analysis. We suggest that wildlife managers continue monitoring recruitment and survival in this recently delisted black bear population given the potential for heightened flood frequency and severity in the future. © 2017 The Wildlife Society.

show abstract

Connectivity among subpopulations of louisiana black bears as estimated by a step selection function

Cited by 57 publications

References 46 publications

Potential paths for male‐mediated gene flow to and from an isolated grizzly bear population

Potential paths for male‐mediated gene flow to and from an isolated grizzly bear population

Demographic rates and population viability of black bears in Louisiana

No flood effect on recruitment in a Louisiana black bear population

Contact Info

Product

Resources

About