Douglas T. Bolger

Douglas T. Bolger

*This is an algorithmically generated author record based on publicly available information.

Current Organizations / Institutes

The organizations/institutes from the scholar's latest article


Douglas T. Bolger has a total of 18 co-authors. Here are the top co-authors by number of shared publications:

  • Andrew V. Suarez

    Department of Entomology and Department of Animal Biology, University of Illinois, Urbana, IL 61801, USA

    2 shared publications
  • Ted J. Case

    Department of Biology, University of California, San Diego, La Jolla, CA 92093, USA

    2 shared publications
  • Thomas A. Morrison

    Department of Biological Sciences, Dartmouth College, Hanover, NH 03755, USA

    2 shared publications
  • Andrew V. Suarez

    Department of Biology 0116, University of California at San Diego, 9500 Gilman Drive, La Jolla, California 92093-0166 USA

    1 shared publication
  • Bennet Vance

    Department of Computer Science, Dartmouth College, Hanover, NH 03755, USA

    1 shared publication
  • Daniel F. Doak

    Department of Biology, University of California, Santa Cruz, Santa Cruz, CA 95064, USA

    1 shared publication

Latest Publications

  • Open Access

    Designing a Real-World Course for Environmental Studies Students: Entering a Social-Ecological System

    by Douglas T. Bolger, Karen Hutchins Bieluch, Flora E. Krivak-Tetley, Gillian Maggs-Kölling, Joseph Tjitekulu

    There is increasing interest in using “real-world pedagogy” to train students in ways that make them better able to contribute toward a more sustainable society. While there is a robust body of literature on the competencies that students need as sustainability professionals, there is a lack of specific guidance in the literature on how to teach for competency development or on how to structure a program or course to support competency development. Our research addresses this gap in the literature through a description and autoethnographic reflection on the design and early implementation of a “real-world” course. The course is from the Environmental Studies Program at Dartmouth College (Hanover, NH, USA), but it takes place in the environs of the Gobabeb Research and Training Centre in the Namib Desert of Namibia and in nearby Topnaar settlements. Our research objective was to articulate strategies to address the primary pedagogical challenges that we faced during the design and first five iterations of the course. These include: How do we frame this course and communicate it to students in a way that is understandable and works within the particular context and constraints of the course? Can we provide students with a coherent framework that helps them to understand the approach and also provides a platform for thoughtful consideration, acquisition, and retention of appropriate competencies? How do we develop collaborations with our community partners that are ethical and effective? How do we frame these real-world experiences in a way that allows for students to integrate their experience with the theory and broader empiricism they learn on campus? To address these pedagogic challenges, we framed the course as a research-based course, more specifically community-based research (CBR), conducted in a social-ecological system (SES). We developed lower-level strategies for implementing this framing, including preparing students for collaborative research, encouraging student ownership of their learning, linking theory to research, and thoughtfully navigating time constraints. Furthermore, program-level and student-level engagement with community have been critical for avoiding becoming “helicopter researchers.” Drawing on our personal reflections and those of our community partners, we conclude with a discussion of emergent outcomes and the next steps for continual improvement and adaptation.


  • Top Cited Papers
    Open Access

    A computer‐assisted system for photographic mark–recapture analysis

    by Douglas T. Bolger, Thomas A. Morrison, Bennet Vance, Derek Lee, Hany Farid

    Summary: 1. Photographic mark–recapture is a cost‐effective, non‐invasive way to study populations. However, to efficiently apply photographic mark–recapture to large populations, computer software is needed for image manipulation and pattern matching.2. We created an open‐source application for the storage, pattern extraction and pattern matching of digital images for the purposes of mark–recapture analysis. The resulting software package is a stand‐alone, multiplatform application implemented in Java. Our program employs the Scale Invariant Feature Transform (SIFT) operator that extracts distinctive features invariant to image scale and rotation.3. We applied this system to a population of Masai giraffe (Giraffa camelopardalis tippelskirchi) in the Tarangire Ecosystem in northern Tanzania. Over 1200 images were acquired in the field during three primary sampling periods between September 2008 and December 2009. The pattern information in these images was extracted and matched resulting in capture histories for over 600 unique individuals.4. Estimated error rates of the matching system were low based on a subset of test images that were independently matched by eye.5. Encounter histories were subsequently analysed with open population models to estimate apparent survival rates and population size.6. This new open‐access tool allowed photographic mark–recapture to be applied successfully to this relatively large population.


  • Open Access

    Increased abundance of native and non‐native spiders with habitat fragmentation

    by Douglas T. Bolger, Karen H. Beard, Andrew V. Suarez, Ted J. Case

    Habitat fragmentation and invasive species often contribute to the decline of native taxa. Since the penetration of non‐native species into natural habitat may be facilitated by habitat fragmentation, it is important to examine how these two factors interact. Previous research documented that, in contrast to most other arthropod taxa, spiders increased in density and morphospecies richness with decreasing fragment area and increasing fragment age (time since insularization) in urban habitat fragments in San Diego County, California, USA. We tested whether a specific mechanism, an increase in non‐native species with fragmentation, is responsible for this pattern. We found that both native and non‐native taxa contributed to the pattern. Abundance of native spiders per pitfall trap sample increased significantly with decreasing fragment size (i.e. a negative density–area relationship) and abundance of non‐natives increased significantly with increasing fragment age. The proportion of non‐native individuals also increased significantly with age. One non‐native species, Oecobius navus, comprised the majority of non‐native individuals (82.2%) and a significant proportion of total individuals (25.1%). Richness of spider families per sample (family density) increased with fragment age due to an increase in the occurrence of non‐natives in older fragments, however, native family richness did not vary with age or area. Due to increasing dominance by non‐native and some native families, family evenness declined with decreasing fragment size and increasing fragment age. Native and non‐native abundance covaried positively arguing against strong negative interactions between the two groups. O. navus had a strong positive association with another common non‐native arthropod, the Argentine ant (Linepitheme humile), suggesting a possible direct interaction. In contrast, abundance of native spiders was negatively correlated with Argentine ant abundance. We hypothesize that fragmentation in this semiarid habitat increases productivity in smaller and older fragments enhancing the density of both native and non‐native taxa.


  • Top Cited Papers
    Open Access

    The need for integrative approaches to understand and conserve migratory ungulates

    by Douglas T. Bolger, William D. Newmark, Thomas A. Morrison, Daniel F. Doak

    Over the last two centuries overhunting, anthropogenic barriers and habitat loss have disrupted many ungulate migrations. We review the literature on ungulate migration disruptions and find that for many species the disruption of migratory routes causes a rapid population collapse. Previous research has focused on the proximal ecological factors that might favour migration, particularly spatiotemporal variation in resources and predation. However, this does not provide an adequate basis for understanding and mitigating anthropogenic effects on migratory populations. Migration is a complex behaviour and we advocate an integrative approach that incorporates population dynamics, evolution, genetics, behaviour and physiology, and that borrows insights and approaches from research on other taxa. We draw upon research on avian migration to illustrate research approaches that might also be fruitful in ungulates. In particular, we suggest that the migratory cycle should be evaluated in the context of seasonal population limitation, an approach we highlight with a preliminary demographic perturbation analysis of the Serengeti wildebeest (Connochaetes taurinus) population. We provide suggestions for avenues of future research and highlight areas where we believe rapid progress can be made by applying recent advances in theory, technology and analytical approaches.


  • Avian reproductive failure in response to an extreme climatic event

    by Douglas T. Bolger, Michael A. Patten, David C. Bostock

    Recently, climate change research has emphasized the potential increase in the frequency and severity of climatic extremes. We compared the reproductive effort and output among four species of passerine birds in coastal southern California, USA, a semi-arid region, during a normal precipitation year (2001) and the driest year in a 150-year climate record (2002). Both reproductive effort and output differed dramatically between years. Mean reproductive output among the four species was 2.37 fledglings/pair in 2001 and 88.4% of all pairs observed attempted at least one nest. The birds attempted a mean of 1.44 nests per pair and were successful in 47.7% of those attempts. In 2002, only 6.7% of the pairs even attempted a nest and only 1.8% were successful, for a total output of 0.07 fledglings per pair. The abundance of suitable arthropod prey items in the environment was also much lower in 2002, suggesting that low food availability was the proximal cause of the reproductive failure. The data for one of these species, the rufous-crowned sparrow (Aimophila ruficeps), were combined with reproductive and rainfall data from a previous 3-year study (1997–1999) in the same sites. The combined data sets suggest that the response of reproduction to rainfall variation is linear, and that the low end of the precipitation range brings the population near reproductive failure. Any change in climate that would increase the frequency of extreme dry conditions would likely endanger populations of these species.


  • Extinction and Colonization of Birds on Habitat Islands

    by Kevin R. Crooks, Andrew V. Suarez, Douglas T. Bolger, Michael E. Soule