• A multi-model approach to guide habitat conservation and restoration for the endangered San Bernardino kangaroo rat

      Chock, Rachel Y.; Hennessy, Sarah McCullough; Wang, Thea B.; Gray, Emily; Shier, Debra M. (2020)
      The San Bernardino kangaroo rat (Dipodomys merriami parvus) is a federally listed endangered species endemic to Southern California and limited to three remaining populations. Its native habitat of alluvial fan sage scrub faces many anthropogenic threats, including urban and agricultural development, and the resulting flood control and fire suppression. With the loss of natural processes such as scouring or burning from floods and fires, the mosaic of seral stages across the landscape has shifted to dense vegetation, and active restoration may be necessary to provide suitable habitat for the San Bernardino kangaroo rat. Species distribution modeling using the partitioned Mahalanobis distance method on all occurrence points collected in the past 16 years revealed that alluvial scrub cover and fluvent soils were most strongly associated with San Bernardino kangaroo rat occupancy. Through surveys at 14 locations across the species’ range, we identified non-native grass cover, shrub cover, bare ground and sandy soils as microhabitat features related to San Bernardino kangaroo rat abundance. We also calculated the optimal range of cover for each habitat type that was correlated with higher kangaroo rat abundance. The results of this multiple-model approach can be used by the agencies to assess the value of conserved habitat, set targets for microhabitat enhancement to facilitate population growth and expansion, or identify receiver sites should translocation be required for recovery. This work lays the foundation for more coordinated and strategic restoration efforts, given the compressed and rigid timelines of development projects that continue to impact remaining San Bernardino kangaroo rat populations.
    • Climate change and landscape-use patterns influence recent past distribution of giant pandas

      Tang, Junfeng; Swaisgood, Ronald R.; Owen, Megan A.; Zhao, Xuzhe; Wei, Wei; Pilfold, Nicholas W.; Wei, Fuwen; Yang, Xuyu; Gu, Xiaodong; Yang, Zhisong; et al. (The Royal Society, 2020)
      Climate change is one of the most pervasive threats to biodiversity globally, yet the influence of climate relative to other drivers of species depletion and range contraction remain difficult to disentangle.... We conclude that the panda's distribution has been influenced by changing climate, but conservation intervention to manage habitat is working to increasingly offset these negative consequences.
    • Contrasting patterns of movement across life stages in an insular iguana population

      Moss, Jeanette B.; Gerber, Glenn P.; Goetz, Matthias; Haakonsson, Jane E.; Harvey, Jessica C.; Laaser, Tanja; Welch, Mark E. (2020)
    • Effects of body size on estimation of mammalian area requirements

      Noonan, Michael J.; Fleming, Christen H.; Tucker, Marlee A.; Kays, Roland; Harrison, Autumn-Lynn; Crofoot, Margaret C.; Abrahms, Briana; Alberts, Susan C.; Ali, Abdullahi H.; Altmann, Jeanne; et al. (2020)
      Accurately quantifying species’ area requirements is a prerequisite for effective area‐based conservation. This typically involves collecting tracking data on species of interest and then conducting home‐range analyses. Problematically, autocorrelation in tracking data can result in space needs being severely underestimated. Based on the previous work, we hypothesized the magnitude of underestimation varies with body mass, a relationship that could have serious conservation implications. To evaluate this hypothesis for terrestrial mammals, we estimated home‐range areas with global positioning system (GPS) locations from 757 individuals across 61 globally distributed mammalian species with body masses ranging from 0.4 to 4000 kg. We then applied block cross‐validation to quantify bias in empirical home‐range estimates. Area requirements of mammals <10 kg were underestimated by a mean approximately15%, and species weighing approximately100 kg were underestimated by approximately50% on average. Thus, we found area estimation was subject to autocorrelation‐induced bias that was worse for large species. Combined with the fact that extinction risk increases as body mass increases, the allometric scaling of bias we observed suggests the most threatened species are also likely to be those with the least accurate home‐range estimates. As a correction, we tested whether data thinning or autocorrelation‐informed home‐range estimation minimized the scaling effect of autocorrelation on area estimates. Data thinning required an approximately93% data loss to achieve statistical independence with 95% confidence and was, therefore, not a viable solution. In contrast, autocorrelation‐informed home‐range estimation resulted in consistently accurate estimates irrespective of mass. When relating body mass to home range size, we detected that correcting for autocorrelation resulted in a scaling exponent significantly >1, meaning the scaling of the relationship changed substantially at the upper end of the mass spectrum.
    • Low MHC variation in the polar bear: Implications in the face of Arctic warming?

      Weber, D.S.; Van Coeverden de Groot, P.J.; Schrenzel, Mark D.; Perez, D.A.; Thomas, S. (2013)
      Animals in the Arctic have low pathogen diversity but with rapid climate warming, this is expected to change. One insidious consequence of climate change is exposure of Arctic species to new pathogens derived from more southern species expanding their range northward. To assess potential vulnerability of polar bears to disease exposure, we examined genetic variation in major histocompatibility complex (MHC) loci (part of immune system) in Canadian polar bears and found low genetic diversity, consistent with long?standing exposure to low pathogen/parasite loads....
    • Population abundance and habitat utilization of bottlenose dolphins in the Mississippi Sound. Aquatic Conservation: Marine and Freshwater

      Miller, Lance J.; Mackey, A.D.; Solangi, M.; Kuczaj, S.A. (2013)
      Distance sampling principles were utilized to examine population density and abundance for bottlenose dolphins (Tursiops truncatus) in the Mississippi Sound. Information was collected during summer and winter to allow for examination of habitat utilization and abundance during two different seasons. Within the study area of the Mississippi Sound there are approximately 2225 bottlenose dolphins. The population was larger during the summer than during the winter months....
    • The conservation status of the world’s reptiles

      Böhm, Monika; Collen, Ben; Baillie, Jonathan E.M.; Bowles, Philip; Chanson, Janice; Cox, Neil; Hammerson, Geoffrey; Hoffmann, Michael; Livingstone, Suzanne R.; Ram, Mala; et al. (2013)
      …We present the first ever global analysis of extinction risk in reptiles, based on a random representative sample of 1500 species (16% of all currently known species). To our knowledge, our results provide the first analysis of the global conservation status and distribution patterns of reptiles and the threats affecting them, highlighting conservation priorities and knowledge gaps which need to be addressed urgently to ensure the continued survival of the world’s reptiles….